AB035. PD-1 checkpoint inhibitors exhibit significant antitumor activity in patients with Masaoka stage IV thymoma: a case report
Case Report

AB035. PD-1 checkpoint inhibitors exhibit significant antitumor activity in patients with Masaoka stage IV thymoma: a case report

Hua Liu, Jiang Fan

Department of Thoracic Surgery, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China

Correspondence to: Jiang Fan, MD. Department of Thoracic Surgery Shanghai General Hospital Shanghai Jiao Tong University School of Medicine, No. 100 Haining Road, Shanghai 200000, China. Email: fan_jiang@sjtu.edu.cn.

Background: Thymoma is a relatively rare tumor originating from the thymic epithelial cells, with a low incidence rate, accounting for approximately 0.2% to 1.5% of all malignant tumors. The primary treatment for thymoma is surgical resection, and early-stage or localized tumors can often be cured through surgery. For locally advanced or invasive thymomas, a multidisciplinary approach centered on surgery is typically adopted. Neoadjuvant chemotherapy before surgery or adjuvant radiotherapy after surgery can improve outcomes. For patients who are not candidates for surgery, chemoradiotherapy is an alternative. Some cases may involve targeted therapy or immunotherapy. The treatment plan must be tailored based on the tumor stage, pathological type, and individual patient factors, and the overall prognosis is relatively favorable.

Case Description: A 40-year-old female presented with an anterior mediastinal mass incidentally detected during routine health screening 4 months prior. Contrast-enhanced computed tomography (CT) revealed a heterogeneous anterior mediastinal mass (maximum diameter: 5.2 cm) with radiologic features suggestive of thymic malignancy (Masaoka-Koga stage IVa), accompanied by multiple metastatic nodules along the left pleura. Ultrasound-guided core needle biopsy performed on 2024-11-05 confirmed histopathological diagnosis of type B3 thymoma. Following three cycles of CAP regimen (cyclophosphamide 500 mg/m2 + doxorubicin 50 mg/m2 + cisplatin 50 mg/m2), serial imaging surveillance demonstrated stable disease (SD) (Figure 1A-1F). Therapeutic strategy was subsequently escalated to second-line therapy comprising albumin-bound paclitaxel (260 mg/m2), carboplatin [area under the curve (AUC) 5], and programmed death-1 (PD-1) inhibitor (200 mg q3w). Post two treatment cycles, CT confirmed partial response (PR) (Figure 1G-1I). The treatment course was notable for grade 1 diarrhea (CTCAE v5.0) managed effectively with symptomatic intervention. No immune-related adverse events (irAEs) or hematologic toxicity ≥ grade 2 were observed during immunotherapy.

Conclusions: PD-1 checkpoint inhibitors exhibit significant antitumor activity in patients with type B3 Masaoka stage IV thymoma.

Keywords: Thymoma; PD-1 checkpoint inhibitors; partial response (PR); case report

Figure 1 CT images demonstrate the course of treatment for type B3 thymoma. (A-C) Upon initial diagnosis, CT imaging revealed metastatic thymoma invading the chest wall and diaphragm accompanied by massive pleural effusion. (D-F) Serial clinical evaluations following three cycles of CAP chemotherapy regimen demonstrated SD status. (G-I) Subsequent therapeutic modification to albumin-bound paclitaxel combined with carboplatin and PD-1 inhibitor immunotherapy resulted in PR after two treatment cycles, as evidenced by radiological reassessment. CT, computed tomography; CAP, cyclophosphamide + doxorubicin + cisplatin; PD-1, programmed death-1; PR, partial response; SD, stable disease.

Acknowledgments

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Footnote

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://med.amegroups.com/article/view/10.21037/med-25-ab035/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

doi: 10.21037/med-25-ab035
Cite this abstract as: Liu H, Fan J. AB035. PD-1 checkpoint inhibitors exhibit significant antitumor activity in patients with Masaoka stage IV thymoma: a case report. Mediastinum 2025;9:AB035.

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