DURABLE RESPONSE IN A CASE OF METASTATIC ANAPLASTIC THYROID CANCER USING A COMBINATION OF TYROSINE KINASE INHIBITORS AND A CHECK POINT INHIBITOR.

Anaplastic thyroid cancer (ATC) is a highly uncommon (less than 2% of thyroid malignancies) and aggressive type of cancer, with aggressive behavior and, therefore, exhibiting poor prognosis. ATC tumors are automatically labeled as stage IV disease regardless of standard criteria such as tumor burden or metastasis. ATC tumors require a diversified treatment approach that includes surgical resection, followed by a complete an aggressive combination of radiation and chemotherapy and/or palliative care. Despite best efforts, 1-year overall survival of patients is 20% to 40% with nearly universal mortality rate. Consequently, novel approaches (targeted therapy, immunotherapy) have been studied, alone or in combination, to improve the dire prognosis of these patients. BRAF V600E mutation is the most common genetic mutation found in ATC. We report the case of a 57-year-old man diagnosed with stage IVc (undifferentiated) ATC with hepatic and osseous metastases. The molecular analysis of the tumor revealed a V600E BRAF-mutation. The patient was treated with Dabrafenib and Trametinib, and achieved remission 5 weeks after starting the treatment. Subsequently, he had a thyroidectomy, and pembrolizumab was added to the two tyrosine kinase inhibitors. 9 months later he is still in remission. This case illustrates the importance of obtaining molecular information in anaplastic thyroid cancer and the urgent need of studies investigating the combination of tyrosine kinase inhibitors and check-point inhibitors in patients with V600E BRAF- mutations.