This study is a multicenter, single-arm, non-randomized, open-label trial designed to evaluate the efficacy and safety of chidamide and azacitidine in combination with prednisone, cyclophosphamide, and thalidomide (CAPCT regimen) in patients with peripheral T-cell lymphoma (PTCL). A total of 58 patients with PTCL are planned to be enrolled after providing written informed consent and meeting all eligibility criteria. Enrolled patients will receive the CAPCT regimen, with each cycle consisting of 21 days, for a total of 6 cycles. Participants who do not experience disease progression or unacceptable toxicity after 6 cycles of combination therapy will continue to receive the CPCT regimen (chidamide combined with prednisone, cyclophosphamide, and thalidomide) for up to 6 months, followed by chidamide monotherapy as maintenance treatment. The primary efficacy endpoint is objective response rate (ORR).