Phase II trial of brentuximab vedotin in relapsed/refractory germ cell tumors

Abstract

Background: CD-30 is highly expressed in some patients with non-seminomatous germ-cell tumors. Brentuximab vedotin is an antibody–drug conjugate directed to CD-30. We report a phase 2 trial of brentuximab vedotin in patients with chemo-refractory GCT.

Patients and methods: This is a single arm, two cohort phase 2 trial investigating brentuximab vedotin 1.8 mg/kg IV every 3 weeks until disease progression or intolerable toxicities in patients with relapsed GCT who have no curative options. Patients with mGCT who progressed after first line cisplatin-based chemotherapy and after at least 1 salvage regimen (high-dose or standard-dose chemotherapy) were eligible. CD30 expression was assessed and two cohorts defined: CD30 positive and CD30 negative/unknown.

Results: 18 patients were enrolled. Median age 34.7 (range, 23–56). All patients had non-seminoma. Median AFP 4.9 (range, 1–219,345) and hCG 282 (range, 0.6–172,064). Five patients had late relapse (> 2 years). Median number of previous chemotherapy regimens was 3 (range, 2–7). Ten patients received prior high-dose chemotherapy. Seven patients had positive CD30 staining. There were two grade 3 treatment-related adverse events. No partial or complete responses were observed. 6 patients achieved radiographic stable disease (range, 9–14.9 weeks), 5 had elevated AFP or hCG at trial entry and all 5 had transient > 50% decline in baseline AFP/hCG: 4 had CD30 −ve and 2 had CD30 + ve staining; 10 patients had progression of disease as their best response; 2 were not evaluable for response.

Conclusion: Brentuximab vedotin does not appear to have clinically meaningful single-agent activity in patients with refractory GCT.