Adult Acute Lymphoblastic Leukemia: 2025 Update on Diagnosis, Therapy, and Monitoring

DISEASE OVERVIEW: Acute lymphoblastic leukemia (ALL) is a disease of lymphoid progenitor cells arising in the bone marrow and extramedullary sites. While it is the most common pediatric cancer, ALL is a rare disease overall, with approximately 6500 new cases diagnosed in the United States, in 2024. Current treatment relies on multiagent chemotherapy administered over 2-3 years, resulting in long-term survival in 80%-90% in pediatric patients compared to 40%-50% in adult patients, depending upon patient- and disease-specific characteristics. PHILADELPHIA CHROMOSOME-POSITIVE B-CELL ALL: Historically considered a poor risk ALL subtype, the treatment and outcome of Philadelphia chromosome (Ph)-positive B-cell ALL were drastically changed with the advent of the BCR::ABL1 tyrosine kinase inhibitors (TKIs). The combination of a TKI with a backbone of multiagent chemotherapy, or more recently blinatumomab, is the mainstay of therapy, resulting in 5-year survival rates of 80+%. Achieving a complete molecular remission, particularly by next generation sequencing, is an important prognostic indicator, which may identify patients who may avoid allogeneic stem cell transplantation (SCT). PHILADELPHIA CHROMOSOME-NEGATIVE B-CELL ALL: The treatment approach for patients with Ph-negative B-cell ALL was historically composed of a chemotherapy backbone (either pediatric-inspired, or Hyper-CVAD based). Novel agents including inotuzumab ozogamicin and blinatumomab are being incorporated into these regimens to improve the rates of measurable residual disease negativity and long-term outcomes. While differences in long-term survival rates differ between age groups, such as adolescents and young adults compared to older adults (≥ 60 years), with these immunotherapy-chemotherapy regimens, the 4-year survival rates have improved to 80%-85% among patients who are able to receive these treatments. Elderly patients represent a difficult population to treat due to poor chemotherapy tolerance, high-risk disease features, and increased risk of developing therapy-related myeloid neoplasms. The use of inotuzumab ozogamicin and blinatumomab in lieu of intensive chemotherapy in this population has improved safety and efficacy in patients ≥ 60 years old. Clinical trials incorporating chimeric antigen receptor (CAR) T-cell therapy into treatment for older patients are in progress. T-CELL ALL: Combination chemotherapy regimens incorporating pegylated asparaginase and nelarabine are the standard for patients with T-cell ALL. Early T-cell precursor (ETP) ALL is a high-risk subgroup for which allogeneic SCT should be considered. Inclusion of the BCL-2 inhibitor venetoclax into treatment for patients with ETP-ALL may be beneficial and is currently being investigated. SALVAGE THERAPY: Several therapies are approved as single agents in the salvage setting. However, the best outcomes are obtained with combination therapy including chemo- and immuno- therapies followed by CAR T-cell consolidation and allogeneic SCT. Clinical trials optimizing this approach are ongoing.