Drug conjugates have become a significant focus of research in the field of targeted medicine for cancer treatments. Peptide-drug conjugates (PDCs), a subset of drug conjugates, are composed of carrier peptides ranging from 5 to 30 amino acid residues, toxic payloads, and linkers that connect the payload to the peptide. PDCs are further broken down into cell-penetrating peptides (CPPs) and cell-targeting peptides (CTPs), each having their own differences in the delivery of cytotoxic payloads. Generally, PDCs as compared to other drug conjugates—like antibody-drug conjugates (ADCs)—have advantages in tumor penetration, ease of synthesis and cost, and reduced off-target effects. Further, as compared to traditional cancer treatments , PDCs have higher specificity for the target cancer with generally less toxic side effects in smaller doses. However, PDCs can have disadvantages such as poor stability and rapid renal clearance due to their smaller size and limited oral bioavailability due to digestion of its peptide structure. Some of these challenges can be overcome with modifications, and despite drawbacks, the intrinsic small size of PDCs with high target specificity still makes them an attractive area of research for cancer treatments. Cancer is a significant cause of death worldwide, with breast and lung cancer having the highest prevalence among women and lung and prostate cancer having the highest prevalence among men . Other lHistorically, the first-line therapy for cancer was surgical excision of a primary tumor . During One approach to reducing these side effects is to develop therapeutics that directly target cells of interest; this was first achieved in the 21st century using monoclonal antibodies to target specific antigens overexpressed or mutated in cancer cells. More selective methods of targeting cancer have developed, such as using chemotherapeutic agents linked to antibodies to deliver therapy to cancer cells. These drugs are known as antibody-drug conjugates (ADCs). Despite their advantages, especially compared to standard chemotherapeutics, ADCs have several drawbacks, including antibody aggregation, premature ADC dissociation, high rates of drug clearance, ineffective tumor penetration, and bystander effect leading to off-target cytotoxicity ,7. To coThe key differences between PDCs and ADCs are generally (1) Immunogenicity, (2) Penetration and (3) Elimination. Immunogenicity: In the context of this review, immunogenicity can be defined as the unwanted ability for a drug or molecule to induce an immune response due to the body recognizing the infused drug as foreign and eliciting a response against it. PDCs generally are considered to have low immunogenicity characteristics since peptides have low intrinsic immunogenicity  ADCs on Penetration: The weight of the PDC molecule is small (~2–20 kDa), allowing the PDC to penetrate the tumor stroma and enter the tumor cells . In compElimination: PDCs generally have a short half-life and are rapidly eliminated by the kidneys . In addiThe strategy and innovation of PDCs utilize the biological activities and potential of small-molecule peptides to improve the efficacy of treatments . Since t177Lu-DOTA-TATE (DOTA-TATE) (There have been various attempts at synthesizing PDCs for cancer treatment. In 2018 TA-TATE)  was apprAlthough ADCs are clinically established for cancer therapy, PDCs are gaining recognition as a new cancer treatment method by increasing targeted drug delivery with improved efficacy and reduced side effects. PDCs utilize a smaller molecular composition than other marketed anticancer drugs (such as ADCs), contributing to PDC biochemical stability, cell membrane penetration, and overall efficacy . PDCs caDirected targeting of specific organs has been considered a crucial step in limiting side effects associated with traditional anticancer therapy. Use of peptides to direct organ specific targeting has emerged as a distinct possibility. Currently there are two main ways to target a peptide 1) rely on natural protein sequences such as vascular endothelial growth factor (VEGF)  or somatThe cell membrane provides a physiological barrier that limits the transportation of various molecules, such as macromolecules, proteins, and nucleic acids, across the plasma membrane. However, the cell membrane can also limit drug penetration. Therefore, it is imperative to develop drugs that can cross the cell membrane of cancer cells to induce destruction.Cell-penetrating peptides (CPPs) can transport drug payloads through cell membranes using specific amino acid sequences ranging from 5 to 30 residues. CPPs provide an effective method for transporting cell-impermeable compounds or drugs to reach their intracellular targets . VariousDue to the ability of CPPs to enter most cells they come into contact with, their therapeutic effects are limited to intra-tumoral injection. However, some treatments have been developed to target lymphatic metastasis via intravenous injection using CPPs modified with nanoparticles; in a study by Hu et al., modifying nanoparticles with CPPs suppressed tumor growth rate by 1.4-fold and showed a 63.3% inhibition rate of lymph metastasis in lung cancer . Other aCell-targeting peptides (CTPs) range from 3–14 amino acids long and utilize receptors that are overexpressed on cancer cell surfaces to target the delivery of the drug . DependipVEC (CPP) (pVEC amino acid sequence LLIILRRRIRKQAHAHSK) was more suitable for transportation and led to significantly higher cancer killing than chlorambucil alone . Th. Th®) (5®) .177Lu-DOTA-TATE for the treatment of adults with somatostatin receptor–positive GEP-NET and FDA approval, our article focuses on other relevant examples of actively recruiting clinical trials that utilize Lu-177 for treatment of various cancers , initially approved in February 2021 for the treatment of refractory multiple myeloma; it was withdrawn from the U.S. market in October 2021 after consistently failing to demonstrate a survival advantage based on results from a phase 3 randomized controlled trial . This caPDCs have limited or non-existent oral bioavailability; this limits their administration to intravenous injection and excludes oral administration . Lack ofDeveloping approaches to allow for the oral administration of PDCs is essential to make these drugs more accessible, allow for better therapeutic adherence, and to increase their representation in clinical trials. As the number of clinical trials evaluating the use of PDCs grows, further research is needed to optimize their delivery, improve their systemic stability, reduce fast renal clearance, and lengthen their half-life in vivo.The need for targeted cancer therapy is more significant than ever. Within the field of targeted cancer therapy, peptides offer unmatched versatility. Established treatments with ADCs have paved the way for the development of PDCs. Compared to other cancer therapy strategies, PDCs offer a more straightforward design, a high degree of selectivity, a broad range of targets, and a wide range of chemical and biological diversity. Although there are several limitations to their implementation, the potential to target tumors and prevent severe adverse effects makes PDCs stand out as attractive alternatives to other cancer therapy methods. The research community is acknowledging the advantages offered by PDCs, and new advances in the field have renewed interest in their use as targeted cancer therapy agents. Several trials are currently underway to determine the efficacy of novel PDCs with non-radioactive payloads and intelligent linkers. Although the development of PDCs has advanced the field of individualized medicine, long-term safety and efficacy are yet to be determined. Similarly, critical technical hurdles to the development of effective PDCs will need to be addressed in the near future.


Seven viruses cause at least 15% of the total cancer burden. Viral cancers have been described as the “low-hanging fruit” that can be potentially prevented or treated by new vaccines that would alter the course of global human cancer. Kaposi sarcoma herpesvirus (KSHV or HHV8) is the sole cause of Kaposi sarcoma, which primarily afflicts resource-poor and socially marginalized populations. This review summarizes a recent NIH-sponsored workshop’s findings on the epidemiology and biology of KSHV as an overlooked but potentially vaccine-preventable infection. The unique epidemiology of this virus provides opportunities to prevent its cancers if an effective, inexpensive, and well-tolerated vaccine can be developed and delivered. It is not widely recognized but approximately one-sixth of all human cancer cases result from only seven viruses, causing well over a million deaths each year2. Preventive vaccines developed decades ago against human papillomaviruses (HPV)3 and hepatitis B virus (HBV)4 reveal the effectiveness of simple vaccinations to reduce the cancer burden. While these two vaccines engender a blockbuster global public health success story, surprisingly little headway has been made by the general cancer research community to extend these results to prevent—or treat—other viral cancers.Follow-up of the Cancer Moonshot’s success requires practical, new, and effective anticancer preventions and therapeuticsRapid and successful development of SARS-CoV-2 vaccines compels revisiting this issue. In October 2021, the National Cancer Institute’s Office of HIV and AIDS-related Malignancies organized an open meeting of over 100 experts and stakeholders to discuss the feasibility of vaccines to control Kaposi sarcoma herpesvirus (KSHV), also known as human herpesvirus 8 (HHV8). This was the first meeting of its kind to explore the worldwide KSHV cancer burden and to raise the issues on whether and how KSHV vaccines should become a research and public health priority. Currently, there are no well-developed KSHV vaccine candidates and little funding for KSHV vaccination research.This meeting addressed critical questions on KSHV cancers and vaccines: What is the cancer burden from KSHV? If an effective vaccine is developed, who should be vaccinated? Would an effective vaccine be preventive by providing sterilizing immunity or therapeutic by controlling the virus-cancer after infection? Would a successful vaccine rely on neutralizing antibodies to KSHV antigens, cell-mediated immunity, or combinations of both? Finally, if an obvious and effective vaccine is developed, what are the barriers to real-world implementation of KSHV vaccination and how can they be overcome?5. Further, the DNA viral genome is highly conserved—particularly in its structural genes—suggesting a single effective vaccine will prevent all variants in different world regions.The participant consensus was surprisingly optimistic: KSHV is biologically very different from its more ubiquitous herpesviral cousins in that it is not common in some populations, consistent with limited viral transmissibility and high susceptibility to immune surveillance that could be bolstered by vaccination. On an evolutionary timescale, KSHV is likely to have been lost from many populations in the world, raising the possibility that artificially stimulated immunity can readily increase this trend6. KS under-reporting, particularly in cancer registries, is a major barrier to assessing this need7, particularly for low- and middle-income countries. Over 90% of the adults in some rural areas of East Africa are KSHV-infected8. This region has high rates of KSHV cancers in both HIV-positive and negative populations. Belts of high KSHV cancer endemicity extend throughout Africa up into Mediterranean and Western Asian populations and into populations of South America11. In high-income countries of Europe and North America, men who have sex with men (MSM) and organ donor recipients remain at high risk for KSHV-related cancers, and hence targeted vaccination programs could be envisioned12.Though poorly recognized outside of the KSHV research community, there is a clear public health need for KSHV prevention that extends beyond the realm of HIV and AIDS13. Similar social changes could set the stage for the emergence of KSHV in populations in which it was previously rare, as already occurred