Original Research ARTICLE
Effect of radiotherapy combined with pembrolizumab on local tumor control in mucosal melanoma patients
- 1Department of Radiation Oncology, Gachon University Gil Hospital, South Korea
- 2Department of Radiation Oncology, College of Medicine, Yonsei university, South Korea
- 3Department of Dermatology, Gangnam Severance Hospital, South Korea
- 4Department of Dermatology, Yonsei University College of Medicine, South Korea
- 5Department of Internal Medicine, College of Medicine, Yonsei university, South Korea
Objective: Mucosal melanoma is an aggressive malignancy with a poor response to conventional therapies. The efficacy of radiotherapy (RT), especially combined with immune checkpoint inhibitors (ICIs), for this rare melanoma subtype remains unknown. We investigated the reciprocal effect of RT and ICI on mucosal melanoma patients.
Materials/Methods: We identified 23 patients with 31 tumors who were treated with RT between July 2008 and February 2017. All patients received RT for primary or metastatic gross tumor mass with a median dose of 4 Gy per fraction (range 1.8–12 Gy). Eleven patients (14 lesions) were treated with RT alone, whereas 12 (17 lesions) were administered pembrolizumab combined with RT (ICI+RT group). The local control (LC) and adverse event (AE) rates were compared between the groups. Eight patients with metastatic mucosal melanoma treated with ICI alone during the same study period were included as a comparison group.
Results: The median follow-up period was 17.4 (range 3.7–95.2) months. The target lesion control rate at 1-year was significantly higher in the ICI+RT group than in the RT-alone group or ICI-alone group (94.1% vs. 57.1% vs. 25%; P<.05). No abscopal effect was observed in our cohort. Treatment-related AEs were not significantly increased in the combined treatment group compared with the RT-alone group (P>.05). No grade ≥3 AEs occurred in the ICI+RT group.
Conclusions: Besides RT acting as an immune adjuvant, ICI might have a radiosensitizing effect and may increase LC without severe toxicity. We have initiated a phase II study to determine the effects of RT in patients with melanoma undergoing anti-PD1 (NCT04017897).
Keywords: Melanoma, Radiotherapy, Immunotherapy, local control, Toxicities and side effects
Received: 10 May 2019;
Accepted: 13 Aug 2019.
Copyright: © 2019 Kim, Chang, Roh, Oh, Chung, Shin and Koom. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Mx. Jee Suk Chang, Department of Radiation Oncology, College of Medicine, Yonsei university, Seoul, South Korea, email@example.com
Mx. Sang Joon Shin, Department of Internal Medicine, College of Medicine, Yonsei university, Seoul, Seoul, South Korea, firstname.lastname@example.org