An Efficacy Study of Adjuvant Treatment With the Personalized Cancer Vaccine mRNA-4157 and Pembrolizumab in Participants With High-Risk Melanoma (KEYNOTE-942)

Key Inclusion Criteria:

* Resectable cutaneous melanoma metastatic to a lymph node and at high risk of recurrence
* Complete resection within 13 weeks prior to the first dose of pembrolizumab
* Disease free at study entry (after surgery) with no loco-regional relapse or distant metastasis and no clinical evidence of brain metastases
* Has an formalin fixed paraffin embedded (FFPE) tumor sample available suitable for sequencing
* Eastern Cooperative Oncology Group (ECOG) Performance Status 0 or 1
* Normal organ and marrow function reported at screening

Key Exclusion Criteria:

* Prior malignancy, unless no evidence of that disease for at least 5 years prior to study entry
* Prior systemic anti-cancer treatment (except surgery and interferon for thick primary melanomas. Radiotherapy after lymph node dissection is permitted)
* Live vaccine within 30 days prior to the first dose of pembrolizumab
* Transfusion of blood or administration of colony stimulating factors within 2 weeks of the screening blood sample
* Active autoimmune disease
* Immunodeficiency, systemic steroid therapy, or any other immunosuppressive therapy within 7 days prior to the first dose of pembrolizumab
* Solid organ or allogeneic bone marrow transplant
* Pneumonitis or a history of (noninfectious) pneumonitis that required steroids
* Prior interstitial lung disease
* Clinically significant heart failure
* Known history of human immunodeficiency virus (HIV)
* Known active hepatitis B or C
* Active infection requiring treatment