Increased survival due to lower toxicity for high-risk T-cell acute lymphoblastic leukemia patients in two consecutive pediatric-inspired PETHEMA trials

Abstract

Objective and methods: Pediatric-inspired regimens have been adopted by several groups as the treatment strategy for adult patients with acute lymphoblastic leukemia (ALL). Whether subsequent modifications of these protocols have led to an improvement in the outcome of patients is uncertain, especially in T-cell ALL. We analyzed 169 patients with high-risk T-cell ALL included in two consecutive trials of the PETHEMA Group (HR-ALL03 [n = 104] and the more contemporary HR-ALL11 [n = 65]). Results: Patients and disease characteristics were balanced between both groups. Regarding efficacy, we observed a similar complete remission (CR) rate, relapse and disease-free survival (DFS) between both protocols. Patients included in the HR-ALL11 trial had better 2-year overall survival (OS) compared with the HR-ALL03 (65% [95% CI 51%-79%] vs 44% [95% CI 34%-54%], P = 0.026). Regarding toxicity, we observed a better safety profile in the HR-11 protocol. Irrespective of the protocol, patients with good measurable residual disease (MRD) clearance had a promising outcome without allogeneic hematopoietic stem cell transplantation (allo-HSCT) in CR1, with 2-year OS of 67%. Conclusion: Patients with T-cell ALL included in the HR-11 trial showed better OS than patients in the HR-03, mostly driven by a reduction of NRM.