A phase II trial of nivolumab for patients with platinum-refractory recurrent or metastatic salivary gland cancer.

[BACKGROUND] Salivary gland cancer (SGC) is rare and has various histological types. This rarity and heterogeneity have hindered elucidation of the therapeutic contribution of systemic therapy, including immune checkpoint inhibitors, to recurrent or metastatic SGC (RM-SGC). The purpose of this trial was to investigate the efficacy and safety of nivolumab for platinum-refractory RM-SGC.

[METHODS] This phase II trial for platinum-refractory RM-SGC was conducted at nine centers. Nivolumab 240 mg was administered intravenously every 2 weeks. The primary endpoint was the objective response rate (ORR), and secondary endpoints were disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and safety.

[RESULTS] Twenty-four patients were enrolled between March 2018 and January 2022. The main histological types were salivary duct carcinoma (n = 10), adenoid cystic carcinoma (n = 6), and adenocarcinoma not otherwise specified (n = 5). The ORR was 8.3% (2/24, 80% CI, 2.2-20.6), with two partial responses in patients with salivary duct carcinoma. The DCR was 29.2% (7/24), while all of the other 17 patients (70.8%) showed progressive disease on first disease evaluation at 12 weeks. With a median follow-up of 21.2 months, median PFS and OS were 3.0 months (95% CI, 2.8-3.2) and 25.0 months (95% CI, 10.9-39.1), respectively. There were no new safety concerns with nivolumab monotherapy.

[CONCLUSIONS] This phase II trial of nivolumab for patients with platinum-refractory RM-SGC did not meet its primary endpoint of ORR. Although nivolumab may be worth further development in salivary duct carcinoma, these results may raise concerns over nivolumab monotherapy for RM-SGC.