Antitumor activity of XXXX against L1210 @entity19 leukemia.

@entity7204 @entity19 @entity5 @entity665 @entity7005 @entity7203 @entity369
We have made a preliminary assessment of the antitumor activity of the @entity369 analog, @entity7203 , in leukemic @entity19 . This analog is known to substitute for @entity369 in protein biosynthesis in many prokaryotic and eukaryotic systems. Previous studies with cells grown in vitro indicated that @entity7204 caused a marked inhibition of DNA synthesis and viability. The system used in the present study was C57BL/6 x DBA/2 F @entity19 bearing L1210 leukemic cells. Following an i.v. injection of 10 mg @entity7204 , the @entity7005 of @entity7204 in the serum was estimated at 16 min. This finding suggested that frequent injections of high doses of @entity7204 would be required for an effect on @entity5 cell proliferation. DNA synthesis by the L1210 cells, assayed by @entity665 incorporation, fell to 9% of the control value after 12 hourly i.p. injections of @entity7204 (20 mg each). A constant s.c. infusion of 20 mg/hr for 24 hr caused an 86% inhibition of DNA synthesis. The antitumor activity of @entity7204 was tested against L1210, using a 24-hr infusion schedule with treatment starting 24 hr after i.p. inoculation of 10(5) cells. An optimal dose of 18 g/kg body weight produced a median increased lifespan of 44% (p less than 0.005). These results suggest that @entity7203 may be useful as an antitumor agent.
