Iadademstat in Combination With Paclitaxel in Relapsed/Refractory SCLC and Extrapulmonary High Grade NET

Patients with SCLC or extrapulmonary high grade neuroendocrine carcinomas with progression on or after platinum-based chemotherapy will be enrolled on this multi-center, single-arm phase II study. Patients must have histologically proven metastatic/unresectable SCLC or extrapulmonary G3 NEC (Ki-67 index \> 20% with poorly differentiated histology), or metastatic/unresectable prostate or bladder cancer with high-grade neuroendocrine or small cell component. Patients must have received at least 1, but no more than 3 prior lines of therapy, which must include a platinum based agent. Patients will be treated with iadademstat given at a dose of 150 microgram PO administered on a 5 day on-2 day off schedule every week and weekly paclitaxel at a dose of 80 mg/m2 IV). This fix dose of 150 microgram (liquid formulation) is in line with the 90 mg /m2/d BSA adjusted dose selected as RP2D in a 5d on, 2d off weekly schedule for iadademstat liquid formulation in combination with azacitidine per the ALICE AML Ph2 trial that showed to consistently achieve on average 90% target engagement. A safety lead-in phase with 12 patients will be conducted and these patients will be included in the final analysis. total of 42 patients with SCLC (21 patients) and G3 NEC (21 patients) will be enrolled (including those enrolled in the safety lead-in portion).