Purpose: At the molecular level, myeloma is characterized by copy number abnormalities and recurrent translocations into the immunoglobulin heavy chain locus. Novel methods, such as massively parallel sequencing, have begun to describe the pattern of tumor-acquired mutations, but their clinical relevance has yet to be established. Methods: We performed whole-exome sequencing for 463 patients who presented with myeloma and were enrolled onto the National Cancer Research Institute Myeloma XI trial, for whom complete molecular cytogenetic and clinical outcome data were available. Results: We identified 15 significantly mutated genes: IRF4, KRAS, NRAS, MAX, HIST1H1E, RB1, EGR1, TP53, TRAF3, FAM46C, DIS3, BRAF, LTB, CYLD, and FGFR3. The mutational spectrum is dominated by mutations in the RAS (43%) and nuclear factor-κB (17%) pathways, but although they are prognostically neutral, they could be targeted therapeutically. Mutations in CCND1 and DNA repair pathway alterations (TP53, ATM, ATR, and ZNFHX4 mutations) are associated with a negative impact on survival. In contrast, those in IRF4 and EGR1 are associated with a favorable overall survival. We combined these novel mutation risk factors with the recurrent molecular adverse features and international staging system to generate an international staging system mutation score that can identify a high-risk population of patients who experience relapse and die prematurely. Conclusion: We have refined our understanding of genetic events in myeloma and identified clinically relevant mutations that may be used to better stratify patients at presentation.

We prospectively analyzed the prognostic relevance of positron emission tomography–computed tomography (PET/CT) at diagnosis, after thalidomide-dexamethasone (TD) induction therapy and double autotransplantation (ASCT) in 192 newly diagnosed multiple myeloma (MM) patients. Presence at baseline of at least 3 focal lesions (FLs; 44% of cases), a standardized uptake value (SUV) > 4.2 (46%), and extramedullary disease (EMD; 6%) adversely affected 4-year estimates of progression-free survival (PFS; ≥ 3 FLs: 50%; SUV > 4.2: 43%; presence of EMD: 28%). SUV > 4.2 and EMD were also correlated with shorter overall survival (OS; 4-year rates: 77% and 66%, respectively). Persistence of SUV > 4.2 after TD induction was an early predictor for shorter PFS. Three months after ASCT, PET/CT was negative in 65% of patients whose 4-year rates of PFS and OS were superior to those of PET-positive patients (PFS: 66% and OS: 89%). In a multivariate analysis, both EMD and SUV > 4.2 at baseline and persistence of fluorodeoxyglucose (FDG) uptake after ASCT were independent variables adversely affecting PFS. PET/CT involvement at diagnosis, after novel agent-based induction and subsequent ASCT is a reliable predictor of prognosis in MM patients. This study is registered at www.clinicaltrials.gov as NTC01341262.

Background and Objectives Bone lesions in multiple myeloma (MM) have been traditionally detected by whole body X-ray (WBXR) survey although magnetic resonance imaging (MRI) has become the gold standard for detecting MM involvement of the spine and pelvis. The aim of this study was to compare a new technique, positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) integrated with computed tomography (18F-FDG PET-CT), with MRI and WBXR for baseline assessment of bone disease in MM. Design and Methods We prospectively compared 18F-FDG PET-CT, MRI of the spine-pelvis and WBXR for baseline assessment of bone disease in a series of 46 patients with newly diagnosed MM. In 23 patients who received up front autologous transplantation, we also compared post-treatment PET-CT scans with MR images of the spine and pelvis. Results Overall, PET-CT was superior to planar radiographs in 46% of patients, including 19% with negative WBXR. In 30% of patients, PET-CT scans of the spine and pelvis failed to show abnormal findings in areas in which MRI revealed an abnormal pattern of bone marrow involvement, more frequently of diffuse type. In contrast, in 35% of patients PET-CT enabled the detection of myelomatous lesions in areas which were out of the field of view of MRI. By combining MRI of the spine-pelvis and 18F-FDG PET-CT, the ability to detect sites of active MM, both medullary and extramedullary, was as high as 92%. Following transplantation, 15 patients had negative PET-CT scans (including 13 with a very good partial response or at least near complete response), but only 8 had normal MRI. Interpretation and Conclusions MRI of the spine and pelvis still remains the gold standard imaging technique for the detection of bone marrow involvement in MM. 18F-FDG PET-CT provides additional and valuable information for the assessment of myeloma bone disease in areas not covered by MRI.

