Randomized phase II study of carboplatin and etoposide with or without obatoclax mesylate in extensive-stage small cell lung cancer

•Addition of obatoclax to standard regimen failed to significantly improve outcome.•Clinical benefit (ORR+stable disease) trended better with addition of obatoclax.•The obatoclax-based regimen was well tolerated.•A biomarker-determined population may reveal potential improvement in outcomes.