among gay and bisexual men in the US and elsewhere in the 1970s–80s. Since primary KSHV infection is generally asymptomatic and ongoing KSHV surveillance is minimal, research and development on effective KSHV vaccines are prudent to address future KSHV transmission and pandemics caused by changes in the virus, host, or society.As revealed by the AIDS epidemic Fig. , KSHV in14. Later studies revealed that KS is an endothelial cell cancer that is often indolent15. For some time, it remained a clinical curiosity, mainly manifested as a relatively rare cancer among the Mediterranean, particularly Ashkenazi Jewish, populations15. It was subsequently found to be common among sub-Saharan African (SSA) populations, particularly in the Central and Southeastern belt of African countries where it was the second to third most common malignancy in the general pre-AIDS populations16. KS cases in the US markedly increased in the 1960s–70s with the development of organ transplant-related therapies, focusing attention on the immune system to control this cancer17.Kaposi sarcoma (KS) was first described in 1872 by Moriz Kaposi as an aggressively malignant skin tumor18. The major AIDS-related cancer burden, however, has been highest among African populations where, for example, KS rose 10-fold, from 5% to 49% of all adult Ugandan male cancer patients, with the emergence of AIDS16. Despite effective anti-retroviral therapies, KS remains leading cancer among HIV/AIDS patients worldwide19. KSHV was discovered in 1994 as the cause of all forms of KS, including various manifestations of HIV-related and unrelated KS, and lifelong infection with KSHV clearly predisposes to the development of KS20. In addition to KS, other malignancies associated with KSHV include primary effusion lymphoma (PEL) and one of the forms of multi-centric Castleman disease (MCD) occurring primarily among persons with HIV/AIDS19.The onset of the AIDS pandemic in 1981 was heralded by the epidemic of KS, mainly among previously healthy MSM21. Even with imperfect antibody testing22, the worldwide distribution of KSHV infection can be clearly delineated21. SSA is by far the region with the highest KSHV seroprevalence, in both children and adults, where the virus is mainly transmitted through non-sexual, but as yet undefined, behaviors and practices most probably related to saliva exposure24. Estimates are that ~20–80% of the general SSA adult population are persistently KSHV-infected, with the variability often reflecting either geographic or assay performance differences. Mirroring historically high KS rates in SSA countries prior to AIDS, serum banks collected in the 1970s from East African populations have KSHV antibody positivity of >80% among adults25. Childhood KSHV infection is acquired through non-sexual transmission and is common in SSA countries26 but is uncommon or rare in most other portions of the world. Pediatric KS, which is also frequent SSA countries27, can have a fulminant lymphadenopathic presentation that is rapidly fatal in both HIV-infected and HIV-uninfected patients29. Thus, prevention of pediatric KSHV infection will have important public health consequences, particularly in highly endemic areas of SSA.The epidemiology of KSHV infection has been recently summarized by Cesarman et al.30 is generally low  with increased prevalence in some Mediterranean populations,  with up to ~20–40% of persons commonly reported. In these otherwise low seroprevalence areas, MSM (who are often excluded from some blood donor serosurveys leading to an underestimation bias) often harbor the highest prevalence of KSHV infection with rates rivaling those seen in SSA. In the US, South America, Europe, and Australia, 30–65% of HIV-infected MSM and 20–30% of HIV-uninfected MSM are KSHV antibody-positive33.In contrast, adult seroprevalence in the populations of northern Europe and North America34 and South American35 populations may reflect ancient original co-migration of the virus with human populations36. High KSHV seroprevalence is seen in some Western Asian populations37 that may reflect a historical reintroduction of KSHV from Mediterranean trading routes (the Silk Road hypothesis) to Chinese populations5. However, serologic studies in this region are uneven, and if vaccine development moves forward, it will be essential to re-survey representative populations using up-to-date and reliable assays to determine if the initially-described patterns of KSHV distribution persist.Similar to Europe and North America, KSHV prevalence is low in most populations of South and East Asia, consistent with the virus likely being lost after human outmigration through this region Fig. , and hig38. This pattern of infection suggests that horizontal non-sexual spread predominates in this setting, consistent with direct parent-to-child or child-to-child transmission via saliva as occurs with other herpesviruses. Outside of SSA, most transmission research has focused on MSM, in whom KSHV antibody-positivity rapidly increases after sexual debut and is highly correlated with the number of intimate male partners21. Despite attempts to delineate specific modes of person-to-person spread, the specific mechanisms of spread are unclear but are likely to involve sexual or non-sexual saliva transmission. Methodologically, the inherent difficulties associated with distinguishing the roles of tightly correlated behavioral acts in MSM  make this research challenging.The modes of KSHV transmission vary in high versus low KSHV endemicity areas. In SSA, transmission often occurs in pre-pubescent children prior to the age of sexual debut50. KSHV DNA has occasionally been detected in genital fluids and breast milk, but at a lower frequency and lower quantities relative to saliva43. These findings favor contact with saliva as the medium likely to favor KSHV transmission and suggest the promotion of vaccines that generate mucosal immunity. The acts that spread saliva, however, are diverse including those heretofore under-appreciated . Abrogation of KSHV oral shedding among KSHV-infected persons might be another objective for vaccines in which the measurement of viral DNA in saliva could be used as a vaccine efficacy end-point.Although epidemiologic studies have been unable to define specific routes of transmission, the clinical virology of KSHV has narrowed the possibilities and has implications for vaccine efficacy. Among bodily fluids readily passed between humans, saliva by far harbors KSHV most frequently47, cross-sectional assessments may underestimate transmission risk and are likely to be insensitive as markers of vaccine efficacy if sterilizing immunity is the goal. The prevalence of oral shedding among seropositive persons varies from 3% to 100%, based on studies conducted among KSHV-infected women45. A study of seropositive participants from SSA, US, and Peru found that about 40% were frequent or persistent oral shedders for 20 or more days in a 30-day period of observation47. These data point to the frequency and quantity of KSHV shedding in saliva as a potential target for efforts to reduce KSHV transmission.Because shedding in the saliva is intermittent50, younger age, particularly in SSA50, and higher lytic KSHV antibodies, e.g. anti-K8.150. In SSA, parasitic infections  are associated with increased KSHV detection in blood, but their relationship with shedding in saliva has yet to be determined50. HIV infection is a risk factor for KSHV DNA detection in blood and KS, but the relationship with KSHV shedding in the saliva is unclear49. It will be essential to study representative populations to better characterize factors that influence shedding to inform decisions about the value of KSHV shedding as a marker of vaccine efficacy.A few factors have been associated with the frequency or quantity of KSHV detection, such as male sex52 have often been ignored as a public health burden. Also, while access to antiretroviral therapy (ART) has proved a potent intervention to prevent AIDS-KS in resource-rich countries, ART availability in low- and middle-income countries (LMIC) has not been uniform. Furthermore, KS incidence has fallen less dramatically in SSA after ART rollout compared with reductions seen in the Global North53. Despite the effectiveness of ART in preventing AIDS-KS, it does not eliminate KSHV latency so the resurgence of KSHV-related cancers in aging HIV/AIDS patients remains a significant concern in both high-income and LMIC countries.High KS rates in some HIV-uninfected populations, particularly in SSA and western ChinaFor SSA populations with high childhood KSHV transmission, the introduction of a childhood sterilizing preventive vaccine could interrupt childhood KSHV transmission and prevent KS. This strategy could be integrated broadly into the Expanded Program for Immunization. Outside of SSA, vaccination might be geared towards high-risk populations based on local geographic regions  or risk groups  for low-prevalence countries, instead of universal vaccination. For a solely preventive vaccine to be effective, it must be given prior to virus exposure. Given the evidence supporting KSHV as a sexually transmitted infection in low-prevalence countries, an approach similar to HPV vaccination might be effective, with administration prior to the onset of sexual debut. In contrast, a therapeutic KSHV vaccine to prevent cancer development regardless of prior infection may have public health importance to protect high-risk individuals  in low-prevalence countries. Whether women should be considered for vaccination in low prevalence countries depends on changes in social behaviors that might lead to an unexpectedly increased risk for KSHV infection and/or KSHV-related malignancies.54. Notably, the universal administration of HBV vaccination during infancy in regions endemic to HBV has nearly eliminated hepatocellular carcinoma in vaccinated infants and young adults55. An effective vaccine would provide a long-term preventive solution to the risk of KSHV malignancies that might emerge during future social changes, such as the expected increase in immune suppression prevalence due to increasing access to solid organ transplantation in SSA.Although the lack of precise knowledge about how KSHV is spread is a limitation, KSHV bears many epidemiological similarities to HBV that has similar limitations, and for which a vaccine was successfully developed and implemented56. KSHV, and related herpesviruses, differ from many other viral infections in having a life-long, persistent (latent) infection. An ideal KSHV vaccine may need to elicit both antibody responses to induce sterilizing immunity to prevent primary infection as well as T cell responses for protection against cancers in latently infected individuals. The use of the whole virus as a candidate antigen is an attractive option but also has potential limitations. A live virus vaccine modeled on the successful herpesvirus Oka strain varicella-zoster virus vaccine would require extensive engineering of putative KSHV oncogenes to ensure safety concerns are met for this cancer virus. Inactivated whole virus, in contrast, provides a simple and inexpensive alternative approach but it is unknown if this can be used to artificially induce effective protective immunity.To design an effective vaccine against KSHV, the identification of viral antigens that are detected by particular arms of the host immune system is critical Fig. , Table 157. Using assays to these antigens, individuals with the clinically apparent disease have higher antibody levels compared to those without the disease who nevertheless were previously exposed and carry the latent virus. Surveys using recombinant KSHV proteins reveal that antibody responses to other KSHV proteins are highly heterogenous but can help discriminate between KSHV-infected persons and uninfected donors58.KSHV infection among asymptomatic persons is generally determined by seropositivity to two viral antigens, K8.1 protein and latency-associated nuclear antigen, LANA59. Measuring cellular immune responses to natural KSHV has proven challenging. Only a handful of studies have examined cellular immune responses to KSHV infection and in general show a lack of cell-mediated