Molecular Partners AG and Orano Med have announced the dosing of the first patients in a US multicenter Phase 1/2a study of MP0712, a Radio-DARPin candidate targeting delta-like ligand 3 (DLL3) for the treatment of small cell lung cancer. The trial aims to establish the clinical safety profile of this novel therapy, which utilizes a lead-212 payload to attack tumors expressing DLL3, a protein present in over 85% of small cell lung cancer tumors. This development marks a significant step in the strategic partnership between the two companies to advance targeted alpha therapies.

MP0712 is the lead candidate under the collaboration, designed to address unmet medical needs in aggressive neuroendocrine tumors. The program uses a "matched-pair" approach, where a diagnostic imaging agent labeled with 203Pb is used to predict tumor uptake prior to treatment. Patients in the study receive up to four doses of the therapeutic agent, 212Pb-labeled MP0712, within assigned dose level cohorts.

The study currently has five centers open and actively recruiting in the US, with additional sites planned to open later this year. Dosing is ongoing in cohort 1, where patients are moving to repeat dosing cycles. The trial includes up to four dose levels to evaluate safety and efficacy.

Patrick Amstutz, Ph.D., CEO of Molecular Partners, highlighted the progress, stating that the company is on track to report initial study data in 2026. He emphasized that the real-time establishment of the clinical safety profile paves the way for other Radio-DARPin candidates. Frédéric Desdouits, Ph.D., CEO of Orano Med, noted that the dosing illustrates the potential of lead-212 to support a broad clinical pipeline of targeted alpha therapies.

Initial data from the Phase 1/2a study are expected in the coming months, with a more comprehensive dataset on safety and efficacy anticipated in 2027. The trial is registered under ClinicalTrials.gov identifier NCT07278479.

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