Experimental chemotherapy (L1210) with 5-aza-2'-deoxycytidine in combination with pyran copolymer (MVE-4), an immune adjuvant.

The life-span of CDF1 (BALB/c X DBA/2)F1 mice that received intraperitoneal implants with 10(5) L1210 tumor cells was prolonged to 23 days (compared to 8 days in L1210 tumor-implanted, untreated mice) when 5-aza-2'-deoxycytidine (DAC) was given to the mice after the tumor cells were allowed to metastasize (3 days after implant); DAC, however, resulted in no cures (survival beyond 48 days). When the pyran copolymer MVE-4, an immune adjuvant, was given the day after DAC, 25% of the mice treated were cured and the life-span of dying mice was increased by 7 days. When MVE-4 was repeated weekly for 4 weeks, 79% of treated mice were cured. Cured mice were able to resist a subsequent challenge of approximately 2 logs of L1210 cells. This combination of DAC plus MVE-4 was more effective than DAC alone only if the tumor cells and MVE-4 were given intraperitoneally. When this combination was repeated weekly, it became lethally toxic after 3 weeks, but only to L1210-tumor-bearing mice and not to normal mice. When DAC alone was given 2 days before tumor implant, it induced an apparent immune effect so that mice could resist a subsequent challenge of approximately 1.5-2 logs of L1210 cells. Support for part of the antitumor action of DAC exerted through the immune system was given by data that show that later treatment with noncurative doses of DAC is superior to early treatment in mice with large L1210 tumor burdens.