Conjugates of mitomycin with anti-alpha-fetoprotein antibody: antitumor effect against alpha-fetoprotein-producing human gastric carcinoma implanted in nude mice.

Conjugates of mitomycin (MMC) with an affinity-purified horse anti-human alpha-fetoprotein (AFP) antibody were prepared by direct conjugation or by indirect conjugation mediated by human serum albumin; 1a-[4-(N-succinimidoxycarbonyl)butyryl]-MMC was used in the preparation. In therapeutic experiments with athymic nude mice inoculated with the human AFP-producing gastric carcinoma OSS, the conjugates caused a greater inhibition of the tumor growth than did an unconjugated mixture of anti-AFP antibody and MMC or similar conjugates with normal horse immunoglobulin. The AFP serum level and its ratio to tumor volume were low in the group of mice treated with anti-AFP conjugate. The enhanced drug activity of the anti-AFP conjugates was not observed against human gastric carcinoma YSS (no AFP production) in nude mice; this suggests the involvement of the specific antibody-antigen interaction in the activity of the anti-AFP conjugates.