Molecular Partners Presents New Preclinical Data Highlighting Radio-DARPins’ Amenability to Multiple Isotopes

Rhea-AI Summary

Molecular Partners (NASDAQ: MOLN) presented preclinical data showing two Radio-DARPin candidates have highly comparable biodistribution when labeled with 177Lu or 203Pb, enabling isotope interchangeability. Imaging with 177Lu/203Pb may predict behavior of therapeutic isotopes 225Ac/212Pb. The company also announced an agreement with Eckert & Ziegler to support development and manufacturing of Radio-DARPins.

MP0712, a DLL3-targeted 212Pb candidate, is in an ongoing Phase 1/2a trial (NCT07278479); presentation delivered March 19–20, 2026.

Positive

• Comparable biodistribution for 177Lu and 203Pb in tumor-bearing mice
• Isotope interchangeability enables flexible selection of 212Pb or 225Ac
• MP0712 in Phase 1/2a (NCT07278479) supporting clinical progress
• Agreement with Eckert & Ziegler for development and manufacturing support

Negative

• Preclinical data from mice; clinical efficacy in humans not established
• Imaging predictive only; 177Lu/203Pb indication of 225Ac/212Pb behavior is not confirmatory

News Market Reaction – MOLN

+3.19%

1 alert

+3.19% News Effect

On the day this news was published, MOLN gained 3.19%, reflecting a moderate positive market reaction.

Data tracked by StockTitan Argus on the day of publication.

Key Figures

Imaging isotopes: 177Lu and 203Pb Therapeutic isotopes: 212Pb and 225Ac Trial phase: Phase 1/2a +3 more

6 metrics

Imaging isotopes 177Lu and 203Pb Preclinical Radio-DARPin biodistribution studies in tumor-bearing mice

Therapeutic isotopes 212Pb and 225Ac Therapeutic payloads enabled by Radio-DARPin design

Trial phase Phase 1/2a Ongoing MP0712 trial in the US (NCT07278479)

Summit date March 19–20, 2026 3rd Global Radiopharmaceuticals Development Summit presentation in Shanghai

Presentation time 9:25 am CST Oral presentation on March 20 in Meeting Room B

Tumor type Small cell lung cancer MP0712 therapeutic development focus with 212Pb payload

Market Reality Check

Price: $4.30 Vol: Volume 6474 is 52% above ...

high vol

$4.30 Last Close

Volume Volume 6474 is 52% above the 20-day average of 4273, indicating elevated interest ahead of the preclinical presentation. high

Technical Shares at 4.545 are trading above the 200-day MA of 4.03, but remain 15.21% below the 52-week high of 5.36.

Peers on Argus

MOLN is up 4.72% while key biotech peers like NKTX (-3.03%), ACTU (-6.67%) and A...

MOLN is up 4.72% while key biotech peers like NKTX (-3.03%), ACTU (-6.67%) and AVTX (-3.74%) are down, indicating a stock-specific move tied to the Radio-DARPin update rather than a sector-wide rotation.

Historical Context

5 past events · Latest: Mar 12 (Neutral)

Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Mar 12	Full-year earnings	Neutral	-10.4%	Reported 2025 results, cash of CHF 93.1M and net loss of CHF 61.7M.
Feb 26	Conference schedule	Neutral	-3.4%	Announced March investor conference participation and timing of 2025 results.
Feb 26	Development agreement	Positive	-3.4%	Signed non-exclusive development deal with Eckert & Ziegler for Radio-DARPins.
Feb 02	Clinical data update	Positive	+7.5%	Presented first-in-human imaging and dosimetry data for MP0712 at TWC 2026.
Jan 11	Clinical progress	Positive	+1.6%	Outlined MP0712 Phase 1/2a start, cash of CHF 93.1M and broader pipeline plans.

Pattern Detected

Recent pipeline and earnings updates often saw negative price reactions, while early clinical data for MP0712 previously coincided with a positive move, suggesting investors have reacted more favorably to concrete clinical evidence than to general corporate updates.

Recent Company History

Over recent months Molecular Partners has highlighted steady progress in its Radio-DARPin pipeline, especially lead candidate MP0712. A Jan 11 clinical development update and a Feb 2 presentation of first imaging/dosimetry data for MP0712 both supported the Phase 1/2a program and coincided with modest to strong gains. In contrast, the Mar 12 full-year 2025 results and earlier February corporate/partnering announcements saw share price declines. Today’s preclinical multi-isotope data further elaborates the same Radio-DARPin theme, reinforcing the pipeline story that has driven prior positive reactions when supported by specific clinical findings.

Market Pulse Summary

This announcement emphasizes new preclinical data showing comparable biodistribution for Radio-DARPi...

