NCT06946225 · Immatics US, Inc.
ACTengine® IMA203 Combined With mRNA-4203
What this study is about
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).
View original scientific description
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).
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
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
Where
- San Francisco, California
- Boston, Massachusetts
- New York, New York
- Houston, Texas
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jan 8, 2026 · Source of record for eligibility and locations