In a randomized, phase 3 study, superior complete/near-complete response (CR/nCR) rates and extended progression-free survival were demonstrated with bortezomib-thalidomide-dexamethasone (VTD) versus thalidomide-dexamethasone (TD) as induction therapy before, and consolidation after, double autologous stem cell transplantation for newly diagnosed myeloma patients (intention-to-treat analysis; VTD, n = 236; TD, n = 238). This per-protocol analysis (VTD, n = 160; TD, n = 161) specifically assessed the efficacy and safety of consolidation with VTD or TD. Before starting consolidation, CR/nCR rates were not significantly different in the VTD (63.1%) and TD arms (54.7%). After consolidation, CR (60.6% vs 46.6%) and CR/nCR (73.1% vs 60.9%) rates were significantly higher for VTD-treated versus TD-treated patients. VTD consolidation significantly increased CR and CR/nCR rates, but TD did not (McNemar test). With a median follow-up of 30.4 months from start of consolidation, 3-year progression-free survival was significantly longer for the VTD group (60% vs 48% for TD). Grade 2 or 3 peripheral neuropathy (8.1% vs 2.4%) was more frequent with VTD (grade 3, 0.6%) versus TD consolidation. The superior efficacy of VTD versus TD as induction was retained despite readministration as consolidation therapy after double autologous transplantation. VTD consolidation therapy significantly contributed to improved clinical outcomes observed for patients randomly assigned to the VTD arm of the study. The study is registered at www.clinicaltrials.gov as #NCT01134484.

The mechanisms involved in the progression from monoclonal gammopathy of undetermined significance (MGUS) and smoldering myeloma (SMM) to malignant multiple myeloma (MM) and plasma cell leukemia (PCL) are poorly understood but believed to involve the sequential acquisition of genetic hits. We performed exome and whole-genome sequencing on a series of MGUS (n=4), high-risk (HR)SMM (n=4), MM (n=26) and PCL (n=2) samples, including four cases who transformed from HR-SMM to MM, to determine the genetic factors that drive progression of disease. The pattern and number of non-synonymous mutations show that the MGUS disease stage is less genetically complex than MM, and HR-SMM is similar to presenting MM. Intraclonal heterogeneity is present at all stages and using cases of HR-SMM, which transformed to MM, we show that intraclonal heterogeneity is a typical feature of the disease. At the HR-SMM stage of disease, the majority of the genetic changes necessary to give rise to MM are already present. These data suggest that clonal progression is the key feature of transformation of HR-SMM to MM and as such the invasive clinically predominant clone typical of MM is already present at the SMM stage and would be amenable to therapeutic intervention at that stage.

Although intratumor heterogeneity has been inferred in multiple myeloma (MM), little is known about its subclonal phylogeny. To describe such phylogenetic trees in a series of patients with MM, we perform whole-exome sequencing and single-cell genetic analysis. Our results demonstrate that at presentation myeloma is composed of two to six different major clones, which are related by linear and branching phylogenies. Remarkably, the earliest myeloma-initiating clones, some of which only had the initiating t(11;14), were still present at low frequencies at the time of diagnosis. For the first time in myeloma, we demonstrate parallel evolution whereby two independent clones activate the RAS/MAPK pathway through RAS mutations and give rise subsequently to distinct subclonal lineages. We also report the co-occurrence of RAS and interferon regulatory factor 4 (IRF4) p.K123R mutations in 4% of myeloma patients. Lastly, we describe the fluctuations of myeloma subclonal architecture in a patient analyzed at presentation and relapse and in NOD/SCID-IL2Rγ^null xenografts, revealing clonal extinction and the emergence of new clones that acquire additional mutations. This study confirms that myeloma subclones exhibit different survival properties during treatment or mouse engraftment. We conclude that clonal diversity combined with varying selective pressures is the essential foundation for tumor progression and treatment resistance in myeloma.