A phase 2 multicenter study of tivantinib (ARQ 197) monotherapy in patients with relapsed or refractory germ cell tumors

Summary: Background Tivantinib is a selective, small-molecule inhibitor of the MET receptor tyrosine kinase. Preclinical and phase 1 data suggested a possible role for MET in the pathophysiology of germ cell tumors (GCTs) and a potential clinical benefit from tivantinib in patients with these tumors. Methods Men (≥16 years) with relapsed or refractory, histologically confirmed, non-central nervous system GCTs received oral tivantinib 360 mg twice daily in 28-day cycles until progressive disease or unacceptable toxicity. The primary endpoint was objective response rate in the first 4 cycles, with study termination for <2 responses among the first 21 patients. Secondary endpoints included 12-week progression-free survival (PFS), overall survival (OS), and safety. Results Twenty-seven patients were enrolled in 9 months (median age, 32 years). Most patients had tumors with nonseminoma histology (n = 25), and primary tumor sites were testis (n = 24) and mediastinum (n = 3). Among 25 evaluable patients, no objective responses were observed; accrual was halted when the 21st patient became evaluable. Best response was stable disease (n = 5). Median PFS was 1 month, the 12-week PFS rate was 21 %, and median OS was 6 months. Grade 3 or 4 adverse events considered related to study drug included grade 3 pneumonia and grade 3 syncope (n = 1, each). Conclusions Tivantinib was well tolerated but did not demonstrate single-agent activity in patients with relapsed/refractory GCTs. Rapid accrual to this phase 2 trial was achieved in this rare patient population through multicenter collaboration.