An open-label, phase II study of the polo-like kinase-1 (Plk-1) inhibitor, BI 2536, in patients with relapsed small cell lung cancer (SCLC)

- BI 2536 inhibits polo-like kinase 1 (Plk-1), a critical regulator of the cell cycle.
- Plk inhibitors prevent growth of several small cell lung cancer (SCLC) cell lines.
- In this phase II study, BI 2536 was not effective for patients with relapsed SCLC.

ObjectivesThis phase II, open-label study was designed to evaluate the response rate to the polo-like kinase 1 (Plk-1) inhibitor BI 2536 in patients with sensitive-relapsed small cell lung cancer (SCLC). Secondary endpoints included progression-free survival (PFS), overall survival (OS), duration of response, and safety.Materials and methodsPatients were treated with the recommended phase II dose of 200 mg of BI 2536 intravenously every 21 days. This was a two-stage design with an early stopping rule in place if responses were not seen in at least 2 of the first 18 enrolled patients.Results and conclusionTwenty-three patients were enrolled in the study and 21 patients were evaluable for response. No responses were observed and all 23 patients have progressed. The median PFS was 1.4 months. Treatment was generally well tolerated and the most frequent adverse events were neutropenia, fatigue, nausea, vomiting, and constipation. BI 2536 is not effective in the treatment of sensitive relapsed SCLC. The criteria for expanding the trial to the second stage were not achieved, and the study was terminated for a lack of efficacy.