Antilymphoma Activity of a Glutaminase-Free L-Asparaginase of Microbial Origin

The antilymphoma activity and blood clearance behavior of the glutamin-ase-free L-asparaginase from Vibrio succino-genes was tested in C3H mice with transplanted 6C3HED lymphosarcoma. Seven animals in which tumors had been implanted 12 days earlier each received two ip injections of 0.33 IU of homogeneous enzyme per day over a 4-day period. All animals appeared to be in complete regression 3 days after the injections were terminated and showed regression profiles that were at least comparable to those obtained with a second group of 6C3HED mice injected with equivalent levels of EC-2 L-asparaginase. The tumors did not return within 30 days in the enzyme-treated groups, whereas all animals injected with buffer or heat-inactivated V. succinogenes enzyme died during this period. Half-lives of 17-42 hr were observed for the V. succinogenes L-asparaginase in the blood stream of eight tumor-bearing mice. These results demonstrate that the L-asparaginase from V. succinogenes is an effective antilymphoma agent. We thank David Lester and David E. Mallon for assistance with the statistical analyses and K. Sieglinde Neuhauser for aid with the tumor measurements.