Abstract
Thymic carcinoma (TC) is a rare and aggressive malignancy of the thymus associated with less than 25% 5 years survivability. Our case report showcases the successful treatment of advanced metastatic TC using a multidisciplinary approach and the utility of checkpoint inhibitors in treatment of recurrent TC. A 50-year-old man presented with Raynaud's phenomenon and was found to have a stage IVb TC (T3N2M0). Eight months after management with neoadjuvant chemotherapy, surgical resection and adjuvant chemoradiotherapy, patient was diagnosed with metastasis of TC to the liver and a concurrent stage III (T2N1M0) primary sigmoid colon adenocarcinoma. Following complete resection of the colon adenocarcinoma, the patient started palliative-intent treatment for TC with pembrolizumab given PD-L1 tumor proportionate score of 100%. This resulted in a sustained complete response for 38 months. Our patient did have immune-related adverse events involving multiple organs but was able to continue pembrolizumab for a standard treatment duration of 2 years with multidisciplinary care. When recurrent disease was noted in a portocaval lymph node, pembrolizumab was reinitiated and a second complete response was achieved. The patient has maintained that complete response while maintaining an acceptable quality of life, showing that treatment with pembrolizumab is effective in patients after discontinuation with prior immunotherapy.