Heterogeneity in XXXX as demonstrated by an ex vivo chemo response assay.

@entity1 @entity43 @entity5
UNASSIGNED: 5059 Background: Only a subset of @entity1 responds to a given chemotherapeutic regimen. The purpose of this analysis was to determine whether @entity5 are generally sensitive or resistant regardless of regimen, or do they demonstrate heterogeneity in responsiveness across regimens. METHODS: We examined the ex vivo chemoresponse of @entity43 cells from 256 @entity1 across 9 practices. An average of 8 drug regimens, including combinations, were tested per @entity5 . The assay results were scored for sensitivity or resistance based on live cell number after exposure to varied concentrations of each chemotherapeutic regimen. @entity1 were classified into three groups: predominantly sensitive (>83% of regimens tested scored sensitive for their @entity5 ), predominantly resistant (>83% tested resistant), and heterogeneous. RESULTS: 51 of 256 (20%) cases were predominantly sensitive, with a median progression free interval (PFI) of 17.7 months. 34 (13%) cases were predominantly resistant, with a median PFI of 9.9 months. Two thirds of cases (N=171) exhibited heterogeneity of response, with a median PFI of 11.4 months. Within the heterogeneous group, those who received a regimen scored as sensitive ex-vivo (no other regimens tested were scored more sensitive than the regimen they received) vs resistant ex-vivo had an improved median PFI: 12.4 months (N=46) vs 8.6 months (N=125). CONCLUSIONS: The majority of @entity5 tested demonstrated heterogeneity of response ex vivo. As heterogeneity of chemotherapy response for an individual @entity1 cannot be assessed clinically, an ex vivo assay assessment is informative. Moreover, our data suggests that individualizing therapy by incorporating an ex vivo assay has the potential to increase the response rates to chemotherapy. [Table: see text].
