A multicenter phase II study of irinotecan in combination with G17DT immunogen in subjects with metastatic colorectal adenocarcinoma (CRC) refractory to previous irinotecan-based chemotherapy

3573 Background: G17DT is a novel immunogen that raises antibodies to the growth factor gastrin-17 (G17). The purpose of this study was to determine the safety and efficacy of G17DT in combination with irinotecan in metastatic CRC subjects refractory to previous treatment with irinotecan-based chemotherapy and to correlate this with anti-G17 immune response. Methods: The study was an open-label, multinational, phase II trial in subjects with intact organ function, KPS≥70, and measurable disease. Subjects received irinotecan 125 mg/m2/90 min wk 5–8 q42 days. 500 μg G17DT was administered I.M. wk 1, 5, 9 with a booster at wk 26. Results: 158 subjects received G17DT, with 98 evaluable for tumor response. Best overall response was: CR (0%), 3 PR (3%), 32 SD (33%), and 63 PD (64%). Median survival was 219 days. 103 (69%) of subjects evaluable for antibody titers were immune responders (i.e., had at least one anti-G17 antibody titer ≥1 ELISA unit). Non-whites (95%) were more likely to be immune responders than ...