Patients
From November 1, 2004 to January 7, 2011, COG AALL02P2 enrolled patients 18 months to <30 years old at the time of relapse with B-or T-ALL and first iCNS-R or testicular relapse occurring ≥18 months from the date of initial diagnosis. Only patients with <5% marrow blasts by morphology assessed locally were eligible. Children with Down syndrome were excluded, as were those who underwent bone marrow transplant in first remission. Patients with known optic nerve and or retinal involvement were not eligible because they could not delay radiotherapy for 12 months.
COG AALL02P2 included modifications to the POG 9412 backbone aimed at providing intensified systemic therapy for 12 months prior to radiation to address the issue of marrow relapse, as well as optimize use of drugs known to better target the CNS compartment including dexamethasone, with HD cytarabine and methotrexate (dose increased from 1 to 5 g/m2 per cycle), plus 1200 cGy CRT. Additionally, pegaspargase was given (POG 9412 used native E. coli asparaginase). A secondary objective was to determine if the frequency of bone marrow involvement via flow-cytomery at the time of extramedullary relapse, and to assess if the level of pre-treatment minimal residual disease (MRD) correlated with outcomes.