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BXCL701 plus Pembrolizumab

Phase 1

Prostate Cancer | Small molecule | Oncology |BioXcel Therapeutics, Inc.|Last Updated: May 15, 2026

Target and mechanism

ModalitySmall molecule

Also known as BXCL701

Success Probability

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Market & Valuation

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Trial Design

RandomizedCONTROLLEDDMC
Total Trials1
Total Enrollment98

FDA Designations

FAST_TRACKORPHAN_DRUG

Clinical trial landscape

BXCL701 plus Pembrolizumab · 1 trial · 3 indications

Phase 1 1
NCT03910660A Trial of BXCL701 and Pembrolizumab in Patients With mCRPC Either Small Cell Neuroendocrine Prostate Cancer or Adenocarcinoma Phenotype.Prostate Cancer
COMPLETED98 Analytics
PHASE1COMPLETED
A Trial of BXCL701 and Pembrolizumab in Patients With mCRPC Either Small Cell Neuroendocrine Prostate Cancer or Adenocarcinoma Phenotype.
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Study Endpoints

Primary Endpoints

Phase 2a: Estimate the composite response rate of the combination of BXCL701 + PEMBRO
up to 36 months

Response Evaluation Criteria In Solid Tumors (RECIST) 1.1 criteria; circulating tumor cell (CTC) conversion from \>5/7.5 mL to \<5/7.5 mL per Veridex assay; and 50% or greater prostate-specific antigen (PSA) decline from baseline.

Phase 2b: Evaluate response rates in patients treated with the combination of BXCL701 + PEMBRO and with BXCL701 monotherapy
up to 36 months

To evaluate the response rates, defined by RECIST 1.1 criteria, by histologic subtype in patients treated with the combination of BXCL701 + PEMBRO and with BXCL701 monotherapy.

Secondary Endpoints

Phase 2a: Estimate the median radiographic progression-free survival (rPFS) of the combination of BXCL701 and PEMBRO in Cohort A and B
up to 36 months
Phase 2a: Estimate the median PSA progression-free survival (PSA PFS) of the combination of BXCL701 and PEMBRO in Cohort A and B.
up to 36 months
Phase 2a: Estimate the median overall survival (OS) of the combination of BXCL701 and PEMBRO in Cohort A and B.
up to 36 months
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Study Design & Arms

AllocationRANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Phase 1bOTHERPatients will be observed for dose-limiting toxicity (DLT) during Cycle 1. 3 patients will be treated initially with 0.4 mg BXCL701 plus PEMBRO: If there are no DLTs, the dose of BXCL701 will be escalated to 0.6 mg in the next cohort. If ≥1/3 of patients has a DLT in Cycle 1, either 3 patients (if 1 experience a DLT) or 6 to 9 patients (if 2 or 3 experiences a DLT) will be added at the 0.4 mg dose. At the 0.4mg dose: If \<1/3 of the patients experience a DLT, consideration will be given to dose to 0.6 mg BXCL701 plus PEMBRO. If 1/3 of the patients experience a DLT, the Phase 2a can commence. If \>1/3 of the patients experience a DLT, a discussion will be held as to how to proceed. Following 0.6 mg dose. If there are no DLTs, the Phase 2a can commence. If ≥1/3 patients have a DLT in Cycle 1, after a discussion, 6 to 9 patients will be added at the 0.6 mg dose. For this cohort of 6 to 9 patients: If \</=1/3 of the patients experience a DLT, the Phase 2a can commence
Phase 2aOTHERAfter assessment of the safety and confirmation of the BXCL701/+PEMBRO dose schedule to be used in the subsequent stage, the Phase 2a will begin. Eligible 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.
Phase 2b combinationOTHERUpon completion of the Phase 2a and achievement of the protocol required composite responses for a given histologic subtype, the Phase 2b enrollment will begin for that subtype. Eligible patients will be randomized to receive: • Combination therapy of BXCL701 on Days 1 to 14 of a 21-day cycle plus PEMBRO 200 mg administered IV on Day 1 of every 21 days.
Phase 2b monotherapyOTHERUpon completion of the Phase 2a and achievement of the protocol required composite responses for a given histologic subtype, the Phase 2b enrollment will begin for that subtype. Eligible patients will be randomized to receive: * Monotherapy BXCL701 on Days 1 to 14 of a 21-day cycle. Upon radiographic disease progression with monotherapy, crossover to combination treatment is allowed.

