Effects of 5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide, 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea, and L-phenylalanine mustard on B16, Cloudman S91, and Harding-Passey mouse melanomas.

The effects of 5-(3,3-Dimethyl-1-triazeno)imidazole-4-carboxamide (DTIC), 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea (MeCCNU), and L-phenylalanine mustard (L-PAM) have been compared by using three i.p. transplanted mouse melanomas: the B16 melanoma in C57BL/6 mice; the Harding-Passey (HP) malanoma in BALB/c X DBA/2F1 (hereafter called CD2F1) mice; and the Cloudman S91 melanoma in DBA/2 mice. HP melanoma responds well to all three drugs. S91 responds only to L-PAM and MeCCNU. DTIC may accelerate death in mice bearing this tumor. B16 responds well to L-PAM and moderately well to MeCCNU and to multiple injections of DTIC. The best response to DTIC and MeCCNU is given by HP, while the best response to L-PAM is given by S91. Tumor cell-doubling times were found to be 1.5 days for B16, 2 DAYS FOR HP, and 3 days for S91. HP would seem to be the most responsive malanmoma with respect to the 3 agents studied. This may be due to an interaction between the chemotherapeutic agents and the host immune response, since the HP tumor arose in a noninbred mouse and is thus nonsyngeneic with the CD2F1 host. All three tumors appear to be interesting biological models for studying drug combinations and combined therapeutic modalities against melanoma.