Pembrolizumab, Dabrafenib, and Trametinib Before Surgery for the Treatment of BRAF-Mutated Anaplastic Thyroid Cancer

Inclusion Criteria: * Pathologic findings supporting the clinical impression of anaplastic thyroid carcinoma. Diagnosis may include consistent with or suggestive of terminology associated with: anaplastic thyroid carcinoma, undifferentiated carcinoma, squamous carcinoma; carcinoma with spindled, giant cell, or epithelial features; poorly differentiated carcinoma with pleomorphism, extensive necrosis with tumor cells present * Must have a BRAFV600E mutation-positive tumor, as determined by BRAF V600E immunohistochemistry on tumor tissue, genetic/molecular testing of tumor, or cell free (cf)NDA liquid biopsy * Have measurable disease based on RECIST 1.1 * Total bilirubin =\< 1.5 x upper limit of normal (ULN). Total bilirubin =\< 3 x ULN for patients with Gilbert's syndrome * Aspartate aminotransferase (AST) (serum glutamic-oxaloacetic transaminase \[SGOT\])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase \[SGPT\]) =\< 2.5 x ULN, (5 x ULN for patients with concurrent liver metastases) * Serum creatinine =\< within 1.5 x ULN * Absolute neutrophil count (ANC) \>= 1.0 x 10\^9/L * Platelets \>= 100 x 10\^9/L * Hemoglobin \>= 9.0 g/dL or 5.6 mmol/L * International normalized ratio (INR) or prothrombin time (PT) =\< 1.5 x ULN unless participant is receiving anticoagulant therapy as long as PT or activated partial thromboplastin time (aPTT) is within therapeutic range of intended use of anticoagulant * Subjects must be willing to ultimately undergo surgery if the…