Cohort Analysis:
A total of 347 newly-diagnosed children with ALL identified from pediatric oncology research database based on the study-defined inclusion and exclusion criteria. The study cohort comprised of thirty-one children who either relapsed or were resistant to first-line therapy and received salvage therapy , statistical analysis analysis was performed on these patients and their clinical characteristics at diagnosis and at relapse are shown in Table 1.
Three patients experienced induction failures (IF) and 28 relapsed, total of 31 patients with a cohort relapse incidence of 9% (31/347) identified. Overall, 4/28 (14%) relapses occurred on first-line therapy and 24 /28(86%) after completion of therapy. In the patients who relapsed, the CR1 duration ranged from 2.3 to 99 months with a mean of 26 months and median of 2 months. while with 15 (48%) patients relapsed ≤ 18 months, while seven (23%) relapsed during 18 to 36 months and nine (29%) patients relapsed > 36 months of IF or CR1.Eighteen patients (62%) had isolated Bone Marrow (BM) relapse, six (20%) patients experienced isolated Extra-medullary relapse (four patients experienced isolated CNS relapse and one-patient experienced isolated testicular relapse) and the remaining five (17%) patients experienced BM with other sites(BM+CNS in four patients and BM + Testis in one patient). Risk stratification of patients at relapse was completed as LR in two (6%) patients, IR in seven (23%) patients and majority of the patients twenty-two (71%) patients were stratified as HR prior to salvage therapy was administered. Seventeen patients (55%) patients first-salvage chemotherapy, while fourteen (45%) received second-salvage therapy and Thirteen (42%) patients proceeded to receive Hematopoietic Stem Cell Transplantation (HSCT). The above-mentioned clinical features of relapsed patient are shown in Table 2.