Camrelizumab plus apatinib for patients with advanced mucosal melanoma: A prospective single-arm study.

9550 Background: Mucosal melanoma is a rare subtype in white populations, but the second most common subtype in Asian populations. This subtype is a more aggressive malignancy, with high risk of metastasis and death. Immune checkpoint inhibitor combined with anti-angiogenic agent has been investigated in many solid tumors, including some preliminary evidence (NCT03086174 and NCT04091217) in Chinese patients with advanced mucosal melanoma. This study investigated the efficacy and safety of camrelizumab plus apatinib in patients with advanced mucosal melanoma. Methods: In this prospective, single-arm study (ChiCTR1900023277), patients with inoperable stage III-IV or recurrent/metastatic mucosal melanoma and Eastern Cooperative Oncology Group performance status of 0-1 were enrolled. Patients received camrelizumab 200 mg once every 2 weeks and apatinib 500 mg once daily until disease progression or intolerable toxicity. The primary endpoint was objective response rate (ORR) according to the Response Evaluation Criteria In Solid Tumors, version 1.1. Results: Between April 2019 and January 2022, a total of 30 patients were enrolled (Table). As of January 2022, 21 patients had at least one efficacy assessment, and the median follow-up duration was 8.1 months. The ORR was 42.9%, including one (4.8%) patient with confirmed complete response, six (28.6%) with confirmed partial response (PR), and two (9.5%) with unconfirmed PR. The disease control rate (DCR) was 81.0%. The median progression-free survival was 7.2 months (95%CI, 5.8-not reached [NR]) in 21 patients, 7.7 months (95%CI, 5.8-NR) in 19 patients with first-line camrelizumab plus apatinib treatment, and 9.8 months (95%CI, 4.2-NR) in 11 patients without prior chemotherapy. The most common treatment-related adverse events in 27 patients with available safety data were fatigue (17 [63.0%]), hypertension (15 [55.6%]), and elevated transaminase (14 [51.9%]). No treatment-related deaths occurred. Exploratory analysis found a tendency that patients with high T cell receptor diversity had better prognosis. Higher frequencies of Vβ-Jβ (including Vβ5-8Jβ2-7, Vβ28J2-4 and Vβ12-5Jβ1-1) indicate better survival, and Vβ12-5Jβ1-1 is an independent factor after multivariate adjustment. Conclusions: Camrelizumab plus apatinib showed favorable ORR and DCR in patients with advanced mucosal melanoma, with an acceptable safety profile. Follow-up for survival outcomes is ongoing. Clinical trial information: ChiCTR1900023277. [Table: see text]