Introduction:
Acute Lymphoblastic Leukaemia (ALL), is one of the most common malignancy diagnosed in children and is characterized by diffuse replacement of bone marrow and peripheral blood with neoplastic cells and constitutes for more than a quarter of all pediatric cancers(1, 2). Front-line treatment in ALL is considered a major success and one of the most curable cancers in children with an overall survival rate > 80%, these favourable survival outcomes are attributable to several strategies including combination of chemotherapeutic agents, risk-based stratification and allocation of treatment and prophylactic CNS therapy.(3, 4) Despite substantial improvements in the treatment strategies, approximately 20% of the patients are predicted to relapse and with high incidence of ALL in children, recurrent leukaemia is a relatively common diagnosis being managed by pediatric oncologists(1, 3).
Certain risk-determining factors for relapse have been identified guiding the treating pediatric oncologists in planning treatment strategies (intensity) and prognosis, factors those have been extensively reported in the literature includes time to relapse from first complete remission (< 36 months from diagnosis) , site of relapse and immunophenotype (B-cell vs. T-cell). Survival amongst relapsed patients is generally predicted by site of relapse and duration of first complete remission, with bone marrow and early relapse reported to be associated with inferior prognosis when compared to isolated extra-medullary or late relapse. Although, clinical remission can be accomplished in majority of relapses, however, long-term survival rates ranges from 40% -50% (5, 6).
Treatment of relapsed patients involves reinduction with conventional agents identical to the one’s used at initial diagnosis, and Hematopoietic stem-cell transplantation (HSCT) is widely adapted as consolidation therapy in relapsed ALL patients, however benefit of stem cell tranplant in late or multiple relapses needs to established firmly. Therefore, given the overall suboptimal outcomes with conventional, high-dose therapy involved in treating relapsed or refractory patients warrants new therapeutic agents and strategies (3, 7).
Risk-stratified approach is adapted at our institution when treating pediatric patients with relapse or resistance to first-line therapy and through this study we report outcomes from a single tertiary care centre.