Abstract
Acute lymphoblastic leukemia (ALL) in infants (<1 year of age) is an aggressive disease. About 80% of infant ALL patients harbor a mixed lineage leukemia (MLL) translocation, which is a strong independent predictor of poor outcome.1 Furthermore, infant ALL is associated with higher white blood cell (WBC) counts at diagnosis, very immature pro-B ALL phenotype and glucocorticoid resistance.1, 2 Although most infant ALL patients (~95%) achieve morphological complete remission (CR) after induction therapy, owing to high relapse-rates their outcome is poor.1 Most relapses occur early, within the first year after diagnosis.
The largest series of infant ALL, described by the Interfant-99 study group, reported a relapse rate of 34%. Relapsed infant ALL is generally assumed to be inevitably fatal.
Published data on outcome of relapsed infant ALL are very limited, and available ones report on small cohorts.3 Here, we describe the clinical outcome of 202 infant ALL patients, who relapsed on or after receiving the Interfant-99 treatment protocol.1 Design and inclusion criteria of the Interfant-99 trial have been described previously.1 Therapy after relapse differed in participating countries according to local policy and individual choice. We retrospectively asked the physicians whether the therapy was based on curative or palliative intent.