Phase II study of single-agent volasertib (BI 6727) for second-line treatment of urothelial cancer (UC).

Abstract

253 Background: Polo-like kinase 1 (Plk1) controls multiple essential steps of mitosis. Volasertib (BI 6727) is a first-in-class, selective inhibitor of Plk1. In vitro, Plk1 depletion in cancer cells leads to activation of the mitotic checkpoint, prolonged mitotic arrest, and eventually apoptosis. No standard therapy exists for metastatic urothelial cancer (UC) progressing after initial chemotherapy. Thus, there is an urgent need for novel treatment options. Interim efficacy and tolerability results are presented from an open-label, single-arm, multi-center phase II trial of volasertib in patients (pts) with previously treated advanced UC. Methods: Pts progressing after one prior systemic chemotherapy for locally advanced or metastatic UC or relapsing within 2 years of adjuvant/ neoadjuvant treatment received 300 mg volasertib (2-hour intravenous infusion) on day 1 every 21 days. If well tolerated, dose escalation to 350 mg in cycle 2 was encouraged. Primary endpoint was objective tumor response, defined by RECIST. The trial follows a modified Gehan-two-stage design with an early stopping rule based on the observed response rate of the first 20 pts receiving up to 4 courses of treatment. A minimum response rate of 10% (2/20) was required to recommend additional study. Results: This trial is ongoing: 31 pts (median age 67) were treated between December 2009 and August 2010. All pts were eligible for interim safety/efficacy analysis. As of August 2010, 6 pts (19%) demonstrated a partial response, 7 pts (23%) had stable disease and 16 (52%) progressed between 3-6 weeks after study initiation. Thirteen (42%) pts remain on trial between 13-41 weeks (median time on trial 5 months) without disease progression. Major grade 3 or 4 adverse events (irrespective of drug relatedness) were neutropenia (10 pts, 32%), thrombocytopenia (7 pts, 23%), anemia (5 pts, 16%), hyponatremia (3 pts, 10%), dehydration (2 pts, 7%), and urinary tract infection (2 pts, 7%). Conclusions: Single-agent volasertib was well tolerated and demonstrates clinical activity in the second-line treatment of pts with advanced UC. The early signs of clinical benefit allows proceeding per protocol to the second stage of the trial. [Table: see text]