immunodominance60. Further, during natural virus infection, KSHV encodes multiple mechanisms to subvert an effective immune response that otherwise would allow clearance of the viral genome, particularly by skewing T cell responses through the expression of multiple cytokines/chemokines and through cis-protein coding mechanisms62. The nonstructural (NS) protein LANA is required for viral persistence and KS patients can have anti-LANA antibody titers >1:100,00063 but this antibody response is ineffective against this intracellular antigen. Evidence also indicates that superinfection of previously exposed individuals is possible, suggesting that prior natural infections to the virus do not generate sufficient sterilizing immunity to prevent secondary infections64. Ideally, a KSHV vaccine should provoke sufficient memory B and T cell responses to continue to give protection even if the vaccinee later develops HIV CD4+ lymphopenia.To be successful, a KSHV vaccine will need to generate more potent and specific neutralizing antibody and/or cell-mediated immune (CMI) responses than occurs during natural infection65. CMI responses to structural proteins may also contribute to sterilizing immunity but, in contrast to antibody responses, have not been extensively studied. There is a practical advantage to assessing preventive KSHV vaccines since an efficacy end-point can be determined using seroconversion to non-structural latency antigens  that are not present in the vaccine. With extremely high KSHV seroconversion rates occurring in some populations, such as East African children26, this study design would be able to use smaller cohorts followed over a shorter period of time than cancer prevention trials, and would both simplify and improve the cost-effectiveness of the vaccine trials. One key lesson for preventing KSHV infection comes from the closely related murine gammaherpesvirus 68 (MHV68), in which a single infectious particle is predicted to be sufficient for establishing chronic infection in mice66. The MHV68 model also reveals that the mode of antigen administration and antibody-independent immunity may be important for a preventive KSHV vaccine. In one study, initial nasopharyngeal administration of MHV68 prevented systemic super-infection during the secondary nasopharyngeal challenge and this was achieved through local nasopharyngeal CMI responses rather than elevated antibody responses67.A preventive KSHV vaccine is likely to be based on neutralizing antibody responses to viral glycoproteins required for cell entry so that systemic infection and latency cannot be established Fig. 65. CMI r70. KSHV glycoproteins K8.1, ORF8 (gB), ORF22 (gH), ORF 46 (gL), ORF39 (gM), and ORF53 (gN) are virion-associated and are prime candidates for KSHV attachment, fusion, and entry functions76. The gN/gM complex appears to play a role in egress rather than viral entry77. In the current model of KSHV entry, the first viral contact is mediated by envelope-associated K8.1 and gB binding to heparan sulfate (HS) on the host-cell surface78. Although this binding is reversible and not critical for entry, it localizes the virus on the cell surface, providing the initial direct contact between viral glycoproteins and specific cellular entry receptors80. Upon binding, conformational changes allow the gH/gL complex to access specific host-cell receptors, including integrins and ephrin receptors A273, EphA481, and EphA782. This is followed by fusion of the viral envelope via gB with endosomal membranes, the release of the viral capsid in the cytosol, trafficking of the capsid to the nuclear membrane, and delivery of the KSHV genome into the nucleus83. Additionally reported cell receptors for KSHV include cystine/glutamate antiporter (xCT) and dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN), which may allow entry into various cell compartments84. The complexity of these processes suggests a vaccine directed at eliciting antibodies to multiple epitopes (dominant and subdominant) should be considered.KSHVcauses a systemic infection and displays a broad tropism, including epithelial cells, endothelial cells, fibroblasts, keratinocytes, lymphocytes, and monocytes, in which multiple viral entry receptors have been identified87. This resulted in KSHV-neutralizing antibodies in immunized mice and rabbits that prevented in vitro infection of epithelial, endothelial fibroblast, and B cells. This suggests that these glycoproteins might hold an important role in viral entry, but only the role of gH/gL has been thoroughly studied in multiple cell types89. In these studies, gH/gL was shown to be indispensable for epithelial, endothelial, and fibroblast cells89, but whether this holds true in vivo in the oral cavity is unknown. KSHV is present in the saliva and salivary shedding is widely accepted as the primary conduit of KSHV transmission92. Using a similar approach, K8.1 was shown to be dispensable for entry into epithelial cells in vitro but not into B cells94. Research on conserved glycoprotein-based vaccines for other herpesviruses95 may provide helpful guidance for the development of a KSHV vaccine.KSHV K8.1, gB, and gH/gL were recently tested as components of a virus-like particle-based candidate vaccine62. As an intracellular nuclear antigen, it is unlikely to be targeted by humoral immunity. Evidence suggests that CMI during natural infection against LANA and other antigens is heterogenous and may not limit virus replication, so CMI-based vaccine targets may have to be individually tested to determine if the enhanced immunity from vaccination provides protection59. Several KSHV nonstructural proteins potentially critical for viral persistence are expressed on the infected cell-extracellular surface or are secreted and that could, in theory, be neutralizing targets for vaccine-induced antibodies. These proteins include the viral K1 protein96, vIL-697, viral G protein-coupled receptor98, and viral chemokines99, as well as other potential antigens. The heterogeneity of both antibody and cellular immune responses to KSHV suggests that until a singular viral protein has been validated as the dominant target, vaccine candidates with as many viral antigens as possible may be preferable and platforms incorporating inactivated viruses or live-attenuated viral vectors, virus-like particles expressing multiple viral antigens, or multivalent RNA vaccines may be needed. Replicating vaccine viruses engineered to remove latency and antiviral effectors represents another promising strategy as they present a wide breadth of antigens and provide durable protection100.Little systematic research is available on non-structural protein targets for potential KSHV vaccines. Unlike KSHV structural proteins, which are highly conserved and even cross-reactive to other herpesvirus entry proteins, KSHV encodes an array of nonstructural proteins that are unique to the virus. The LANA1 genome maintenance protein is constitutively expressed in all KSHV-infected cells and may be a good candidate for CMI-based vaccines via mRNA delivery if the antigen is modified to eliminate its CMI-escape motif101 might be a useful prelude to help define an ideal preventive vaccine antigen. The success of adoptive immunotherapy trials against EBV-related malignancies102 suggests that a boost in the breadth and magnitude of adaptive T cell responses may confer protection against KSHV-related disease. Whether this could possibly clear the latent viral infection and prevent KSHV reinfection in healthy persons remains to be explored. Vaccines that elicit oral IgA are also attractive in interrupting salivary KSHV transmission. Additional investigations on the immune correlates of KSHV infection and KSHV-related disease are needed to assess whether these vaccine strategies can be beneficial.Although an ideal vaccine would induce sterilizing immunity, this may prove to be challenging and it may not be necessary to reduce KSHV-associated morbidity and mortality. A program to define human monoclonal antibodies that block infection in in vitro cell culture and for animal modelsThe development of an effective vaccine candidate that can prevent KSHV infection and onward transmission or prevent secondary tumorigenesis after infection is a tractable scientific problem. But even if an ideal vaccine candidate is developed, implementing sustainable and economically viable public health programs devoted to KSHV prevention will face major hurdles.11. Consequently, a vaccine against KSHV will need to not just be well-tolerated and immunogenic, but also must be inexpensive to manufacture and simple to distribute/deliver. In regions of the world where KSHV is endemic, the infection begins in childhood but continues through adulthood103. The ideal target product profile of a vaccine against KSHV would therefore include the ability to safely deliver a vaccine to infants that is durable, thermostable, and potentially needleless to enhance acceptance in this age group.KS is a malignancy with complex epidemiology, and an overwhelming number of cases occur in low-income countries104. Subunit protein vaccines with modern adjuvant formulations have been shown to be safe in children, highly immunogenic, thermostable, and durable106. RNA vaccines have also been designed against herpesviruses including cytomegalovirus (CMV)107 and EBV108, and may eventually be a promising vaccine platform for KSHV in the future should costs of manufacturing decrease. As with SARS-CoV-2 mRNA vaccines, thermostability for a KSHV mRNA vaccine might be a critical barrier in some LMIC. Taken together with promising recent advances in the thermostability of adjuvanted protein105 and RNA vaccines109, preventative KSHV vaccines should be encouraged for development on these platforms. New technologies such as mRNA vaccines, the use of multivalent virus-like particles, self-assembling proteins, and novel viral vectors capable of encoding multiple antigens all offer potential platforms for delivering antigens once protective immune responses are known.The only gamma-herpesvirus vaccine to advance to Phase 2 testing in humans is an Epstein Barr Virus (EBV) envelope glycoprotein with a potent toll-like receptor 4 adjuvant formulation111. Prior vaccination could be practical for prophylaxis of infants or children in high incidence areas of the world such as SSA, Western Asia, and Eastern Mediterranean countries if immunity is lasting. Varicella zoster virus is the only human herpesvirus for which vaccines112 have been licensed both for acute infection (varicella) and for reactivation (zoster)113, although Epstein-Barr virus has also been targeted with promising efficacy in virus-naïve populations when a subunit gp350 in the adjuvant vaccine was evaluated104.Even in the early stages of KSHV vaccine research, vaccine target product profiles (TPP) can guide the choices for antigens and methods used for vaccine manufacture and delivery Box . The dev115). Preclinical studies may be advanced using related viruses such as the murine MHV68116.There is no ready or predictive animal model for KSHV-related cancers  or surrogate measures that can reasonably predict efficacy, may overcome this limitation. Surrogate measures, for example, could include protection against infection (measured by antibodies against KSHV antigens not included in the vaccine), high-level immune responses, or prevention of oral shedding.Government and non-governmental organization support for the development and deployment of a vaccine are critical since this viral disease mainly targets socially and economically marginalized populations.In describing the TPP most likely to succeed, it is important to recognize several limitations of KSHV vaccine research and development:Box 1 Possible KSHV Vaccine Target Product Profile CriteriaVaccine target product profiles (TPP) are used to predict practical problems and issues in vaccine development, efficacy testing, manufacture and ultimate use of vaccine candidates.Goal: Prevent primary KSHV infection? Prevent progression to disease in previously KSHV-infected population?Target populations: Children and adults in high incidence, low-income areas? High-risk adults in low-incidence, medium- or high-income