12 and older, any sex, with Merkel Cell Carcinoma. Patients with the condition only — healthy volunteers not accepted.
Results — posted to ClinicalTrials.gov
Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.
Objective Response Rate (ORR)Primary· Up to ~34 months
ORR was defined as the percentage of participants with Complete Response (CR: disappearance of all target lesions) or Partial Response (PR: at least a 30% decrease in the sum of diameters of target lesions) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1). The percentage of participants who experienced CR or PR as assessed by blinded independent central review (BICR) were presented.
Group
Value
95% CI
Pembrolizumab 200 mg
49.1
35.4 – 62.9
Duration of Response (DOR)Secondary· Up to ~58 months
For participants who demonstrated a confirmed Complete Response (CR: disappearance of all target lesions) or Partial Response (PR: At least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1, DOR was defined as the time from first documented evidence of a CR or PR until progressive disease (PD) or death. DOR for participants who had not progressed or died at the time of analysis was censored at the date of their last tumor assessment. Per RECIST 1.1, PD was defined as at least a 20% increase in the sum of diameters of target lesions as well as an absolute increase of at l
Group
Value
95% CI
Pembrolizumab 200 mg
39.8
23.8 – NA
Progression-free Survival (PFS)Secondary· Up to ~58 months
Progression-Free Survival was defined as the time from the first dose of study treatment to the first documented evidence of disease progression per RECIST 1.1 by BICR or death due to any cause, whichever occurred first. Per RECIST 1.1, PD was defined as ≥20% increase in the sum of diameters of target lesions. In addition to the relative increase of 20%, the sum must also have demonstrated an absolute increase of ≥5 mm. The appearance of one or more new lesions was also considered PD. PFS as assessed by BICR per RECIST 1.1 was presented.
Group
Value
95% CI
Pembrolizumab 200 mg
9.3
3.0 – 25.5
Overall Survival (OS)Secondary· Up to ~58 months
OS was defined as the time from the first dose of study treatment until death from any cause.
Group
Value
95% CI
Pembrolizumab 200 mg
24.3
12.4 – NA
Number of Participants With One or More Adverse Events (AEs)Secondary· Up to ~58 months
An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. The number of participants with at least one AE was assessed.
Group
Value
95% CI
Pembrolizumab 200 mg
52
Number of Participants Who Discontinued From Study Treatment Due to an AESecondary· Up to ~27 months
An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. The number of participants who discontinued from study treatment due to an AE was assessed.
Group
Value
95% CI
Pembrolizumab 200 mg
18
Adverse events — posted to ClinicalTrials.gov
Time frame: Up to ~58 months.
Reporting threshold: 5%.
Adverse-event reports describe events observed during the trial — not all are caused by the drug.
Pembrolizumab 200 mg
Serious: 24/55 (44%)
Deaths: 32/55
Serious adverse events (30 terms)
Reaction
System
Pembrolizumab 200 mg
Basal cell carcinoma
Neoplasms benign, malignant and unspecified (incl cysts and polyps)
—
Pulmonary embolism
Respiratory, thoracic and mediastinal disorders
—
Colitis
Gastrointestinal disorders
—
Dysphagia
Gastrointestinal disorders
—
Obstructive pancreatitis
Gastrointestinal disorders
—
Small intestinal obstruction
Gastrointestinal disorders
—
Subileus
Gastrointestinal disorders
—
Fatigue
General disorders
—
Cellulitis
Infections and infestations
—
Cystitis
Infections and infestations
—
Empyema
Infections and infestations
—
Encephalitis
Infections and infestations
—
Erysipelas
Infections and infestations
—
Pneumonia
Infections and infestations
—
Respiratory syncytial virus infection
Infections and infestations
—
Upper respiratory tract infection
Infections and infestations
—
Wound infection
Infections and infestations
—
Muscular weakness
Musculoskeletal and connective tissue disorders
—
Squamous cell carcinoma
Neoplasms benign, malignant and unspecified (incl cysts and polyps)
—
Squamous cell carcinoma of skin
Neoplasms benign, malignant and unspecified (incl cysts and polyps)
—
Transitional cell carcinoma
Neoplasms benign, malignant and unspecified (incl cysts and polyps)
This is a single-arm, open-label, multicenter, efficacy, and safety study of pembrolizumab in adult and pediatric participants with previously untreated advanced Merkel Cell Carcinoma (MCC). The primary objective of the trial is to assess the objective response rate, as assessed by blinded independent central review per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) modified to follow a maximum of 10 target lesions and a maximum of 5 target lesions per organ, following administration of pembrolizumab.
Publications & conference data
8 peer-reviewed publications reference this trial (live from Europe PMC):
NCT03111732 — Pembrolizumab, a Monoclonal Antibody Against PD-1, in Combination With Capecitabine and Oxaliplatin (CAPOX) in People Wi
· Phase 2
· completed
NCT07288073 — TIL Therapy in cSCC and MCC
· Phase 2
· recruiting
NCT07285044 — The Cancer Connected Access and Remote Expertise Beyond Walls Program to Provide In-Home Cancer Treatment and Improve Tr
· Phase 2
· recruiting
NCT07115043 — A Study to Investigate Safety of AZD6750 in Adult Participants With Select Advanced or Metastatic Solid Tumors
· Phase 1, PHASE2
· recruiting
NCT06753136 — Electrochemotherapy (ECT) in Patients With Primary Visceral Tumors and/or Secondary Visceral Localizations, of Any Histo
· NA
· recruiting
NCT06223659 — EMLA Topical Cream for Treatment of Pain in Patients Receiving Intra-Dermal Technetium 99 Injections for Lymphoscintigra
· Phase 2
· recruiting
Other Merck Sharp & Dohme LLC trials
Trials by the same sponsor.
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· Phase 2
· not yet recruiting
NCT07302347 — A Study of Pembrolizumab in Japanese Pediatric Participants With Solid Tumors or Lymphomas and Japanese Adult Participan
· Phase 1, PHASE2
· recruiting
NCT07528508 — A Clinical Trial in Healthy Participants to Study the Effect of a Single Dose of MK-8527 on Levels of Methadone (MK-8527
· Phase 1
· not yet recruiting
NCT07513376 — A Clinical Trial of Adjuvant Intismeran (V940) With or Without Pembrolizumab Coformulated With Berahyaluronidase Alfa (M
· Phase 3
· not yet recruiting
NCT07532304 — A Clinical Trial of MK-4646 With Bictegravir/Emtricitabine/Tenofovir Alafenamide and Dolutegravir in Healthy Adult Parti
· Phase 1
· not yet recruiting
Publications: Europe PMC API search by NCT ID, retrieved 10 June 2026
Drug + disease cross-links: matched in real time against Drug Landscape's normalised drug + company + condition tables
Sponsor: as reported to ClinicalTrials.gov by Merck Sharp & Dohme LLC
Last refreshed: 28 May 2025
Drug Landscape aggregates and links these public records for informational use only. Always verify against the primary source before clinical or regulatory decisions. Canonical URL: https://druglandscape.com/trial/NCT03783078.