Testing GS-2121 alone or with zimberelimab in adults with advanced solid tumors

A Phase 1 Study to Evaluate the Safety and Tolerability of GS-2121 as Monotherapy and in Combination in Adults With Advanced Solid Tumors

PHASE1 · Gilead Sciences · NCT06532565

This study is testing a new treatment called GS-2121, alone and with another drug called zimberelimab, to see how safe it is for adults with advanced solid tumors.

Quick facts

PhasePHASE1
Study typeInterventional
Enrollment154 (estimated)
Ages18 Years and up
SexAll
SponsorGilead Sciences (industry)
Drugs / interventionschemotherapy, immunotherapy, radiation, zimberelimab
Locations6 sites (Palo Alto, California and 5 other locations)
Trial IDNCT06532565 on ClinicalTrials.gov

What this trial studies

This first-in-human study aims to evaluate the safety and dosing of GS-2121, both as a standalone treatment and in combination with zimberelimab, in adults suffering from advanced solid tumors. The primary objectives include assessing the safety and tolerability of these treatments and determining the maximum tolerated dose and recommended phase 2 dose for both monotherapy and combination therapy. Participants will be closely monitored for adverse effects and treatment responses throughout the study.

Who should consider this trial

Good fit: Ideal candidates include adults with confirmed advanced solid tumors that have progressed despite standard therapies or who are intolerant or ineligible for such treatments.

Not a fit: Patients who are currently receiving prohibited medications or those with ongoing anti-cancer therapies may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide a new treatment option for patients with advanced solid tumors who have limited alternatives.

How similar studies have performed: While this approach is novel, similar studies involving combination therapies for advanced solid tumors have shown promising results in the past.

Eligibility criteria

Show full inclusion / exclusion criteria
Key Inclusion Criteria:

* Participants diagnosed with histologically or cytologically confirmed advanced solid tumors who have progressed despite standard therapy, are intolerant to standard therapy, or are ineligible for standard therapy.
* Measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 criteria.
* Eastern Cooperative Oncology Group (ECOG) performance status 0 to 1.
* Tissue requirements:

  1. Parts A-D: Pre-treatment tumor tissue is required.
  2. Parts A and C backfill cohorts: Participants must agree to fresh pre- and on-treatment biopsies.
* Adequate organ function.

Key Exclusion Criteria:

* Positive serum pregnancy test or participant who is breastfeeding.
* Requirement for ongoing therapy with any prohibited medications.
* Any anti-cancer therapy, whether investigational or approved within protocol specified time prior to initiation of study including: major surgery (\<4 weeks), experimental therapy (\<21 days or \<5 half-lives whichever is shorter), approved immunotherapy or biologic therapy (\<28 days), approved chemotherapy (\<21 days or \<42 days for mitomycin or nitrosoureas), approved targeted small molecule therapy (\<14 days or \<5 half-lives whichever is longer), hormonal therapy or other adjunctive therapy for cancers other than cancer under evaluation in this study (\<14 days) or radiation therapy (\<21 days).
* Any prior allogeneic tissue/solid organ transplantation, including allogeneic stem cell transplantation.
* Have not recovered (ie, returned to Grade 1 or baseline) from AEs due to a previously administered agent.
* Have known active central nervous system (CNS) metastases and/or leptomeningeal disease (LMD).
* Diagnosis of immunodeficiency, either primary or acquired.
* History of autoimmune disease or active autoimmune disease that has required systemic treatment within 2 years prior to the start of study treatment.
* Have an active second malignancy.
* Active and clinically relevant bacterial, fungal, or viral infection that is not controlled or requires systemic antibiotics, antifungals, or antivirals, respectively.
* History of pneumonitis requiring treatment with corticosteroids, interstitial lung disease, or severe radiation pneumonitis (excluding localized radiation pneumonitis).
* Ascites or pleural effusion that is symptomatic and/or requiring medical intervention.
* Have active hepatitis B virus (HBV) or hepatitis C virus (HCV), or HIV.
* Meet any of the following criteria for cardiac disease: Myocardial infarction or unstable angina pectoris within 6 months of enrollment. History of serious ventricular arrhythmia (ie, ventricular tachycardia or ventricular fibrillation), high-grade atrioventricular block, or other cardiac arrhythmias requiring antiarrhythmic medications (except for atrial fibrillation that is well controlled with antiarrhythmic medication). Mean QT interval corrected for heart rate using the Fridericia's formula (QTcF) ≥ 470 msec. New York Heart Association Class \> III congestive heart failure or known left ventricular ejection fraction \< 40%.
* Live vaccines within 28 days of initiation of study drug(s).

Note: Other protocol defined Inclusion/Exclusion criteria may apply.

Where this trial is running

Palo Alto, California and 5 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Advanced Solid Tumors

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.