This is an open-label phase 1 study to assess the safety and feasibility of autologous T
cells expressing a single-chain scFv targeting GFRα4 with tandem TCR/CD3ζ and 4-1BB
(TCRζ/4-1BB) co-stimulatory domains (referred to as "CART-GFRa4 cells") in patients with
incurable medullary thyroid cancer (MTC).