AB026. LA11. Thymic malignancies tumor board: medical oncology

Abstract: The management of thymic epithelial tumors is a paradigm of cooperation between clinicians, surgeons, and pathologists from establishing the diagnosis to organizing the multimodal therapeutic strategy. Systemic treatment may be delivered in a curative-intent approach, for patients presenting with locally-advanced tumor at time of diagnosis, with invasion of intra-thoracic neighboring structures, and/or dissemination to the pleura and the pericardium, precluding upfront complete resection to be achieved. In such cases, chemotherapy has been used both to reduce the tumor burden—possibly allowing subsequent surgery and/or radiotherapy—and to achieve prolonged disease control. In this setting, cisplatin-based combination regimens should be administered; combinations of cisplatin, adriamycin, and cyclophosphamide, and cisplatin and etoposide have been recommended, based on historical studies. When the patient is not deemed to be a surgical candidate—either because R0 resection is not thought to be achievable, or because of poor performance status or co-existent medical condition, definitive radiotherapy is recommended part of a sequential chemoradiotherapy strategy. Chemotherapy is also a palliative-intent treatment of unresectable, metastatic, and recurrent tumors, which are more frequently thymic carcinomas than thymomas. Again, cisplatin-based combination regimens with anthracyclines and/or etoposide are standard. Combination of carboplatin and paclitaxel is an option for thymic carcinoma, based on results of recent phase II trials. Recurrences of thymic epithelial tumors should be managed according to the same strategy as newly diagnosed tumors. In non-resectable recurrences, several consecutive lines of chemotherapy may be administered when the patient presents with tumor progression. Several trials assessing the efficacy of PD-1 checkpoint inhibitors are currently ongoing. Phase II studies of pembrolizumab were recently reported, collectively enrolling 63 patients, showing response rates of 24%, but occurrence of serious, autoimmune adverse events in 20% to 30% of patients. The off-label use of checkpoint inhibitors is currently not recommended.

Keywords: Thymoma; thymic carcinoma; chemotherapy; immunotherapy