Recruiting
Phase 1

IMA203 & mRNA-4203

Sponsor:

Immatics US, Inc.

Code:

NCT06946225

Conditions

Cutaneous Melanoma

Synovial Sarcoma

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Interventions

IMA203

mRNA-4203

Study Details

Brief summary:

This purpose of this clinical trial is to evaluate the safety, tolerability and anti-tumor activity of IMA203 in combination with different doses of mRNA-4203. The trial includes participants with previously treated unresectable or metastatic cutaneous melanoma (CM) or synovial sarcoma (SS).

Conditions

Cutaneous Melanoma

Synovial Sarcoma

Study ID

NCT06946225

Start date

Jul 25, 2025

Status verified date

Jan, 2026

Completion date

Aug, 2029

Anticipated

Primary completion date

Aug, 2029

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Inclusion Criteria:

  • Pathologically confirmed and documented cutaneous melanoma (CM) or synovial sarcoma (SS) with unresectable or metastatic disease
  • HLA-A\*02:01 positive
  • Adequate selected organ function per protocol
  • Eastern Cooperative Oncology Group (ECOG) performance status 0-1
  • Measurable disease according to Response Evaluation Criteria in Solid Tumors (RECIST 1.1)
  • Life expectancy more than 5 months
  • CM participants who must have disease progression (resistance, toxicity) on or after at least one PD-1 inhibitor
  • SS participants must have received (or declined) at least one line of treatment (including SoC) and are still in need of further systemic therapy.
  • Female participants of childbearing potential must use adequate contraception prior to trial entry until 12 months after the infusion of IMA203 and 15 days after the last mRNA 4203 dose administration

Other protocol defined inclusion criteria could apply

Exclusion Criteria:

  • History of other malignancies (except for adequately treated basal or squamous cell carcinoma or carcinoma in situ) within the last 3 years
  • Pregnant or breastfeeding
  • Serious autoimmune disease
  • History of cardiac conditions as per protocol
  • Prior allogenic stem cell transplantation or solid organ transplantation
  • Concurrent severe and/or uncontrolled medical disease that could compromise participation in the study
  • History of hypersensitivity to cyclophosphamide, fludarabine, or IL-2
  • History of hypersensitivity to mRNA-based medicines
  • Positive for HIV infection or with active hepatitis B virus (HBV) or active hepatitis C virus (HCV) infection
  • Any condition contraindicating leukapheresis
  • Participants with lactate dehydrogenase (LDH) greater than threshold allowed per protocol
  • Participants with active brain metastases prior to lymphodepletion
  • Concurrent treatment in another clinical trial or a device trial that could interfere with the IMA203 treatment
  • Participants with renal impairment AND reduced bone marrow reserve per protocol

Other protocol defined exclusion criteria could apply

Study Design

Enrollment

15 participants

Anticipated

Intervention Model

Single group

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: IMA203 with mRNA-4203 in participants with metastatic cutaneous melanoma or synovial sarcoma

This is a non-comparative, open-label trial with different cohorts investigating IMA203 in combination with mRNA-4203.

Interventions

IMA203

Following non-myeloablative chemotherapy for lymphodepletion (LD) with fludarabine (FLU) and cyclophosphamide (CY), participants will receive a single infusion of IMA203 on Day 1 and adjunctive therapy with low dose interleukin (IL)-2 for up to 10 days, starting approximately 24 h after IMA203 infusion.

mRNA-4203

mRNA-4203 will be administered starting on Day 15 after IMA203 infusion at the earliest. mRNA-4203 will be given for 12 cycles (28 day cycle length); during Cycle 1 it will be given on Day 1 and Day 15 and in Cycles 2-12 it will be given on Day 1.

Primary outcome measure

  • Number of participants with dose-limiting toxicities (DLTs) [ Time Frame: one year post infusion of IMA203 ]
  • Number of treatment emergent adverse events (AEs), AEs of special interest, serious AEs (SAEs), changes in laboratory parameters and vital signs, and frequency of dose interruptions, reductions and discontinuations [ Time Frame: one year post infusion of IMA203 ]

Central Contacts and Locations

Central contacts

Immatics US, Inc.

+1 346 204-5400ctgovinquiries@immatics.com

Locations

University of California San Francisco

Recruiting

San Francisco, California, United States, 94143

Contacts

Adil Daud, MD

hdfccc.cip@ucsf.edu

Dana Farber Cancer Institute

Recruiting

Boston, Massachusetts, United States, 02215

Contacts

Sydney Srnka

sydney_srnka@dfci.harvard.edu

Memorial Sloan Kettering Cancer Center

Recruiting

New York, New York, United States, 10065

Contacts

James Smithy, MD

smithyj@mskcc.org

MD Anderson Cancer Center

Recruiting

Houston, Texas, United States, 77030

Contacts

Dejka Araujo, MD

daraujo@mdanderson.org

Rodabe Amaria, MD

RNAmaria@mdanderson.org

More Information

Sponsor

Immatics US, Inc.

Last update posted

Jan 8, 2026

Last verified

Jan, 2026

Keywords

  • immunotherapy
  • T-cell therapy
  • cutaneous melanoma
  • synovial sarcoma
  • RNA vaccine
  • Immatics
  • Moderna

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-09. This information was provided to ClinicalTrials.gov by Immatics US, Inc. on 2026-01-08.