areas ? HIV+ vs. HIV− populations?Main criterion for success: Vaccine efficacy to prevent KSHV infection? Vaccine efficacy to prevent KS disease? Secondary criteria: Decrease other KSHV-associated illnesses?Formulation: Subunit/adjuvant, inactivated virus, attenuated live virus, DNA- or RNA-based?Immune mechanism: Induction of sterilizing antibody immunity? Induction of CD4+ and CD8+ T cell immunity?Dosing and administration: One or two-dose intramuscular injection? Oral delivery for the mucosal-based vaccine?Safety: Well-tolerated without serious adverse eventsStorage: Lyophilized antigen? Cold-chain requirement?Cost: Including manufacture, distribution, and delivery of the vaccine.Value proposition: Reduce the lifelong impact of KSHV-associated diseases, cost–benefit analyses?117. Various product development partnership (PDP) models, however, have been successful to develop vaccines for LMIC.Even successful development of an effective vaccine based on a well-defined TPP can face “valleys of death” in implementation for LMIC. These result from market failures that exist for vaccines that have a low potential for return on investment and/or high development riskPDPs aim to share the risk and cost to accelerate vaccine development by filling market failure gaps. Some vaccines have dual high-income country and LMIC markets, such as for rotavirus and HPV, and some have primarily LMIC markets only, such as vaccines for typhoid, Japanese encephalitis, and group A meningococcal disease. None of these vaccines were developed completely de novo through the PDP model.118.Significant challenges arise for PDPs when developing new vaccines for pathogens in which a vaccine currently does not exist, particularly if it is a novel pathogen and/or has a novel mechanism of action without a surrogate of protection that requires a full-fledged randomized controlled trial, such as the recently recommended malaria vaccine. These novel vaccines face inordinate investment most of which are incurred in late-stage development, creating a second valley of death that dwarfs the original one identified in early translation research and developmentKSHV vaccines have the potential to overcome these barriers, but this depends on the vaccine and the target population. For example, universal childhood vaccination is mainly practical for high-risk LMIC populations, but research and development costs may in part be borne if the same vaccine is used for high-risk individuals in high-income country settings.Six critical vaccine attributes  contribute to optimally achieving impact. A favorable and sustainable value proposition for a KSHV vaccine must balance affordability and acceptability against sustainability by manufacturers and those procuring the vaccine. In the past, the limited perspective on valuing vaccines just from the direct individual health benefit has left on the table the value that vaccines bring to a population, both in direct and indirect health, social, and economic benefits.Vaccine prevention or treatment of viral cancers is the underappreciated low-hanging fruit of oncology. Research on viral cancer vaccines not only has the potential to prevent a significant fraction of human cancer but may provide additional scientific benefits as well. Lessons learned from successfully developing viral cancer vaccines may provide fundamental insights into vaccines and immunotherapeutics for non-infectious cancers expressing neo-antigens.119 underestimates the burden of KSHV-related diseases, a problem that also might be exacerbated by its aggregation with unreported non-melanotic skin cancers as well as clinical diagnoses that never get recorded by registries relying on pathology-based diagnoses. Revisiting the global KSHV cancer burden and epidemiology, as has been done for other viral cancers121 is needed to guide KSHV vaccine development. The potential targets for an effective vaccine are known and new vaccine platforms for an effective vaccine hold great promise. But refocusing governmental research support for research on specific antigens and their delivery will be critical. Further, non-governmental organization support for KSHV research has been conspicuously absent yet will be critical for establishing practical and effective transnational use of KSHV vaccines. Finally, even a perfect vaccine will have no impact on KSHV-related cancer unless it is delivered to those most at risk. Since the casualties of KSHV tend to be socially and/or economically marginalized, market forces alone are unlikely to provide the resources needed for the research and development of a KSHV vaccine. Nonetheless, several important resources have been overlooked for the promotion of a practical and effective KSHV vaccine. Active HIV vaccine trial groups in highly endemic KSHV areas  may be a “two-for” since they have experience, training, and facilities from HIV vaccine clinical trials in populations that are also at high risk for KS and may be a ready platform for KSHV vaccine trials123. Making use of these existing resources would markedly reduce costs and improve clinical research for KSHV vaccine trials. Shortages of SARS-CoV-2 vaccines have also prompted the local generation of mRNA vaccines in Africa that could be repurposed to address diseases of regional importance, such as KS once the COVID-19 crisis has abated124. A KSHV vaccine will require a new approach to vaccine development based on the common good to ensure that a safe and effective KSHV vaccine can be delivered to those who are in the most need. Although little systematic progress has been made toward developing a KSHV vaccine, this conference highlighted paths that can be followed to achieve practical KSHV control.The recent international NIH workshop on KSHV vaccines highlighted both the optimism and the barriers to reducing KSHV-related mortality and morbidity through new vaccines. A concerted effort to accurately measure the global KSHV cancer burden is needed and standardization of KSHV detection methods will be essential. The conflation of KSHV cancers with AIDS in cancer registriesFurther information on research design is available in the REPORTING SUMMARY


Polymeric biomaterials are biological or synthetic substances which can be engineered to interact with biological systems for the diagnosis or treatment of diseases. These biomaterials have immense potential for treating eyes diseases, particularly the retina—a site of many inherited and acquired diseases. Polymeric biomaterials can be engineered to function both as an endotamponade agent and to prevent intraocular scarring in retinal detachment repair surgeries. They can also be designed as a drug delivery platform for treatment of retinal diseases. Finally, they can be used as scaffolds for cellular products and provide non-viral gene delivery solutions to the retina. This perspective article explains the role of polymeric biomaterials in the treatment of retinal conditions by highlighting recent advances being translated to clinical practice. The article will also identify potential hurdles to clinical translation as future research directions in the field. Biomaterials are engineered substances which can interact with biological systems to diagnose or treat diseases. Early biomaterials were designed to perform mainly mechanical functions as implants. These implants can be found in all specialties of medicine. For example, metal and alloys like titanium are commonly used to produce heart valves, vessel stents and joint implants due to their high mechanical strength, immunity to corrosion and complete inertness to the body environment . MeanwhiUnlike other body systems, the eye confers several key advantages for biomaterial applications. Firstly, the immune privilege status of the eye allows foreign biomaterials to be introduced with limited immunogenicity . SecondlThe earliest applications of biomaterials in the eye were intraocular implants for cataract replacement . CataracGlaucoma drainage device, like the Ahmed tube, are examples of more recent implants used for the treatment of advanced glaucoma. To achieve optimal intraocular pressure, the tube-shaped glaucoma drainage device, acts as a conduit to shunt aqueous humor away from the anterior chamber of the eye . These dAdvances in material science have enabled the development of next generation biomaterials through modifications at the molecular level. Polymeric biomaterials are one such example. They are made of repeated subunits of smaller molecules, and can be naturally-derived or synthetic. Naturally-derived polymers can be made of polysaccharides, polypeptides or polynucleotides. These can be further modified chemically to confer useful properties . SynthetThe posterior segment of the eye consists of key structures like the vitreous humor, retina, choroid and optic nerve. These structures are affected in diseases such as retinal detachment, proliferative vitreoretinopathy, retinal neovascular diseases and inherited retinal diseases. For the posterior segment of the eye, various polymeric biomaterials are currently being developed as vitreous substitutes, sustained and topical drug delivery systems, scaffolds for cellular therapeutics and non-viral gene delivery agents . These p6) and perfluoropropane (C3F8), or non-biodegradable fluids such as silicone oil. Intraocular gases can result in corneal decompensation and cataract formation. Patients also have to adopt a prolonged face-down position. Most importantly, these patients cannot partake in air travel as low atmospheric pressure can result in gaseous expansion. Meanwhile, prolonged use of silicone oil can cause corneal decompensation, if migrated into the anterior chamber, and even silicone oil glaucoma , poly(propylene glycol) (PPG) and poly(e-caprolactone) (PCL) polymer, termed EPC. The thermogel exists in liquid form at lower temperatures, and turns into gel status at body temperature. This unique feature allows easy administration by injecting via 25-gauge syringe into the vitreous cavity and enables the tamponade effect once heated to body temperature. While other polymeric hydrogel formulations have been researched as endotamponade agents  optically clear to allow visual inspection of the retina during follow-ups, (2) easily administered during surgery, (3) exert sufficient surface tension across the retina to allow adequate tamponade of the repaired retina, and (4) biodegradable to avoid a removal surgery. Polymeric hydrogels have the potential to fulfill these criteria through careful polymer selection and various chemical modifications –25. A hye agents , EPC's he agents , 30.via the nuclear factor erythroid 2-related factor (NRF2) signaling pathway. This is a first report, whereby a synthetic polymeric material alone can target intracellular signaling pathways to prevent retinal scarring. More importantly, it offers insight into how synthetic polymeric materials no longer function merely as inert drug carriers and challenges the conventional belief that a small molecule (drug) is always required to achieve a therapeutic effect at a cellular level. It lays the foundation for next generation nanomedicine, whereby polymers alone can be used to elicit specific biological responses , a major complication characterized by the development of contractile cellular membranes, leading to tractional retinal detachments . Currentesponses .