Used in the treatment of multiple myeloma and mantle cell lymphoma, this compound functions as a proteasome inhibitor, disrupting the degradation of regulatory proteins in cancer cells. By inhibiting the 20S proteasome, it leads to the accumulation of misfolded proteins, triggering cell cycle arrest and apoptosis in malignant cells. It is particularly effective in patients who have relapsed or are refractory to prior therapies, including those involving immunomodulatory drugs or chemotherapy. Its oral bioavailability allows for convenient outpatient treatment, improving patient compliance. Ongoing studies explore its potential in other hematologic malignancies and solid tumors, often in combination with agents like dexamethasone or histone deacetylase inhibitors to enhance efficacy.