Parsaclisib is primarily used in the field of oncology as a targeted therapy for certain types of cancers. It functions as a PI3K inhibitor, specifically targeting the delta isoform of the enzyme, which is often involved in the growth and survival of cancer cells. This makes it particularly effective in treating hematologic malignancies, such as non-Hodgkin lymphoma and chronic lymphocytic leukemia. By inhibiting the PI3K delta pathway, Parsaclisib helps to reduce the proliferation of malignant cells and induce apoptosis, thereby slowing the progression of the disease. It is often considered for patients who have not responded well to other treatments or who have relapsed after initial therapy. Ongoing clinical trials are exploring its efficacy in combination with other anticancer agents to enhance therapeutic outcomes.