Minimal residual disease and outcome characteristics in infant KMT2A-germline acute lymphoblastic leukaemia treated on the Interfant-06 protocol
Janine Stutterheim, Paola De Lorenzo, Inge M. van der Sluis, Julia Alten, Philip Ancliffe, Andishe Attarbaschi, Luis Aversa, Judith M. Boer, Andrea Biondi, Benoît Brethon, P. Diaz, Giovanni Cazzaniga, Gabriele Escherich, Alina Ferster, Rishi S. Kotecha, Birgitte Lausen, Alex Wing Kwan Leung, Franco Locatelli, Lewis B. Silverman, Jan Starý, Tomasz Szczepański, Vincent H. J. van der Velden, Ajay Vora, Jan Zuna, Martin Schrappe, Maria Grazia Valsecchi, Rob Pieters
Abstract
BackgroundThe outcome of infants with KMT2A-germline acute lymphoblastic leukaemia (ALL) is superior to that of infants with KMT2A-rearranged ALL but has been inferior to non-infant ALL patients. Here, we describe the outcome and prognostic factors for 167 infants with KMT2A-germline ALL enrolled in the Interfant-06 study.MethodsUnivariate analysis on prognostic factors (age, white blood cell count at diagnosis, prednisolone response and CD10 expression) was performed on KMT2A-germline infants in complete remission at the end of induction (EOI; n = 163). Bone marrow minimal residual disease (MRD) was measured in 73 patients by real-time quantitative polymerase chain reaction at various time points (EOI, n = 68; end of consolidation, n = 56; and before OCTADAD, n = 57). MRD results were classified as negative, intermediate (<5∗10−4), and high (≥5∗10−4).ResultsThe 6-year event-free and overall survival was 73.9% (standard error [SE] = 3.6) and 87.2% (SE = 2.7). Relapses occurred early, within 36 months from diagnosis in 28 of 31 (90%) infants. Treatment-related mortality was 3.6%. Age <6 months was a favourable prognostic factor with a 6-year disease-free survival (DFS) of 91% (SE = 9.0) compared with 71.7% (SE = 4.2) in infants >6 months of age (P = 0.04). Patients with high EOI MRD ≥5 × 10−4 had a worse outcome (6-year DFS 61.4% [SE = 12.4], n = 16), compared with patients with undetectable EOI MRD (6-year DFS 87.9% [SE = 6.6], n = 28) or intermediate EOI MRD <5 × 10−4 (6-year DFS 76.4% [SE = 11.3], n = 24; P = 0.02).ConclusionWe conclude that young age at diagnosis and low EOI MRD seem favourable prognostic factors in infants with KMT2A-germline ALL and should be considered for risk stratification in future clinical trials.