Last updated on June 2019

A Trial of BXCL701 and Pembrolizumab in Patients With Small Cell Neuroendocrine Prostate Cancer


Brief description of study

An open-label, multicenter, Phase 1b/2 study to determine the composite response rate of BXCL701 administered orally and daily, combined wit PEMBRO, in patients with Small Cell Neuroendocrine Prostate Cancer(SCNC). This study will also assess other efficacy parameters as well as the safety of the combined treatment. This study will consist of two (2) stages. Lead-in Stage, in which the safety and tolerability of the combination will be assessed and confirmed. And the Efficacy Stage, in which patients with SCNC will be treated with BXCL701 combined with PEMBRO.

Detailed Study Description

This is an open-label, multicenter, Phase 1b/2 study to determine the composite response rate of BXCL701 administered orally and daily, combined with PEMBRO, in patients with SCNC. The study will also assess other efficacy parameters, such as rPFS, PSA PFS, OS and DOR, as well as the safety of the combined treatment. The study will consist of 2 stages:

  1. Lead-in Stage - in which the safety and tolerability of the combination of BXCL701 administered once daily (QD) on Days 1 to 14 of a 21-day cycle plus PEMBRO 200 mg administered intravenously (IV) on Day 1 every 21 days will be assessed and confirmed in patients with SCNC. In Cycle 1, the initial dose level of BXCL701 will be 0.4 mg; if there are no safety concerns, this will be escalated to 0.6 mg.
  2. Efficacy Stage (Simon 2-Stage) - in which patients with SCNC will be treated with BXCL701 combined with PEMBRO.

Lead-in Stage:

Patients will be observed for dose-limiting toxicity (DLT) during Cycle 1. Three patients will be treated initially with 0.4 mg BXCL701 plus PEMBRO:

  • If there are no DLTs in Cycle 1, the dose of BXCL701 will be escalated to 0.6 mg in the next cohort of 3 patients.
  • If 1 of the 3 original patients has a DLT in Cycle 1, after a discussion between the sponsor and the investigator, either 3 patients (if 1 patient experiences a DLT) or 6 to 9 patients (if 2 or 3 patients experiences a DLT) will be added at the 0.4 mg BXCL701 dose level. For this expanded 0.4 mg cohort:
  • If less than one-third of the patients experience a DLT, consideration will be given to dose escalation to 0.6 mg BXCL701 plus PEMBRO
  • If one-third of the patients experience a DLT, the Efficacy Stage can commence
  • If more than one-third of the patients experience a DLT, a discussion will be held between the investigators and sponsors as to how to proceed.

Efficacy Stage:

After assessment of the safety and confirmation of the BXCL701/PEMBRO dose schedule (i.e., either 0.6 mg or 0.4 mg BXCL701) to be used in the subsequent stage, the Efficacy Stage will begin. Eligible SCNC patients will receive BXCL701 QD on Days 1 to 14 of a 21-day cycle plus PEMBRO 200 mg administered IV on Day 1 every 21 days.

Clinical Study Identifier: NCT03910660

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Recruitment Status: Open


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