A Phase 1 Study in Patients With Metastatic Castration-Resistant Prostate Cancer

July 17, 2026 updated by: Flare Therapeutics Inc.

A Phase 1, First-in-Human, Dose-Finding Study to Evaluate the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of FX-111 in Patients With Metastatic Castration-Resistant Prostate Cancer

The goal of this clinical trial is to find out if FX-111 is safe enough to permit further studies in adult male participants with metastatic castration-resistant prostate cancer (mCRPC). It will also study the drug's pharmacokinetics (how the body breaks down FX-111) and how well FX-111 treats mCRPC. The main questions it aims to answer are:

What are the side effects of FX-111?

Does FX-111 work to reduce or prevent progression of mCRPC?

The study doctor will oversee participants' treatment with FX-111 and ask about any side effects. Participants will take FX-111 every day by mouth and will have regular physical and laboratory examinations to check health and tumor status.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

60

Phase

  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Janine Koucheki, Associate Director, Clinical Operations
  • Phone Number: 857-706-4400
  • Email: clinops@flaretx.com

Study Contact Backup

  • Name: Carolyn McCrone, Sr Clinical Trial Associate
  • Phone Number: 857-706-4400
  • Email: clinops@flaretx.com

Study Locations

  • United States
    • California
      • Los Angeles, California, United States, 90025
        • Recruiting
        • START Los Angeles
        • Contact:
        • Principal Investigator:
          • Navid Hafez, MD, MPH
    • Massachusetts
      • Boston, Massachusetts, United States, 02114
        • Not yet recruiting
        • Massachusetts General Hospital
        • Principal Investigator:
          • Xin Gao, MD
    • Michigan
      • Grand Rapids, Michigan, United States, 49546
        • Recruiting
        • START Midwest
        • Principal Investigator:
          • Emerson Lim, MD
        • Contact:
    • New Jersey
      • East Brunswick, New Jersey, United States, 08816
    • South Carolina
      • Myrtle Beach, South Carolina, United States, 29572
    • Tennessee
      • Nashville, Tennessee, United States, 37203
        • Not yet recruiting
        • Tennessee Oncology
        • Principal Investigator:
          • Katy Beckermann, MD, Ph.D.
    • Texas
      • Fort Worth, Texas, United States, 76104
        • Recruiting
        • START Dallas-Fort Worth
        • Contact:
        • Principal Investigator:
          • Salwan Al Mutar, MD, M.Sc.
      • Houston, Texas, United States, 77054
        • Not yet recruiting
        • NEXT Houston
        • Principal Investigator:
          • Jennifer Segar, MD
      • San Antonio, Texas, United States, 78229
        • Not yet recruiting
        • NEXT Oncology
        • Principal Investigator:
          • Ildefonso Ismael Rodriguez Rivera, MD
    • Virginia
      • Fairfax, Virginia, United States, 22031
        • Not yet recruiting
        • NEXT Virginia
        • Principal Investigator:
          • Mohamad Salkeni, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Confirmed adenocarcinoma of the prostate.
  • PSA levels ≥ 2 ng/mL at screening visit.
  • Progressing PSA, defined as two consecutive increases in the most recent PSA measurements taken at least 1 week apart.
  • Progressed on Androgen Deprivation Therapy (ADT) and at least one prior potent Androgen Receptor (AR) pathway inhibitor given in castration-sensitive prostate cancer setting or approved for castration-resistant prostate cancer (eg, apalutamide, darolutamide, abiraterone, enzalutamide).
  • Ongoing primary ADT with gonadotropin-releasing hormone agonist or antagonist in the absence of bilateral orchiectomy.
  • Acceptable physical functioning and laboratory measurements, per the study protocol.
  • Discontinued prior therapies within protocol-specified timeframes.
  • Commit to use of highly-effective contraception while on study and for 90 days after.
  • Willing and able to adhere to the study visit schedule and other protocol defined requirements.

