Combination effect of recombinant human interleukin 1 alpha with antitumor drugs on syngeneic tumors in mice.

To investigate the combination effects of recombinant human interleukin 1 alpha (rHu IL-1 alpha) and antitumor drugs, groups of 7 mice bearing syngeneic tumors (Meth A sarcoma in BALB/c mice and colon 26 adenocarcinoma in BALB/c x DBA/2 F1 mice) were treated i.v. with the antitumor drugs according to the early (once daily on days 1, 4, 7, 10, and 13) and/or late (once daily on days 7, 10, 13, 16, and 19) medication schedules in combination with rHu IL-1 alpha administered i.m. at various timings (1 day before, concurrently with, and 1 day after every drug administration). Inhibition rates of the antitumor drugs (mitomycin C, doxorubicin, cisplatin, cyclophosphamide, and 5-fluorouracil) for both the murine tumors were more or less raised by coadministration of rHu IL-1 alpha irrespective of medication schedules and combination timings. After both early and late treatments with the optimal combinations of rHu IL-1 alpha (0.1-3 micrograms/mouse) and cisplatin (2-4 mg/kg) and by the late treatment with the optimal combinations of rHu IL-1 alpha (0.3-3 micrograms/mouse) and carboplatin (32 mg/kg) or thiotepa (4 mg/kg), many mice were completely cured of colon 26 adenocarcinoma and survived for more than 90 days. Combined use of rHu IL-1 alpha and antitumor drugs seems to be beneficial in antitumor chemotherapy.