Safety and efficacy of nelarabine in children and young adults with relapsed or refractory T-lineage acute lymphoblastic leukaemia or T-lineage lymphoblastic lymphoma: results of a phase 4 study

Summary Nelarabine is an antineoplastic agent approved for the treatment of relapsed/refractory T‐lineage acute lymphoblastic leukaemia (T‐ ALL ) or T‐lineage acute lymphoblastic lymphoma (T‐ LBL ). The purpose of this phase 4, multicentre, single‐arm, observational, open‐label trial was to provide additional data on the safety and efficacy of nelarabine under licensed conditions of use in children and young adults ≤21 years of age. Patients ( N = 28) had a mean ± standard deviation age of 11·5 ± 4·6 years; 71% were male and 61% had a diagnosis of T‐ ALL . Adverse events ( AE s) and treatment‐related AE s were experienced by 46% and 21%, respectively, and included few haematological AE s and no haematological serious AE s. Neurological AE s from one of four predefined categories (peripheral and central nervous systems, mental status change and uncategorized) were reported in four patients. There were no AE ‐related treatment discontinuations/withdrawals. The overall response rate was 39.3%: complete response ( CR ), 35.7%; CR without full haematological recovery ( CR *), 3.6%. Post‐treatment stem cell transplantation was performed for 46% of the cohort. Median overall survival ( OS ) was 3·35 months for non‐responders and not reached for responders ( CR + CR *). The response rate, median OS , and safety profile of nelarabine in this disease setting and population were consistent with those reported previously.