®) and FDA-approved, ranibizumab (Lucentis®) and aflibercept (Eylea®). These drugs have to be given by intravitreal injections at regular frequencies of between 1 to 3 months (®) for up to 3-months. Other non-polymeric approaches have been utilized to reduce the frequency of intravitreal injections. These include FDA-approved Brolucizumab (Brolu®), a humanized monoclonal single-chain variable fragment which has a longer duration of effect than current anti-VEGF compounds, and the Port Delivery System® (PDS), a surgically implanted drug reservoir which allows the slow administration of ranibizumab over time. However, Brolucizumab is potentially associated with higher rates of intraocular inflammation, such as retinal vasculitis , diabetic retinopathy (DR) and diabetic macular oedema (DMO) affect a significant amount of people globally. For instance, AMD is expected to affect approximately 288 million people by 2040 . Signifi3 months , which m3 months . The holsculitis , while Psculitis .A key challenge in developing polymeric hydrogels suitable for sustained anti-VEGF delivery, is the preservation of antibody bioactivity during both hydrogel formulation and biodegradation. For instance, most hydrogels require chemical cross-linking agents for gelation. This can inadvertently result in drug inactivation. Thermogels, on the other hand, rely on small changes in temperature to induce physical cross-linking for gelation to occur, thus enabling preservation of anti-VEGF bioactivity. Indeed, we demonstrated in our EPC thermogel system, that sustained release of bevacizumab or aflibercept is achieved over 40 days, a duration greater than standard current clinical treatment interval. Furthermore, aflibercept released from biodegradable EPC gel retained its bioactivity and was capable of inhibiting vascular leakage in a rabbit choroidal neovascularisation model , suggestNano-micelles are globular structures which comprise of an internal hydrophobic fatty acyl chain and external hydrophilic polar head. The discovery of a topically administered nano-micellar system to deliver biologics to the retina—is the holy grail in ocular therapeutics—as it can overcome the multiple sight-threatening complications associated with invasive intravitreal injections. However, multiple static and dynamic ocular barriers between the cornea and the retina, prevent drugs from attaining a therapeutic concentration at the retina sufficient for disease control –42. A na®) is an adeno-associated serotype 2-delivered gene therapy for patients with biallelic RPE-65 mediated IRDs  has demonstrated effective transfection of various human cell lines through the proton-sponge effect . However of mice . Natural of mice . Lipid n of mice . These sUnfortunately, gene therapy is only viable for early stage IRDs. For patients who have undergone significant disease progression, retinal stem cell therapeutics hold greater promise. Since the proof-of-concept clinical trial by Schwartz et al. on embryonic stem cell (ES) derived retinal cell transplantation, research in this field has evolved tremendously . Many faCurrently, retinal cellular therapeutics can be classified into either RPE or photoreceptor transplantation. RPE is a cell monolayer sitting beneath the photoreceptors and above Bruch's membrane, thus there is a need to use either biostable or biodegradable scaffolds as a cell carrier to support long term function of the transplanted RPE cells. Two types of biostable scaffolds, polyethylene terephthalate (PET)  and paryIn photoreceptor transplantation, the goal is to prevent remaining healthy photoreceptors from undergoing further degeneration and eventual apoptosis . This caPolymeric biomaterials hold great potential for treating many retinal diseases. However, significant hurdles have to be overcome to fully achieve clinical translation.Firstly, better characterization of polymer-tissue relationship is required. Polymer development is largely based on an iterative process which requires significant resources, time and intuition. Increasingly, the field is developing machine-learning tools to predict properties of polymers in-silico . This daSecondly, the ocular pharmacokinetics of novel polymers have to be explored. Important aspects such as bio-distribution, metabolism and excretion mechanisms can affect the biocompatibility of the polymer significantly. While the systemic pharmacokinetics of polymers like PEG and PCL may have been established previously, their effects on local ocular tissue structure and function still needs to be studied in order to better understand the safety and clearance path of the byproducts while polymers are degrading .Thirdly, manufacturing considerations have to be addressed for successful translation. A large part of the translation process is identifying a manufacturing process that is scalable, maintains the material's original physico-chemical properties and meets the sterility requirements of regulatory agencies. Most often, these aspects are inter-related. For instance, adjusting a polymer's structure to increase the mechanical strength can lead to the reduction of the material's clarity. Furthermore, common sterilization methods that are recognized by regulatory authorities are often physico-chemical methods involving heat, radiation and chemicals such as ethylene oxide, which may inadvertently alter the physico-chemical properties of polymers, rendering them unsuitable. Moreover, due to the complexity of the polymer synthesis processes, adequate monitoring and quality control is required to ensure functionality of final polymer product. As such, the final polymer synthesis process optimized for industry manufacturing, may be very different from the initial conceptualized process laid out in the research laboratory.Biomaterials have played significant roles in ophthalmology including intraocular lenses and glaucoma drainage devices. The applications of biomaterials are rapidly expanding, especially for polymeric biomaterials. Today, many polymeric biomaterials are being studied to address the challenges of treating retinal diseases. These applications range from endotamponade agents in retinal detachment surgery, drug delivery for retinal neovascular diseases and gene/cell delivery carriers. However, many translational hurdles still exist. Future work should focus on understanding the ocular pharmacokinetics of novel polymeric biomaterials and establishing synthesis methods that are suitable for large-scale manufacturing.Project conceptualization: IS and XS. Data collection: IS and CO. Manuscript writing: IS, CO, ZL, and XS. Project supervision: XS. All authors contributed to the article and approved the submitted version.*STAR), Singapore, and HMBS Domain under its Industry Alignment Fund Pre-Positioning (IAF-PP) programme (H20/H7/a0/034) awarded to XS.This work was supported by the National Research Foundation (NRF), Singapore, under its Competitive Research Programme (CRP) (NRF-CRP21-2018-00103), Agency for Science, Technology and Research (AThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Klebsiella pneumoniae-induced liver abscess (KP-PLA) is a common type of pyogenic liver abscess, severe acute pancreatitis (SAP) has high mortality, and poor prognosis in advanced colon cancer. There have been no report of SAP complicated with colon cancer after KP-PLA as so far. In this study, we reported a case of SAP secondary to KP-PLA with colon cancer for the first time, so as to provide reference for clinical diagnosis and treatment of these diseases.A 64-year-old woman with a history of diabetes visited our hospital with abdominal pain for 5 + days. He was diagnosed with KP-PLA a month ago, which had not healed when he was admitted. He was diagnosed with SAP, and histological examination of colonic biopsy confirmed the diagnosis of moderately differentiated adenocarcinoma.He was treated with intravenous antibiotics and underwent modified endoscopic mucosal resection under colonoscopy. We conducted a 2-month follow-up, and there was no recurrence of liver abscess and pancreatitis.Screening for intestinal tumors is necessary in patients with cryptogenic liver abscess, especially KP-PLA with diabetes. Klebsiella pneumoniae is the most common bacteria in PLA in our country. Endophthalmitis caused by Klebsiella pneumoniae induced liver abscess (KP-PLA) was first reported in Taiwan in the 1980s, and some rare complications of liver abscess such as brain abscess and lung abscess have been reported successively in recent years.,4 As medicine progressed, acute pancreatitis (AP) was characterized by bacterial infections, including salmonella and tuberculosis, in addition to the common causes such as Biliary tract disease, alcohol, and high triglycerides.,6Klebsiella pneumoniae usually causes secondary infection after AP, there have been no cases of primary infectious pancreatitis caused by Klebsiella pneumoniae excluding other causes. The fatality rate of severe acute pancreatitis (SAP) is as high as 40%, and the 5-year survival rate of advanced colon cancer is significantly lower than that of early colon cancer. Therefore, it is particularly important to avoid secondary SAP of KP-PLA, and early diagnosis and treatment of colon cancer. At present, there has been no report of KP-PLA secondary SAP complicated with colon cancer at home and abroad. We report the first case of early colon cancer with KP-PLA and its secondary SAP as the initial symptom, aiming to provide reference for clinical diagnosis and treatment of this disease.Pyogenic liver abscess (PLA) is a serious infectious disease and Klebsiella pneumoniae was cultured in both the drainage fluid and venous blood. Abdominal CT scan indicated abscess in S6 segment of liver , C-reactive protein, and procalcitonin. Hemoglobin A1c (HbA1c) 13.01%. ver Fig. . HepaticKlebsiella pneumoniae was cultured in the drainage fluid and blood of some KP-PLA patients with secondary extrahepatic infection, suggesting that Klebsiella pneumoniae could cause extrahepatic infection through blood transfer.,9 A retrospective study suggested that KP-PLA patients with sepsis were more prone to extrahepatic infection, suggesting that hematogenous infection was a viable route. Biliary tract infection: According to the anatomical structure of liver and pancreas, the intrahepatic and intrahepatic bile ducts eventually converge to the common bile duct and accompany the pancreatic duct to eventually open at the duodenal papilla; part of the common bile duct may converge with the pancreatic duct and open at the duodenal papilla; bacterial infection in the liver may enter the pancreatic tissue through the biliary tract system and lead to AP. Hepatopancreatic fistula and pancreatic portal vein fistula: There have been cases reported in the past that secondary hepatic abscess in patients with chronic pancreatitis is due to the formation of hepatopancreatic fistula, and the formation of pancreatic portal vein fistula can lead to multiple focal hepatic abscess secondary to acute pancreatitis. If hepatic abscess rupture causes hepatopancreatic fistula, bacteria can also infect pancreatic tissue through fistulas and lead to AP. Patients with diabetes are more likely to suffer from Klebsiella pneumoniae infection, and KP-PLA patients with high blood glucose level are more likely to develop extrahepatic metastatic infections.,14 The generally accepted theory is that high glucose levels reduce the adhesion, chemotaxis, phagocytosis of neutrophils, and increase the aggressiveness of Klebsiella pneumoniae. The most common bacterial infection of PLA originates from the biliary tract, and some cryptogenic liver abscesses with unknown infection source were reclassified as enteric after intestinal examination, even were associated with intestinal tumors. Unfortunately, the patient had no intestinal infection symptom when he was admitted to hospital for the first time due to liver abscess, which was classified as cryptogenic liver abscess without complete colonoscopy, thus missing the opportunity for early screening of intestinal tumors. He was diagnosed with colon cancer due to SAP readmitted to hospital, suggesting that liver abscess and extrahepatic metastatic infection were closely related to delayed diagnosis of colon cancer. Colon cancer is one of the cancers with the highest prevalence in the world, its early clinical symptoms are not typical, and most of them are found in the late stage, so the mortality is high. Although there are no guidelines to determine whether PLA patients should be routinely screened for colon cancer, many scholars believe that PLA is closely associated with colon cancer, especially in patients with Klebsiella pneumoniae infection and diabetes.,19 Mohan et al conducted a meta-analysis, which showed that patients with PLA had a much higher incidence of colon cancer than the general population, and over 90% of the pathogenic bacteria were Klebsiella pneumoniae. Therefore, early colon cancer screening for patients with cryptogenic KP-PLA was recommended. It is generally accepted that colon cancer