Molecular Partners (MOLN) starts first patient dosing in DLL3 Radio-DARPin MP0712 Phase 1/2a

Rhea-AI Filing Summary

Molecular Partners filed a Form 6-K to share news that, together with Orano Med, it has dosed the first patients in a US multicenter Phase 1/2a trial of MP0712, a DLL3-targeting Radio-DARPin carrying a lead-212 (212Pb) payload. This drug candidate is designed for tumors that express DLL3, which is present in over 85% of small cell lung cancer tumors and certain other aggressive neuroendocrine cancers, while remaining low in healthy tissue. The study uses a matched-pair approach: patients first receive 203Pb-labeled MP0712 for imaging and dosimetry, then up to four doses of 212Pb-labeled MP0712 at their assigned dose level. Five US centers are currently recruiting across up to four dose levels. Initial data from this trial are anticipated in the coming months, with a more comprehensive readout on safety and efficacy planned for 2027.

Key Figures

Recruiting sites: 5 centers Dose levels: 4 dose levels Patient doses per course: Up to 4 doses +5 more

8 metrics

Recruiting sites 5 centers Centers open and actively recruiting in US Phase 1/2a MP0712 study

Dose levels 4 dose levels Maximum planned dose levels in MP0712 Phase 1/2a trial

Patient doses per course Up to 4 doses 212Pb-labeled MP0712 doses per patient in Phase 1/2a study

DLL3 expression in SCLC Over 85% Proportion of small cell lung cancer tumors expressing DLL3 target

Initial data timing Upcoming months Expected timing for first data from MP0712 Phase 1/2a

Comprehensive data timing 2027 Planned timing for fuller safety and efficacy dataset for MP0712

Founding year 2004 Year Molecular Partners was founded

Radioisotopes used 212Pb and 203Pb Therapeutic and imaging isotopes in MP0712 program

Key Terms

Radio-DARPin, Targeted Alpha Therapy, DLL3, Phase 1/2a study, +2 more

6 terms

Radio-DARPin medical

"MP0712, targeting the tumor-associated protein delta-like ligand 3 (DLL3) and carrying the therapeutic payload 212Pb, is the lead Radio-DARPin candidate"

A radio-darpin is a small, engineered protein that is chemically attached to a tiny radioactive atom and designed to find and stick to a specific molecule on cells, such as a tumor marker. Think of it as a guided homing beacon that either lights up a disease location for imaging or delivers a focused dose of radiation. Investors care because radio-darpins can speed diagnosis, enable more precise treatments, and, if clinically successful, create commercial opportunities or regulatory milestones that drive company value.

Targeted Alpha Therapy medical

"lead-212 (212Pb) based targeted alpha therapies (TAT), today announced that the first patients were dosed"

A cancer treatment that attaches tiny, highly energetic bits of radiation called alpha particles to a molecule that seeks out tumor cells, delivering a powerful, localized dose much like a guided missile hitting only its target. Investors care because it can offer strong anti-tumor effects with fewer whole-body side effects than traditional radiation, creating significant commercial upside, clinical and regulatory risks, and clear milestones that affect company value.

DLL3 medical

"MP0712, targeting the tumor-associated protein delta-like ligand 3 (DLL3) and carrying the therapeutic payload 212Pb"

DLL3 is a protein found on the surface of some cells that helps control how cells communicate and develop; in certain cancers it becomes much more common on tumor cells than on healthy tissue. Investors watch DLL3 because it can serve as a visible target or marker for drugs and diagnostics—like a unique flag on bad cells—so therapies or tests that successfully exploit DLL3 can drive clinical progress, licensing deals, and potential future revenue.

Phase 1/2a study medical

"first patients were dosed in the ongoing US multicenter Phase 1/2a study of drug candidate MP0712"

matched-pair approach medical

"The program employs a “matched-pair” approach, in which a diagnostic imaging agent and a therapeutic agent share the same targeting molecule"

Targeted Alpha Therapy (TAT) medical

"one of the more potent therapeutic payloads against cancer cells known as Targeted Alpha Therapy (TAT)"

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

Available on EDGAR 07/02/2026 - 06:05 AM Accepted by SEC EDGAR 07/02/2026 - 06:00 AM Learn about SEC filing dates

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

For the month of July 2026

Commission File Number: 001-40488

Molecular Partners AG
(Translation of registrant's name into English)

Wagistrasse 14
8952 Zurich-Schlieren
Switzerland
(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 [   ]

On July 2, 2026, the Registrant issued a press release, a copy of which is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

(c) Exhibit 99.1. Press release dated July 2, 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.

