Molecular Partners presents new preclinical data on Radio-DARPin and Switch-DARPin programs at AACR 2025

ZURICH-SCHLIEREN, Switzerland and CONCORD, Mass., April 25, 2025 (GLOBE NEWSWIRE) — Ad hoc announcement pursuant to Art. 53 LR Molecular Partners AG (SIX: MOLN; NASDAQ: MOLN), a clinical-stage biotech company developing a new class of custom-built protein drugs known as DARPin therapeutics (“Molecular Partners” or the “Company”), today announced the presentation of three posters at the American Association for Cancer Research (AACR) Annual Meeting 2025, taking place April 25–30 in Chicago, IL. The first poster includes positive Investigational New Drug (IND)-enabling data for MP0712, a Radio-DARPin targeting DLL3 and labeled with 212Pb for small cell lung cancer patients. The second poster presents initial preclinical data on the second 212Pb-based Radio-DARPin, targeting mesothelin (MSLN) in solid tumors – both programs are co-developed with Orano Med. The third poster includes additional preclinical proof-of-concept data on the logic-gated CD3 Switch-DARPin T cell engager with CD2 co-stimulation in solid tumors.

“Our presentations at AACR highlight the breadth of Molecular Partners’ DARPin innovation and the progress in our strategic Radio-DARPin partnership with Orano Med. Our first Radio-DARPin program, MP0712, targeting DLL3, is well advanced and on track to provide initial clinical data in the second half of 2025. Additionally, we are proud to present the first preclinical data from our second program with Orano Med, targeting MSLN. The results show substantial uptake into MSLN-positive tumors, with limited accumulation in other organs, justifying continued investment in our RDT x MSLN program for solid tumors,” said Patrick Amstutz, Ph.D., CEO of Molecular Partners.

“Furthermore, we continue to advance our wholly-owned logic-gated and co-stimulated T cell engager program. Our SWITCH approach activates CD3/T-cells only when binding to tumor-associated antigens, while remaining inactive in circulation. This gating allows us to add a CD2 DARPin for co-stimulation without the risk of fratricide. This project demonstrates the value of our platform, which can be used for any target combination.”

Preclinical data presented on MP0712, a DLL3-targeting and 212Pb-labeled Radio-DARPin, show a high tumor uptake and a favorable safety profile for MP0712, with good efficacy and tumor reduction in mouse models matching clinically relevant DLL3 expression levels. With these data, the IND-enabling package is complete; IND filing and initial first-in-human clinical data are expected in 2025. DLL3 is a promising target for radioligand therapy as it is highly upregulated in small cell lung cancer and other high-grade neuroendocrine tumors, while not expressed in healthy tissues.

The MSLN x 212Pb Radio-DARPin poster outlines how MSLN may be a promising target for ovarian cancer due to its differentiated expression profiles – high in tumor, and lower in healthy tissues. High levels of shed MSLN, however, can act as a decoy receptor and have historically hampered the development of MSLN-targeted therapeutics. Molecular Partners has leveraged the unique properties of DARPins to develop a Radio-DARPin able to selectively bind membrane-bound MSLN without being impacted by shed MSLN. In vivo results show a favorable biodistribution with strong tumor accumulation of the Radio-DARPin in a MSLN-overexpressing model in mice.

Preclinical proof-of-concept data on Molecular Partners’ conditionally activated CD3 Switch-DARPin shows it activates T cells specifically in the presence of cells co-expressing MSLN and epithelial cell adhesion molecule (EpCAM), increasing tumor specificity. Concurrent CD2 co-engagement leads to sustained T cell activation and cytotoxic capacity, preventing T cell dysfunction. The Switch-DARPin effectively induces significant tumor regression in mice engrafted subcutaneously with MSLN- and EpCAM-expressing cells, without signs of T cell activation in the periphery, indicating a favorable safety profile.

Click here to access the poster presentations, which will be made available on Molecular Partners’ website.

Details of the presentations:

MP0712, the first anti-DLL3 212Pb Radio-DARPin (RDT) candidate for targeted radiotherapy of small cell lung cancer (SCLC)
Session Category: Experimental and Molecular Therapeutics
Session Title: Biochemical Modulators of Cancer / Differentiation Therapeutic Strategies
Session Timing: Sunday April 27 at 2:00pm – 5:00pm CST
Location: Poster Section 16, Poster Board Number: 13
Published Abstract Number: 346

Development of 212Pb-based Radio-DARPin therapy (RDT) for the treatment of mesothelin (MSLN)-positive solid tumors
Session Category: Experimental and Molecular Therapeutics
Session Title: Biochemical Modulators of Cancer / Differentiation Therapeutic Strategies
Session Timing: Sunday April 27 at 2:00 – 5:00pm CST
Location: Poster Section 16, Poster Board Number: 6
Published Abstract Number: 339

Next-generation multi-specific and conditionally activated CD3 Switch-DARPins with CD2 co-stimulation to tackle the current limitations of T cell engagers in solid tumors
Session Category: Experimental and Molecular Therapeutics
Session Title: Therapeutic Approaches to Attack the Tumor Microenvironment
Session Timing: Monday April 28 at 2:00pm – 5:00pm CST
Location: Poster Section 24, Poster Board Number: 3
Published Abstract Number: 3119

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