[Efficacy and safety of a JAK1 inhibitor for relapsed/refractory large granular lymphocytic leukemia]

Objective: To evaluate the efficacy and safety of monotherapy with the JAK1 inhibitor golidocitinib in patients with relapsed/refractory large granular lymphocytic leukemia (LGLL) . Methods: We retrospectively analyzed 16 patients with relapsed/refractory LGLL who received oral golidocitinib monotherapy at the Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences, between January and December 2025 (13 with T-LGLL and 3 with NK-LGLL). The starting dose was 0.15 g once daily, and efficacy and safety were evaluated. Results: The median age was 58 years (range, 26-76 years). At baseline, the median HGB level was 58.5 g/L (range, 43.0-101.0), the median absolute neutrophil count was 1.04×10(9)/L (range, 0.02-4.18), the median absolute lymphocyte count was 1.59×10(9)/L (range, 0.38-7.20), and the median absolute large granular lymphocyte count was 0.60×10(9)/L (range, 0.06-3.63). Six patients had secondary pure red cell aplasia. With a median follow-up of 4.0 (0.8-11.1) months, the overall hematologic response rate was 87.5% (14/16), with a median time to hematologic response of 2.9 (1.4-7.6) weeks. The complete hematologic response rate was 43.8% (7/16). The incidence of drug-associated adverse events (DAE) was 75.0% (12/16). Five patients experienced grade 3 adverse events, including grade 3 neutropenia in 2 cases, grade 3 thrombocytopenia in 2 cases, and grade 3 elevation of aspartate aminotransferase in 1 case. All remaining DAEs were grade 1-2. Conclusion: Golidocitinib monotherapy showed activity in patients with relapsed/refractory LGLL, with a rapid onset of response and a manageable short-term safety profile.