Highlights 

  • Initial human case study shows MP0712 uptake in primary tumors and metastases. 
  • Phase 1 IND for MP0712 submitted, US clinical trial expected to start by end-2025. 
  • MP0712 Radio-DARPin uses DLL3 internalization and replenishment to achieve high tumor accumulation. 

Molecular Partners AG (NASDAQ:MOLN), a clinical-stage biotech developing DARPin therapeutics, presented new data on MP0712, its lead Radio-DARPin targeting DLL3, at the Targeted Radiopharmaceuticals Summit Europe 2025. The presentation included first human images and supporting mechanism of action data, illustrating targeted tumor delivery. MP0712 is being developed with Orano Med for patients with small cell lung cancer and other neuroendocrine tumors. 

The data, provided by the Nuclear Medicine Research Infrastructure in South Africa, show MP0712 uptake in both primary tumors and metastatic lesions, while limiting exposure to key organs such as the liver and kidneys. NuMeRI plans to report complete imaging and dosimetry data at the Theranostics World Congress in January 2026. 

Management Statement 

Patrick Amstutz, Ph.D., CEO of Molecular Partners, said: “The images show targeted delivery of MP0712 into tumors and limited exposure in healthy organs of concern such as kidney and liver. This is an important milestone for MP0712, which is indicative of its potential performance in a clinical setting when carrying 212Pb as therapeutic radioactive payload and providing a strong basis for advancing its clinical development. We are continuing preparations for the upcoming Phase 1 trial with MP0712 and look forward to advancing additional Radio-DARPin programs in 2026.” 

Mechanism of Action and Preclinical Findings 

The patient received 203Pb-MP0712 through a Named Patient Access Program, providing imaging data to anticipate the behavior of 212Pb-labeled MP0712. Images demonstrated tumor-specific uptake within 24 hours, maintained over four days, while minimizing exposure to healthy organs. MP0712 is engineered for optimized half-life to maintain therapeutic blood levels and leverage rapid DLL3 internalization and replenishment, achieving high intracellular tumor concentrations even at low DLL3 expression levels. 

Phase 1 Clinical Trial Plans 

Molecular Partners has submitted a Phase 1 Investigational New Drug application in the US for MP0712 to treat SCLC and other DLL3-expressing neuroendocrine cancers. The Phase 1/2a study will evaluate safety, establish a recommended Phase 2 dose of 212Pb-labeled MP0712, and incorporate an imaging and dosimetry step using 203Pb-labeled MP0712.  

About DARPin and Molecular Partners 

DARPin (Designed Ankyrin Repeat Protein) therapeutics are engineered proteins offering high specificity, multifunctionality, and targeted delivery. Molecular Partners is developing multiple Radio-DARPins against targets including DLL3 and Mesothelin. Headquartered in Zurich, Switzerland, with US operations in Concord, MA, the company focuses on oncology and other indications not easily addressed by conventional therapeutics.