Faculty Bibliography

Does the dogma that multiple myeloma is incurable still hold?. The genomic chaos and resulting resistance to apoptosis of myeloma, long considered an obstacle to cure, formed the basis of Total Therapy (TT) program. The TT approach uses all myeloma-active drugs upfront to target drug-resistant subclones during initial treatment to prevent later relapse. Long-term follow-up of 1202 patients (TT1: n = 231, median follow-up: 21 years; TT2: 668, median follow-up: 12 years; TT3a: n = 303, median follow-up: 9 years) permitted investigation of whether progression-free survival (PFS) and complete response (CR) duration were consistent with curability, ie observation of plateaus in Kaplan-Meier plots for PFS and CR duration. In the subset of 627 patients with plasma cell gene expression profiling data, cure plateaus were apparent at 5 years in the 14% with high-risk myeloma compared with 10 years in the remainder with low-risk disease. A parametric model based on PFS and CR duration supported an increase in curability: 10-year PFS and CR estimates increased from 8.8%/17.9% in TT1 to 15.5%/28.2% in TT2's control arm to 25.1%/35.6% in TT2's thalidomide arm and to 32.9%/48.8% in TT3a. Toward developing novel therapies, we recommend a concerted focus on patients with high-risk myeloma whose outcome has not been advanced.

Constitutive NF-κB signaling promotes survival in multiple myeloma (MM) and other cancers; however, current NF-κB-targeting strategies lack cancer cell specificity. Here, we identify the interaction between the NF-κB-regulated antiapoptotic factor GADD45β and the JNK kinase MKK7 as a therapeutic target in MM. Using a drug-discovery strategy, we developed DTP3, a D-tripeptide, which disrupts the GADD45β/MKK7 complex, kills MM cells effectively, and, importantly, lacks toxicity to normal cells. DTP3 has similar anticancer potency to the clinical standard, bortezomib, but more than 100-fold higher cancer cell specificity in vitro. Notably, DTP3 ablates myeloma xenografts in mice with no apparent side effects at the effective doses. Hence, cancer-selective targeting of the NF-κB pathway is possible and, at least for myeloma patients, promises a profound benefit.

Glycosylation is a stepwise procedure of covalent attachment of oligosaccharide chains to proteins or lipids, and alterations in this process, especially increased sialylation, have been associated with malignant transformation and metastasis. The role of altered sialylation in multiple myeloma (MM) cell trafficking has not been previously investigated. In the present study we identified high expression of β-galactoside α-2,3-sialyltransferase, ST3GAL6, in MM cell lines and patients. This gene plays a key role in selectin ligand synthesis in humans through the generation of functional sialyl Lewis X. In MRC IX patients, high expression of this gene is associated with inferior overall survival. In this study we demonstrate that knockdown of ST3GAL6 results in a significant reduction in levels of α-2,3-linked sialic acid on the surface of MM cells with an associated significant reduction in adhesion to MM bone marrow stromal cells and fibronectin along with reduced transendothelial migration in vitro. In support of our in vitro findings, we demonstrate significantly reduced homing and engraftment of ST3GAL6 knockdown MM cells to the bone marrow niche in vivo, along with decreased tumor burden and prolonged survival. This study points to the importance of altered glycosylation, particularly sialylation, in MM cell adhesion and migration.

In recent years significant progress has been made in the understanding of multiple myeloma (MM) biology and its treatment. Current strategies for the treatment of MM involve the concept of sequential blocks of therapy given as an induction followed by consolidation and maintenance. In an age characterized by emerging and more powerful laboratory techniques, it is of primary importance to understand the biology of MM and how this biology can guide the development of new treatment strategies. This review focuses on the genetic basis of myeloma, including the most common genetic abnormalities and pathways affected and the effects that these have on MM treatment strategies. MM biology is discussed also in the light of more recent theory of intraclonal heterogeneity.

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.

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.