MP0632 nominated as first logic-gated Switch-DARPin T cell engager candidate for the treatment of MSLN/EpCAM expressing solid tumors, with preclinical data indicating favorable therapeutic window
MP0712, Radio-DARPin candidate in on-going US Phase 1/2a trial, leverages high affinity to DLL3, half-life extension and DLL3 internalization for high tumor accumulation

ZURICH-SCHLIEREN, Switzerland and CONCORD, Mass, April 19, 2026 (GLOBE NEWSWIRE) -- Molecular Partners AG ((SIX: MOLN, NASDAQ:MOLN), a clinical-stage biotech company developing a novel class of custom-built protein drugs known as DARPin therapeutics ("Molecular Partners" or the "Company"), today announced the presentation of new preclinical data across three posters at the American Association for Cancer Research (AACR) Annual Meeting 2026.

The first poster outlines preclinical data supporting proof-of-concept for MP0632, a logic-gated Switch-DARPin CD3 T cell engager with CD2 co-stimulation designed to selectively kill cells co-expressing mesothelin (MSLN) and epithelial cell adhesion molecule (EpCAM). MP0632 leads to regression of established tumors expressing both EpCAM and MSLN, with minimal impact on tumors expressing only one antigen, indicating a favorable therapeutic window. In addition, the Switch-DARPin candidate allowed for safe use of potent costimulation for efficient tumor cell killing with low cytokine release profile. The data support MP0632's potential as clinical lead candidate for the treatment of ovarian cancer and other MSLN- and EpCAM-positive solid tumors.

"We are excited to present new data on MP0632, our first logic-gated T cell engager candidate leveraging our Switch-DARPin technology. We designed MP0632 to achieve potent yet safe tumor-localized immune activation through incorporation of CD2 costimulation and through unmasking of the CD3 binder upon binding to two co-expressed tumor antigens – MSLN and EpCAM. We are looking forward to advancing MP0632 and building on the strong preclinical data package, which indicates its potential to make a difference to cancer patients," said Martin Steegmaier, Ph.D., CSO of Molecular Partners.

The second poster presents a computational workflow to identify and prioritize tumor-associated antigen pairs for improved tumor-selectivity and safety in support of designing novel Switch-DARPin candidates, such as MP0632. This scalable, data-driven platform provides a strong foundation for the discovery of next-generation multispecific immunotherapies. This workflow could also be leveraged for the identification of complementary tumor antigen pairs to address heterogeneous tumors, which could enable the design of next-generation multispecific Radio-DARPin candidates.

The third poster outlines the molecular characteristics of MP0712, the Company's first ²¹²Pb-based Radio-DARPin candidate, with high affinity binding to DLL3 and optimized half-life extended properties. MP0712's properties are hypothesized to facilitate sustained tumor uptake through repeated DLL3 internalization-replenishment despite low cell surface density of the target, thereby supporting the attractive biodistribution profile of MP0712 observed in preclinical studies as well as in first patient imaging data from a Named Patient Access Program in South Africa using MP0712 with ²⁰³Pb.

MP0712, co-developed with strategic partner Orano Med, is evaluated in an ongoing Phase 1/2a trial in the US for the treatment of patients with small cell lung cancer (SCLC) and other DLL3-expressing neuroendocrine cancers.

Details of the presentations at AACR 2026:

Logic-gated Switch-DARPin T cell engager with CD2 co-stimulation for improved safety and efficacy in MSLN and EpCAM co-expressing ovarian cancer

Session Category: Immunology

Session Title: T Cell Engagers 1

Session Start: 4/20/2026 9:00 AM PT

Session End: 4/20/2026 12:00 PM PT

Location: Poster Section 10

Poster Board Number: 16

Poster Number: 1624

Logic-gated Switch-DARPin–based immune cell engagers guided by data-driven tumor-antigen profiling: A computational workflow for the development of cancer immunotherapies

Session Category: Bioinformatics / Computational Biology / Systems Biology / Convergent Science