		Molecular Partners AG
		(Registrant)
Date: July 2, 2026		/s/ PATRICK AMSTUTZ
		Patrick Amstutz
		Chief Executive Officer

EXHIBIT 99.1

Molecular Partners and Orano Med Announce First Patients Dosed in Phase 1/2a Trial of DLL3 Radio-DARPin MP0712

• Five sites recruiting in US study of DLL3-targeting ²¹²Pb-labelled Radio-DARPin MP0712
  
  
• Dosing ongoing in first patients, consecutively moving to subsequent dosing cycles
  
  
• Initial data anticipated within the coming months, comprehensive efficacy data expected in 2027
  
  

ZURICH-SCHLIEREN, Switzerland and CONCORD, Mass. and VILLEJUIF, France, July 02, 2026 (GLOBE NEWSWIRE) -- Ad hoc announcement pursuant to Art. 53 LR – 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”), and Orano Med, a clinical-stage radiopharmaceutical company and a pioneer in the development of lead-212 (²¹²Pb) based targeted alpha therapies (TAT), today announced that the first patients were dosed in the ongoing US multicenter Phase 1/2a study of drug candidate MP0712.

MP0712, targeting the tumor-associated protein delta-like ligand 3 (DLL3) and carrying the therapeutic payload ²¹²Pb, is the lead Radio-DARPin candidate being developed under a strategic partnership between Molecular Partners and Orano Med. DLL3 is a highly relevant target for radiopharmaceutical therapy due to its abundant expression in tumors of patients with small cell lung cancer (DLL3 is present in over 85% of SCLC tumors) and multiple other aggressive neuroendocrine tumors, while expression in healthy tissues is low.

“MP0712 is a Radio-DARPin designed to attack tumors by specifically leveraging DLL3 biology. With the first patient now in repeat dosing and Cohort 1 now recruited, we are establishing the clinical safety profile of this novel therapy in real time. Working closely with investigators in our trial, we remain on track to report initial study data in 2026, and, also paving the way for other Radio-DARPin candidates to move forward,” said Patrick Amstutz, Ph.D., CEO of Molecular Partners.

“The dosing of the first patients in this study marks an important step for Orano Med and our collaboration. It further illustrates the potential of lead-212 to support a broad clinical pipeline of targeted alpha therapies, leveraging its versatility across different vector formats to address a wide range of cancer types,” said Frédéric Desdouits, Ph.D., CEO of Orano Med.

The program employs a “matched-pair” approach, in which a diagnostic imaging agent and a therapeutic agent share the same targeting molecule, allowing for accurate prediction of tumor uptake prior to treatment. Following an imaging and dosimetry step with ²⁰³Pb-labeled MP0712, patients in the Phase 1/2a study receive up to four doses of ²¹²Pb-labeled MP0712 within their assigned dose level cohort. Dosing of patients is ongoing in cohort 1, with patients moving to repeat dosing. The study contains up to four dose levels. At present, five centers are open and actively recruiting in the US, with additional sites planned to open this year (ClinicalTrials.gov: NCT07278479). Initial data from the MP0712 Phase 1/2a study are expected in the upcoming months, with a more comprehensive dataset on safety and efficacy in 2027.

About Radio-DARPins
Molecular Partners develops targeted alpha therapeutics leveraging its Radio-DARPins as isotope-agnostic vectors with the potential to unlock a broad range of cancer targets and indications. Molecular Partners designs its Radio-DARPin candidates matching disease and target biology with vector and isotope properties to address unmet medical needs. Building on the DARPins’ unique properties, Molecular Partners has developed a proprietary Radio-DARPin platform for precise delivery of potent radioactive payloads to tumor lesions. Molecular Partners’ Radio-DARPins address historic limitations of radioligand therapy, such as kidney accumulation and suboptimal tumor uptake, through optimized half-life extension and surface engineering approaches, while preserving the advantages of the small protein format.

