Innate Pharma (Nasdaq: IPHA) highlights MATISSE IPH5201 lung cancer data at AACR

Rhea-AI Filing Summary

Innate Pharma reported encouraging interim results from the Phase 2 MATISSE trial of IPH5201 in resectable non-small cell lung cancer. The study combines IPH5201, a first-in-class anti-CD39 antibody, with durvalumab and platinum-based chemotherapy in previously untreated, resectable NSCLC.

In a pre-planned interim analysis of 40 patients, the combination showed higher pathological complete response rates than a benchmark of durvalumab plus chemotherapy alone. Pathological complete response reached 35.7% in tumors with PD-L1 ≥1% and 50% in tumors with PD-L1 ≥50%.

On the basis of these data, MATISSE continues enrolling patients whose tumors express PD-L1 ≥1%. The interim results will be presented in a Clinical Trials Plenary Session at the AACR Annual Meeting 2026, highlighting IPH5201’s potential role in enhancing anti-tumor immune responses in early-stage lung cancer.

Insights

Biotech clinical-trials analyst

Early Phase 2 lung cancer data for IPH5201 look promising but remain preliminary.

Innate Pharma shared interim results from 40 patients in the Phase 2 MATISSE trial testing IPH5201, an anti-CD39 antibody, with durvalumab and platinum chemotherapy in resectable NSCLC. The goal is to improve perioperative outcomes by dual CD39 and PD-L1 pathway inhibition plus chemotherapy.

Pathological complete response rates of 35.7% in PD-L1 ≥1% tumors and 50% in PD-L1 ≥50% tumors exceeded an internal benchmark of durvalumab plus chemotherapy alone. This supports continued enrollment in the PD-L1–positive population but does not yet establish long-term benefit or survival impact.

The data will be highlighted in an AACR 2026 Clinical Trials Plenary Session on April 21, 2026, which signals scientific interest. Future readouts from the completed MATISSE study, including durability, safety, and broader clinical outcomes, will be important for understanding IPH5201’s potential role in early-stage lung cancer treatment.

Key Figures

Interim analysis patients: 40 patients pCR rate PD-L1 ≥1%: 35.7% pCR rate PD-L1 ≥50%: 50% +3 more

6 metrics

Interim analysis patients 40 patients Pre-planned interim analysis in MATISSE Phase 2 NSCLC trial

pCR rate PD-L1 ≥1% 35.7% Pathological complete response in tumors with PD-L1 ≥1%

pCR rate PD-L1 ≥50% 50% Pathological complete response in tumors with PD-L1 ≥50%

AACR session date April 21, 2026 Clinical Trials Plenary Session presentation at AACR 2026

Session time 10:45–11:00 AM PDT Presentation slot for MATISSE interim results

Trial identifier NCT05742607 ClinicalTrials.gov identifier for MATISSE Phase 2 study

Key Terms

pathological complete response, perioperative, non-small cell lung cancer, monoclonal antibody, +2 more

6 terms

pathological complete response medical

"The combination of IPH5201 with durvalumab and chemotherapy demonstrated higher pathological complete response (pCR) rates"

Pathological complete response is when tissue examined under a microscope after cancer treatment and surgery shows no remaining invasive tumor cells. Investors care because it is a strong signal that a therapy is working, often used as a key endpoint in clinical trials and a predictor of better long‑term outcomes; like finding an empty crime scene after a cleanup, it can boost confidence in a drug’s market potential and regulatory prospects.

perioperative medical

"a multicenter study investigating perioperative treatment with IPH5201 in combination with durvalumab"

Pertaining to the entire span around a surgical operation — before, during and after the procedure — covering preparation, anesthesia, monitoring and recovery. Investors watch perioperative care because it shapes how often hospitals use devices, drugs and services, affects complication rates and patient stay length, and therefore influences revenue, costs and reimbursement risk; think of it like the full service cycle around a car repair that determines how long the shop is busy and what customers pay.

non-small cell lung cancer medical

"in patients with resectable non-small cell lung cancer (NSCLC)"

A broad category of lung tumors that grow from the cells lining the airways and make up the majority of lung cancer cases; it includes several subtypes that behave and respond to treatment differently, like different models of the same car family. It matters to investors because its large patient population and variety of treatment options — surgery, traditional chemo, targeted drugs and immunotherapies — create major markets where clinical trial results, drug approvals or changing treatment guidelines can quickly affect a company’s revenue and stock value.

monoclonal antibody medical

"IPH5201 is a first-in-class monoclonal antibody targeting CD39"

A monoclonal antibody is a laboratory-made protein designed to recognize and attach to a specific target in the body, such as a disease-causing substance or cell. It functions like a highly precise lock-and-key tool, helping to treat or detect illnesses. For investors, companies developing monoclonal antibodies can represent promising opportunities in the healthcare sector, especially as these treatments often address unmet medical needs.

