Bortezomib API (CAS 179324-69-7) is a high-potency, synthetic, dipeptidyl boronic acid proteasome inhibitor used to treat multiple myeloma and mantle cell lymphoma. As a first-in-class oncology agent, it induces cancer cell death by inhibiting the 26S proteasome. It is available as a GMP-grade, lyophilized powder for injectable formulations.