Analysis

This announcement emphasizes new preclinical data showing comparable biodistribution for Radio-DARPins labeled with 177Lu and 203Pb, supporting an isotope-agnostic design that can pair with therapeutic isotopes such as 212Pb and 225Ac. It builds on earlier updates about the ongoing Phase 1/2a trial of MP0712 and the development agreement with Eckert & Ziegler. Investors may focus on upcoming clinical readouts, continued progress of the Radio-DARPin pipeline, and how these data relate to timelines and risks outlined in recent regulatory filings.

Key Terms

radio-darpins, lutetium-177 (177lu), lead-203 (203pb), actinium-225 (225ac), +4 more

8 terms

radio-darpins medical

"new preclinical data on Radio-DARPins at the 3rd Global Radiopharmaceuticals..."

Radio-darpins are small, engineered proteins tagged with a tiny radioactive label so they can find and stick to a specific molecule in the body and either show up on a medical scan or deliver a focused dose of radiation. Think of them as a compact guided beacon or delivery truck that homes in on a target, helping doctors see disease more clearly or attack it more precisely; for investors, they matter because they signal potential for faster imaging, more effective targeted treatments, and distinct regulatory and commercial opportunities compared with conventional antibodies.

lutetium-177 (177lu) medical

"candidates labeled with Lutetium-177 (177Lu) or with Lead-203 (203Pb)..."

Lutetium-177 (177Lu) is a radioactive element used as the “payload” in certain cancer drugs that deliver targeted radiation directly to tumor cells. Think of it as a tiny guided missile that kills cancer cells while minimizing damage to surrounding tissue; investors watch its clinical success, regulatory approvals, manufacturing capacity and supply chain because those factors drive demand, pricing and revenue potential for companies developing these therapies.

lead-203 (203pb) medical

"candidates labeled with Lutetium-177 (177Lu) or with Lead-203 (203Pb)..."

Lead-203 (203Pb) is a radioactive isotope of lead used in medical imaging and drug development as a tracer to track where a drug goes inside the body. For investors, it matters because companies use 203Pb to visualize a candidate therapy’s distribution and safety before advancing to costly therapeutic trials, reducing technical and regulatory risk much like a dress rehearsal reveals problems before opening night.

actinium-225 (225ac) medical

"Imaging with 177Lu can be indicative of behavior with the therapeutic isotope Actinium-225 (225Ac)..."

Actinium-225 (225Ac) is a rare, highly radioactive isotope used as the active ingredient in certain cancer therapies that deliver powerful, short-range particles to destroy tumor cells while sparing most nearby healthy tissue. For investors, its importance lies in being a critical, limited raw material: production is complex and costly, so availability and manufacturing capacity directly affect the development timeline, cost and commercial potential of related medicines.

212pb medical

"similarly with 203Pb for 212Pb."

212Pb is a radioactive form of the metal lead used as a delivery vehicle in certain cancer treatments; it decays to produce short-range, high-energy particles that can destroy tumor cells near where it lodges. For investors, it matters because drugs using 212Pb combine scientific promise with regulatory, manufacturing and safety challenges—similar to a precision-guided tool that can be powerful but costly and complex to develop and commercialize.

dll3 medical

"MP0712, Molecular Partners’ DLL3-targeted 212Pb-based Radio-DARPin candidate..."

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 trial medical

"MP0712 ... is in an ongoing Phase 1/2a trial in the US (NCT07278479)."

A phase 1/2a trial is an early-stage clinical study that first checks how a new drug or therapy behaves in people (safety and appropriate dose) and then expands to see if it shows initial signs of benefit in a small group. For investors, these results are an early proof point similar to a prototype demo: positive findings can sharply increase a program’s value and reduce uncertainty, while problems can indicate higher risk or delays.

ind filing regulatory

"Location: Meeting Room B – IND Filing and Clinical Development Progress"

An IND filing is a formal application submitted to a drug regulator asking permission to begin testing a new medicine or biological therapy in people. Think of it like obtaining a building permit before construction begins: it signals that preclinical safety data were enough for regulators to allow human trials, making it a key milestone that can reduce uncertainty, unlock funding or deals, and increase a biotech company's near-term value—while still leaving clinical risk.

AI-generated analysis. Not financial advice.

• Highly comparable biodistribution profiles of Radio-DARPin candidates labeled with imaging isotopes ¹⁷⁷Lu or ²⁰³Pb allows for rapid expansion of pipeline with multiple therapeutic isotopes
  

ZURICH-SCHLIEREN, Switzerland and CONCORD, Mass., March 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 it will hold an oral presentation outlining new preclinical data on Radio-DARPins at the 3rd Global Radiopharmaceuticals Development Summit, taking place in Shanghai, China on March 19–20, 2026.

The presentation will outline the Radio-DARPins’ suitability to different isotopes with data on two Radio-DARPin candidates, each specific for a different tumor target. The results of studies in tumor-bearing mice show highly comparable biodistribution profiles for both Radio-DARPin candidates labeled with Lutetium-177 (¹⁷⁷Lu) or with Lead-203 (²⁰³Pb), with similar uptake and washout rates. Imaging with ¹⁷⁷Lu can be indicative of behavior with the therapeutic isotope Actinium-225 (²²⁵Ac), and similarly with ²⁰³Pb for ²¹²Pb.

