Pembrolizumab With Chemotherapy for Poorly Chemo-responsive Thyroid and Salivary Gland Tumors

Eligible patients will be divided into two cohorts. Cohort 1: salivary gland tumors without SOC treatment option Cohort 2: 'aggressive' thyroid cancer without SOC treatment option Both cohorts will undergo a biopsy and will begin immunotherapy plus chemotherapy. Pembrolizumab and steroid sparing taxane: docetaxel will be given every three weeks for 3 to 6 cycles. For accessible tumors only, at week three patients will receive an on-treatment biopsy. Patients will move on to immunotherapy maintenance after completing their cycles. Pembrolizumab will be given every three weeks until disease progression or up to 35 cycles (about 2 years).