Duvelisib is used as a targeted therapy in the treatment of certain blood cancers, particularly chronic lymphocytic leukemia (CLL), small lymphocytic lymphoma (SLL), and relapsed or refractory follicular lymphoma. It functions by inhibiting phosphoinositide 3-kinase (PI3K) enzymes, specifically the delta and gamma isoforms, which play key roles in B-cell signaling, survival, and proliferation. By blocking these pathways, duvelisib promotes apoptosis and reduces tumor growth in malignant B-cells. It is especially considered for patients who have not responded to or have relapsed after other treatments, including chemoimmunotherapy or targeted agents. Due to its mechanism, duvelisib offers a therapeutic option in cases where conventional therapies are no longer effective. Its oral administration also provides a convenient treatment route in outpatient settings. However, clinical use requires careful monitoring for immune-related adverse effects, such as pneumonitis, colitis, and infections, due to its impact on immune cell function.