The efficacy of nivolumab for unresectable metastatic mucosal melanoma

Background

As there is no established systemic therapy for unresectable metastatic mucosal melanoma, treatment has been selected on the basis of the available treatment for primary cutaneous melanomas. In Japan, although dacarbazine (DTIC) or DTIC-based combination therapy has been performed, it has been difficult to achieve certain therapeutic outcomes. After nivolumab, an anti-PD-1 antibody, was approved, it was anticipated to be effective against primary mucosal melanomas; however, this remains unclear. This study was conducted to investigate the efficacy of nivolumab against unresectable metastatic mucosal melanoma.

Methods

We retrospectively analysed 27 unresectable metastatic mucosal melanoma cases for which nivolumab had been administered at National Cancer Center Hospital between July 2014 and January 2016. All cases were administered nivolumab (2 mg/kg, every 3 weeks) at least three times and therapeutic effects were evaluated according to RECIST 1.1 on the basis of diagnostic imaging.

Results

The subjects included 12 men and 15 women, and the median age was 68 years (48–85 years). The primary onset sites included the nasal cavity (12 cases), esophagus (4 cases), conjunctiva (4 cases), the palate (3 cases), the urethra/bladder (2 cases), and rectum (2 cases). The number of metastasized organs including lymph node metastasis prior to nivolumab administration ranged from 1 to a maximum of 7. The best overall responses were complete response (2 cases: 7.4%), partial response (7 cases: 25.9%), stable disease (4 cases: 14.8%), and progressive disease (14 cases; 51.9%), resulting in the overall response rate of 33.3%. The response rates for the melanoma of primary onset sites were 25% (3/12 cases) for the nasal cavity, 50% (2/4 cases) for the esophagus, 50% (2/4 cases) for the conjunctiva, 50% (1/2 cases) for the urethra/bladder, 33.3% (1/3 cases) for the palate, and 0% (0/2 cases) for the rectum. The therapeutic effects were still maintained for 8 of the 9 successful cases as of April 2016.

Conclusions

Nivolumab was effective for unresectable metastatic mucosal melanoma as well as for primary cutaneous melanoma. Furthermore, the therapeutic effects were maintained in successful cases.

Clinical trial identification

Legal entity responsible for the study

National Cancer Center Hospital

Funding

National Cancer Center Hospital

Disclosure

N. Yamazaki: Advisory Board role for Chugai Pharma, Bristol-Myers Squibb (BMS) Japan and Ono Pharmaceutical. The institution has received clinical trial support from Chugai, BMS Japan, Ono, GSK, Takeda, AstraZeneca Japan, Boehringer Ingelheim, and Maruho. All other authors have declared no conflicts of interest.