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Deep MRD profiling defines outcome and unveils different modes of treatment resistance in standard and high risk myeloma

ABSTRACT: Patients with multiple myeloma (MM) carrying high risk cytogenetic abnormalities (CA) have inferior outcome despite achieving similar complete response (CR) rates when compared to cases with standard risk CA. This questions the legitimacy of CR as treatment endpoint for high risk MM, and represents a biological conundrum regarding the nature of tumor reservoirs persisting after therapy in patients with standard and high risk CA. Here, we used next-generation flow (NGF) to evaluate measurable residual disease (MRD) in MM patients with standard (N=300) vs high risk CA (N=90) enrolled in the PETHEMA/GEM2012MENOS65 trial (NCT01916252), and to identify mechanisms determining MRD resistance in both patient subgroups (N=40). The 36-month progression-free and overall survival rates were higher than 90% in patients with undetectable MRD, with no significant differences (PÃ¢Â‰Â¥.202) between cases having standard vs high risk CA. Persistent MRD resulted in median progression-free survival of approximately three and two years in patients with standard and high risk CA, respectively (P<.001). Further use of NGF to isolate MRD followed by whole-exome sequencing of paired diagnostic and MRD tumor cells, revealed greater clonal selection in patients with standard risk CA, higher genomic instability with acquisition of new mutations in high risk MM, and no unifying lost or acquired genetic abnormalities driving MRD resistance. Conversely, RNA sequencing of diagnostic and MRD tumor cells uncovered the selection of MRD clones with singular transcriptional programs and ROS-mediated MRD resistance in high risk MM. Our study supports undetectable MRD as treatment endpoint for MM patients with high risk CA and proposes characterizing MRD clones to understand and overcome MRD resistance.

PROVIDER: EGAS00001004558 | EGA |

REPOSITORIES: EGA

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Project description:During many years, chemo-immunotherapy fludarabine-cyclophosphamide-rituximab (FCR) was considered as the gold standard for the first line treatment of medically fit patients with symptomatic B-chronic lymphocytic leukemia (CLL). Over the last decade, targeted biotherapies have revolutionized the management of B-CLL patients' treatment and almost entirely supplanted FCR. However, no biomarker still exists to predict the complete remission (CR) with undetectable minimal residual disease (uMRD), which remains so far the best predictive factor for survival. Circulating miRNAs represent a class of molecular biomarkers which expression is altered in hematological disorders including B-CLL. Our present study aimed at identifying before treatment circulating miRNAs that predict the treatment outcome in previously untreated B-CLL patients (NCT 01370772, https://clinicaltrials.gov/ct2/show/NCT01370772). Using hierarchical clustering of miRNA expression profiles discriminating 8 patients who achieved CR with bone marrow (BM) uMRD, from 8 patients who do not achieved CR and displayed detectable BM MRD, we identified 25 miRNAs differentially expressed before treatment. The expression of 11 representative miRNAs was further validated on a larger cohort (n=123). Based on the dosage of 5 miRNAs at diagnosis, a decision tree was constructed to predict treatment outcome. Our results identified 6 groups of patients with a distinct probability of being CR with BM uMRD to FCR treatment, ranging from 72% (miR-125b, miR-15b and miR-181c high) to 4% (miR-125b and miR-193b low). Progression-free survival (PFS) was significantly different between the established groups (p=0.019). None of the patients displaying high expression levels of miR-125b, miR-15b and miR-181c (HHH group) relapsed during the follow-up of the study. In contrast, patients with miR-15b low and miR-412 high (HLH group), and patients with low expression levels of miR-125b and miR-193b (LL group) demonstrated a significant low PFS. By RNA sequencing blood at diagnosis, we compared mRNA expression profiles of these three groups, achieving or not CR with uMRD. We identified that patients relapsing after treatment are characterized by significant enrichment of gene signatures related to cell cycle, MYC target genes, metabolism and translation regulation at diagnosis. Conversely, patients achieving CR with uMRD displayed significant enrichment in genes related to communication between CLL cells and the microenvironment, immune system activation and upregulation of polycomb PRC2 complex target genes at diagnosis. Our results suggest that blood miRNAs are potent predictive biomarkers for treatment efficacy of FCR and might be implicated in the FCR efficacy in B-CLL patients. Further investigations could establish whether these miRNAs might also be used to stratify patients for new-generation treatments. Overall, our work provides insight into unmet need for the treatment of B-CLL patients and identified pathways potentially predictive of patients’ remission.

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Deep MRD profiling defines outcome and unveils different modes of treatment resistance in standard and high risk myeloma

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