Vorinostat or placebo in combination with bortezomib in patients with multiple myeloma (VANTAGE 088): a multicentre, randomised, double-blind study

Multiple myeloma treatment at relapse after autologous stem cell transplantation: A practical analysis

Over the past decade, significant advances have been made in the field of multiple myeloma. Introduction of the so-called novel agents, proteasome inhibitors (PI) and immunomodulatory drugs (IMiD), and improved supportive care have resulted in significantly better outcome. Standard first line treatment in fit patients include PI and IMiD based induction, high dose melphalan with autologous hematopoietic stem cell transplantation (ASCT) and consolidation/maintenance. However, despite these progresses MM remains incurable for the majority of patients and most patients will relapse. Next generation PI (carfilzomib, ixazomib) and IMiD (pomalidomide) and new therapeutic classes: monoclonal antibody (elotuzumab, daratumumab) and pan-deacetylase inhibitors (panobinostat) have been successfully evaluated in relapse multiple myeloma. Some of these new agents are now approved for multiple myeloma treatment at relapse. However choosing the most appropriate treatment at relapse may be difficult. This review sum up the most important studies and provide evidence to choose the most relevant therapeutic strategy for relapse after ASCT, based on disease, patient and previous treatment related parameters.

Bortezomib, thalidomide, dexamethasone, and panobinostat for patients with relapsed multiple myeloma (MUK-six): a multicentre, open-label, phase 1/2 trial

BACKGROUND

Panobinostat (a pan histone deacetylase inhibitor) is approved in combination with bortezomib and dexamethasone for patients with relapsed multiple myeloma who have received two or more previous lines of therapy. We aimed to improve the safety of this combination and investigate efficacy by incorporating low-dose thalidomide, using sub-cutaneous weekly bortezomib, and determining the maximum tolerated dose of panobinostat in this regimen.

METHODS

We did a phase 1/2, multicentre, open-label trial (MUK six) at four hospitals in the UK, enrolling patients with relapsed, or relapsed and refractory, multiple myeloma aged at least 18 years, with an Eastern Cooperative Oncology Group performance status of 2 or less who had previously received 1-4 lines of therapy. Exclusion criteria included any antimyeloma treatment within 28 days of study drugs (except dexamethasone 160 mg >48 h before treatment). We used a rolling six escalation design to determine the maximum tolerated dose of panobinostat, and allocated patients to receive subcutaneous bortezomib 1·3 mg/m², and oral thalidomide 100 mg, dexamethasone 20 mg, and panobinostat 10, 15, or 20 mg (escalated to 20 mg according to the escalation schedule). Treatment was given during a 21-day cycle (bortezomib on days 1 and 8; thalidomide every day; dexamethasone on days 1, 2, 8, and 9; and panobinostat on days 1, 3, 5, 8, 10, and 12) for 16 cycles in the absence of disease progression or unacceptable toxicity. Patients were permitted to come off study for autologous stem cell transplantation. The primary objective was to determine the maximum tolerated dose and recommended dose of panobinostat, and to estimate the proportion of patients with an overall response that was equal to a partial response or greater within 16 cycles of treatment at the recommended panobinostat dose in the modified intention-to-treat population. We assessed safety in all patients who received a trial drug (ie, bortezomib, thalidomide, dexamethasone, or panobinostat). This trial is registered at ClinicalTrials.gov, number NCT02145715, and with the ISRCTN registry, number ISRCTN59395590 and is closed to recruitment.

FINDINGS

Between Jan 31, 2013, and Oct 30, 2014, we enrolled 57 eligible patients who received at least one dose of trial medication or any drug. One dose-limiting toxicity was reported (grade 3 hyponatremia at the 20 mg dose), therefore the maximum tolerated dose was not reached, and 20 mg was deemed to be the recommended dose. 46 patients were treated with panobinostat 20 mg (the intention-to-treat population). 42 patients (91%, 80% CI 83·4-96·2) of 46 achieved the primary endpoint of an overall response that was equal to a partial response or greater. Most adverse events were grade 1-2 with few occurrences of grade 3-4 diarrhoea or fatigue. The most common adverse events of grade 3 or worse in the safety population (n=57) were reduced neutrophil count (15 [26%]), hypophosphatemia (11 [19%]), and decreased platelet count (8 [14%]). 46 serious adverse events were reported in 27 patients; of 14 suspected to be related to the trial medication, seven (50%) were gastrointestinal disorders.

