First In Human Study of CX-801 in Advanced Solid Tumors

August 27, 2026 updated by: CytomX Therapeutics

An Investigational Study of CX-801 as Monotherapy and in Combination With PD1 Inhibition in Participants With Solid Tumors

The purpose of this first-in-human study, CTMX-801-101, is to characterize the safety, tolerability, and antitumor activity of CX-801 as monotherapy and in combination with pembrolizumab in adult participants with advanced solid tumors.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

The study is comprised of 2 parts. Part 1 involves CX-801 dose escalation to identify the maximum tolerated dose (MTD) of CX-801 as monotherapy and as combination therapy (CX-801 combined with pembrolizumab). Part 2 (dose expansion) will further assess safety and tolerability as well as preliminarily assess antitumor activity of CX-801 combination therapy in indication-specific expansion cohorts.

Study Type

Interventional

Enrollment (Estimated)

121

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

Study Locations

  • United States
    • California
      • Los Angeles, California, United States, 90025
        • Recruiting
        • The Angeles Clinic and Research Institute, A Cedars-Sinai Affiliate
    • Colorado
      • Englewood, Colorado, United States, 80113
        • Recruiting
        • The Melanoma and Skin Cancer Institute
    • Pennsylvania
      • Pittsburgh, Pennsylvania, United States, 15232
        • Recruiting
        • University of Pittsburgh Hillman Cancer Center
    • Tennessee
      • Nashville, Tennessee, United States, 37203
        • Recruiting
        • SCRI Oncology Partners
    • Texas
      • Fort Worth, Texas, United States, 76104
        • Recruiting
        • START Dallas Fort Worth, LLC

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:

  • Metastatic or locally advanced unresectable solid tumor that has progressed after standard therapy
  • Eastern Cooperative Oncology Group (ECOG) performance status of 0-1
  • Measurable disease per RECIST v1.1
  • Consent to fresh biopsy or if medically contraindicated, recent (within 6 months) archival tumor tissue
  • Adequate organ function
  • Additional inclusion criteria may apply

Exclusion Criteria:

  • Recent history (within last 2 years) of localized cancers that are not related to the current cancer being treated
  • Known active central nervous system (CNS) involvement by malignancy
  • Prior PD-1/ PD-(L)1 inhibitor treatment discontinued due to grade 3 or higher immune related adverse event
  • Systemic anticancer treatment within 4 weeks or 5 half lives prior to first dose of study treatment
  • Investigational drug or device within 4 weeks prior to first dose of study treatment
  • Radiation within 2 weeks prior to first dose of study treatment
  • Serious concurrent illness
  • Pregnant or breast feeding
  • Additional exclusion criteria may apply

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: CX-801
Drug: CX-801
Investigational drug
Experimental: CX-801 + pembrolizumab
Drug: CX-801
Investigational drug
Drug: pembrolizumab
Standard of Care Therapy
Other Names:
  • KEYTRUDA®

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Determine the recommended Phase 2 dose (RP2D)
Time Frame: 44 months
The number of participants experiencing a dose-limiting toxicity (DLT) as defined in the protocol, AEs (adverse events), and treatment-emergent adverse events (TEAEs) at any dose level
44 months
Safety and tolerability of CX-801 as monotherapy and combination therapy
Time Frame: 44 months
The number of participants experiencing a dose-limiting toxicity (DLT) as defined in the protocol, AEs (adverse events), and treatment-emergent adverse events (TEAEs) at any dose level
44 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Duration of response (DOR)
Time Frame: 60 months
DOR defined as the time from the first documentation of confirmed CR or PR (based on RECIST v1.1) to the first documentation of disease progression or death due to any cause on study, whichever occurs first.
60 months
Progression-free survival (PFS)
Time Frame: 60 months
PFS defined as the time from the first dose of study intervention to the date of first documentation of objective tumor progression (based on RECIST v1.1) or death due to any cause, whichever occurs first.
60 months
Disease control rate (DCR)
Time Frame: 60 months
DCR defined as the proportion of participants with confirmed CR, PR, or stable disease (SD) as per RECIST v1.1 by Investigator assessment.
60 months
Duration of disease control (DODC)
Time Frame: 60 months
DODC defined as the time from the first documentation of confirmed CR, PR, or SD (based on RECIST v1.1) to the first documentation of disease progression or death due to any cause on study, whichever occurs first.
60 months
Objective response rate (ORR)
Time Frame: 60 months
ORR defined as the proportion of participants who achieve a confirmed complete response (CR) or partial response (PR) based on Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 by Investigator assessment.
60 months
Overall survival (OS)
Time Frame: 60 months
OS defined as the time from the first dose of study intervention to death due to any cause.
60 months

Collaborators and Investigators

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

Sponsor

CytomX Therapeutics

Collaborators

Merck Sharp & Dohme LLC

Investigators

  • Study Director: Monika Vainorius, MD, CytomX Therapeutics

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 (Actual)

August 28, 2024

Primary Completion (Estimated)

February 28, 2028

Study Completion (Estimated)

June 30, 2029

Study Registration Dates

First Submitted

June 12, 2024

First Submitted That Met QC Criteria

June 12, 2024

First Posted (Actual)

June 17, 2024

Study Record Updates

Last Update Posted (Actual)

August 28, 2026

Last Update Submitted That Met QC Criteria

August 27, 2026

Last Verified

August 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • CTMX-801-101
  • KEYNOTE-F95 (Other Identifier: Merck Sharp & Dohme LLC)
  • MK-3475-F95 (Other Identifier: Merck Sharp & Dohme LLC)

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.

Subscribe