PurposeThis is a retrospective, single-center PSM study evaluating the efficacy and safety of chidamide combined with the CHOEP (C-CHOEP) regimen versus the single CHOEP regimen in patients with untreated peripheral T cell lymphomas (PTCL).PatientsPatients newly diagnosed with PTCL between January 2015 and June 2021 were recruited, and were 1:1 divided into C-CHOEP and CHOEP groups according to their first-line chemotherapy regimens. The PSM method was used to match the baseline variables to balance the confounding factors.ResultsA cohort of 33 patients each in the C-CHOEP and CHOEP groups was generated after propensity score-matching (PSM). The complete remission (CR) rates of the C-CHOEP regimen were higher than that of the CHOEP regimen (56.3vs. 25.8%,p= 0.014), whereas the duration of response of the C-CHOEP group was shorter (median DOR 30vs.57 months), resulting in roughly similar progression-free survival (PFS) and (overall survival) OS between the two groups. The responding patients who received chidamide maintenance therapy showed a trend of superior PFS and OS compared with patients who did not receive maintenance therapy.ConclusionsThe C-CHOEP regimen was well tolerated but failed to show advantages over the CHOEP regimen in patients with untreated PTCL; however, the chidamide maintenance may contribute to a more durable response and stable long-term survival.