Interventions

NameTypeDescription
BXCL701 plus PembrolizumabDRUGBXCL701 tablets dosage strengths include 0.05mg and 1mg tablets for oral administration. BXCL701 will be administered orally as 0.05mg and 1mg tablets. Patients will take the prescribed number of tablets on Days 1 to 14 of each cycle, for a total daily dose of 0.4 mg, 0.6 mg, or an intermediate dose. BXCL701 will be continued until PD or unacceptable toxicity, or closure of the study by the sponsor; no maximum duration of therapy has been set. BXCL701 should not be taken on an empty stomach. On days when PD studies are being performed, BXCL701 should be administered at the study center and should be administered at approx. the same time of day on each treatment day in the cycle. In cycles in which PD are not evaluated, BXCL701 also should be administered at approx. the same time of day on each treatment day. The PEMBRO dose will be 200 mg, administered as an IV infusion over 30 mins. on Day 1 of each 21-day cycle.
BXCL701 monotherapyDRUGBXCL701 tablets dosage strengths include 0.05mg and 1mg tablets for oral administration. BXCL701 will be administered orally as 0.05mg and 1mg tablets. Patients will take the prescribed number of tablets on Days 1 to 14 of each cycle, for a total daily dose of 0.4 mg, 0.6 mg, or an intermediate dose. BXCL701 will be continued until PD or unacceptable toxicity, or closure of the study by the sponsor; no maximum duration of therapy has been set. BXCL701 should not be taken on an empty stomach. On days when PD studies are being performed, BXCL701 should be administered at the study center and should be administered at approx. the same time of day on each treatment day in the cycle. In cycles in which PD are not evaluated, BXCL701 also should be administered at approx. the same time of day on each treatment day.
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Eligibility Criteria

Age Range18 Years to N/A
SexMALE
Healthy VolunteersNo
Study Sites12

Inclusion Criteria: All patients must satisfy the following inclusion and exclusion criteria to be eligible for entry into the trial. 1. Patient has evidence of progressive, metastatic castration-resistant disease, as defined by PCWG3 criteria. a. Patients with de novo small cell prostate canc...

Countries:United StatesUnited Kingdom
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Competitive Landscape -Prostate Cancer 254 trials

Recent Changes (Last 90 Days)

MEDIUMJun 15, 2026NCT03910660TRIAL_REMOVED: changed

Frequently asked questions about BXCL701 plus Pembrolizumab

What is BXCL701 used for?

BXCL701 is an investigational small molecule being studied for the treatment of metastatic pancreatic ductal adenocarcinoma and prostate cancer. It is currently in Phase 2 clinical development for these oncology indications.

Who makes BXCL701?

BXCL701 is being developed by BioXcel Therapeutics, Inc., a biopharmaceutical company traded on the NASDAQ under the ticker symbol BTAI.

What phase is BXCL701 in?

BXCL701 is in Phase 2 clinical development. It has received Fast Track and Orphan Drug designations from the FDA for its oncology indications.

What clinical trials is BXCL701 in?

BXCL701 is being studied in two clinical trials. NCT03910660 is a completed Phase 1 trial combining BXCL701 with pembrolizumab in patients with prostate cancer. NCT05558982 is an active Phase 2 trial of BXCL701 and pembrolizumab in patients with metastatic pancreatic ductal adenocarcinoma.

Is BXCL701 the same as a drug for neuroendocrine prostate cancer?

BXCL701 has been studied in a Phase 1 trial (NCT03910660) for prostate cancer, including small cell neuroendocrine prostate cancer and adenocarcinoma phenotypes. This trial combined BXCL701 with pembrolizumab and has been completed.