Moderna, Inc. announced on April 19, 2026, that the U.S. Food and Drug Administration (FDA) has granted Fast Track designation for its investigational cancer vaccine, mRNA-4359. The designation applies specifically to the use of mRNA-4359 in combination with pembrolizumab for the treatment of patients with unresectable or metastatic cutaneous melanoma that is PD-L1 positive. This regulatory milestone is intended to expedite the development and review of therapies that address serious conditions and fill unmet medical needs.
The FDA decision is based on clinical data from an ongoing Phase 1/2 open-label study. In this trial, mRNA-4359 is being evaluated as a monotherapy and in combination with pembrolizumab, a PD-1 inhibitor marketed by Merck & Co. as Keytruda. The study focuses on patients with advanced solid tumors who have progressed on or are intolerant to standard-of-care therapies. Initial results presented by the company indicated that the combination therapy demonstrated a manageable safety profile and evidence of clinical activity, including objective responses in the targeted melanoma patient population.
mRNA-4359 is designed as an off-the-shelf cancer vaccine that encodes for two specific proteins: indoleamine 2,3-dioxygenase (IDO) and programmed death-ligand 1 (PD-L1). By targeting these proteins, the therapy aims to stimulate the immune system to recognize and eliminate cells that express these immunosuppressive markers, which are often utilized by tumors to evade immune detection. Unlike personalized cancer vaccines that require individual manufacturing for each patient, mRNA-4359 is a standardized product intended for broader application across patients with specific tumor profiles.
Stephen Hoge, M.D., President of Moderna, stated that the Fast Track designation underscores the potential of mRNA-4359 to provide a new treatment option for patients with advanced melanoma who face limited therapeutic alternatives. He noted that the company remains committed to advancing its oncology pipeline, which leverages mRNA technology to modulate the tumor microenvironment. The company confirmed that it will continue to work closely with the FDA as it progresses through the clinical development stages.
The Fast Track program provides Moderna with opportunities for more frequent meetings with the FDA to discuss the vaccine's development plan and ensure the collection of appropriate data. It also allows for eligibility for Accelerated Approval and Priority Review if relevant criteria are met, as well as Rolling Review, which enables the company to submit completed sections of its Biologics License Application (BLA) for individual review by the agency.
Moderna’s oncology portfolio currently includes several other mRNA-based candidates, such as mRNA-4157, a personalized cancer vaccine being developed in collaboration with Merck. The advancement of mRNA-4359 represents a key component of the company’s strategy to expand its footprint in the immuno-oncology space beyond personalized treatments.