INTERPRETATION

Panobinostat 20 mg in combination with bortezomib, thalidomide, and dexamethasone is an efficacious and well tolerated regimen for patients with relapsed multiple myeloma.

FUNDING

Novartis and Myeloma UK.

The Role of Panobinostat Plus Bortezomib and Dexamethasone in Treating Relapsed or Relapsed and Refractory Multiple Myeloma: A European Perspective

Panobinostat is an oral pan-histone deacetylase inhibitor developed by Novartis. Panobinostat acts via epigenetic modification and inhibition of the aggresome pathway. In August 2015, the European Commission authorized panobinostat for use in combination with bortezomib and dexamethasone for the treatment of relapsed or relapsed and refractory multiple myeloma (MM) in patients who have received ≥2 prior regimens including bortezomib and an immunomodulatory drug. In January 2016, the National Institute for Health and Care Excellence recommended panobinostat for use in the same combination and patient population. The authorization and recommendation were based on results from the pivotal phase 3 PANORAMA 1 (NCT01023308) clinical trial, which demonstrated an improvement in median progression-free survival of 7.8 months for the three-drug combination compared with placebo plus bortezomib and dexamethasone in this patient population. This review will discuss the current treatment landscape for relapsed/refractory MM, the mechanism of action of panobinostat, clinical data supporting the European authorization, concerns about safety and strategies for mitigating toxicity, and how panobinostat fits into the current MM landscape in Europe.

FUNDING

Editorial support, funded by Novartis Pharmaceuticals.

Panobinostat for the management of multiple myeloma

Multiple myeloma (MM) is the second most common blood cancer following non-Hodgkin's lymphoma. While the treatments for MM have improved over the past decade, for the most part, it remains an incurable disease. For this reason newer therapeutic agents are needed to combat this malignancy. Panobinostat is a pan-deacetylase inhibitor that impedes protein destruction by disturbing the enzymatic activity of deacetylases. It was US FDA approved in February 2015 for the management of relapsed/refractory MM in combination with bortezomib and dexamethasone. Several trials are ongoing, exploring the utility of panobinostat in various other settings for the management of MM. This review will detail the biology, clinical efficacy and potential future applications of panobinostat in the treatment of MM.

Vorinostat in Combination With Lenalidomide and Dexamethasone in Lenalidomide-Refractory Multiple Myeloma

BACKGROUND

This is a retrospective chart review to evaluate the efficacy of the addition of vorinostat to lenalidomide and dexamethasone in patients with multiple myeloma relapsed/refractory to lenalidomide and dexamethasone.

METHODS

Charts from 26 consecutive patients able to obtain commercial vorinostat were analyzed for response and safety data.

RESULTS

The overall response rate was 31%, and the clinical beneficial rate was 50%. The median duration of response was 3 months, and the median overall survival was 28.5 months. The most common grade 3 and 4 toxicities were hematologic and metabolic, including neutropenia (44%), thrombocytopenia (53%), and transaminase elevations (aspartate aminotransferase 9% and alanine aminotransferase 6%). No thromboembolic events or febrile neutropenia were observed.

CONCLUSION

These observations demonstrate that the addition of vorinostat to patients with lenalidomide- and dexamethasone-refractory multiple myeloma was associated with moderate response and was well-tolerated, warranting further assessment in a larger prospective study.

