Southwest Oncology Group S0826: A phase 2 trial of SCH 727965 (NSC 727135, dinaciclib) in patients with stage IV melanoma

Background: Cell cycle inhibition is an established therapeutic approach for some cancers. A multicenter, single-arm, phase 2 trial (ClinicalTrials.gov identifier NCT00937937) of the cyclin-dependent kinase inhibitor SCH 727965 (NSC 747135; dinaciclib) was conducted in patients with metastatic melanoma to determine its clinical activity.

Methods: Patients with metastatic melanoma of cutaneous or mucosal origin were eligible if they had zero to one previous treatments, a Zubrod performance status of 0-1, and adequate organ function. SCH 727965 50 mg/m² was given intravenously every 3 weeks until progression. Co-primary end points were 1-year overall survival (OS) and 6-month progression-free survival (PFS).

Results: Seventy-two patients were enrolled from July 1, 2009, to November 1, 2010, at 24 institutions. Sixty-eight percent of patients had M1c disease, and 43% had elevated lactate dehydrogenase levels. Twenty-eight patients (39%) experienced grade 4 adverse events, including 20 cases of neutropenia. Sixty-seven patients were evaluable for response. There was a response in zero of 67 patients (95% confidence interval [CI], 0%-5%), and stable disease was observed in 21%. The estimated median PFS was 1.4 months (95% CI, 1.4-1.5 months), and the 6-month PFS rate was 6% (2%-13%). The median OS was 8.2 months (95% CI, 5.5-10.5 months), and the 1-year OS rate was 38% (95% CI, 26%-49%).

Conclusions: This multicenter, US National Cancer Institute Cancer Therapy Evaluation Program-sponsored trial of SCH 727965 was conducted at a time when the current generation of effective therapies for melanoma were not available. Although the null hypothesis of 1-year OS was rejected, the minimal PFS impact and substantive toxicity indicated that this regimen lacks justification for further investigation as a single agent.