A Retrospective Study on the Efficacy and Safety of Chidamide As a Maintenance Therapy for Peripheral T-Cell Lymphoma

Background: Peripheral T-cell lymphomas (PTCLs) are a set of rare and highly heterogeneous tumors of non-Hodgkin's lymphoma (NHL) with inferior outcomes. Chidamide is a novel benzamide class of histone deacetylase (HDAC) inhibitor (HDACi) that was approved by the Chinese Food and Drug Administration in 2014 for the treatment of relapsed or refractory (R/R) PTCL patients. This study aimed to assess the efficacy and safety of chidamide as a maintenance therapy after induction or salvage treatment in patients with PTCLs. Methods: The clinical data of 58 patients with different PTCL subtypes who received chidamide as a maintenance therapy after first-line or salvage treatment were collected. Progression-free survival (PFS), overall survival (OS), and safety were analyzed. Results: Fifty-eight patients enrolled in our study between January 2015 and July 2022, of whom 39 patients received chidamide as a maintenance therapy after first-line treatment and 19 patients after salvage treatment. All patients started chidamide maintenance after reaching at least partial response (PR). The median age was 66 (29-83) years. Patients with angioimmunoblastic T-cell lymphoma (AITL) represented the largest subgroup (34, 58.6%), followed by PTCL, not otherwise specified (PTCL-NOS) (10, 17.2%), anaplastic large cell lymphoma (ALCL) (8, 13.8%), NK/T cell lymphoma (NKTCL) (5, 8.6%) and monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) (1, 1.7%). Thirty-four (58.6%) patients were stage III-IV, and 38 (65.5%) patients had intermediate or high risk (prognostic index for T-cell lymphoma (PIT) 2-4). Among the 39 patients who underwent chidamide maintenance after first-line treatment, 30/39 (76.9%) patients began maintenance after reaching complete response (CR) and 9/39 (23.1%) after achieving PR. Notably, 8/9 (88.9%) patients achieved CR from PR during maintenance treatment, with a median time of 6 (3-12) months. A total of 11/39 (28.2%) patients experienced disease progression during the maintenance treatment, and their median duration of remission was 6 (3-13) months. Among them, 2 patients experienced disease progression 2 to 3 months after drug withdrawal due to COVID-19 infection. A total of 19 patients who received maintenance treatment after salvage therapy, 9 (47.4%) received maintenance therapy after CR and 10 (52.6%) received maintenance therapy after PR. Among them, 9/19 (47.4%)had disease progression and their median duration of remission was 16 (2-25) months. The remaining 10 patients (8 CR and 2 PR) were still undergoing maintenance treatment and follow-up. The median maintenance treatment time for all patients was 16 (1-72) months, and the median maintenance dose was 20 (15-30) mg twice weekly. The median follow-up time was 39 (2-79) months, the median PFS was 33 months, and the median OS had not been reached (Figure 1 a, b) for all patients. The median PFS and OS of the patients who received first-line maintenance therapy were not reached, which were significantly better compared to patients who received chidamide as salvage treatment maintenance (the median PFS and OS were 7 and 67 months, P < 0.001, P = 0.009, respectively) (Figure 1 c, d). There was no statistical difference in PFS and OS among the different pathological subtypes, but AITL seemed to achieve better PFS (Figure 1 e, f). The most common toxicities were hematologic toxicities, including neutropenia (42, 72.4%), anemia (23, 39.7%), and thrombocytopenia (29, 50.0%), followed by fatigue (35, 60.3%), anorexia (31, 53.4%), liver dysfunction (10, 17.2%), and pneumonia (4, 6.9%). Most adverse events were grade 1 or 2, and the grade 3‒4 adverse events were neutropenia (15/42), thrombocytopenia (7/29), fatigue (1/35), and pneumonia (2/4). Twelve (20.7%) patients underwent a dose reduction and three patients discontinued treatment (two patients with severe pulmonary infections, and one patient had intolerable fatigue) due to adverse events. One patient stopped maintenance treatment after taking chidamide for 10 months for financial reasons and he is still in follow-up. Conclusion: The findings of this study showed that patients with chidamide maintenance therapy had a better PFS and OS with a manageable safety profile, especially as the first-line maintenance therapy. We conclude that chidamide can be used as a maintenance treatment to improve the survival of patients with PTCLs.