The anti-idiotypic antibody abagovomab in patients with recurrent ovarian cancer. A phase I trial of the AGO-OVAR.

ABSTRACT

BACKGROUND: Abagovomab is a murine anti-idiotypic antibody against the antigen CA-125 which has been shown to elicit humoral and cellular immune responses against ovarian cancer (oc). PATIENTS AND METHODS: This phase I trial included 36 patients with recurrent oc comparing two subcutaneous (s.c.) vaccination schedules nine (group L) versus six injections (group S), 18 patients in each group. Four injections of 2.0 mg abagovomab were administered every 2 weeks and then two or five additional doses monthly. Primary endpoint was drop-out rate due to toxicity, and the secondary endpoint was analysis of immunological response. RESULTS: Treatment was completed in eight (44%) and 16 (89%) patients in groups L and S, respectively. Premature termination occurred due to patient withdrawal or disease progression. No treatment-limiting toxicities occurred in either group. The most common toxicity related to the vaccine was grade 1/2 local injection site reaction. Induction of Ab3 was observed in all evaluable patients. There were no differences between the groups with regard to induction of human anti-mouse antibody (P = 0.1006). IFNgamma-expressing CA125-specific CD8+ T-cells were significantly more frequent in group L, while there was no significant difference between CD4+ T-cells in the two groups. CONCLUSIONS: Abagovomab s.c. vaccination is safe and well tolerated. The long vaccination schedule tended to be more effective with regard to AB3-induction and cellular cytotoxicity.