Trial Purpose

The purpose of this study is to assess the efficacy and safety of treatment with definitive chemoradiotherapy (dCRT) + pembrolizumab (MK-3475) compared to treatment with dCRT + placebo with respect to Overall Survival (OS) and Event-free Survival (EFS) in:

  • participants with esophageal squamous cell carcinoma (ESCC),
  • participants whose tumors express Programmed Death-Ligand 1 (PD-L1) Combined Positive Score (CPS) ≥10, and
  • all participants.

The primary study hypotheses are that dCRT+ pembrolizumab is better than dCRT + placebo with respect to:

  • OS in participants with ESCC,
  • OS in participants whose tumors express PD-L1 CPS ≥10,
  • OS in all participants,
  • EFS in participants with ESCC,
  • EFS in participants whose tumors express PD-L1 CPS ≥10, and
  • EFS in all participants.
Learn More on



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

About The Study

Trial Phase Icon

Phase 3

Tests the medicine or vaccine in large groups of trial participants (from several hundred to several thousand). 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 28 February 2020
  • Estimated primary completion date 21 February 2026
  • Estimated study completion date 21 February 2026


Only a qualified healthcare professional can determine your eligibility. However, this information may be useful in starting a conversation with your doctor.

Conditions Icon


Esophageal Adenocarcinoma, Esophageal Squamous Cell Carcinoma, Gastroesophageal Junction Carcinoma

Age Range Icon

Age Range

18 - No Age Maximum

Sex Icon



Trial locations

Locations provided may not reflect the most current site information. Please call the number provided in the location results to confirm.