leads to the destruction of intestinal mucosal barrier, and enteric bacteria enter the blood along with the portal vein to cause liver abscess. In addition, the relationship between diabetes and colon cancer is also attracting increasing attention. A large cross-sectional study showed that diabetes mellitus significantly increases the risk of gastrointestinal tumors, especially colorectal cancer. It has been reported that hyperinsulinemia promotes the proliferation of tumor cells by stimulating the IP3-kinase/AKT pathway, apoptosis was inhibited by up-regulation of insulin-like growth factor-2, hyperinsulinemia promote the development of colon cancer by stimulating mutations in the DNA bases of colon cells. A case of brain abscess due to delayed diagnosis of KP-PLA associated with colon cancer was reported in Japan in 2000. This case is the first time KP-PLA associated with colon cancer has been proposed to cause SAP.KP-PLA can cause extrahepatic metastatic infection, but its secondary SAP has not been reported so far. The patient had no history of biliary tract or pancreatic diseases and drugs taken that may cause pancreatitis, no excessive drinking or overeating before the onset, normal triglyceride level, and negative autoimmune related antibodies. And he have had KP-PLA before the occurrence of pancreatitis, so KP-PLA secondary SAP was considered. By reviewing relevant literature, the potential mechanism of secondary AP of KP-PLA is proposed here: blood infection: Klebsiella pneumoniae infection and diabetes mellitus. Early removal of the etiology can not only reduce the recurrence of PLA, but also reduce the probability of complications of extrahepatic infection. As a rare complication of KP-PLA, the pathogenesis is not very clear, but blood infection is a feasible route, so the treatment of sepsis is helpful to shorten the treatment time and improve the prognosis. High blood glucose level can promote the extension of infection, stabilizing blood glucose level is an important measure to reduce extrahepatic metastatic infection in KP-PLA patients.KP-PLA is closely associated with colon cancer. Even in the absence of intestinal symptoms and positive radiographic findings, screening for intestinal tumors in cryptogenic liver abscesses is necessary, especially in patients with Data curation and investigation: Shan Yang.Supervision: Qi Liu.Writing—original draft: Shan Yang.Writing—review and editing: Jin Zhao.


As tumor mutational burden (TMB) has been approved as a predictive biomarker for immune checkpoint inhibitors (ICIs), next-generation sequencing (NGS) TMB panels are being increasingly used clinically. However, only a few of them have been validated in clinical trials or authorized by administration. The harmonization and standardization of TMB panels are thus essential for clinical implementation. In this review, preanalytic, sequencing, bioinformatics and interpretative factors are summarized to provide a comprehensive picture of how the different factors affect the estimation of panel-based TMB. Among the factors, poor DNA quality, improper formalin fixation and residual germline variants after filtration may overestimate TMB, while low tumor purity may decrease the sensitivity of the TMB panel. In addition, a small panel size leads to more variability when comparing with true TMB values detected by whole-exome sequencing (WES). A panel covering a genomic region of more than 1Mb is more stable for harmonization and standardization. Because the TMB estimate reflects the sum of effects from multiple factors, deliberation based on laboratory and specimen quality, as well as clinical information, is essential for decision making. Along with the investigation of immune checkpoint inhibitors (ICIs), tumor mutational burden (TMB) has been developed to be a predictive biomarker in recent years. By definition, TMB refers to the total load of somatic mutations in tumor cells. As somatic mutations may cause specific tumor neoantigens, patients with a high TMB are likely to be responsive to immunotherapy ,2,3,4. ASeveral sequencing methods and multi-gene panels have been established to test TMB in academic, medical and diagnostic laboratories. Originally, the gold standard to calculate TMB was whole-exome sequencing (WES), where the total number of somatic mutations was calculated and reported. However, this is less feasible in most clinical settings because of its labor intensiveness and high cost, the lengthy turnaround time and the lack of computational or bioinformatics specialists. Panel-based TMB assays were thus developed by many laboratories and diagnostic companies. Generally, a TMB panel includes several hundreds of genes, and the somatic mutation load in tumors is estimated using specified bioinformatics algorithms. However, as the design varies across panels from gene selection to bioinformatics algorithms, no universal cutoff defines a high TMB status. The variation between TMB estimates can confuse clinicians and may hinder clinical decision making. Further harmonization and standardization are mandatory for the clinical implementation of panel-based TMB assays.The standard is still unclear and sometimes confusing, although several TMB panels have been approved or cleared by the U.S. Food and Drug Administration (FDA). In the KEYNOTE-158 study, TMB was defined as a predictive biomarker, and a cutoff of 10 mutations per megabase (muts/Mb) to define a high TMB was proposed and further approved by the FDA as a tumor agnostic indication for the prescription of pembrolizumab ,15. A coAs the harmonization and standardization of TMB are considered to be critical and essential for clinical implementation, international collaboration was initiated in 2018. Two nonprofit organizations—Friends of Cancer Research (FoCR), based in Washington, DC, and Quality Assurance Initiative Pathology (QuIP), based in Berlin, Germany—formed research consortia to involve laboratories and stakeholders from different domains, such as diagnostic companies, academic or medical institutions, pharmaceutical companies and regulatory administrations or government-funded institutions ,20.Several preanalytic factors may influence the TMB estimation, primarily associated with DNA quality. Poor DNA quality, whether resulting from specimen handling, processing or archiving, is known to cause more false-positive calls of somatic mutations, which often feature a low allele frequency . These fTumor fraction and input DNA quantity both affect the sensitivity of TMB testing, though their impacts vary in degrees between cancer types and panels. Some cancer types are known to have a higher TMB, such as NSCLC and melanoma, while others mostly express a low TMB. Generally, a low tumor fraction may cause missed calls of tumor somatic mutation and, thus, underestimation of TMB. However, panel-specific bioinformatics algorithms may partially compensate for these effects, and an acceptance criterion of tumor fraction has been verified in some TMB panels. The effects of a low tumor fraction and DNA input can be minimized through routine measures of laboratory quality assurance/quality control (QA/QC).Although the clinical utility of blood TMB (bTMB) has been increasingly recognized and emphasized, it remains debatable whether bTMB can be harmonized with tissue-based TMB (tTMB) either in its value or clinical interpretation ,32,33. OGene coverage and panel size are key factors affecting the performance of a TMB panel. Genes selected in TMB panels, together with their bioinformatics algorithm, primarily determine the accuracy and variability in TMB estimates . As the Special considerations regarding the sequencing quality or performance of given genes have been applied when designing and constructing a panel-based TMB. Certain genes or coding regions are excluded from TMB calculation because the sequencing results of such genes are frequently unreliable due to some technical gaps. For example, the sequence of central exons was found to be highly repetitive and variable in some mucin genes, e.g., MUC2 and MUC6 . As the Sequencing depth is a major difference between panel-based TMB and WES TMB. In comparison with WES, a TMB panel can have increased sequencing depth. More variants with a low allele frequency can be detected than in WES, which should also be taken into consideration when developing a bioinformatics algorithm; otherwise, this could lead to a potential overestimation. In contrast, TMB can be underestimated when using sequencing methods with a low depth, such as whole-genome sequencing, as some somatic mutations may fail to be detected. Special considerations are necessary to construct bioinformatics algorithms so that the TMB estimates can be calibrated if possible. Therefore, sequencing depth is considered an important QC metric. The sensitivity may be reduced if the depth does not meet the QC requirement with proper bioinformatics pipelines deployed .The initial clinical investigation of TMB was to calculate the sum of somatic mutations detected by WES. Several calculation strategies based on the inclusion types of mutations have been developed in different studies. Although attempts to include all somatic mutation types  and small insertions and deletions (indel)) for TMB calculations have been reported in several studies ,46,47,48The core steps of the panel-based TMB calculation are shown in To achieve a better correlation with WES TMB, many TMB panels have been developed that use bioinformatics approaches that are different from those in WES in terms of variant calling and filtering. For example, in many WES TMB calculations, only non-synonymous mutations are counted. However, both synonymous and non-synonymous mutations are included for bioinformatics computation in some panels, as this approach is believed to increase the sampling of variants in the limited gene list of panels and, thus, is probably better able to represent the overall mutational load across the genome. Although this approach only showed a minimal effect on the correlation between WES TMB based on the FoCR harmonization studies, the data also exhibited reduced inter-panel variability when calculating both synonymous and non-synonymous mutations. The FoCR harmonization study also evaluated the effects of the approach when excluding known somatic pathogenic variants and found that TMB would be overestimated without the filtration of known pathogenic mutation variants ,20. The In addition to somatic mutations, germline variant filtering is critical to estimate TMB. Ideally, all germline variants, including both single-nucleotide pleomorphisms  and mutations , should be excluded from TMB calculation; otherwise, the TMB value will be overestimated. The perfect filtering-out procedure requires a matching normal specimen from the same patient . HoweverThe population database approach is a standard protocol to filter out germline variants. The most commonly used population databases include GnomAD (the Genome Aggregation Database), TCGA (the Cancer Genome Atlas), ExAc (Exome Aggregation Consortium), 1000 Genomes and ddSNP (the Single-Nucleotide Polymorphism Database) . Some laCutoff definition is complicated in the clinical application of a TMB panel. In trials using WES TMB, there are various cutoffs ranging from 100 to 248 mutations ,52,53. TIn addition, as the TMB level varies in distribution across cancer types , whetherAs the clinical utility of TMB as a predictive biomarker for ICIs has been demonstrated in multiple cancer types, the clinical demand for TMB testing has increased in recent years. The standardization and harmonization of various TMB panels are essential for laboratory implementation and clinical interpretation. This article reviewed the technical aspects that have been key to panel harmonization so that we can better understand the complex nature and computation of TMB embedded within the powerful NGS pipeline. Although the FoCR harmonization study has provided experience and principles to establish the possibility of an interchangeable TMB estimate across panels, laboratory measures that assure their testing quality are the real-world foundation to ensure that TMB is successful for clinicians and patients universally.