About DARPin Therapeutics
DARPin (Designed Ankyrin Repeat Protein) therapeutics are a novel class of protein drugs based on natural binding proteins, which have been clinically-validated across several therapeutic areas and developed through to the registrational stage. The key properties of DARPins – intrinsic potential for high affinity and specificity, as well as small size, flexible architecture, and high stability – offer unmatched advantages to drug design, such as multispecificity, broad target range, and tunable half-life. Powered by twenty years of DARPin leadership, Molecular Partners has built an innovative, rapid and cost-effective DARPin drug design engine, including proprietary DARPin libraries and platforms, for candidates produced with optimized properties and tailored to therapeutic needs.

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

About Targeted Alpha Therapy
Targeted alpha therapy (TAT) relies on a simple concept: combining the ability of biological molecules to target cancer cells with the short-range cell-killing capabilities of alpha-emitting radioisotopes. Alpha decay consists of the emission of a helium nucleus (alpha particle) together with very high linear energy transfer and a range emission of only few cell layers, resulting in irreparable double strand DNA breaks in cells adjacent only to area of alpha emission. This approach results in an increased cytotoxic potential toward cancer cells while limiting toxicity to nearby healthy cells. As a result, alpha emitters are considered as the most powerful payloads to be found for targeted therapies.

About Orano Med
Orano Med is a subsidiary of the Orano Group. Orano Med is a clinical-stage biotechnology company that develops a new generation of targeted therapies against cancer using the unique properties of lead-212 (²¹²Pb), an alpha-emitting radioisotope and one of the more potent therapeutic payloads against cancer cells known as Targeted Alpha Therapy (TAT). Leveraging its unique and secured access to 212Pb, the company is developing several ²¹²Pb-based radioligand therapies combined with various targeting agents. Orano Med has ²¹²Pb manufacturing facilities, laboratories, and R&D centers in France and in the US and is currently expanding its GMP-manufacturing capacities for ²¹²Pb radiolabeled pharmaceuticals in North America and Europe. For more information, visit our website at www.oranomed.com and follow us on LinkedIn.

For further details, please contact:
Molecular Partners:
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

Orano Med:
Regina Jehle, Director Communication and Public Affairs
communication@oranomed.com
Tel: +33 6 74 56 11 31

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.

FAQ

What did Molecular Partners (MOLN) announce in this Form 6-K?

Molecular Partners and Orano Med announced first patients were dosed in a US multicenter Phase 1/2a trial of MP0712, a DLL3-targeting Radio-DARPin using a lead-212 payload for hard-to-treat cancers.

What is MP0712 in the Molecular Partners (MOLN) pipeline?

MP0712 is a Radio-DARPin drug candidate targeting DLL3, a protein expressed in over 85% of small cell lung cancer tumors. It carries a lead-212 therapeutic payload, aiming to deliver targeted alpha radiation directly to tumor cells.

How is the MP0712 Phase 1/2a clinical trial for MOLN designed?

The trial uses a matched-pair design. Patients first receive 203Pb-labeled MP0712 for imaging and dosimetry, then up to four doses of 212Pb-labeled MP0712 at their assigned dose level to evaluate safety, dosing, and early signs of activity.

How many sites are recruiting in the MP0712 study for Molecular Partners (MOLN)?

Five US centers are currently open and actively recruiting patients in the Phase 1/2a MP0712 trial. The study includes up to four dose levels, with additional sites planned to open later to support enrollment.

When will initial data from Molecular Partners’ MP0712 trial be available?

Initial data from the MP0712 Phase 1/2a trial are expected within the coming months. A more comprehensive dataset on safety and efficacy is anticipated in 2027, providing a fuller picture of the therapy’s potential.

What cancer types is Molecular Partners (MOLN) targeting with MP0712?

MP0712 targets tumors expressing DLL3, notably small cell lung cancer where DLL3 is found in over 85% of tumors, and other aggressive neuroendocrine tumors. Low expression in healthy tissue supports a targeted treatment approach.

Filing Exhibits & Attachments

1 document

Press Releases

• EX-99.1 PRESS RELEASE 11.5 KB