Faculty Bibliography

PURPOSE/OBJECTIVE:The aim of International Myeloma Working Group was to develop practical recommendations for the use of magnetic resonance imaging (MRI) in multiple myeloma (MM). METHODS:An interdisciplinary panel of clinical experts on MM and myeloma bone disease developed recommendations for the value of MRI based on data published through March 2014. RECOMMENDATIONS/CONCLUSIONS:MRI has high sensitivity for the early detection of marrow infiltration by myeloma cells compared with other radiographic methods. Thus, MRI detects bone involvement in patients with myeloma much earlier than the myeloma-related bone destruction, with no radiation exposure. It is the gold standard for the imaging of axial skeleton, for the evaluation of painful lesions, and for distinguishing benign versus malignant osteoporotic vertebral fractures. MRI has the ability to detect spinal cord or nerve compression and presence of soft tissue masses, and it is recommended for the workup of solitary bone plasmacytoma. Regarding smoldering or asymptomatic myeloma, all patients should undergo whole-body MRI (WB-MRI; or spine and pelvic MRI if WB-MRI is not available), and if they have > one focal lesion of a diameter > 5 mm, they should be considered to have symptomatic disease that requires therapy. In cases of equivocal small lesions, a second MRI should be performed after 3 to 6 months, and if there is progression on MRI, the patient should be treated as having symptomatic myeloma. MRI at diagnosis of symptomatic patients and after treatment (mainly after autologous stem-cell transplantation) provides prognostic information; however, to date, this does not change treatment selection.

Monitoring multiple myeloma (MM) is essential during the evaluation of response to each therapy line, after transplantation and at the time of relapse or progression in all patients. An initial complete workup, including appropriate protein studies in serum and urine is mandatory. The use of uniform criteria is particularly important in the context of clinical trials. Complete remission (CR) definition, the goal for the majority of patients, is now in constant evolution, with immunophenotypic and molecular minimal residual disease measurement in bone marrow as well as imaging techniques. Identification of relapse/progression with traditional and novel techniques for eventual prompt intervention with rescue treatment is a current issue of debate.

In this report, a panel of European myeloma experts discuss the role of pomalidomide in the treatment of relapsed and refractory multiple myeloma (RRMM). Based on the available evidence, the combination of pomalidomide and low-dose dexamethasone is a well-tolerated and effective treatment option for patients with RRMM who have exhausted treatment with lenalidomide and bortezomib. The optimal starting dose of pomalidomide is 4 mg given on days 1-21 of each 28-day cycle, whereas dexamethasone is administered at a dose of 40 mg weekly (reduced to 20 mg for patients aged >75 years). The treatment should continue until evidence of disease progression or unacceptable toxicity. Dose-modification schemes have been established for patients who develop neutropenia, thrombocytopaenia and other grade 3-4 adverse events during pomalidomide therapy. Guidance on the prevention and management of infections and venous thromboembolism is provided, based on the available clinical evidence and the experience of panel members. The use of pomalidomide in special populations, such as patients with advanced age, renal impairment or unfavourable cytogenetic features, is also discussed.

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.

Bendamustine is a unique bifunctional alkylating agent with promising activity in myeloma. Despite the increasing number of studies demonstrating its efficacy in both the upfront and relapse settings, including patients with renal insufficiency, the optimal use of bendamustine, in terms of dosage, schedule and combination with other agents, has yet to be defined. It is currently licensed for use as frontline treatment with prednisolone for patients with myeloma who are unsuitable for transplantation and who are contraindicated for thalidomide and bortezomib. Studies in relapsed/refractory patients are currently ongoing with other combinations. Given the increasing data to date, the UK Myeloma Forum believes that bendamustine with steroids alone or in combination with a novel agent could be considered for patients with multiply relapsed myeloma. This document provides guidance for the use of bendamustine for patients with myeloma until the results of definitive studies are available.

The treatment of multiple myeloma has undergone significant changes and has resulted in the achievement of molecular remissions, the prolongation of remission duration, and extended survival becoming realistic goals, with a cure being possible in a small but growing number of patients. In addition, nowadays it is possible to categorize patients more precisely into different risk groups, thus allowing the evaluation of therapies in different settings and enabling a better comparison of results across trials. Here, we review the evidence from clinical studies, which forms the basis for our recommendations for the management of patients with myeloma. Treatment approaches depend on "fitness," with chronological age still being an important discriminator for selecting therapy. In younger, fit patients, a short three drug-based induction treatment followed by autologous stem cell transplantation (ASCT) remains the preferred option. Consolidation and maintenance therapy are attractive strategies not yet approved by the European Medicines Agency, and a decision regarding post-ASCT therapy should only be made after detailed discussion of the pros and cons with the individual patient. Two- and three-drug combinations are recommended for patients not eligible for transplantation. Treatment should be administered for at least nine cycles, although different durations of initial therapy have only rarely been compared so far. Comorbidity and frailty should be thoroughly assessed in elderly patients, and treatment must be adapted to individual needs, carefully selecting appropriate drugs and doses. A substantial number of new drugs and novel drug classes in early clinical development have shown promising activity. Their introduction into clinical practice will most likely further improve treatment results.

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.

Therapeutic advances and the availability of novel agents have significantly improved outcomes in myeloma; yet, it remains incurable and strategies to improve survival continue to be sought. One approach is to prolong the duration of response and increase progression-free survival (PFS) through consolidation or maintenance treatment with regimens that have low toxicity profiles, and do not negatively impact on quality of life. Data from several studies with thalidomide, lenalidomide and bortezomib consistently show improvements in response and PFS, although results have still to be confirmed with respect to overall survival (OS). Despite the promising data, the optimal use of consolidation and maintenance treatment in terms of regimen, dose and duration has yet to be defined. Given the evidence to date, the UK Myeloma Forum believes that both maintenance and consolidation therapy should be considered as treatment options for patients with myeloma. Patients should be encouraged to enrol in clinical studies. This document reviews the current position of maintenance and consolidation for patients with myeloma treated in the UK.