Rathke’s cleft cysts (RCC) are rare benign cystic lesions that might present with different imaging features, potentially posing a problem in the radiological diagnosis of cystic sellar lesions. The purpose of this pictorial review is to present an overview of the radioclinical features of RCC through four clinical cases with different radiologic findings confirmed by pathology, as well as reviewing the common differential diagnosis to be considered.The subjects are women, aged 11 to 73 who underwent recent transsphenoidal surgical resection with a postoperative follow-up period of a few months to three years. Rathke’s cleft cysts (RCCs) are benign sellar lesions arising from epithelial remnants of Rathke’s pouch that originate between the anterior and posterior lobes of the pituitary gland with a peak in third to fifth decades of life . The resMost RCCs are small and asymptomatic, but larger cysts may compress adjacent neurovascular structures and symptoms may arise, such as headache, endocrine dysfunction, and occasionally visual disturbances.Diagnosis of RCC is strongly suggested at magnetic resonance imaging (MRI). Typical imaging findings include a nonenhancing, noncalcified cyst located between the anterior and posterior lobes of the pituitary gland with sharp contours as well as close contact with the posterior lobe and strict midline location . RCCs maRoutine clinical follow-up with MRI is sufficient for incidental asymptomatic cysts. For rare cases with symptomatic lesions, treatment most often consists of surgery, usually an endonasal transsphenoidal approach.Although considered to be benign lesions, RCCs commonly recur. The recurrence rate may depend on the size of the cyst, presence of squamous metaplasia, or partial excision of the paper-thin wall of the cyst, leaving in place the secretions that may re-accumulate or even result in intraoperative cerebral spinal fluid leak and leading to need for an abdominal fat graft or sellar packing .A 67-year-old woman presenting with tiredness and weight gain was diagnosed with a pituitary insufficiency. MRI evaluation revealed a large cystic intrasellar and suprasellar lesion with superior displacement of the optic chiasm, posterior displacement of the neurohypophysis, and extension to the cavernous sinuses .Patient underwent transsphenoidal surgical resection, which confirmed the diagnosis of RCC. Immediate post-operative follow-up revealed a sphenoidal breach with CSF flow leading to intracranial hypotension which was followed up by MRI  and a suThe postoperative follow-up revealed headaches that were not present before her first operation, persistent pituitary insufficiency requiring hormone substitution therapy: gonadotropic , thyrotropic (low T4 and low TSH), somatotropic (collapsed GH), and corticotropic (low cortisol and ACTH), and slightly elevated but stable prolactin probably related to pituitary stem lesion. No other problems were reported, including no recurrence so far.A 22-year-old woman who presented with chronic headaches underwent an MRI examination, which showed a cystic intrasellar lesion with high protein content. No mass affect was observed . PatientA 73-year-old woman presented with an incidental cystic pituitary lesion discovered in context of malaise with loss of consciousness. The hormonal assessment during hospitalization revealed a pituitary insufficiency affecting the gonadotropic, thyrotropic, corticotropic, and somatotropic functions as well as hyperprolactinemia compatible with a compression of the pituitary stem.MRI examination demonstrated a cystic sellar and suprasellar lesion with a non-enhanced intracystic nodule . An intrIn the course of her follow-up, a significant radiological progression of the cyst was observed at the end of the ten-year follow up. MRI revealed an increase in the size of both the cystic lesion and the intracystic nodule showing chiasmatic mass affect and without extension to the cavernous sinuses .Considering the radiological progression of the cyst and given the context, the patient underwent surgical resection after discussion at a multidisciplinary oncology meeting. In the postoperative course, persistence of a relatively important pituitary insufficiency was revealed, justifying the continuation of hormone substitution therapy. No post-operative complication or recurrence has been observed so far.A 11-year-old female patient who presented with failure to thrive and diabetes insipidus underwent an MRI examination, which revealed a cystic intrasellar and suprasellar lesion with heterogeneous content with an irregular solid component and peripheral enhancement coming into contact with the optic chiasm .Patient underwent transsphenoidal surgical resection without immediate post-operative complication, and no recurrence has been observed so far. During her postoperative follow-up, a nice recovery of her growth curve was reported. Initially, a decrease in her growth hormone level was reported, for which a substitution treatment was continued for a few months in addition to the antidiuretic hormone therapy.Although the recurrence rate of RCCs appears to be relatively high, none of our patients have demonstrated postoperative recurrence to date. This can be explained probably by their short follow-up period after surgery, ranging from a few months to three years, which can be considered a limitation in our case series.There is currently no clinical consensus on the best strategy to treat recurrences, but radiotherapy seems to be a good emerging alternative to surgery in RCC treatment, according to Chalif, especially for the cases that tend to recur .In our study, all patients underwent transsphenoidal surgical resection, but it should be kept in mind that surgery exposes the patient to a risk of postoperative complications and RCC treatment remains controversial for some authors. Based on Truong’s study, surgery would appear to be particularly suitable for treating visual disturbances, and regular follow-up is more appropriate than surgery regarding headaches, hyperprolactinemia, endocrine disruptions, and diabetes insipidus . This waDiagnosis of RCCs might be challenging because they can mimic other intra- or suprasellar lesions, such as cystic pituitary adenoma and cystic craniopharyngioma, or less frequently, arachnoid cyst, epidermoid cyst, mucocele, abscess, or pituitary apoplexy . RCC is 4On the other hand, suprasellar localization, the presence of calcification or a solid enhancing component is characteristic for craniopharangioma . HistoloCystic portions of both pituitary adenoma and craniopharyngioma can show an enhancing thick wall which can be attributed to squamous metaplasia, inflammation, deposition of haemosiderin, or cholesterol crystals in the cyst wall .We describe a wide spectrum of radiological features that are dependent on cystic content and that a radiologist should be aware of to make a correct diagnosis. Although radiological findings can be nonspecific, some MRI features may be helpful in differentiating it from other well-circumscribed intrasellar processes; nonetheless sometimes surgery is necessary to lead to the definitive diagnosis.It is also important to point out that even though RCCs are benign changes pathologically every RCC case should have serious and rigorous multidisciplinary follow-up, primarily because of its location regarding compression effects and multiple important pituitary functions. Indeed, according to the literature, one RCC case reported by Sawano resulted in cardiac arrest induced by a lack of cortisol .