“Our recent data confirms that our Radio-DARPin-vector design allows interchangeability of alpha-isotopes, including ²¹²Pb and ²²⁵Ac,” said Patrick Amstutz, Ph.D., CEO of Molecular Partners. “This feature offers us the opportunity and flexibility to evaluate Radio-DARPin candidates in an isotope-agnostic manner and to choose the most suitable therapeutic isotope, as late as with initial clinical data, without having to restart the entire drug discovery and development process – a significant advantage to tailor our candidates to patient needs.”

Details of the presentation

DARPins for targeted alpha therapy: from promising MP0712 first in-human data to opportunities for next Radio-DARPin candidates
Presenter: Daniel Steiner, Ph.D., SVP of Technology and Research
Time: 9:25 am CST, Friday, March 20
Location: Meeting Room B – IND Filing and Clinical Development Progress

The full presentation can be found here.

MP0712, Molecular Partners’ DLL3-targeted ²¹²Pb-based Radio-DARPin candidate co-developed with strategic partner Orano Med, is in an ongoing Phase 1/2a trial in the US (NCT07278479). Imaging data of MP0712 carrying the diagnostic isotope ²⁰³Pb under compassionate care are supportive of clinical development plans of MP0712 carrying the therapeutic isotope ²¹²Pb for patients with small cell lung cancer (SCLC) and other DLL3-expressing neuroendocrine cancers.

In February 2026, Molecular Partners entered into an agreement with Eckert & Ziegler, leading specialist in isotope-related components for nuclear medicine and radiation therapy, to enable the development and manufacturing of Radio-DARPin therapeutics. Eckert & Ziegler will support Molecular Partners with a comprehensive range of services covering development activities for Radio-DARPins with ²²⁵Ac as therapeutic payload and ¹⁷⁷Lu as imaging payload.

About Radio-DARPins
Molecular Partners’ Radio-DARPins are designed as ideal vectors for precise delivery of potent alpha-emitting isotopes to tumor lesions and have the potential to unlock a broad range of tumor targets for targeted radiopharmaceuticals. Building on the DARPins’ unique properties, Molecular Partners has developed a proprietary Radio-DARPin platform to address historic limitations of radioligand therapy, such as kidney accumulation and toxicity, and suboptimal tumor uptake. Molecular Partners’ Radio-DARPins addresses these limitations through half-life extension technologies 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 high affinity and specificity, small size, flexible architecture, and high stability – offer unmatched advantages to drug design, such as multispecificity, broad target range, and tunable half-life. The Company’s Radio-DARPins enable highly effective and specific delivery of potent radioactive payloads to tumor lesions while sparing healthy tissues. Molecular Partners’ Switch-DARPins allow conditional, tumor-localized immune activation, which enables increased safety and potency for next-generation immune cell engagers. Powered by twenty years of DARPin leadership in the clinic, 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

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, Ph.D., 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.

FAQ

What did Molecular Partners (MOLN) report about Radio-DARPin isotope flexibility on March 19, 2026?

They reported highly comparable biodistribution for two Radio-DARPins labeled with 177Lu or 203Pb in mice. According to the company, this supports isotope interchangeability and the ability to evaluate therapeutic isotopes like 225Ac or 212Pb without restarting discovery.

How does imaging with 177Lu or 203Pb relate to therapeutic isotopes for MOLN Radio-DARPins?

Imaging with 177Lu or 203Pb can be indicative of therapeutic behavior with 225Ac or 212Pb. According to the company, similar uptake and washout in mice suggest imaging isotopes may predict choice of therapeutic isotope in development.

What is the clinical status of MP0712 (MOLN) as of March 19, 2026?

MP0712 is in an ongoing Phase 1/2a trial (NCT07278479) investigating 212Pb for DLL3-expressing cancers. According to the company, compassionate-use imaging with 203Pb supports continued clinical development for SCLC and related neuroendocrine tumors.

What does the Eckert & Ziegler agreement mean for Molecular Partners' Radio-DARPin manufacturing?

The agreement provides development and manufacturing support for Radio-DARPins using 225Ac (therapeutic) and 177Lu (imaging). According to the company, Eckert & Ziegler will supply isotope-related development services and manufacturing capabilities.

When and where did Molecular Partners present the new Radio-DARPin preclinical data?

The company presented at the 3rd Global Radiopharmaceuticals Development Summit in Shanghai on March 19–20, 2026. According to the company, the oral presentation covered isotope-agnostic Radio-DARPin data and development opportunities.

What are the principal limitations of the new Radio-DARPin data announced by MOLN?

The main limitation is that results derive from tumor-bearing mouse studies and are not proof of human efficacy. According to the company, imaging data are supportive but require clinical validation in ongoing and future trials.