Nucleic acid based risk assessment and staging for clinical practice in multiple myeloma

The recently introduced Revised International Staging System (R-ISS) for multiple myeloma (MM) integrates albumin, beta 2 microglobulin, lactate dehydrogenase (LDH) with high-risk cytogenetic aberrations (CA), i.e., t(4;14) and t(14;16) and del17p using fluorescent in situ hybridization (FISH). We evaluated utility of nucleic acid-based tests of multiplex ligation-based probe amplification (MLPA) and quantitative real-time polymerase chain reaction (qRT-PCR) to define the CA and the R-ISS categories as per this approach were evaluated for their ability to predict outcome in terms of response, progression-free (PFS), and overall survival (OS). In this study (n = 180), 17 (9.4%), 118 (65.6%), and 45 (25%) patients were assigned to R-ISS1, R-ISS2, and R-ISS3 categories with statistically significant differences in median PFS (p = 0.02) and OS (p < 0.001).On univariate analysis, serum creatinine, LDH, 17p deletion, chromosome 1q gain, and response after first induction therapy were associated with statistically significant differences (p < 0.05) in PFS and in addition, age > 65 years and use of triplet therapy with OS. On multivariate analysis, only serum creatinine, LDH, and response after first induction therapy retained significance for predicting PFS and in addition, use of triplet therapy retained significance for the OS. The proposed nucleic acid-based algorithm using qRT-PCR and MLPA for R-ISS is resource-effective in terms of small quantities of sample required; feasibility of batch processing and reduced overall cost for the total number of regions evaluated and retained the prognostic significance of R-ISS, making it suitable for clinical practice for molecular characterization of MM.