A review of 565 phase II trial abstracts from ASCO 2005: Design characteristics of contemporary trials evaluating cytotoxic versus non-cytotoxic regimens
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6569 Background: New phase II trial designs have been proposed to accommodate the non-cytotoxic nature of molecularly targeted agents. In particular, the use of alternative endpoints and controls has been suggested. The objectives of this survey are to review the designs of contemporary phase II trials, to compare trials of cytotoxic versus non-cytotoxic regimens, and to identify predictors of acceptance for presentation. Methods: Abstracts of phase II trials of systemic anticancer therapy published in the 2005 ASCO Proceedings were hand searched. The trial context, type of intervention, trial design, endpoints, and completeness of reporting were assessed. Results: Our search yielded 565 abstracts: 72% were multi-center, 44% North American, 25% clearly identified as industry-sponsored, the median number of patients was 44 (range 8–346). Only 83% explicitly reported the study phase, 29% the primary endpoint, 11% the number of stages, and 5% the statistical design. For design properties, 16% used multiple arms and 6% used enrichment. Of trials reporting the primary endpoint, 48% used radiological or marker response and 22% time-to-event endpoints. The median number of endpoints was 4 (range 1–8). Non- cytotoxic regimens, which included targeted agents, hormone- or immunotherapy, constituted 22% of the trials reviewed, purely cytotoxic regimens 60%, the remaining 18% contained combinations of both. Trials of non-cytotoxic and combination regimens were more likely to report the primary endpoint (p=0.02), use time-to-event endpoints (p=0.006), have multiple arms, use enrichment, be conducted in North America, be industry-sponsored, and be accepted for oral or poster presentation (all p<0.001). Other predictors of publication type in multivariate analysis were multi-centricity, higher number of patients, industry involvement, and being conducted in North America (all p<0.05). Conclusions: Design properties of contemporary phase II trials of non-cytotoxic agents differ from trials of cytotoxic chemotherapy, and are more likely to be accepted for presentation at ASCO. Proposed new trial designs start to be more widely adopted. Most abstracts incompletely report design properties. No significant financial relationships to disclose.