PD-L1 medical

"in combination with perioperative durvalumab (anti-PD-L1) in addition to neoadjuvant platinum-based chemotherapy"

PD-L1 is a protein found on the surface of some cells that acts like a stop sign for the immune system, telling certain immune cells to back off. It matters to investors because many cancer drugs and diagnostic tests target or measure PD-L1 to unlock immune responses or predict which patients will benefit, affecting clinical success, regulatory approval, and potential sales in the oncology market.

adenosine pathway medical

"targeting CD39, a key immunosuppressive enzyme in the adenosine pathway"

Form 6-K: How Foreign Companies Report to the SEC →

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549 FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE 13a-16 OR 15d-16 UNDER THE SECURITIES EXCHANGE ACT OF 1934

Date of report: April 17, 2026

Commission File Number: 001-39084

Innate Pharma S.A.

(Translation of registrant's name into English)

Innate Pharma S.A.

117 Avenue de Luminy—BP 30191

13009 Marseille, France

+ 33 (0) 4 30 30 30

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F. Form 20-F [ X ]    Form 40-F [ ]

INCORPORATION BY REFERENCE

This Report on Form 6-K and Exhibit 99.1 to this Report on Form 6-K (excluding the quotation from Sonia Quaratino, Chief Medical Officer at Innate Pharma) shall be deemed to be incorporated by reference into the registration statement on Form F-3 (File No. 333-276164) and registration statement on Form S-8 (File No. 333-282031) of Innate Pharma S.A. (including any prospectuses forming a part of such registration statements) and to be a part thereof from the date on which this report is furnished, to the extent not superseded by documents or reports subsequently filed or furnished.

EXHIBIT INDEX

Exhibit Description

99.1    Press Release dated April 17, 2026

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

INNATE PHARMA S.A.

Date: April 17, 2026    By:    /s/ JONATHAN DICKINSON     Name:    Jonathan Dickinson

Title:    Chief Executive Officer

EXHIBIT 99.1

INNATE PHARMA TO PRESENT MATISSE PHASE 2 INTERIM RESULTS

OF IPH5201 IN CLINICAL TRIALS PLENARY SESSION AT AACR 2026

•Encouraging early results catalyze continued investigation in the MATISSE Phase 2 study evaluating IPH5201, a first-in-class anti-CD39 monoclonal antibody, in combination with durvalumab and chemotherapy in resectable NSCLC; these results will be presented at the Clinical Trials Plenary Session at the AACR Annual Meeting 2026, on April 21

Marseille, France, April 17, 2026, 9:00 PM CEST

Innate Pharma SA (Euronext Paris: IPH; Nasdaq: IPHA) (“Innate” or the “Company”), today announced that interim results from the MATISSE Phase 2 study evaluating IPH5201 in combination with durvalumab and platinum-based chemotherapy in resectable non-small cell lung cancer (NSCLC) will be presented in one of the Clinical Trials Plenary Sessions at the American Association for Cancer Research (AACR) Annual Meeting 2026, taking place April 17–22, 2026 in San Diego, California.

The MATISSE study (NCT05742607) is a single arm Phase 2 clinical trial evaluating perioperative IPH5201, an anti-CD39 blocking antibody, in combination with perioperative durvalumab (anti-PD-L1) in addition to neoadjuvant platinum-based chemotherapy in previously untreated patients with resectable NSCLC. The trial is designed to assess whether dual inhibition of the CD39 and PD-L1 pathways, together with chemotherapy, can enhance anti-tumor immune responses and improve clinical outcomes in early-stage lung cancer.

