Risk Stratification and Targets in Multiple Myeloma: From Genomics to the Bedside

Abstract

In the past 15 years, significant improvements in overall survival have been observed in multiple myeloma (MM), mainly due to the availability of novel drugs with variable mechanisms of action. However, these improvements do not benefit all patients, and some of them, defined as high risk, still display short survival. The most important risk factors are the genetic abnormalities present in the malignant plasma cells. The most important high-risk features are the del(17p), the del(1p32), the t(4;14), and 1q gains. Assessing these markers is mandatory at diagnosis and at least at first relapse, since it has been clearly shown that the lenalidomide-dexamethasone combination is not efficient in these high-risk patients. In contrast, a triplet combination adding a proteasome inhibitor or a monoclonal antibody to the lenalidomide-dexamethasone backbone clearly improves the survival. Another way to improve the outcome would be to specifically target genetic abnormalities with specific inhibitors. The sequencing of more than 1,000 MM exomes revealed again a huge heterogeneity. The most frequent mutations involve the KRAS and NRAS genes (20%-25% each). However, to date, no good RAS-inhibitors are clinically available, preventing targeted therapy. The only drugable target is the V600E BRAF mutation. Unfortunately, this specific mutation is present in only 3% of the patients. Finally, it has been recently reported a specific efficiency of the BCL2-inhibitor venetoclax in patients with the t(11;14) translocation, which is found in 20% of the patients.