IMA203 PRAME Cell Therapy in Advanced Melanoma
- Phase 1b Dose Expansion Clinical Data Update
May 31, 2025
Data cut-off April 7, 2025
Delivering the Power of T cells to Cancer Patients
© Immatics. Not for further reproduction or distribution.
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Frequent recurrence and limited long-term survival with unresectable or metastatic melanoma highlight the critical need for new treatments that deliver deeper, more durable responses1-3
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IMA203 is a PRAME-directed TCR T-cell therapy engineered to recognize an intracellular PRAME-derived peptide presented by HLA-A*02:01 on the cell surface and initiate a potent and specific anti-tumor response4
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IMA203 exhibited favorable tolerability, with anticipated lymphodepletion-associated cytopenias, mostly mild-to-moderate CRS,
infrequent ICANS, and no IMA203-related grade 5 events
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One-time infusion of IMA203 has promising clinical activity in heavily pretreated patients with metastatic melanoma (n=33):
- cORR: 56% (18/32)
- mDOR: 12.1 mo (range: 1.8+, 32.6+) at mFU of 13.4 mo
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mPFS: 6.1 mo (range: 1.4, 34.0+) at mFU of 14.4 mo
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mOS: 15.9 mo (range: 2.4, 34.2+) at mFU of 14.4 mo
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Encouraging activity was seen in both cutaneous melanoma (cORR 50%) and uveal melanoma (cORR 67%)
1 Mooradian MJ, et al. Oncology (Williston Park). 2019;33:141-148. 2Hamid O, et al. Ann Oncol. 2019;30:582-588. 3Goldinger SM, et al. Eur J Cancer. 2022;162:22-33. 4Wermke M, et al. Nat Med. 2025; doi: 10.1038/s41591-025-03650-6 [online ahead of print]. cORR, confirmed objective response rate; CRS, cytokine release syndrome; ICANS, Immune effector cell-associated neurotoxicity syndrome; mDOR, median duration of response; mFU, median follow-up; mPFS, median progression-free survival; mOS, median overall survival
Data cut-off Apr 7, 2025 2
ASCO 2025
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Indication |
% PRAME+ patients1 |
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Cutaneous Melanoma |
95% |
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Uterine Carcinoma |
95% |
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Uterine Carcinosarcoma |
95% |
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Synovial Sarcoma |
95% |
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Uveal Melanoma |
90% |
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Mucosal Melanoma |
90% |
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Ovarian Carcinoma Subtypes |
85% |
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Squamous Cell NSCLC2 |
70% |
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Triple-negative Breast Carcinoma |
65% |
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Small Cell Lung Cancer |
45% |
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Esophageal Carcinoma Subtype |
45% |
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Kidney Carcinoma Subtype |
40% |
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Cholangiocarcinoma |
35% |
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HER2-Enriched Breast Carcinoma |
30% |
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Adenocarcinoma NSCLC2 |
25% |
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Head & Neck Squamous Cell Carcinoma |
25% |
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Hepatocellular Carcinoma |
20% |
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Bladder Carcinoma |
20% |
PRAME prevalence in selected indications
Precision targeting
of PRAME
≥95 % ≥10 %
1 Data on file: PRAME target prevalence is based on a proprietary mass spec-guided expression threshold applied to RNAseq and/or IHC data (approximate values, values between 95-100% shown as 95%); 2 NSCLC: Non-small cell lung cancer;
3
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Indication |
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Cutaneous Melanoma |
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Endometrioid Endometrial Carcinoma |
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Uterine Carcinosarcoma |
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Synovial Sarcoma |
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Acral Melanoma |
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Uveal Melanoma |
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Mucosal Melanoma |
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Endometrial Clear Cell Carcinoma |
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Endometrial Serous Carcinoma |
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Ovarian Serous Cystadenocarcinoma |
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Ovarian Clear Cell Carcinoma |
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Ovarian Endometrioid Carcinoma |
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Head and Neck Salivary Duct Carcinoma |
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Adenoid Cystic Carcinoma |
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Neuroblastoma |
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Malignant Rhabdoid Tumor |
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Wilms Tumor (Nephroblastoma) |
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Squamous Cell NSCLC |
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Triple Negative Breast Carcinoma (TNBC) |
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Cervical Adenosquamous Cell Carcinoma |
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Large Cell Neuroendocrine Lung Carcinoma (LCNEC) |
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Basal Cell Carcinoma |
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Mucoepidermoid Carcinoma |
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Large Cell Lung Carcinoma (LCLC) |
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Spindle Cell Melanoma |
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Testicular Germ Cell Tumor (Seminoma and Non-Seminoma) |
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Myxoid Liposarcoma |
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Angiosarcoma |
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Small Cell Lung Cancer (SCLC) |
