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.

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. 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. 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%). 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.