This study will be a non-randomized pilot trial using Cyclophosphamide and Sirolimus for the treatment of metastatic differentiated thyroid cancer. Patients will be treated with Sirolimus 4 mg, PO, days 1-28 as well as Cyclophosphamide 100 mg, PO, days 1-5 and 15-19. Cycle length will be 28 days. Patients will be monitored closely for toxicity and undergo imaging to evaluate efficacy once every 2 cycles.
Histologically documented differentiated thyroid cancer with or without metastases, not amenable to curative treatment; or the patient has documented refusal of curative treatment
Measurable disease (>10 mm) and have progression of disease based on RECIST criteria. Previously irradiated tumor lesions are not considered measurable unless they have progressed since radiation.
Previous failure of Iodine-131 (131I) therapy or not candidates to receive 131I as assessed by treating physician.
Age ≥ 18 years
Inability to obtain Foundation One testing on archival tissue, or, lack of previous Next Generation Sequencing
Chemotherapy, tyrosine kinase inhibitor, or radiation therapy within 4 weeks
Prior experimental therapy within 4 weeks of planned start of this trial
131I therapy within 24 weeks before entry (4 weeks if negative post-treatment scan)