Immunotherapy for advanced melanoma: current situation in Japan

Treatment with immune checkpoint inhibitors provides long-term survival for patients with advanced melanoma. Improvements in the overall survival of advanced melanoma patients have been achieved with anti-PD-1 monotherapy and anti-PD-1+ CTLA4 combination therapy, but there are still many issues to resolve. Acral, mucosal and uveal melanoma have been less responsive to immune checkpoint inhibitors than cutaneous melanoma. For patients who have achieved a good response, it is still not known how long the anti-PD-1 therapy should be administered. Moreover, there is limited treatment for patients who relapse during or after adjuvant anti-PD-1 therapy. Here, we review the current evidence regarding the clinical effects of immunotherapy for advanced melanoma. Moreover, we review previous studies of acral, mucosal and uveal melanoma, and we discuss the recent findings regarding durable response after the cessation of anti-PD-1 therapy, and treatment options for recurrence after adjuvant therapy.

Immune checkpoint inhibitors in advanced or metastatic mucosal melanoma: a systematic review

Background

Conventional cytotoxic chemotherapy offers minor benefit to patients with mucosal melanoma (MM). Although immune checkpoint inhibitors (ICIs) have become the preferred approach in patients with advanced or metastatic cutaneous melanoma, the evidence of their clinical use for MM is still limited. This systematic review aims to summarize the efficacy and safety of ICIs in advanced or metastatic MM.

Methods

We searched electronic databases, conference abstracts, clinical trial registers and reference lists for relevant studies. The primary outcomes included the overall response rate (ORR), median progression-free survival (PFS), median overall survival (OS), one-year PFS rate, and one-year OS rate.

Results

This review identified 13 studies assessing anti-CTLA-4 monotherapy, 22 studies assessing anti-PD-1 monotherapy, two studies assessing anti-CTLA-4 and anti-PD-1 combination therapy, one study assessing anti-PD-1 antibodies combined with axitinib, and three studies assessing anti-PD-1 antibodies combined with radiotherapy. For most patients who received ipilimumab monotherapy, the ORR ranged from 0% to 17%, the median PFS was less than 5 months, and the median OS was less than 10 months. For patients who received nivolumab or pembrolizumab monotherapy, most studies showed an ORR of more than 15% and a median OS of more than 11 months. The combined administration of anti-CTLA-4 and anti-PD-1 agents showed benefits over single-agent therapy with an ORR of more than 33.3%. In a phase Ib trial of toripalimab in combination with axitinib, approximately half of patients had complete or partial responses. Three retrospective studies that investigated anti-PD-1 antibodies combined with radiotherapy showed an ORR of more than 50%, which was higher than each single modality treatment.

Conclusions

Immune checkpoint inhibitors, especially anti-PD-1 monoclonal antibodies alone and in combination with anti-CTLA-4 monoclonal antibodies or other modalities, are promising treatment options for advanced or metastatic MM. However, high-level evidence is still needed to support the clinical application.