Current and emerging triplet combination therapies for relapsed and refractory multiple myeloma.

Despite significant improvement in outcomes have been observed for multiple myeloma (MM) patients over the past 10-15 years, mainly due to the introduction of novel agents targeting the tumor clone and the bone marrow microenvironment, treatment of refractory and/or relapsed (RR) disease remains a challenge, particularly for patients who have failed prior bortezomib- and lenalidomide-based therapies. More recently, new drugs with different mechanisms of action, including second generation proteasome inhibitors, third generation immunomodulatory drugs, histone deacetylase inhibitors and monoclonal antibodies, have been developed and are under investigation, further increasing treatment options for RRMM patients. Overall, novel agent-based triplet combinations demonstrated superior response rates and prolonged disease control when compared with two-drug regimens in several randomized clinical trials, without adding any relevant additional toxicity. Salvage triplet therapies are likely to play a key role in overcoming drug-resistance and hold promise to further improve long-term outcomes of RRMM patients.

Successful mobilization of PBSCs predicts favorable outcomes in multiple myeloma patients treated with novel agents and autologous transplantation.

Incorporation of novel agents into auto-SCT for patients with multiple myeloma has led to improvement in their outcomes. However, the effects of new drugs, either single or combined, on PBSC mobilization have not been fully evaluated, particularly in phase 3 clinical studies. We analyzed the impact of two novel agent-based induction treatments in patients enrolled in the GIMEMA MMY-3006 study comparing bortezomib, thalidomide and dexamethasone (VTD) versus thalidomide and dexamethasone (TD) in preparation for double auto-SCT. Results showed that a short-term induction therapy with VTD did not adversely affect CD34(+) cell yields as compared with TD (9.75 vs 10.76 × 10(6) CD34(+) cells/kg, P=0.220). For poor mobilizers (<4 × 10(6) CD34(+) cells/kg), 5-year rates of time to progression (TTP), progression-free survival (PFS) and overall survival (OS) were significantly shorter than for successful mobilizers (TTP:17 vs 48%, P<0.0001; PFS: 16 vs 46%, P<0.0001; OS: 50 vs 80%, P<0.0001). These differences were retained across patients randomized to the TD arm; conversely, no differences in outcomes were seen in patients treated with VTD, irrespective of the number of harvested CD34(+) cells. The number of collected PBSCs predicted better outcomes after auto-SCT and VTD overcame the negative impact of a poor stem cell mobilization.

Translocations at 8q24 juxtapose MYC with genes that harbor superenhancers resulting in overexpression and poor prognosis in myeloma patients.

Secondary MYC translocations in myeloma have been shown to be important in the pathogenesis and progression of disease. Here, we have used a DNA capture and massively parallel sequencing approach to identify the partner chromosomes in 104 presentation myeloma samples. 8q24 breakpoints were identified in 21 (20%) samples with partner loci including IGH, IGK and IGL, which juxtapose the immunoglobulin (Ig) enhancers next to MYC in 8/23 samples. The remaining samples had partner loci including XBP1, FAM46C, CCND1 and KRAS, which are important in B-cell maturation or myeloma pathogenesis. Analysis of the region surrounding the breakpoints indicated the presence of superenhancers on the partner chromosomes and gene expression analysis showed increased expression of MYC in these samples. Patients with MYC translocations had a decreased progression-free and overall survival. We postulate that translocation breakpoints near MYC result in colocalization of the gene with superenhancers from loci, which are important in the development of the cell type in which they occur. In the case of myeloma these are the Ig loci and those important for plasma cell development and myeloma pathogenesis, resulting in increased expression of MYC and an aggressive disease phenotype.

Single-cell genetic analysis reveals the composition of initiating clones and phylogenetic patterns of branching and parallel evolution in myeloma.

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.

Contrast enhanced MRI and ¹8F-FDG PET-CT in the assessment of multiple myeloma: a comparison of results in different phases of the disease.

OBJECTIVES: The aim of our study was to compare the accuracy of contrast enhanced MRI and FDG PET-CT in the staging, treatment evaluation and follow-up of multiple myeloma. METHODS: We retrospectively reviewed 210 PET-CT and 210 MRI studies of patients affected by multiple myeloma. MRI was always performed within 15 days of PET-CT. All the images have been evaluated by two expert oncologic radiologists. RESULTS: Patient population included 81 females and 110 males (age 61.9 ± 9.9 years-old). Sixty-two patients have been evaluated at diagnosis, 58 at the end of therapies and 90 during follow-up. In 12/62 patients (19.4%) at diagnosis, differences between MRI and PET-CT findings determined changes in the staging: PET-CT was responsible for 11 down-staging (17.7%) and MRI only for one (1.6%). In 27/40 patients (67.5%) with good or complete clinical response to therapies the normalization of findings was faster for PET-CT than MRI. Ten out of 90 patients (10/90 - 11.1%) in follow-up protocol presented clinical recurrence of the disease: MRI detected active lesions in 8 of them (80.0%) and PET-CT in 5 patients (50.0%, all detected by MRI too). CONCLUSIONS: MRI achieved better results than PET-CT in the staging and in patients with multiple myeloma recurrence. PET-CT, showed prompt change of imaging findings, faster than MRI, in patients with positive response to therapy.