Upfront Immunotherapy Approaches in the Management of Adults with Acute Lymphoblastic Leukemia

The therapeutic landscape of adults with B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is undergoing a paradigm shift, driven by the development of immunotherapy-based "chemo-free" and "chemo-light' regimens. These strategies aim to achieve high efficacy with reduced toxicity, particularly in older adults who may not tolerate intensive chemotherapy. In Philadelphia chromosome-positive (Ph+) BCP-ALL, the incorporation of ABL tyrosine kinase inhibitors (TKIs) with blinatumomab (CD3/CD19 bispecific T-cell engager) has shown remarkable efficacy, with some studies reporting molecular response rates in the range of 90-100% and long-term survival exceeding 80% without the need for intensive chemotherapy or allogeneic hematopoietic cell transplantation (allo-HCT). In Philadelphia-negative (Ph-) BCP- ALL, an immunotherapy-based combination of blinatumomab and inotuzumab ozogamicin (anti-CD22 antibody-drug conjugate) has demonstrated high rates of complete remission and measurable residual disease (MRD) negativity, with manageable toxicity. While chimeric antigen receptor (CAR) T-cell therapy remains a transformative option for relapsed/refractory B-ALL, its integration into frontline treatment is still under investigation. Ongoing trials are evaluating the optimal sequencing and combinations of these agents and their potential to obviate the need for chemotherapy and/or allo-HCT in selected patients. As evidence continues to accumulate, chemo-free and chemo-light regimens, incorporating minimal chemotherapy with targeted agents to balance efficacy and reduced toxicity, are poised to redefine the standard of care for adults BCP-ALL, offering the possibility of durable remissions with reduced treatment-related morbidity.