Chronic liver diseases represent a prevalent pathology that exerts considerable pressure on healthcare providers and various healthcare systems worldwide. In addition to the vast spectrum of complications that could appear because of disease progression to liver cirrhosis, anesthesia and surgery pose a considerable risk to a patient with chronic liver disease . For a bSpecial consideration should be focused on perioperative risk assessment strategies and fast-track-adapted surgical protocols. The main goals in preoperative settings are to optimize the fluid balance and coagulopathy, treat hepatic encephalopathy, avoid nephrotoxic drugs, maintain a familiar social environment, and improve nutritional status and cardiopulmonary function. Intraoperative care should focus on goal-directed fluid therapy, a point-of-care analysis of coagulopathy, an assessment of the stress response to surgery due to the appropriate invasive monitoring, sufficient anesthesia depth and nociception assessments, the rational use of various anesthetic drugs, considering the modified pharmacokinetic in cirrhotic patients, and specific surgery-related challenges . Postoperative clinical practice should address the following issues: optimal management based on enhanced recovery after surgery (ERAS) protocols; comprehensive pain management; counteracting the postoperative hyperdynamic status; and, regarding hypotension, which is normal in this patient subgroup, identifying and treating postoperative renal impairments; and optimizing neurocognitive status using a multidisciplinary approach . Additionally, novel epigenetic biomarkers could serve as potential predictors in identifying the patients at risk for developing various perioperative complications or surgery-related cirrhosis decompensation . SpecialSubmissions regarding these factors and their possible influence on patient outcomes are welcomed for the current Special Issue entitled “Chronic Liver Diseases and Liver Surgery in Anesthesia” to analyze, prioritize, and identify solutions for better intensive care and surgical practice.


In this volume, 15 scientific reports give a snapshot of some of the most exciting current research on how sleep helps regulate negative emotion. Articles illustrate state-of-the-art research paradigms from the cognitive, affective, and behavioral neurosciences, sleep medicine, biological psychiatry, and dream research.Cunningham et al. and a meta-analysis of sleep and emotional reactivity by Lipinska et al.. Cunningham et al. focus on the timing of sleep manipulations and assessments in relation to memory encoding. They note that inconsistent findings in the literature may result when different memory processes occurring at different times following encoding confound one another. Both studies emphasize the limitations of empirical findings to date and advocate for increased sophistication, rigor and statistical power in sleep science. Specifically, they note that two tenets of conventional wisdom in sleep science—that sleep preferentially consolidates emotional memories while serving to moderate emotional reactivity—are generally unsupported or supported only under certain conditions.This collection begins with a narrative review of sleep and emotional memory by Cunningham et al. note that extreme sleep deprivation imposed at all stages of information processing negatively impacts memory, irrespective of whether or not memory holds emotional content  after 40 h TSD following either a week of sleep-restriction (SR) or sleep-satiated laboratory sleep. They additionally examined changes in PANAS across the course of a forced desynchrony (FD) protocol. Interestingly, they showed larger effect sizes on positive vs. negative mood scales of the PANAS for all three of these sleep manipulations.Kurinec et al. examined whether changes in electrodermal activity (EDA) during TSD compared to normal sleep correspond to changes in sleepiness, vigilant attention, and affect in a large sample of healthy adults. Skin conductance level (SCL) and rate of spontaneous skin conductance responses (NSSCR) were obtained over a 5-min rest interval. TSD produced expected changes in positive affect, sleepiness, and vigilance, while NSSCR but not SCL decreased following TSD. Neither parameter, however, correlated with any other measurements, suggesting that EDA does not adequately reflect experiences of arousal during either rested wakefulness or TSD.Sundelin and Holding tracked state anxiety  across two large samples of healthy young adults, one of which underwent a full night's TSD while the other underwent two continuous days of sleep restricted to 4 h. In both, sleep loss resulted in an increase in state anxiety which correlated with trait anxiety (STAI-T). However, trait anxiety did not moderate the relationship between sleep loss and state anxiety suggesting that those with high levels of trait anxiety do not show a proportionately greater effect of sleep loss on state anxiety. These results notably conflict with findings from other published studies  and suppressed the morning cortisol peak. In addition, they found TSD increased reaction time (RT) on some cognitive tasks (without impairing accuracy) and increased negative mood states  and anxiety (STAI-S).Borghese et al. and Halonen et al. applied targeted memory reactivation (TMR), a cutting-edge experimental paradigm in sleep science  when preparing for a subsequent exposure.These results concur in finding no effect of TMR during REM . Blue light treatment lengthened sleep relative to the amber control whereas the amber light improved sleep efficiency . Structural MRI showed increased amygdala volume in the blue-light group that correlated with decreased nightmare severity. Vanuk et al. showed that the blue light treatment was superior in reducing participants' sleep complaints. Although both treatments reduced the severity of PTSD symptoms, only in the blue light group did these improvements correlate with improved sleep. Additionally, the blue group better maintained extinction learning at 6 weeks compared to the amber group.In addition to the well-known circadian entrainment function of intrinsically photosensitive retinal ganglion cells, photostimulation of this pathway also affects mood, alertness and cognition  and sleep continuity. In contrast, an evoked response potential (ERP) index of inhibitory processing was positively correlated with SWS. The authors point out that this pattern mirrors the REM disinhibition and decreased SWS that is associated with adult depression.Similarly, Mamede et al. used structural equation modeling (SEM) of data from a large online questionnaire study to examine interrelationships of sleep and trait mindfulness among other factors in explaining depressive and anxiety symptoms during the COVID-19 pandemic. They found significant mediation of the effects of mindfulness on overall mental health by the combined effects of rumination and insomnia symptoms.Barbeau et al. report evidence for an emotion regulatory function of dreams by comparing emotionality reported by the dreamer to emotionality rated by judges. They describe lesser emotionality in dream self-reports as a “positivity bias”, quantified by subtracting the dreamers' mood ratings from judges' ratings. These authors found positivity bias to predict degree of positive mood reported upon waking.Sikka et al. provide evidence for a lack of an emotion regulatory effect of dreaming. Beginning with the common hypothesis that negative emotion in dreams functions to discharge or “work-through” negative emotion in wakefulness, these investigators tested whether, following nights containing negatively-toned dreams, individuals were less reactive to negatively-toned images and were better able to down-regulate negative responses via cognitive reappraisal. However, they found just the opposite: more negatively-toned dreams were associated with more negatively-toned post-sleep mood and affected neither the reactivity to negative images nor the ability to re-appraise. They postulate their findings support a continuity between dream and waking mood, as would be predicted by the “continuity hypothesis” (Schredl and Hofmann, In contrast, The mixed findings in this volume are instructive in illustrating how differences in experimental paradigms and measures can lead to quite different conclusions. Such differences aside, findings indicate that sleep is indeed an important component of emotion regulation, and that the specific mechanisms are fertile ground for future research.All authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.


Nutrients and xenobiotics cross the blood–placenta barrier, potentially depositing in the fetal brain. The prenatal exposure affects the neuroendocrine and microbial development. The mechanism underlying maternal risk factors reprograming the microbiota–gut–brain axis with long-term effects on psychosocial behaviors in offspring is not clear. In humans, it is not possible to assess the nutrient or xenobiotic deposition in the fetal brain and gastrointestinal system for ethical reasons. Moreover, the maternal–fetal microbe transfer during gestation, natural labor, and breast-feeding constitutes the initial gut microbiome in the progeny, which is inevitable in the most widely utilized rodent models. The social predisposition in precocial birds, including chickens, provides the possibility to test behavioral responses shortly after being hatched. Hence, chickens are advantageous in investigating the ontogenetic origin of behaviors. Chicken embryos are suitable for deposition assessment and mechanistic study due to the accessibility, self-contained development, uniform genetic background, robust microbiota, and easy in vivo experimental manipulation compared to humans and rodents. Therefore, chicken embryos can be used as an alternative to the rodent models in assessing the fetal exposure effect on neurogenesis and investigating the mechanism underlying the ontogenetic origin of neuropsychiatric disorders. Nature and nurture contribute to psychosocial development . RecentlSutterellaceae and Enterobacteriaceae and decreased abundance of genus Bifidobacterium fluoro-D-glucose (18FDG) [The modern magnetic resonance imaging (MRI) technique is a powerful tool for investigating the embryonic brain; it averts sacrifices and allows serial monitoring of longitudinal developmental processes in a single brain ,63. Subm (18FDG) . The non (18FDG) . These t (18FDG) .Precocial birds are already equipped with a mature sensory motor system and fast learning mechanisms, e.g., filial imprinting, as early as the day of hatching . Even duThe chicken embryo is recruited in the developmental endocrinological studies due to the ease of in vivo experimental manipulation, especially in investigating the development of the hypothalamic–pituitary–thyroid (HPT), hypothalamic–pituitary–adrenocortical (HPA), and hypothalamic–pituitary–somatotropic (HPS) axes . Hence, The 5-HTergic development and its modulatory effect on the dopaminergic (DAergic) system and related neural circuits have been investigated during mid-late embryogenesis (E12–20) in chickens . Growth-Gestational VPA exposure increases the risk of ASD in humans , and theBoth hypo- and hyper-serotonemia have been proposed as potential risk factors for ASD . IdenticOlsenella, Ruminococcaceae UCG-005, Oscillospira, and Ruminococcus_2, are detected in the tryptophan-treated roosters. These bacteria are identified as the core microbes in the crypt of human colon [Tryptophan is essential for neurodevelopment and immunomodulation during pregnancy . A highean colon . FurtherThe chicken embryo skirts the maternal influence on the neuroendocrine and gastrointestinal development, i.e., the maternal metabolic fluctuation and maternal–fetal microbe transmission seen in humans and other mammals. The current studies have revealed that chickens could offer an alternative model to rodents in the ontogenetic origin of psychiatric disorders, including but not limited to: modeling the disease syndrome, assessing the dosage effect and uncovering the relative paths, and identifying novel insights for embryonic exposure altering postnatal psychosocial exhibition. The social predisposition in precocial birds provides the possibility to test behavioral responses shortly after hatching, which can be intervened during the pre-hatching period. This perspective article provided insights for using the chicken as an ideal species in studying the ontogenetic origin of neuropsychiatric disorders.