Response to alemtuzumab-based therapy and long-term survival after allogeneic transplantation in T-Cell prolymphocytic leukemia: a systematic review and meta-analysis of proportions.

INTRODUCTION: T-cell prolymphocytic leukemia (T-PLL) is a rare, aggressive neoplasm with poor outcomes. Alemtuzumab and allogeneic hematopoietic cell transplantation (allo-HCT) are the mainstays of treatment, yet estimates rest on small single-arm studies, and no synthesis has pooled both outcomes. We quantified response to alemtuzumab-based therapy and long-term survival after allo-HCT. METHODS: We performed a systematic review and meta-analysis of proportions. MEDLINE, CENTRAL, ClinicalTrials.gov, Google Scholar, were searched from inception to June 2026. Studies reporting response to alemtuzumab-based therapy or survival after allo-HCT in adults with T-PLL were eligible. Sensitivity analyses assessed robustness, while publication bias (Egger's test), risk of bias (JBI), and certainty (GRADE) were assessed. RESULTS: Seven studies (200 patients) informed the primary analysis. The pooled overall response rate was 81.9% (95% CI 66.6-91.1; I²=78%) and complete response rate 58.5% (95% CI 39.6-75.2; I²=76%); heterogeneity was explained by line of therapy (frontline 85%, relapsed/refractory 51%; p<0.0001). Across three independent registries (363 patients), long-term survival after allo-HCT was 30.3% (95% CI 25.8-35.3; I²=0%). CONCLUSIONS: Alemtuzumab-based therapy was associated with high response rates in T-PLL-approximately 85% frontline-and approximately one-third of transplanted patients achieved long-term survival. These pooled values are descriptive benchmarks derived from low-certainty, single-arm evidence and require prospective confirmation.