Exclusion Criteria:

  • Predominance of small cell carcinoma of the prostate/neuroendocrine prostate cancer in most recent tumor biopsy.
  • Participants with brain metastases that require ongoing treatment with radiation or high-dose steroids.
  • Not recovered from side effects of prior surgery or cancer treatments.
  • Evidence of active viral, bacterial, or fungal infection requiring treatment with antivirals, antibiotics, or anti-fungal medications.
  • Prior treatment with AR degraders and molecules with an AR ligand such as AR Regulated Induced Proximity Targeting Chimera (RIPTAC).
  • Blood clots ≤ 4 weeks prior to start of treatment.
  • Concurrent malignancy requiring treatment or history of prior malignancy active within 2 years prior to the first dose of study drug. Patients may be eligible if the malignancy is clinically stable or has been treated with curative intent.
  • Any evidence of severe or uncontrolled systemic diseases.
  • Any condition that, in the opinion of the Investigator, would interfere with evaluation of the investigational product or interpretation of the patient's safety or study results.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: FX-111 Dose Level 1
Drug: FX-111
FX-111 will be administered orally once daily in continuous 28-day cycles.
Experimental: FX-111 Dose Level 2
Drug: FX-111
FX-111 will be administered orally once daily in continuous 28-day cycles.
Experimental: FX-111 Dose Level 3
Drug: FX-111
FX-111 will be administered orally once daily in continuous 28-day cycles.
Experimental: FX-111 Dose Level 4
Drug: FX-111
FX-111 will be administered orally once daily in continuous 28-day cycles.
Experimental: FX-111 Dose Level 5
Drug: FX-111
FX-111 will be administered orally once daily in continuous 28-day cycles.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
The number of adverse events (AEs), serious adverse events (SAEs), and drug withdrawal due to AE in participants receiving FX-111
Time Frame: Study day 1 throughout the study, estimated to be 6 months.
Study day 1 throughout the study, estimated to be 6 months.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Area Under the Concentration Time Curve
Time Frame: Study day 1 throughout the study for 6 months.
Total body exposure of FX-111
Study day 1 throughout the study for 6 months.
Maximum concentration (Cmax) of FX-111 in the bloodstream.
Time Frame: Study day 1 throughout the study for 6 months.
Study day 1 throughout the study for 6 months.
Time required (Tmax) to reach Cmax of FX-111 in the bloodstream.
Time Frame: Study day 1 throughout the study for 6 months.
Study day 1 throughout the study for 6 months.
Rate of confirmed prostate-specific antigen (PSA) decline of ≥ 50% from baseline (PSA50).
Time Frame: Baseline and every 4 weeks throughout the study, estimated to be 6 months.
Baseline and every 4 weeks throughout the study, estimated to be 6 months.
Objective Response Rate (ORR)
Time Frame: Tumor assessments at baseline and every 8 weeks throughout the study, estimated to be 6 months.

The number of patients who achieve either a Complete Response (CR) or Partial Response (PR) to FX-111.

CR: disappearance of all lesions and pathologic lymph nodes. PR: ≥30% decrease in sum of lesions, no new lesions, no progression of non-target lesions.
Tumor assessments at baseline and every 8 weeks throughout the study, estimated to be 6 months.
Duration of Response (DoR)
Time Frame: Tumor assessments at baseline and every 8 weeks throughout the study, estimated to be 6 months.
DoR is the time from initial CR or PR until disease progression.
Tumor assessments at baseline and every 8 weeks throughout the study, estimated to be 6 months.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Flare Therapeutics Inc.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

July 1, 2026

Primary Completion (Estimated)

February 15, 2028

Study Completion (Estimated)

February 15, 2029

Study Registration Dates

First Submitted

July 17, 2026

First Submitted That Met QC Criteria

July 17, 2026

First Posted (Actual)

July 22, 2026

Study Record Updates

Last Update Posted (Actual)

July 22, 2026

Last Update Submitted That Met QC Criteria

July 17, 2026

Last Verified

July 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • FX-111-CLINPRO-1

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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