ANTIIDIOTYPIC ANTIBODIES IN OVARIAN-CANCER PATIENTS TREATED WITH THE MONOCLONAL-ANTIBODY B72.3

Immunotherapy with monoclonal antibodies has become a hopeful approach to the adjuvant therapy of cancer patients, Recently, formation of an tiidiotypic antibodies (Ab2) has been demonstrated in ovarian cancer p atients after immunization with F(ab')(2) fragments of the monoclonal antibody OC 125 (MAb OC 125), Preliminary results suggested that patie nts with high Ab2 serum concentrations had better survival rates compa red to those where low or no Ab2 serum levels were detected, Beginning in 1999, 23 patients with advanced ovarian adenocarcinomas have been treated with repeated intravenous applications of the MAb B72.3, which is directed against the ovarian carcinoma associated antigen TAG-72. Five of them had been pretreated with several F(ab')(2) MAb OC 125 inf usions, Blood sample analysis revealed a remarkable antiidiotypic anti body (Ab2) response in 14 patients, with five patients developing high serum levels >1000 U/ml. Ab2 serum concentrations increased with incr easing number of Mab B72.3 applications, In terms of serum levels, cor responding antiidiotypic antibody responses in patients who received b oth the F(ab')(2) MAb OC 125 and the MAb B72.3 differed considerably, We conclude that the use of MAb B72.3 may be an additional beneficial approach to the immunological therapy of ovarian cancer, Subsequent MA b B72.3 application after failure of the F(ab')(2) MAb OC 125 may indu ce appreciable Ab2 serum concentrations and vice versa.