Integration between MCL1 gene co-expression module and the Revised International Staging System enables precise prognostication and prediction of response to proteasome inhibitor-based therapy in individual multiple myeloma. Integration between MCL1 gene co-expression module and the Revised International Staging System enables precise prognostication and prediction of response to proteasome inhibitor-based therapy in individual multiple myeloma

We recently identified a gene module of 87 genes co-expressed with MCL1 (MCL1-M), a critical regulator of plasma cell survival. MCL1-M captures both MM cell-intrinsically acting signals and the signals regulating the interaction between MM cells with bone marrow microenvironment. MM can be clustered into MCL1-M high and MCL1-M low subtypes. While the MCL1-M high MMs are enriched in a preplasmablast signature, the MCL1-M low MMs are enriched in B cell-specific genes. In multiple independent datasets, MCL1-M high MMs exhibited poorer prognosis compared to MCL1-M low MMs. Re-analysis of the phase III HOVON-65/GMMG-HD4 showed that only MCL1-M MMs, but not MCL1-M low MMs, benefited from bortezomib-based treatment. To translate the MCL1-M clustering scheme into a platform for individual diagnosis, we refined the classifier genes and developed a support vector machine-based algorithm. Individual MMs with transcriptome assessed at the RNA-seq or U133 plus 2.0 array platform can be robustly assigned as the MCL1-M high or low subtype with high confidence. Analyses of the MM samples in the HOVON-65/GMMG-HD4 trial and APEX trial reinforce that only MCL1-M high MMs benefit from bortezomib-based treatment with a hazard ratio of 0.58 (P = 0.010) and 0.47 (P = 0.009), respectively. Thus, MCL1-M based subtyping assigns MMs into prognostic and predictive molecular subtypes driven by subtype-specific pathogenic pathways. Overall design: We also generated our own data set based on 72 newly diagnosed MM samples from Chaoyang hospital in Beijing. All participants signed the informed consent form, and the study was approved by the institutional ethical review board of the Chao-Yang Hospital, Capital Medical University (Beijing, China). Patients were treated between August 2015 and September 2019, the longest follow-up period was 67 months. Bone marrow CD138+ cells were purified for the preparation of total mRNA for the transcriptome profiling using Affymetrix PrimeView array according to standard protocols.