Session Title: Application of Bioinformatics to Cancer Biology 3

Session Start: 4/20/2026 2:00 PM PT

Session End: 4/20/2026 5:00 PM PT

Location: Poster Section 1

Poster Board Number: 16

Poster Number: 2691

Molecular characteristics of MP0712, a clinical stage ²¹²Pb-based Radio-DARPin candidate for targeted anti-DLL3 radiotherapy of small cell lung cancer (SCLC)

Session Category: Experimental and Molecular Therapeutics

Session Title: Targeted Radiopharmaceuticals and Combination Strategies in Cancer Therapy

Session Start: 4/22/2026 9:00 AM PT

Session End: 4/22/2026 12:00 PM PT

Location: Poster Section 17

Poster Board Number: 16

Poster Number: 7197

The posters will be made available on Molecular Partners' website after the presentations.

About Molecular Partners AG

Molecular Partners AG ((SIX: MOLN, NASDAQ:MOLN) is a clinical-stage biotech company pioneering a novel class of protein drugs known as DARPin therapeutics, for medical challenges other treatment modalities cannot readily address. Molecular Partners leverages the key properties of DARPins to design and develop differentiated therapeutics for cancer patients, including targeted radiopharmaceuticals and next-generation immune cell engagers. The Company has proprietary programs in various stages of pre-clinical and clinical development, as well as programs developed through partnerships with leading pharmaceutical companies and academic centers. Molecular Partners, founded in 2004, has offices in both Zurich, Switzerland and Concord, MA, USA. For more information, visit www.molecularpartners.com and find us on LinkedIn and Twitter / X @MolecularPrtnrs

For further details, please contact:

Seth Lewis, EVP Corporate Finance

Concord, Massachusetts, U.S.

seth.lewis@molecularpartners.com

Tel: +1 781 420 2361

Laura Jeanbart, PhD, Head of Portfolio Management & Communications

Zurich-Schlieren, Switzerland

laura.jeanbart@molecularpartners.com

Tel: +41 44 575 19 35

Cautionary Note Regarding Forward-Looking Statements

This press release contains forward-looking statements. Any statements contained in this press release that do not describe historical facts may constitute forward-looking statements as that term is defined in the Private Securities Litigation Reform Act of 1995, as amended, including without limitation: implied and express statements regarding the clinical development of Molecular Partners' current or future product candidates; expectations regarding timing for reporting data from ongoing clinical trials or the initiation of future clinical trials; the potential therapeutic and clinical benefits of Molecular Partners' product candidates and its RDT and Switch-DARPin platforms; the selection and development of future programs; Molecular Partners' collaboration with Orano Med including the benefits and results that may be achieved through the collaboration; the expected benefits of the strategic review; and Molecular Partners' expected business and financial outlook, including anticipated expenses and cash utilization for 2026 and its expectation of its current cash runway. These statements may be identified by words such as "aim", "anticipate", "expect", "guidance", "intend", "outlook", "plan", "potential", "will" and similar expressions, and are based on Molecular Partners' current beliefs and expectations. These statements involve risks and uncertainties that could cause actual results to differ materially from those reflected in such statements. Some of the key factors that could cause actual results to differ from Molecular Partners' expectations include, but are not limited to, those set forth in under the heading "Risk Factors" in Molecular Partners' Annual Report on Form 20-F for the year ended December 31, 2025 and other filings Molecular Partners makes with the SEC from time to time. These documents are available on the Investors page of Molecular Partners' website at www.molecularpartners.com. In addition, this press release contains information relating to interim data as of the relevant data cutoff date, results of which may differ from topline results that may be obtained in the future.

Any forward-looking statements speak only as of the date of this press release and are based on information available to Molecular Partners as of the date of this release, and Molecular Partners assumes no obligation to, and does not intend to, update any forward-looking statements, whether as a result of new information, future events or otherwise.

Molecular Partners presents three posters at AACR 2026, with new preclinical data for first Switch-DARPin T cell engager MP0632 and DLL3 Radio-DARPin MP0712