Trial Purpose

This 2-part study will evaluate the safety and efficacy of pembrolizumab (MK-3475) compared to placebo in participants with surgically resected high-risk Stage II melanoma. Participants in Part 1 will receive either pembrolizumab or placebo in a double-blind design for up to 17 cycles (each cycle = 21 days). Participants who receive placebo or who stop treatment after receiving 17 cycles of pembrolizumab in Part 1, do not experience disease recurrence within 6 months of completing pembrolizumab in Part 1, and do not stop treatment with pembrolizumab for disease recurrence or intolerability, may be eligible to receive up to 35 additional cycles of pembrolizumab in Part 2 in an open-label design. The primary hypothesis of this study is that pembrolizumab increases recurrence-free survival (RFS) compared to placebo.

View full trial information on



When speaking to your doctor, please have the trial identifier number available.

About The Trial

This trial will be done in 2 parts. In Part 1, patients who enroll in the trial will receive the following.

50% will receive pembrolizumab

50% will receive placebo

*If your cancer returns following Part 1, you may be able to receive pembrolizumab in Part 2. Your doctor will let you know if you can receive pembrolizumab and discuss your treatment options with you.

Trial Phase Icon

Phase 3

Tests the medicine or vaccine in approximately 1,000 to 5,000 volunteers. For medicines, volunteers have the disease or condition the medicine is designed to treat. In vaccine studies, the volunteers may be healthy or have diseases or conditions. Phase 3 trials take place in hospitals, clinics or physician offices.

Trial start Icon


  • Actual study start date September 12, 2018
  • Estimated primary completion date June 21, 2021
  • Estimated study completion date October 12, 2033


Conditions Icon



Age Range Icon

Age Range

12 - No Age Maximum

Sex Icon



Trial locations

What Can You Do Next?

If you think this trial might be a fit and are interested in participating, take the next step to see if you are eligible.

Discuss Icon

Discuss With Your Doctor

Print this page or email it to your doctor to discuss at your next visit.



When speaking to your doctor, please have the trial identifier number available.

Participating in a clinical trial is an important decision.

Anyone participating in a trial should know as much as possible about what is being studied, what risks are involved and what potential benefits may be gained before deciding to enroll. If you are interested in participating in a clinical trial, please talk to your doctor first.