Enhanced antitumor activity of mitomycin C conjugated with anti-alpha-fetoprotein antibody by a novel method of conjugation.

Mitomycin C (MMC) was conjugated to horse anti-rat alpha-fetoprotein (AFP) antibody at the N-1a position through a glutaric acid-derived spacer arm. In vitro studies showed that MMC was spontaneously and slowly released from the conjugate. The conjugate caused a greater inhibition of both the in vitro and in vivo tumor growth of the AFP-producing rat hepatoma AH66 than did a mixture of anti-rat AFP antibody and MMC or a similar conjugate of MMC with normal horse immunoglobulin.