[Analysis of treatment response and post-discontinuation efficacy maintenance of cyclophosphamide monotherapy in T-cell large granular lymphocytic leukemia].

Objective: To evaluate the efficacy of cyclophosphamide in patients with T-cell large granular lymphocytic leukemia (T-LGLL) and the maintenance of treatment-free remission (TFR) following drug discontinuation. Methods: Clinical data were collected from 37 patients with T-LGLL who received oral cyclophosphamide at the Regenerative Medicine Clinic of the Institute of Hematology and Blood Diseases Hospital between June 2019 and March 2024. Patient clinical characteristics, treatment efficacy, and long-term TFR were analyzed. Results: The median age of the 37 patients was 60 years (range: 37-86), and 22 (59.5%) were male. Anemia was observed in 30 patients (81.1%), and 28 (75.7%) met the diagnostic criteria for secondary pure red cell aplasia. Neutropenia occurred in 15 patients (40.5%), lymphocytosis in 11 (29.7%), and thrombocytopenia in three (8.1%). Sixteen patients (43.2%) had not received prior immunosuppressive therapy (treatment-naive group), while 21 patients (56.8%) were refractory to or had relapsed after immunosuppressive treatment (refractory/relapsed group). All patients met the treatment criteria and received oral cyclophosphamide at doses of 50-100 mg/day. Among the 36 evaluable patients, hematologic remission was achieved in 25 (69.4%), with a median time of 2.0 months (range: 0.7-7.0). There was no statistically significant difference in remission rates between the treatment-naive and refractory/relapsed groups (68.5% vs. 66.7%, P=0.589). Among the 25 patients who achieved hematologic remission, 24 discontinued cyclophosphamide. With a median follow-up of 39.0 months (range: 8.0-56.0), the median TFR duration was not reached. The estimated TFR rates were (90.87± 6.16) % at 12 months and (75.72±11.04) % at 36 months. No significant difference in TFR was observed between the treatment-naive and refractory/relapsed groups (P=0.451) . Conclusion: Oral cyclophosphamide is effective in the treatment of T-LGLL, and patients may maintain long-term TFR following drug discontinuation.