Moderna's Cancer Antigen Therapy Shows Promise in Melanoma Study

Moderna, the biotechnology company known for its mRNA-based vaccines, has reported encouraging results from a Phase I/II study of its investigational cancer antigen therapy, mRNA-4359, in combination with Merck's Keytruda for the treatment of melanoma. The data, presented at the 2025 European Society for Medical Oncology meeting, demonstrate the potential of mRNA technology in oncology and highlight Moderna's expanding presence in the cancer treatment landscape.

Promising Efficacy in Combination Therapy

The study evaluated mRNA-4359 in combination with Keytruda in 29 evaluable patients with melanoma who had previously undergone at least one line of checkpoint inhibitor treatment. The combination therapy demonstrated a 24% overall objective response rate (ORR), with a notable increase to 67% in patients whose tumors were positive for PD-L1 expression.

Kyle Holen, head of Development, Therapeutics and Oncology at Moderna, emphasized the significance of these early findings, stating, "These results are unique in the field and incredibly promising for future development options." Holen highlighted the ability of mRNA-4359 to induce a target-specific T cell response, contrasting it with typical checkpoint inhibitors that trigger nonspecific activity.

Mechanism of Action and Potential Advantages

mRNA-4359 is designed to encode broad epitopes of PD-L1 and the enzyme IDO1, both of which play roles in helping tumor cells evade the immune system. This mechanism allows the therapy to specifically target cancer cells expressing these markers while also rebalancing the tumor microenvironment to promote immune activity.

The combination therapy showed a 60% disease control rate, with six out of ten treated patients achieving tumor response or stable disease. Moderna believes this approach could enable broader and more durable immune responses in cases where previous therapies have failed.

Ongoing Development and Future Prospects

While these results are promising, Moderna acknowledges that they are still in the early stages of development. The ongoing Phase I/II trial, which is testing mRNA-4359 as both a monotherapy and in combination with Keytruda in patients with advanced solid tumors, is set to continue until February 2032.

This latest development adds to Moderna's growing oncology portfolio, which includes mRNA-4157, a personalized cancer vaccine being developed in partnership with Merck. Previous Phase IIb data for mRNA-4157 in combination with Keytruda showed a 49% reduction in the risk of recurrence or death in high-risk melanoma patients who had undergone complete resection. The launch of this combination regimen is anticipated in 2027, further solidifying Moderna's position in the cancer treatment arena.