Last reviewed 2026-04-23 · How we verify

IMA203

IMA203 is a T-cell engager that redirects patient T cells to recognize and kill cancer cells expressing the PRAME antigen.

IMA203 is a T-cell engager that redirects patient T cells to recognize and kill cancer cells expressing the PRAME antigen. Used for PRAME-positive melanoma, PRAME-positive solid tumors.

At a glance

Mechanism of action

IMA203 is a bispecific antibody construct that simultaneously binds to CD3 on T cells and to PRAME (preferentially expressed antigen in melanoma), a tumor-associated antigen present on various cancers. By bridging T cells directly to PRAME-expressing tumor cells, it activates and redirects cytotoxic T-cell killing against cancer cells. This approach leverages the patient's own immune system to target malignant cells.

Approved indications

• PRAME-positive melanoma
• PRAME-positive solid tumors

Common side effects

• Cytokine release syndrome
• Fatigue
• Fever
• Infusion-related reactions

Key clinical trials

• ACTengine® IMA203/IMA203CD8 as Monotherapy or in Combination With Nivolumab in Recurrent and/or Refractory Solid Tumors (PHASE1, PHASE2)
• SUPRAME-ACTengine® IMA203 vs. Investigator's Choice of Treatment in Previously Treated, Unresectable or Metastatic Cutaneous Melanoma (PHASE3)
• ACTengine® IMA203 Combined With mRNA-4203 (PHASE1)

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• IMA203 CI brief — competitive landscape report
• IMA203 updates RSS · CI watch RSS
• Immatics US, Inc. portfolio CI