These results follow a pre-planned interim analysis on 40 patients. The combination of IPH5201 with durvalumab and chemotherapy demonstrated higher pathological complete response (pCR) rates compared with the benchmark set by durvalumab plus chemotherapy alone. Notably, pCR was 35.7% and 50% in patients with tumors expressing PD-L1 ≥1% and PD-L1 ≥50%, respectively. Based on these results, the study continues to recruit patients with tumors expressing PD-L1≥1%.

“Patients with resectable NSCLC remain at significant risk of recurrence, underscoring the need for novel perioperative treatment strategies. Disrupting the adenosine pathway through CD39 inhibition with IPH5201, in combination with PD-1 blockade and chemotherapy, could enhance anti-tumor immune responses—particularly in patients with PD-L1 positive tumors, where we observed up to 50% pCR rate in the MATISSE trial. This signal will be further investigated as we complete enrollment of the study in the PD-L1-positive population,” commented Dr. Sonia Quaratino, Chief Medical Officer of Innate Pharma.

The presentation will be available in the publication section of Innate Pharma’s website.

Abstract details

Dual CD39 and PD-L1 inhibition: Interim results from the Phase 2 MATISSE trial of IPH5201 plus durvalumab and platinum-based chemotherapy in patients with resectable NSCLC

Abstract Code: CT231

Session: CTPL04 – Advances in Immunotherapy

Session Date/Time: Tuesday, April 21, 2026, 10:45 – 11:00 AM PDT

Presenter: Pr. Fabrice Barlesi, CEO of Institut Gustave Roussy

About IPH5201

IPH5201 is a first-in-class monoclonal antibody targeting CD39, a key immunosuppressive enzyme in the adenosine pathway. CD39 is expressed on tumor-infiltrating immune and stromal cells and contributes to immunosuppression by degrading extracellular adenosine triphosphate (ATP) into adenosine monophosphate (AMP), which is then further degraded into adenosine by CD73. By blocking CD39, IPH5201 promotes the accumulation of immunostimulatory ATP and reduces the production of immunosuppressive adenosine, thereby enhancing anti-tumor immune responses.

IPH5201 is being co-developed in collaboration with AstraZeneca and is currently being evaluated in the Phase 2 MATISSE trial (NCT05742607), a multicenter study investigating perioperative treatment with IPH5201 in combination with durvalumab (anti-PD-L1) and platinum-based chemotherapy in patients with resectable non-small cell lung cancer (NSCLC).

The MATISSE trial is designed to assess anti-tumor activity, including pathological complete response, and safety, with the goal of determining whether dual inhibition of the CD39 and PD-L1 pathways, in combination with chemotherapy, can enhance anti-tumor immunity and improve clinical outcomes in early-stage NSCLC.

About Innate Pharma

Innate Pharma S.A. is a global, clinical-stage biotechnology company developing immunotherapies for cancer patients. Leveraging its expertise on antibody-engineering and innovative target identification, Innate Pharma is developing innovative and differentiated next-generation antibody therapeutics.

Innate Pharma is advancing a portfolio of differentiated potential first- and/or best-in-class assets, focused on areas of high unmet medical need, including IPH4502, a differentiated Nectin-4 ADC developed in solid tumors, lacutamab, an anti-KIR3DL2 antibody developed in cutaneous T cell lymphomas and peripheral T cell lymphomas, and monalizumab, an anti-NKG2A antibody developed in collaboration with AstraZeneca in non-small cell lung cancer.

Innate Pharma has established collaborations with leading biopharmaceutical companies, including Sanofi and AstraZeneca, as well as renowned academic and research institutions, to advance innovation in immuno-oncology.

Headquartered in Marseille, France with a US office in Rockville, MD, Innate Pharma is listed on Euronext Paris and Nasdaq in the US.

Learn more about Innate Pharma at www.innate-pharma.com and follow us on LinkedIn and X.

