Successful implementation of the Randomized discontinuation trial design: An application to the study of the putative antiangiogenic agent carboxyaminoimidazole in renal cell carcinoma CALGB 69901

Purpose To assess the disease-stabilizing activity of carboxyaminoimidazole (CAI) in patients with metastatic renal cell cancer (RCC) using a randomized discontinuation trial (RDT) design. Patients and Methods Recruited patients had a performance status of 0 to 2, minimal neuropathy or cerebellar dysfunction, measurable disease, and normal organ function. Treatment with 250 mg/d CAI was initiated in all patients and continued until disease progression in those with an objective response. Protocol treatment was discontinued for unacceptable toxicity or progressive disease, patients with stable disease at the 16-week evaluation point were randomly assigned in a double-blind manner to continued CAI or placebo. The primary end point was the stable disease rate in the randomized groups. Results A total of 368 patients were accrued and received therapy. Ninety percent had a performance status of 0 or 1, 80% underwent a prior nephrectomy, and 41 % had received no prior systemic therapy. Serious or life-threatening toxicity was experienced by 34%, with asthenia (15%) and neuropsychiatric difficulties (7%) being most common. At the randomization point, 51 % of patients had progressed, 30% withdrew, I % experienced a partial response, and 17% had stable disease and were randomly assigned. A Bayesian futility analysis utilizing the first 49 randomly assigned patients suggested that the probability of demonstrating a higher stable disease rate in the experimental group was less than 9% even under the most optimistic a priori assumptions, and further trial accrual was halted. Conclusion CAI is inactive in BCC, The RDT design should be further explored for evaluating activity of putative disease stabilizing agents.