Relapsed/refractory CLL: the role of allo-SCT, CAR-T, and T-cell engagers.

Chronic lymphocytic leukemia (CLL) patients who are refractory to both Bruton's tyrosine kinase and B-cell/CLL lymphoma 2 (BCL2) inhibitors face a significant treatment challenge, with limited and short-lasting disease control options. This underscores the urgent need for novel therapeutic strategies. Immunotherapy has emerged as a promising approach to address this unmet need, offering the potential for durable remissions and improved patient outcomes. Historically, allogeneic stem cell transplantation has been used for high-risk CLL patients, demonstrating promising survival rates. However, its applicability is limited by high treatment-related mortality and chronic graft-versus-host disease, especially in older and frail patients. Chimeric antigen receptor (CAR) T-cell therapy is gaining attention for its potential in relapsed/refractory CLL. Early clinical trials have shown that CAR T cells can induce durable remissions, with encouraging overall response rates in heavily pretreated patients. Additionally, bispecific antibodies are being explored as immunotherapeutic strategies, showing promising preclinical and early clinical results in targeting CLL cells effectively. One of the major challenges in CLL treatment with T-cell-based therapies is the acquired T-cell dysfunction observed in patients. To overcome these limitations, strategies such as combining targeted agents with cellular immunotherapies, modifying CAR designs, and incorporating immunomodulatory compounds into the manufacturing process are being investigated. These innovative approaches aim to enhance T-cell engagement and improve outcomes for CLL patients, offering hope for more effective and sustainable treatments in the future.