Response assessment:
An interim response assessment was done post completion of induction phase I (D35) either with PET-CT or by using conventional imaging techniques. Care was taken to also include the same imaging modality that was used in initial assessment for ease of comparison. Complete response (CR) was defined as the absence of all clinical and cytological evidence of disease with >70% reduction in diameter of all the lesions assessed by either X-ray/CT/MRI or a complete metabolic response with Deauville’s score of 1-3 in PET-CT. Partial response (PR) was defined as Clinico-cytologic response with <70% decrease in any of the lesion with no new lesions by X-ray/CT/MRI or a PET positivity with Deauville’s score 4 with a decrease in metabolic activity compared to baseline scans and Progressive disease (PD) as clinico-radiologic worsening with Duvellie’s score 5 and/or appearance of new leisions in interim PET. Patients who had PR in the post-induction phase I (D35), response assessment were re-assessed at the end of the induction phase II (D64). Patients who had baseline bone marrow involvement with >5% blasts underwent reassessment only by flow-cytometric minimal residual disease (MRD) post-induction phase I (D35). Post-phase I induction MRD was considered positive when the levels >0.01%. In CNS-3 patients, CSF analysis was repeated weekly along with Intra-thecal methotrexate administration until two consecutive CSF analysis remained negative for blasts.