FOLH1 and neoplasm: We present rare chemotherapy-naïve mCRPC cases treated with tandem PSMA-RPT and explore their molecular characteristics through plasma circulating tumor DNA (ctDNA).<h4>Methods</h4>Blood samples were obtained from mCRPC patients receiving [<sup>225</sup>Ac]Ac-/[<sup>177</sup>Lu]Lu-PSMA-617 therapy.