An open label phase II trial of the Plk1 inhibitor BI 2536, in patients with sensitive relapse small cell lung cancer (SCLC)

Abstract

8108 Background: BI 2536 is a potent, selective inhibitor of polo-like kinase 1 (Plk1), a regulator of mitotic progression. BI 2536 demonstrated favorable tolerability and antitumor activity in phase I trials. We investigated the antitumor efficacy, safety and PK of BI 2536 in patients (pts) with sensitive relapse SCLC. Methods: This open label single arm phase II study followed a Gehan two-stage design. Primary objective was to determine the antitumor efficacy of BI 2536 in SCLC pts with disease recurrence ≥60 days after completion of first-line chemotherapy. 18 pts had to complete 2 courses to be evaluable for stage 1 analysis. In case of ≥2 partial or complete antitumor responses (RECIST criteria), stage 2 accrual would continue until 40 pts were entered. Patients received 200 mg BI 2536 as a 1h i.v. infusion on Day 1 every 3 weeks. Dose escalation to 250 mg (cycle 3 onwards) was encouraged in pts with <Grade 2 drug related non-hematologic and <Grade 3 hematologic toxicity. Results: 23 pts (14 female, 9 male, 21 extensive disease, 2 limited disease), median age 60 yrs (range: 35–77) were treated. All patients had disease recurrence >60 days after completion of first-line therapy. Of 23 pts, no objective antitumor responses were observed, 7 had stable disease as best response, 14 had progression, 2 were not evaluable. A median of 2 courses were given, up to a maximum of 12 in 1 pt. The PFS rate at 3 months was 25%. Due to the lack of antitumor responses, trial accrual was terminated after stage 1. Overall, BI 2536 was well tolerated. Frequent AEs were neutropenia (48%), fatigue (39%), nausea (30%), anemia, vomiting, constipation (26% each), and thrombocytopenia (22%). Drug related grade 3/4 AEs were neutropenia (13%/26%), grade 3/4 thrombocytopenia (1 pt each), grade 3/4 anemia (1 pt each), grade 4 sepsis (1 pt), Grade 4 ARDS (1 pt) and Grade 3 fatigue (1 pt). PK analyses indicate that BI 2536 has high clearance (>1,000 mL/min) and quickly distributes in multiple compartments in a large volume of distribution (>1,000 L). Estimated elimination half-life was >25 h. Conclusions: BI 2536 was well tolerated in relapsed SCLC pts, but demonstrated no convincing antitumor efficacy after stage I of the study. Therefore, BI 2536 will not be assessed further as a single agent in SCLC. [Table: see text]