The effect of novel therapies in high-molecular-risk multiple myeloma

Multiple myeloma is a heterogeneous disease with a prognosis that varies with patient factors, disease burden, tumor biology, and treatments. Certain molecular abnormalities confer a worse prognosis and thus are considered high-risk. These include t(4;14), del(17p), t(14;16), t(14;20), hypodiploidy, and gain(1q)/del(1p). In our previous review in 2013, we discussed the effect of available therapies on prognosis in these high-risk patients. Since then, seven phase 3 clinical trials in relapsed myeloma with 1 to 3 lines of therapy have been conducted, resulting in the approval of panobinostat, ixazomib, daratumumab, and elotuzumab, as well as additional data on carfilzomib. In our current review of these studies, all the novel therapies resulted in an improvement in progression-free survival for high-risk patients, but none of the trials provided clear statistical evidence that they overcame high-risk status. Moreover, there are several limitations in the currently available data. For example, the patient's Revised International Staging System score is generally not reported, and even when it is reported, it is usually at the time of initial diagnosis rather than at the time of study entry. Furthermore, the methodology used to determine risk suffers from technologic issues. Finally, the clonal and allele burden and concurrent molecular abnormalities can affect risk status and prognosis. To determine the optimal therapy for high-risk patients, future clinical trials should provide standardized risk assessments for all patients in addition to hazard ratios for Kaplan-Meier survival curves of high-risk patients vs those of standard-risk patients to determine if high-risk status has truly been overcome by a novel agent.