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Phase 1b/2 Clinical Trial to Evaluate the Safety and Efficacy of Combination Therapy With Pembrolizumab and Irinotecan in Patients With Metastatic or Recurrent Malignant Melanoma
Sponsor: Yonsei University
Summary
This is a single-center, open-label, single-arm Phase 1b/2 clinical trial designed to evaluate the safety, tolerability, and preliminary efficacy of pembrolizumab in combination with irinotecan in patients with metastatic melanoma who have relapsed at least 6 months after completion of adjuvant pembrolizumab therapy or who are immune checkpoint inhibitor-naïve. The study consists of two sequential parts: a Phase 1b safety lead-in and a Phase 2 efficacy evaluation using Simon's optimal two-stage design. During the Phase 1b portion, six patients will be enrolled to assess the initial safety and tolerability of the combination regimen. Dose-limiting toxicities (DLTs) will be evaluated during the first two treatment cycles (42 days). Following completion of the safety observation period, a safety review will be conducted. If fewer than two of six patients experience a DLT, the regimen will be considered adequately tolerable and the study will proceed to the Phase 2 portion. Patients enrolled in the Phase 1b portion will be included in the efficacy analysis of Phase 2. In the Phase 2 portion, efficacy will be evaluated using Simon's optimal two-stage design with objective response rate (ORR) as the primary endpoint. The null hypothesis ORR is 30%, and the alternative hypothesis ORR is 50%, with a one-sided type I error rate of 5% and 80% power. In Stage 1, a total of 15 evaluable patients, including the six patients enrolled during the Phase 1b portion, will be assessed. If five or fewer objective responses are observed, the study will be terminated early for futility. If six or more responses are observed, additional patients will be enrolled in Stage 2. A total of 46 patients will be enrolled, and the regimen will be considered worthy of further investigation if at least 19 objective responses are observed. Participants will receive pembrolizumab 200 mg intravenously on Day 1 of each 21-day cycle. Irinotecan 125 mg/m² will be administered intravenously on Days 1 and 8 beginning in Cycle 2. Cycle 1 consists of pembrolizumab monotherapy to allow evaluation of early immunologic changes induced by PD-1 blockade without potential interference from irinotecan. Blood and tumor samples will be collected at baseline and prior to irinotecan administration on Cycle 2 Day 1 for translational immune analyses. Tumor assessments will be performed according to RECIST version 1.1 every 6 weeks during the first year and every 12 weeks thereafter. The primary endpoint is objective response rate (ORR). Secondary endpoints include disease control rate (DCR), progression-free survival (PFS), overall survival (OS), dose-limiting toxicity (DLT), and safety and tolerability as assessed by the incidence of adverse events graded according to CTCAE version 5.0. Exploratory analyses will evaluate tumor microenvironment characteristics and peripheral blood immune biomarkers, including immune cell phenotypes, cytokine profiles, and potential biomarkers associated with treatment response and resistance.
Key Details
Gender
All
Age Range
19 Years - Any
Study Type
INTERVENTIONAL
Enrollment
46
Start Date
2026-11-01
Completion Date
2028-06-08
Last Updated
2026-09-14
Healthy Volunteers
No
Conditions
Interventions
Pembrolizumab and Irinotecan
Participants will receive pembrolizumab 200 mg intravenously on Day 1 of each 21-day cycle. Cycle 1 consists of pembrolizumab monotherapy, and irinotecan 125 mg/m² will be added on Days 1 and 8 from Cycle 2 onward. The study includes a Phase 1b safety lead-in and a Phase 2 efficacy evaluation using Simon's optimal two-stage design. Treatment will continue for up to 35 cycles or until disease progression, unacceptable toxicity, or study discontinuation.