Pembrolizumab treatment for Japanese children with solid tumors or lymphomas and Japanese adults with Merkel cell carcinoma

A Phase I/II Study of Pembrolizumab (MK-3475) in Japanese Pediatric Participants With Specific Solid Tumors or Lymphomas, or in Japanese Adult Participants With Advanced Merkel Cell Carcinoma (KEYNOTE-G21)

This study will try pembrolizumab in Japanese children with solid tumors or lymphomas and in Japanese adults with Merkel cell carcinoma to learn about safety, how the drug moves through the body, and whether tumors shrink.

Quick facts

• Phase: Phase1; Phase2
• Study type: Interventional
• Enrollment: 20 (estimated)
• Ages: 6 Months and up
• Sex: All
• Sponsor: Merck Sharp & Dohme LLC (Industry-sponsored)
• Drugs / interventions: radiation, pembrolizumab
• Locations: 3 sites (Nagoya, Aichi-ken and 2 other locations)
• Trial ID: NCT07302347 on ClinicalTrials.gov

What this trial studies

This Phase 1/2, open-label trial gives pembrolizumab to Japanese pediatric participants with solid tumors or lymphomas and to Japanese adults with Merkel cell carcinoma to collect safety, pharmacokinetic, and tumor response data. Participants are enrolled into cohorts based on cancer type (for example relapsed or refractory classical Hodgkin lymphoma, primary mediastinal large B-cell lymphoma, resected or advanced melanoma, or Merkel cell carcinoma) and receive defined doses of pembrolizumab with regular monitoring for side effects and radiographic tumor measurements. Early-phase dosing and pharmacokinetic sampling will guide safe dose selection, followed by expansion cohorts to observe antitumor activity. The trial is sponsored by Merck Sharp & Dohme and is conducted at multiple hospitals in Japan.

Who should consider this trial

Good fit: Ideal candidates are Japanese children with relapsed or refractory solid tumors or lymphomas, or Japanese adults with Merkel cell carcinoma, who meet the study's medical and laboratory eligibility requirements.

Not a fit: Patients without these tumor types, those with active autoimmune disease or other contraindications to PD-1 inhibitors, or those already doing well on standard therapies are unlikely to benefit from joining this trial.

Why it matters

Potential benefit: If successful, this could provide an effective immunotherapy option that shrinks tumors or helps control disease in these Japanese patient groups.

How similar studies have performed: Other trials have shown pembrolizumab can be highly effective in adult melanoma, Merkel cell carcinoma, and Hodgkin lymphoma, while pediatric evidence is more limited and remains under study.

Eligibility criteria

Inclusion Criteria:

The main inclusion criteria include but are not limited to the following:

Arm 1:

* For participants with relapsed or refractory classical Hodgkin lymphoma (cHL) or primary mediastinal large B-cell lymphoma (PMBCL)

  * Has a confirmed diagnosis of relapsed or refractory cHL or PMBCL after the most recent therapy
  * Has radiographically measurable disease per Lugano classification
* For participants with completely resected melanoma:

  * Has surgically completely resected and histologically/pathologically confirmed diagnosis of Stage IIB, IIC, III or IV cutaneous melanoma
  * Has not received any prior systemic therapy for their melanoma beyond surgical resection
  * All suspicious lesions amenable to biopsy are confirmed negative for malignancy
* For participants with locally advanced or metastatic melanoma:

  * Has histologically confirmed diagnosis of locally advanced (unresectable Stage III) or metastatic (Stage IV) melanoma (including acral) not amenable to local therapy
  * Has radiographically measurable lesion(s) as defined by RECIST 1.1
* For participants with microsatellite instability-high (MSI-H)/mismatch repair deficiency (dMMR) solid tumors:

  * Has histologically/cytologically documented, locally-advanced, or metastatic solid malignancy that is incurable and has either (a) failed prior standard therapy, (b) for which no standard therapy exists, or (c) standard therapy is not considered appropriate by the participant and treating physician
  * Has a documented positive local MSI-H or dMMR test result
  * Has radiographically measurable disease based on RECIST 1.1
* For participants with tumor mutational burden-high (TMB-H) solid tumors:

  * Has histologically/cytologically documented, locally-advanced, or metastatic solid malignancy that is incurable and has either (a) failed prior standard therapy, (b) for which no standard therapy exists, or (c) standard therapy is not considered appropriate by the participant and treating physician
  * Has radiographically measurable disease based on RECIST 1.1
* For participants with MCC:

  * Has histologically confirmed diagnosis of locoregional MCC that has recurred following standard locoregional therapy with surgery and/or radiation therapy and is not amenable to local therapy or metastatic MCC (Stage IV)
  * Has radiographically measurable disease based on RECIST 1.1

Arm 2:

* For participants with MCC:

  * Has been untreated for advanced or metastatic disease

Arm 1 \& Arm 2:

* Life expectancy of \>3 months (Arm 1) or \>6 months (Arm 2)

Exclusion Criteria:

The main exclusion criteria include but are not limited to the following:

* Has known additional malignancy that is progressing or has required active treatment
* Has known active (central nervous system) CNS metastases and/or carcinomatous meningitis
* Has active autoimmune disease that has required systemic treatment in past 2 years
* Has history of (noninfectious) pneumonitis/interstitial lung disease that required steroids or has current pneumonitis/interstitial lung disease
* Has active infection requiring systemic therapy
* Has known history of human immunodeficiency virus (HIV) infection
* Has known history of Hepatitis B infection or known active Hepatitis C virus
* Has undergone solid organ transplant at any time, or prior allogeneic hematopoietic stem cell transplantation within the last 5 years
* Has not adequately recovered from major surgery or has ongoing surgical complications

Where this trial is running

Nagoya, Aichi-ken and 2 other locations

• Nagoya City University Hospital ( Site 0003) — Nagoya, Aichi-ken, Japan (Recruiting)
• Sapporo Hokuyu Hospital ( Site 0005) — Sapporo, Hokkaido, Japan (Recruiting)
• National Hospital Organization Kyushu Cancer Center ( Site 0001) — Fukuoka, Japan (Recruiting)

Study contacts

• Study coordinator: Toll Free Number

Conditions Malignant Neoplasm; Carcinoma, Merkel Cell; Lymphoma