Umbralisib hydrochloride is primarily used in the treatment of certain types of cancer, particularly relapsed or refractory marginal zone lymphoma and follicular lymphoma. It works by inhibiting specific enzymes involved in the growth and survival of cancer cells, thereby slowing down or stopping the progression of the disease. This medication is often prescribed when other treatments have not been effective, offering a targeted approach to managing these conditions. Additionally, it is being studied for its potential in treating other hematologic malignancies, expanding its therapeutic applications in oncology.