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Esophageal Small Cell Carcinoma |
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Cutaneous Squamous Cell Carcinoma |
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Thymoma |
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Merkel Cell Carcinoma |
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Endometrial Sarcoma |
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Esophageal Squamous Carcinoma |
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Esophageal Adenosquamous Carcinoma |
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Kidney Renal Papillary Cell Carcinoma |
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Malignant Peripheral Nerve Sheath Tumor (MPNST) |
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Cholangiocarcinoma |
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Cervical Adenocarcinoma |
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Head and Neck Salivary Gland Carcinoma |
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Osteosarcoma |
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HER2-Enriched Breast Carcinoma |
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Embryonal Rhabdomyosarcoma |
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Adenosquamous NSCLC |
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Diffuse Large B-cell Lymphoma (DLBCL) |
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Sarcomatoid Carcinoma of the Lung |
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Adenocarcinoma NSCLC |
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Head and Neck Squamous Cell Carcinoma (HNSCC) |
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Alveolar Rhabdomyosarcoma |
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Ovarian Mucinous Carcinoma |
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Adrenocortical Carcinoma |
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Kidney Renal Clear Cell Carcinoma |
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Hepatocellular Carcinoma |
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Bladder Urothelial Carcinoma |
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Cervical Squamous Cell Carcinoma |
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Non-Squamous Anal Carcinoma |
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Pancreatic Neuroendocrine Adenocarcinoma |
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Prostate Neuroendocrine Adenocarcinoma |
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Liposarcoma |
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Undifferentiated Pleomorphic Sarcoma |
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Acute Myeloid Leukemia (AML) |
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Ewing Sarcoma |
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Ovarian Leiomyosarcoma |
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Breast Carcinoma, Luminal A |
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Breast Carcinoma, Luminal B |
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Squamous Anal Carcinoma |
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Stomach Adenocarcinoma |
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Esophageal Adenocarcinoma |
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Fibrosarcoma |
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Anaplastic Thyroid Carcinoma |
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(…) |
a Outpatient administration at investigator's discretion.
BID, twice daily; IU, international unit; ECOG, Eastern Cooperative Oncology Group; FU, follow-up; RP2D, recommended phase 2 dose at 1-10x109 TCR T cells; QC, quality control; SC, subcutaneous; SOC, standard of care.
1 Gragert et al. 2013 and census numbers. HLA-A*02:01 prevalence in Immatics' clinical trials: US 65% and Germany 55% as of March 2025. Manufacturing success rate as of Apr 7, 2025
Data cut-off Apr 7, 2025 4
ASCO 2025
Patient Journey
SCREENING/MANUFACTURING
TREATMENT / OBSERVATION FU
HLA-A*02:01 Testing
Blood
Inclusion of HLA-A*02:01-
positive patients
Leukapheresis
IMA203
One-time infusion
Prevalence1:
US: 41%
EU: 48%
Manufacturing
of IMA203
~2 weeks turnaround time (applying CD8/CD4 T cell selection, incl. QC release testing)
95% success rate to reach RP2D
PRAME Testing
Biopsy or archived tissue Inclusion of PRAME-positive patients
Lymphodepletion
Fludarabine 30mg/m2Cyclophosphamide 500mg/m2Days -6 to -3
Low Dose IL-2a
1m IU SC Days 1-5;
1m IU SC BID Days 6-10
Key Eligibility Criteria
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Confirmed advanced and/or metastatic solid tumor
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Patients ≥ 18 years of age
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ECOG performance status 0-1
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HLA-A*02:01 and PRAME positive
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Patients having received, or not been eligible for all available indicated SOC treatment
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Adequate organ function
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No active brain metastasis
Key Objectives
Primary:
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Tolerability
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Determination of RP2D (Phase 1a)
Secondary:
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IMA203 T cell engraftment, persistence
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Efficacy
RP2D defined at
1-10x109TCR T cells
n=1 in Phase 1a
started lymphodepletion but did not receive IMA203
n=27
Phase 1a Dose Escalation
(DL1-4)
n=46
Phase 1b Dose Expansion
(RP2D)
n=13
non-melanoma
Melanoma Efficacy
Population1(n=33)
n=14
cutaneous melanoma
n=16
uveal melanoma
n=3
other melanoma2
1 Melanoma efficacy population excludes 1 patient with uveal melanoma with ongoing unconfirmed PR from cORR; 2Mucosal melanoma n=2, melanoma of unknown primary n=1;
RP2D: 1-10x109TCR T cells; DL4: 0.2-1.2x109TCR T cells/m2BSA; DL: dose level.
Data cut-off Apr 7, 2025 5
ASCO 2025
Total Safety
Population
(N=74)
Attachments
Disclaimer
Immatics NV published this content on May 31, 2025, and is solely responsible for the information contained herein. Distributed via Public Technologies (PUBT), unedited and unaltered, on May 31, 2025 at 12:34 UTC.
