Background: Data in East Asian patients and in other epithelial skin cancers, including extramammary Paget's disease (EMPD) and adnexal carcinomas, are scarce. Therefore, we conducted a phase II trial of nivolumab in Japanese patients with advanced non-melanoma skin cancers (NMSCs).
Patients and methods: This multicentre, open-label, single-arm phase II study enrolled adults (≥ 20 years) with histologically confirmed unresectable or recurrent epithelial cutaneous malignancies, Eastern Cooperative Oncology Group performance status 0-1, and at least one measurable lesion (RECIST v1.1). Nivolumab 480 mg was administered intravenously every 4 weeks for up to 26 cycles. The primary endpoint was overall response rate (ORR), assessed by blinded independent central review (BICR; RECIST v1.1). Secondary endpoints included progression-free survival, overall survival, and safety.
Results: Thirty-one patients were enrolled (20 cSCC, 4 EMPD, 2 BCC, 5 other NMSCs); median age was 73 years (range 58-86), and 71% were male. ORR by BICR was 22.6% (7/31), and the disease control rate was 54.8% (17/31). Responses were durable, with a median duration of 21.3 months. In the cSCC cohort, median tumour mutational burden (TMB) was 9.0 mut/Mb, lower than in Western series; among three patients with TMB ≥ 30 mut/Mb, two achieved objective responses. Common adverse events included pyrexia, hypothyroidism, adrenal insufficiency, and pruritus.
Conclusions: Nivolumab showed durable antitumour activity with manageable toxicity in Japanese patients with advanced NMSCs, including rare non-cSCC. The lower ORR compared with Western trials may reflect intrinsic biological differences and support biomarker-driven, region-specific immunotherapy.
Clinical trial registration: jRCT2031190048; registered 2 July 2019.
Keywords: Epithelial skin malignancy; Nivolumab; Non-melanoma skin cancer; Programmed death-1; Squamous cell carcinoma.
© 2026. The Author(s).