This clinical trial is for men and women who have had surgery to remove their melanoma.
   
The purpose of this study is to test the safety and anti-cancer activity of an experimental treatment called MK-7684A (a combination of MK-7684 and pembrolizumab) compared to pembrolizumab alone in adults who have had surgery to remove their melanoma.
   
MK-7684A is a combination of 2 drugs: MK-7684 and pembrolizumab (pembro). MK-7684 is an experimental drug. It has not been approved by the Food & Drug Administration (FDA). Pembro has been approved by certain health authorities for treating melanoma and other cancers. It has become a standard treatment for melanoma in many countries, though it may not be approved for participants’ exact type of melanoma in all countries.

This trial will compare MK-7684A to pembro alone. The drug a participant gets will depend on which group they are placed in. This trial has 2 groups:

   --Group 1: will get MK-7684A
   --Group 2: will get pembro
   
A computer will decide which group a participant is put in. Participants have an equal chance of being in Group 1 or Group 2.
   
All trial drugs will be given once every 3 weeks by a needle in the arm (intravenous [IV] infusion).
   
The length of participation in the trial depends on a participant’s health and how well they tolerate the trial drugs. Participants will be in the Treatment Phase for about 1 year, as long as their cancer does not get worse, and they tolerate the trial drugs. After the Treatment Phase, participants will be in the Follow-up Phase for approximately 8 years. Follow-up visits will continue until their cancer becomes worse or they start a new cancer treatment. Once participants have completed the follow-up visits, the trial team will contact them every 12 weeks to check on their health.