Efficacy of Targeted Radionuclide Therapy Using [I]ICF01012 in 3D Pigmented BRAF- and NRAS-Mutant Melanoma Models and In Vivo NRAS-Mutant Melanoma.

PURPOSE

To assess the efficiency of targeted radionuclide therapy (TRT), alone or in combination with MEK inhibitors (MEKi), in melanomas harboring constitutive MAPK/ERK activation responsible for tumor radioresistance.

METHODS

For TRT, we used a melanin radiotracer ([I]ICF01012) currently in phase 1 clinical trial (NCT03784625). TRT alone or combined with MEKi was evaluated in three-dimensional melanoma spheroid models of human BRAF SK-MEL-3, murine NRAS 1007, and WT B16F10 melanomas. TRT in vivo biodistribution, dosimetry, efficiency, and molecular mechanisms were studied using the C57BL/6J-NRAS 1007 syngeneic model.

RESULTS

TRT cooperated with MEKi to increase apoptosis in both BRAF- and NRAS-mutant spheroids. NRAS spheroids were highly radiosensitive towards [I]ICF01012-TRT. In mice bearing NRAS 1007 melanoma, [I]ICF01012 induced a significant extended survival (92 vs. 44 days, < 0.0001), associated with a 93-Gy tumor deposit, and reduced lymph-node metastases. Comparative transcriptomic analyses confirmed a decrease in mitosis, proliferation, and metastasis signatures in TRT-treated vs. control tumors and suggest that TRT acts through an increase in oxidation and inflammation and P53 activation.

CONCLUSION

Our data suggest that [I]ICF01012-TRT and MEKi combination could be of benefit for advanced pigmented BRAF-mutant melanoma care and that [I]ICF01012 alone could constitute a new potential NRAS-mutant melanoma treatment.