Immatics N.V.

On June 1, 2026, the Company announced extended data from the ongoing Phase 1b clinical trial evaluating anzu-cel (anzutresgene autoleucel, IMA203) PRAME TCR T-cell therapy in heavily pretreated patients with advanced melanoma.

Patient Population. As of the September 24, 2025 data cutoff, 33 heavily pretreated patients with metastatic (stage IV) melanoma received a one-time infusion of anzu-cel at RP2D (1 – 10×109 TCR T cells). The treated patient population consisted of cutaneous melanoma (n=14), uveal melanoma (n=16), mucosal melanoma (n=2) and melanoma of unknown primary (n=1). All patients with cutaneous melanoma, mucosal melanoma and melanoma of unknown primary had metastatic stage IV disease including lesions in liver, brain and/or lung. All patients with uveal melanoma had metastatic stage IV disease with liver and/or extrahepatic metastases. Patients had a median of two prior lines of systemic treatment. The subgroup of patients with cutaneous melanoma (n=14) had a median of 2.5 lines of prior systemic treatments, thereof a median of two prior lines of immune checkpoint inhibitors. Of these, 64% (9/14) received a combination of ipilimumab and nivolumab and 29% (4/14) received a combination of nivolumab and relatlimab prior to anzu-cel infusion.

Safety Data. Anzu-cel has maintained a predictable and manageable tolerability profile, which was consistent across patients with different melanoma subtypes. The most frequent TEAEs were anticipated cytopenias associated with lymphodepletion. Expected and manageable CRS was observed, consistent with the mechanism of action (Grade 1 or 2: 82%, Grade ≥ 3: 18%). Some patients infrequently experienced ICANS (Grade 1 or 2: 6%, Grade ≥ 3: 6%) and HLH (Grade 1 or 2: 3%, Grade ≥ 3: 3%). The following table shows TEAEs occurring in 30% or more of patients:

a Includes rash and rash maculopapular.

Anti-Tumor Activity.

1 cORR excludes one patient with uveal melanoma who left study (withdrew consent) with ongoing unconfirmed PR.

The PFS rate was 55% at six months and 37% at 12 months. The overall survival rate was 70% at 12 months and 46% at 24 months. 42% (14/33) of patients experienced a deep response (≥50% tumor reduction). In these patients, mPFS was 15.9 months at 39.6 months mFU.

• Maximum change of target lesions and RECIST1.1 response at different timepoints. BL, baseline; BOR, best overall response; (c)CR, (confirmed) complete response; (c)PR, (confirmed) partial response; PD, progressive disease; RECIST, Response Evaluation Criteria in Solid Tumors; SD, stable disease.

Anzu-cel induced systemic anti-tumor activity across multiple metastatic sites, including difficult-to-treat metastases, such as liver, lung, lymph node, abdomen/peritoneum, skin and others. Even patients who had a best overall response of Progressive Disease (PD) according to RECIST 1.1 (n=3) experienced shrinkage of individual lesions. Progressive disease was frequently the result of new lesions, progression of non-target lesions, or selective outgrowths of individual lesions, while many target lesions remained controlled, indicating continued control of baseline disease. Responses occurred rapidly (median time to BOR: 1.4 months) and were durable across multiple metastatic sites, including target and non-target lesions.

These findings support the continued development of anzu-cel in advanced melanoma. Immatics’ ongoing Phase 3 clinical trial, SUPRAME, is evaluating the efficacy, safety and tolerability of anzu-cel PRAME TCR T-cell therapy as a monotherapy vs. investigator's choice in patients with unresectable or metastatic cutaneous melanoma who have received prior treatment with a PD-1 immune checkpoint inhibitor.

In parallel, a Phase 2 cohort in metastatic uveal melanoma is ongoing and intended to support a potential label expansion for anzu-cel following expected initial approval in cutaneous melanoma.

Certain statements in this report may be considered forward-looking statements. Forward-looking statements generally relate to future events or the Company’s future financial or operating performance. For example, statements concerning timing of data read-outs for product candidates, observations from the Company’s clinical trials, the timing, outcome and design of clinical trials, the nature of clinical trials (including whether such clinical trials will be registration-enabling), the timing of IND, CTA or BLA filings, estimated market opportunities of product candidates, the Company’s focus on partnerships to advance its strategy, and other metrics are forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as “may”, “should”, “expect”, “plan”, “target”, “intend”, “will”, “estimate”, “anticipate”, “believe”, “predict”, “potential” or “continue”, or the negatives of these terms or variations of them or similar terminology. Such forward-looking statements are subject to risks, uncertainties, and other factors which could cause actual results to differ materially from those expressed or implied by such forward-looking statements. These forward-looking statements are based upon estimates and assumptions that, while considered reasonable by Immatics and its management, are inherently uncertain. New risks and uncertainties may emerge from time to time, and it is not

possible to predict all risks and uncertainties. Factors that may cause actual results to differ materially from current expectations include, but are not limited to, various factors beyond management's control including general economic conditions and other risks, uncertainties and factors set forth in the Company’s Annual Report on Form 20-F and other filings with the Securities and Exchange Commission (SEC). Nothing in this report should be regarded as a representation by any person that the forward-looking statements set forth herein will be achieved or that any of the contemplated results of such forward-looking statements will be achieved. You should not place undue reliance on forward-looking statements, which speak only as of the date they are made. The Company undertakes no duty to update these forward-looking statements. All the scientific and clinical data presented within this report are – by definition prior to completion of the clinical trial and a clinical study report – preliminary in nature and subject to further quality checks including customary source data verification.

In connection with the foregoing, the Company issued press releases, copies of which are attached hereto as Exhibit 99.1, Exhibit 99.2 and Exhibit 99.3, respectively, made available presentations, copies of which are attached hereto as Exhibit 99.4, Exhibit 99.5, Exhibit 99.6 and Exhibit 99.7, and made available an updated corporate presentation, a copy of which is attached hereto as Exhibit 99.8.