Department of Dermatology and Plastic Surgery, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
Department of Gastroenterology and Hepatology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
J Dermatol. 2020 Nov;47(11):1317-1321. doi: 10.1111/1346-8138.15543. Epub 2020 Aug 13.
Merkel cell carcinoma (MCC) is an aggressive neoplasm and patients with metastasis have poor survival outcomes. Recently, avelumab, an anti-programmed death ligand 1 (PD-L1) immune checkpoint inhibitor, was approved for first-line treatment in patients with metastatic MCC. While the administration interval of avelumab is every 2 weeks, the durable effect of a single administration of avelumab is unknown. Additionally, the effect of avelumab in pure MCC or combined MCC concurrent with non-MCC histology has not been fully elucidated. Herein, we report a case of combined MCC concurrent with squamous cell carcinoma; the patient had a complete response after a single administration of avelumab. Although the levels of avelumab were outside the detection limit within 12 weeks, a remarkable efficacy remained for more than 28 weeks after administration. Immunohistochemical analyses revealed that the expression of PD-L1 and Merkel cell polyomavirus large T antigen was almost negative or only partial in the primary tumor lesion of this patient. Conversely, thyroid transcription factor 1 (TTF-1) expression was positive in the primary MCC lesion, which is consistent with a previous report that combined MCC is positive for TTF-1 expression. In conclusion, this case study presents a rare case of TTF-1-positive combined MCC showing complete response after a single administration of avelumab.
默克尔细胞癌（Merkel cell carcinoma，MCC）是一种侵袭性肿瘤，发生转移的患者生存预后较差。近期，avelumab（一种抗程序性死亡配体 1（PD-L1）免疫检查点抑制剂）被批准用于转移性 MCC 患者的一线治疗。avelumab 的给药间隔为每 2 周一次，但单次给药的持久疗效尚不清楚。此外，avelumab 在单纯 MCC 或与非 MCC 组织学同时存在的 MCC 中的作用尚未充分阐明。在此，我们报告了一例合并 SCC 的 MCC 患者，单次给予avelumab 后达到完全缓解。尽管在 12 周内avelumab 水平超出检测限，但给药后超过 28 周仍保持显著疗效。免疫组化分析显示，该患者的原发性肿瘤病变中 PD-L1 和 Merkel 细胞多瘤病毒大 T 抗原的表达几乎为阴性或仅部分阳性，而甲状腺转录因子 1（thyroid transcription factor 1，TTF-1）在原发性 MCC 病变中呈阳性，这与先前关于合并 MCC 表达 TTF-1 的报道一致。总之，本病例研究报告了一例罕见的 TTF-1 阳性合并 MCC 患者，单次使用avelumab 后达到完全缓解。
