Acute lymphoblastic leukemia (ALL) is the most common malignancy in children and the second most frequent acute leukemia in adults. B-cell ALL constitutes approximately 85% of all ALL diagnoses. In Pakistan, ALL represents the most prevalent haematological malignancy presenting to tertiary centres, with AFBMTC receiving the largest national referral volume for haematological malignancies and transplantation.
First-line combination chemotherapy achieves complete remission (CR) in \>95% of paediatric patients; however, 15-20% relapse. Outcomes following first relapse are substantially inferior: second-line salvage chemotherapy achieves CR2 in 30-50% of patients, and long-term event-free survival (EFS) after conventional chemotherapy alone is \<10%. Outcomes in adult ALL are even more dismal, with OS at 5 years below 40% even in first CR without allogeneic transplant.
Patients with primary refractory ALL or multiply relapsed ALL have an unmet medical need for novel therapeutic approaches. The classical paradigm of chemotherapy followed by allogeneic haematopoietic stem cell transplantation (allo-HSCT) is limited by donor availability, conditioning-related mortality, and inability to achieve remission before transplant.