Phase 1, First-in-human, Dose-finding and Expansion Study to Evaluate XmAb®808 in Combination With Pembrolizumab in Advanced Solid Tumors

August 5, 2025 updated by: Xencor, Inc.

A Phase 1, First-in-Human, Dose-Finding and Expansion Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Activity of XmAb®808 in Combination With Pembrolizumab in Selected Advanced Solid Tumors

The purpose of this study is to evaluate the safety, tolerability, and pharmacokinetics of intravenous (IV) administration of XmAb808 in combination with pembrolizumab in subjects with selected advanced solid tumors and to identify the minimum safe and biologically effective/recommended dose (RD) and schedule for XmAb808.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

This is a Phase 1, open-label, first-in-human (FIH), multiple-dose, dose escalation study with cohort expansion at the RD, designed to evaluate the safety and tolerability of XmAb808 in combination with pembrolizumab. This study will be conducted in 2 parts: Part A (dose escalation) and Part B (cohort expansion).

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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 Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • United States
    • California
      • Los Angeles, California, United States, 90095
        • UCLA Hematology/Oncology
    • Colorado
      • Denver, Colorado, United States, 80218
        • Sarah Cannon Research Institute at HealthOne
    • Florida
      • Sarasota, Florida, United States, 34232
        • Florida Cancer Specialists
    • Georgia
      • Atlanta, Georgia, United States, 30322
        • Winship Cancer Institute, Emory University
    • Illinois
      • Chicago, Illinois, United States, 60611
        • Northwestern Memorial Hospital
    • New York
      • New York, New York, United States, 10032
        • Columbia University Irvine Medical Center
    • Ohio
      • Cincinnati, Ohio, United States, 45219
        • University of Cincinnati Medical Center
    • Pennsylvania
      • Pittsburgh, Pennsylvania, United States, 15213
        • UPMC Hillman Cancer Center
    • Tennessee
      • Nashville, Tennessee, United States, 37203
        • Tennessee Oncology
    • Texas
      • Houston, Texas, United States, 77030
        • The University of Texas MD Anderson Cancer Center
    • Utah
      • Salt Lake City, Utah, United States, 84112
        • Huntsman Cancer Institute, University of Utah
    • Wisconsin
      • Milwaukee, Wisconsin, United States, 53226
        • Froedtert Hospital & the Medical College of Wisconsin

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Key Inclusion Criteria:

  • Part A: Histologically confirmed advanced/metastatic castration-resistant prostate adenocarcinoma, epithelial ovarian cancer, head and neck squamous cell carcinoma, non-small cell lung cancer, urothelial carcinoma, melanoma, renal cell carcinoma, triple-negative breast cancer, or colorectal cancer that has progressed on standard therapies
  • Part B: Histologically confirmed advanced/metastatic castration-resistant prostate cancer that is PD1-naïve; head and neck squamous cell carcinoma that is PD1-naïve or has progressed on prior PD1 therapy; or melanoma that is PD1-naïve or has progressed on prior PD1 therapy
  • Measurable disease by RECIST 1.1; subjects with prostate cancer who have evaluable disease according to PCWG3 criteria may enroll
  • Life expectancy > 3 months
  • Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

Key Exclusion Criteria:

  • Subjects currently receiving other anticancer therapies
  • Any prior treatment with an investigational agent targeting CD28
  • History of a life-threatening adverse event related to prior immunotherapy
  • Known active central nervous system involvement by malignant disease. Subjects with previously treated brain metastases may participate provided they are radiologically and clinically stable

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: N/A
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Dose Escalation and Expansion XmAb®808 administered in combination with pembrolizumab
XmAb®808 in combination with pembrolizumab
Biological: XmAb®808
Monoclonal bispecific antibody
Biological: Keytruda® (pembrolizumab)
Monoclonal antibody

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Incidence of treatment-emergent adverse events (TEAEs)
Time Frame: Up to 5 years
Safety and tolerability as assessed by incidence of TEAEs, including clinically significant changes in safety laboratory tests and clinical findings
Up to 5 years
Incidence of dose-limiting toxicities (DLTs)
Time Frame: 49 days
Safety and tolerability as assessed by incidence of DLTs and all available data which will be used to determine the optimal dose regimen
49 days

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Measurement of Cmax
Time Frame: Through study completion, Up to 5 years
Peak plasma concentration (Cmax)
Through study completion, Up to 5 years
Measurement of AUCtau
Time Frame: Through study completion, Up to 5 years
Area under the plasma concentration versus time curve (AUCtau)
Through study completion, Up to 5 years
Objective Response Rate
Time Frame: Through study completion, Up to 5 years
Objective response rate by RECIST 1.1 assessment of CT/MRI imaging, as modified by PCWG3 for participants with prostate cancer
Through study completion, Up to 5 years
Progression-free Survival
Time Frame: Through study completion, Up to 5 years
Progression-free survival by RECIST 1.1 assessment of CT/MRI imaging, as modified by PCWG3 for participants with prostate cancer
Through study completion, Up to 5 years
Duration of Response
Time Frame: Through study completion, Up to 5 years
Duration of Response by RECIST 1.1 assessment of CT/MRI imaging, as modified by PCWG3 for participants with prostate cancer
Through study completion, Up to 5 years

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Xencor, Inc.

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Mira Kistler, MD, Xencor, 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 (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 14, 2022

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
May 20, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
May 20, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
October 11, 2022

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 13, 2022

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 18, 2022

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 7, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 5, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
August 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • XmAb808-01

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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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