Information about Innate Pharma shares

ISIN code Ticker code LEI FR0010331421 Euronext: IPH Nasdaq: IPHA 9695002Y8420ZB8HJE29

Disclaimer on forward-looking information and risk factors

This press release contains certain forward-looking statements, including those within the meaning of applicable securities laws, including Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and the Private Securities Litigation Reform Act of 1995. These are based on the management’s current beliefs, expectations and assumptions about future events, conditions and results and on information currently available to the management. When used in this press release, certain words, including “anticipate,” “plan,” “believe,” “can,” “could,” “estimate,” “project,” “expect,” “may,” “might,” “potential,” “expect” “should,” “will,” or the negative of these and similar expressions, identify forward-looking statements. Although the Company believes its expectations are based on reasonable assumptions, these forward-looking statements are subject to numerous risks and uncertainties, which could cause actual results to differ materially from those anticipated. These risks and uncertainties include, among other things, the uncertainties inherent in research and development, including related to safety, progression of and results from its ongoing and planned clinical trials and preclinical studies, review and approvals by regulatory authorities of its product candidates, enrolment, results and other milestones of its preclinical trials, the Company’s reliance on third parties to manufacture its product candidates, the Company’s commercialization efforts and the Company’s continued ability to raise capital to fund its development and product trials given its current cash position and the impact an inability to raise further financing would have on the Company’s ability to meet its financial or business objectives. For an additional discussion of risks and uncertainties, which could cause the Company's actual results, financial condition, performance or achievements to differ materially from those contained in the forward-looking statements, please refer to the Risk Factors (“Facteurs de Risque") section of the Universal Registration Document filed with the French Financial Markets Authority (“AMF”), which is available on the AMF website http://www.amf-france.org or on Innate Pharma’s website, and public filings and reports filed with the U.S. Securities and Exchange Commission (“SEC”), including the Company’s Annual Report on Form 20-F for the year ended December 31, 2025, and subsequent filings and reports filed with the AMF or SEC, or otherwise made public by the Company. References to the Company’s website and the AMF website are included for information only and the content contained therein, or that can be accessed through them, are not incorporated by reference into, and do not constitute a part of, this press release.

In light of the significant uncertainties in these forward-looking statements, you should not regard these statements as a representation or warranty by the Company or any other person that the Company will achieve its objectives and plans in any specified time frame or at all. The Company undertakes no obligation to publicly update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

This press release and the information contained herein do not constitute an offer to sell or a solicitation of an offer to buy or subscribe to shares in Innate Pharma in any country.

For more information

Investors & Media Relations

Innate Pharma

Stéphanie Cornen

stephanie.cornen@innate-pharma.fr

Investor Relations

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Media

communication@innate-pharma.fr

FAQ

What did Innate Pharma (IPHA) announce about the MATISSE Phase 2 trial?

Innate Pharma announced interim Phase 2 MATISSE results for IPH5201 in resectable NSCLC. The perioperative combination with durvalumab and chemotherapy showed higher pathological complete response rates than a benchmark of durvalumab plus chemotherapy alone in a 40-patient interim analysis.

What is IPH5201 in Innate Pharma’s MATISSE NSCLC study?

IPH5201 is a first-in-class monoclonal antibody targeting CD39, an immunosuppressive enzyme in the adenosine pathway. By blocking CD39, IPH5201 increases immunostimulatory ATP and reduces immunosuppressive adenosine, aiming to enhance anti-tumor immune responses when combined with durvalumab and chemotherapy.

What pathological complete response rates were reported in Innate Pharma’s MATISSE trial?

The MATISSE interim analysis reported pathological complete response rates of 35.7% in tumors with PD-L1 ≥1% and 50% in tumors with PD-L1 ≥50%. These rates were higher than a benchmark based on durvalumab plus chemotherapy alone, supporting continued enrollment in PD-L1–positive patients.

How many patients were included in the interim analysis of MATISSE?

The MATISSE interim analysis was conducted on 40 previously untreated patients with resectable non-small cell lung cancer. All received perioperative IPH5201 plus durvalumab and neoadjuvant platinum-based chemotherapy. These early data guide ongoing recruitment, especially in tumors with PD-L1 expression ≥1%.

When and where will Innate Pharma present the MATISSE IPH5201 data?

Innate Pharma’s MATISSE Phase 2 interim results will be presented in a Clinical Trials Plenary Session at the AACR Annual Meeting 2026. The session is scheduled for Tuesday, April 21, 2026, from 10:45 to 11:00 AM PDT in San Diego, California.

What cancer type is targeted in Innate Pharma’s MATISSE trial of IPH5201?

The MATISSE trial targets resectable non-small cell lung cancer (NSCLC). It evaluates perioperative treatment with IPH5201 in combination with durvalumab and platinum-based chemotherapy to test whether dual CD39 and PD-L1 inhibition plus chemotherapy can improve clinical outcomes in early-stage lung cancer.

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