Robust and durable response to first-line treatment of pembrolizumab combined with chemotherapy in two patients with metastatic thymic squamous cell carcinoma: Case report

A case report of successful treatment of advanced thymic squamous cell carcinoma with poor performance status using multimodal therapy

Thymic squamous cell carcinoma (TSCC) is a rare yet aggressive tumor associated with a dismal prognosis. The patient, a 76-year-old male, presented with symptoms of fatigue, bloody sputum and dyspnea. Computed tomography (CT) and positron emission tomography/computed tomography (PET/CT) scans demonstrated a significant mass in the chest, accompanied by metastasis to adjacent lymph nodes. Vascular ultrasound and CT angiography both indicated thrombosis in the jugular, innominate, and left subclavian veins. A CT-guided needle biopsy subsequently confirmed the diagnosis of TSCC. The patient had an Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) score of 4 and exhibited high PD-L1 expression. The treatment plan entailed multiple administrations of low-dose carboplatin via intrapleural injection, infusions of albumin-bound paclitaxel (ABP), and pembrolizumab. Concurrent anticoagulation and nutritional therapy were also provided. A combination of carboplatin and ABP was administered for six cycles, followed by a single cycle of ABP alone. Subsequently, pembrolizumab was administered for ten cycles. After this, pembrolizumab was temporarily discontinued, and radiation therapy was administered to the primary tumor site and mediastinal lymph nodes. Five weeks later, pembrolizumab therapy was resumed. The patient's PS has recovered to 0, and have survived for 23 months with a good quality of life. This experience suggests that combining pembrolizumab with low-dose chemotherapy drugs could be a beneficial treatment option for patients with advanced TSCC, poor PS, and high PD-L1 expression.

Immunotherapy for Thymomas and Thymic Carcinomas: Current Status and Future Directions

Thymic epithelial tumors are a histologically diverse group of cancers arising from the epithelial compartment of the thymus. These tumors are characterized by a low tumor mutation burden, a lack of actionable genomic changes, and, especially with thymomas, defects in immune tolerance. Surgery is the mainstay of the management of resectable disease, whereas advanced, unresectable tumors are treated with platinum-based chemotherapy. Disease recurrence can occur months to years after frontline treatment. Although several options are available for conventional treatment of recurrent thymic tumors, response rates are generally low, and treatment-related toxicity can affect quality of life. A subset of patients benefit from biologic therapies, but there remains an unmet need for the development of new treatments. Immune checkpoint inhibitors are safe, clinically active, and have contributed to an improvement in survival for patients with a wide variety of cancers. However, the application of these revolutionary treatments for thymic cancers is limited to their use for the management of recurrent thymic carcinoma because of the risk of immune toxicity. In this paper, we review the current uses of immunotherapy for the management of thymic epithelial tumors and highlight potential strategies to improve safety and broaden the application of these treatments for patients with thymic cancers.