Kournoutas Ioannis, Monga Varun, Davick Jonathan, Rieth John
Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, USA.
Division of Hematology, Oncology, and Blood and Marrow Transplantation, Department of Internal Medicine, University of Iowa, Iowa City, IA, USA.
Case Rep Oncol. 2024 Feb 23;17(1):344-351. doi: 10.1159/000535959. eCollection 2024 Jan-Dec.
Pleomorphic rhabdomyosarcoma is a rare subtype of rhabdomyosarcoma, a soft tissue sarcoma with skeletal muscle differentiation. Although rhabdomyosarcoma is typically seen in the pediatric population, the pleomorphic variant most frequently presents in adulthood and is characteristically aggressive with no currently established treatment regimen in the setting of metastatic disease. There has been growing interest in the application of immune checkpoint inhibitors alongside conventional chemotherapeutic agents in the treatment of pleomorphic rhabdomyosarcoma.
In the present case series, we report 2 patients with metastatic pleomorphic rhabdomyosarcoma treated with combination doxorubicin and pembrolizumab who had confirmed objective responses. Of note, these 2 patients had variable PD-L1 status - negative and low positive. Duration of treatment response was notable at 14 months and 9 months, respectively, with the first patient remaining on maintenance pembrolizumab therapy and the second patient subsequently achieving complete response with third-line trabectedin. Both patients are currently undergoing routine interval imaging with no evidence of disease at this time.
This report highlights and discusses the potential role of PD-1 blockade in the treatment of pleomorphic rhabdomyosarcoma and also discusses burgeoning immunological data that may explain the clinical responses seen in these 2 cases.
多形性横纹肌肉瘤是横纹肌肉瘤的一种罕见亚型，横纹肌肉瘤是一种具有骨骼肌分化的软组织肉瘤。虽然横纹肌肉瘤通常见于儿童人群，但多形性变体最常出现在成年期，其特征是具有侵袭性，在转移性疾病的情况下目前尚无既定的治疗方案。在多形性横纹肌肉瘤的治疗中，将免疫检查点抑制剂与传统化疗药物联合应用的兴趣日益浓厚。
在本病例系列中，我们报告了2例接受多柔比星和帕博利珠单抗联合治疗的转移性多形性横纹肌肉瘤患者，他们均有确诊的客观反应。值得注意的是，这2例患者的程序性死亡受体配体1（PD-L1）状态不同——阴性和低阳性。治疗反应持续时间分别为14个月和9个月，显著较长，第一例患者继续接受帕博利珠单抗维持治疗，第二例患者随后接受三线曲贝替定治疗后实现完全缓解。目前，这2例患者均在进行常规的间隔期影像学检查，此时均无疾病证据。
本报告强调并讨论了PD-1阻断在多形性横纹肌肉瘤治疗中的潜在作用，还讨论了可能解释这2例临床反应的新兴免疫学数据。
