Molecular Partners Advances DLL3 Radioligand Program With New Phase 1/2a Cancer Trial

Molecular Partners (MLLCF) announced an update on their ongoing clinical study.

Molecular Partners’ new phase 1/2a trial targets a tough group of cancers, including small cell lung cancer and other tumors that carry the DLL3 marker. The study, officially titled “A Phase 1/2a Study to Assess Safety, Tolerability, and Efficacy of [212Pb]Pb-DOTAM-MAM279 in Patients With Small Cell Lung Cancer and Other DLL3 Expressing Solid Tumors,” aims to find a safe dose, understand early signs of benefit, and map how the drug moves through the body. For investors, this is an early but important test of the company’s radioligand platform in high-need indications where treatment options remain limited.

The main treatment is [212Pb]Pb-MP0712, a radioligand therapy designed to deliver targeted radiation directly to DLL3-positive cancer cells while sparing healthy tissue. Before treatment, patients receive [203Pb]Pb-MP0712, an imaging agent that helps doctors see where the drug goes and estimate the radiation dose. This paired approach aims to customize treatment and improve safety, which could be a competitive edge if results are positive.

The study is interventional and runs in two steps. First, dose escalation tests rising doses in small groups to identify a safe exposure range. Then, a dose expansion phase treats more patients at the selected dose to gather early data on tumor response. There is no randomization or placebo; all enrolled patients receive the experimental drug. The trial is open-label, meaning both doctors and patients know they are getting [212Pb]Pb-MP0712, and the main goal is treatment rather than prevention or diagnosis.

The trial is listed as recruiting, signaling active site startup and patient enrollment. Key operational dates include the initial submission in November 2025, which marked the move from planning into formal regulatory engagement. The most recent update on January 8, 2026, indicates the record has been refreshed, often a sign of protocol refinements or broader site activation. Primary and final completion dates are not yet specified, underlining that investors should treat this as an early-stage, multi-year catalyst rather than an immediate data event.

From a market angle, this update confirms Molecular Partners’ push into radioligand oncology alongside partner Orano Med, placing it in the same broad field as players working on targeted radiotherapies. While revenue impact is distant, recruiting status and an updated protocol reduce execution risk and support the long-term pipeline story, which can underpin sentiment in weak biotech markets. Any later signs of safety and activity in small cell lung cancer and related neuroendocrine tumors could re-rate the stock, particularly given limited competition in DLL3-targeted radioligands. For now, investors may view this as a high-risk, high-upside option on future clinical data, with the study currently ongoing and further details available on the ClinicalTrials portal.

To learn more about MLLCF’s potential, visit the Molecular Partners drug pipeline page.