Safety and efficacy of subcutaneous formulation of bortezomib versus the conventional intravenous formulation in multiple myeloma

The discovery of the ubiquitin-proteasome pathway first, and the proteasome inhibitors thereafter were not made in the hope of improving the treatment of malignant diseases. However, bortezomib, the first in class proteasome inhibitor introduced in the clinical practice has contributed to improve the outcome of patients with multiple myeloma, at relapse or disease progression as well as upfront. The results observed in a large randomized trial (APEX) comparing bortezomib and high-dose dexamethasone demonstrated a significant benefit for bortezomib in terms of response rate, progression-free and overall survival. These results led to bortezomib being approved for use in relapsed and/or refractory myeloma patients. Subsequent studies demonstrated that its activity could be enhanced in combination with other drugs; and the next step was to move to the newly diagnosed patient population; in fact, bortezomib-melphalan-prednisone (VMP) is approved as a standard of care for newly diagnosed elderly patients. However, toxicity, especially peripheral neuropathy, as well as the intravenous route required for its administration are the two most significant bortezomib-related issues. To try to reduce the peripheral neuropathy, new guidelines for its management and the introduction of weekly schedules of administration have contributed to significantly decrease its incidence and the subcutaneous administration has been recently introduce to avoid the intravenous (IV) route. Results obtained in phase I/II and III studies have confirmed that subcutaneous administration is feasible and represents an additional step towards the optimization of bortezomib use, resulting in a probably more convenient method than the IV route that is at least as effective.