Studies on antibody-anticancer drug conjugate Part 2. In vivo antitumor activity of anti-Ia monoclonal antibody-Neocarzinostatin conjugate

In vivo antitumor activity of anti-Ia monoclonal IgM antibody (H-2)-Neocarzinostatin (NCS) conjugate (H-2-NCS) was evaluated in immunosuppressed newborn hamsters implanted with a transplantable human leukemia cell line (BALL-1). After intraperitoneal injection of H-2-NCS, hamsters preinoculated i.p. with BALL-1 cells survived longer than hamsters treated with control solutions (p<0.001). The control solutions included nonimmune monoclonal IgM-NCS conjugate, H-2 antibody, free NCS and phosphatebuffered saline. Growth inhibition of subcutaneously implanted BALL-1 tumors was not observed in hamsters injected i.p. with H-2-NCS or H-2 monomer subunit antibody-NCS conjugate. These results indicate that H-2-NCS was effective against i.p. implanted BALL-1 tumors, but was not effective against s.c. implanted tumors.