MC-339

MC-339 is a peptidic small molecule radiopharmaceutical engineered to deliver an actinium payload for targeted radioligand therapy (RLT) of small cell lung cancer. Developed by Mariana Oncology (now a subsidiary of Novartis), it leverages peptide-based targeting to enhance tumor penetration and distribution compared to antibody-based approaches. The drug is designed as a precision medicine that binds to specific receptors on tumor cells—though the precise biological target has not been publicly disclosed—and delivers alpha-emitting radiation directly into the tumor microenvironment. This causes DNA damage, inhibits cell proliferation, and may induce cell death while minimizing off-target toxicity. As of June 2025, MC-339 remains in preclinical development[1][2][3][4][5][7][8][9].

Other names

DLL3-targeting radioligand therapyDLL-3-targeting radioligand therapyDLL 3-targeting radioligand therapyMariana Oncology DLL3 RLT