David Simpson, MBChB, FRACP, FRCPA of North Shore Hospital, Auckland, New Zealand, explains the resistance mechanism of myeloma cells to carfilzomib, and describes the success of infusion with ritonavir in patients who have reduced response. Dr Simpson goes on to outline the need to assess the most efficient time for the administration of carfilzomib in myeloma patients in order to eliminate resistance-related cells. This interview was filmed at the International Myeloma Workshop (IMW) 2019, in Boston, MA.