Management of relapsed and refractory multiple myeloma in modern times: Incorporating new agents into decision-making

Although upfront treatment of multiple myeloma has become more effective, relapses are the norm, often driven by the emergence of a genetically divergent clone selected by the initial therapy. Recent trials have demonstrated the safety and efficacy of combination therapy also in the relapsed and refractory setting and supported the regulatory approval of several new agents including new proteasome inhibitors, immunomodulatory agents, and monoclonal antibodies. We provide a detailed summary of recent practice-changing trials in relapsed and refractory MM and share a practical approach to assimilate disease and patient-features into treatment decision. Am. J. Hematol. 91:1044-1051, 2016. © 2016 Wiley Periodicals, Inc.

Advances in targeted therapy for the treatment of patients with relapsed/refractory multiple myeloma

The development of proteasome inhibitors (PIs) and immunomodulatory drugs has significantly improved outcomes for patients with relapsed/refractory multiple myeloma (RRMM); however, not all patients benefit from treatment with these agents and some patients can become drug refractory over time. Due to the largely incurable nature of multiple myeloma, the development of newer agents is ongoing and includes new oral PIs (ixazomib), immunotherapies (e.g., CD38- or SLAMF7-targeted antibodies), and small molecules. This review provides an overview of the advances in targeted therapy for patients with RRMM, including recently approved agents, with a focus on monotherapy and combined targeted therapies.

Ricolinostat plus lenalidomide, and dexamethasone in relapsed or refractory multiple myeloma: a multicentre phase 1b trial

BACKGROUND

Histone deacetylase (HDAC) inhibitors are an important new class of therapeutics for treating multiple myeloma. Ricolinostat (ACY-1215) is the first oral selective HDAC6 inhibitor with reduced class I HDAC activity to be studied clinically. Motivated by findings from preclinical studies showing potent synergistic activity with ricolinostat and lenalidomide, our goal was to assess the safety and preliminary activity of the combination of ricolinostat with lenalidomide and dexamethasone in relapsed or refractory multiple myeloma.

METHODS

In this multicentre phase 1b trial, we recruited patients aged 18 years or older with previously treated relapsed or refractory multiple myeloma from five cancer centres in the USA. Inclusion criteria included a Karnofsky Performance Status score of at least 70, measureable disease, adequate bone marrow reserve, adequate hepatic function, and a creatinine clearance of at least 50 mL per min. Exclusion criteria included previous exposure to HDAC inhibitors; previous allogeneic stem-cell transplantation; previous autologous stem-cell transplantation within 12 weeks of baseline; active systemic infection; malignancy within the last 5 years; known or suspected HIV, hepatitis B, or hepatitis C infection; a QTc Fridericia of more than 480 ms; and substantial cardiovascular, gastrointestinal, psychiatric, or other medical disorders. We gave escalating doses (from 40-240 mg once daily to 160 mg twice daily) of oral ricolinostat according to a standard 3 + 3 design according to three different regimens on days 1-21 with a conventional 28 day schedule of oral lenalidomide (from 15 mg [in one cohort] to 25 mg [in all other cohorts] once daily) and oral dexamethasone (40 mg weekly). Primary outcomes were dose-limiting toxicities, the maximum tolerated dose of ricolinostat in this combination, and the dose and schedule of ricolinostat recommended for further phase 2 investigation. Secondary outcomes were the pharmacokinetics and pharmacodynamics of ricolinostat in this combination and the preliminary anti-tumour activity of this treatment. The trial is closed to accrual and is registered at ClinicalTrials.gov, number NCT01583283.

FINDINGS

Between July 12, 2012, and Aug 20, 2015, we enrolled 38 patients. We observed two dose-limiting toxicities with ricolinostat 160 mg twice daily: one (2%) grade 3 syncope and one (2%) grade 3 myalgia event in different cohorts. A maximum tolerated dose was not reached. We chose ricolinostat 160 mg once daily on days 1-21 of a 28 day cycle as the recommended dose for future phase 2 studies in combination with lenalidomide 25 mg and dexamethasone 40 mg. The most common adverse events were fatigue (grade 1-2 in 14 [37%] patients; grade 3 in seven [18%]) and diarrhoea (grade 1-2 in 15 [39%] patients; grade 3 in two [5%]). Our pharmacodynamic studies showed that at clinically relevant doses, ricolinostat selectively inhibits HDAC6 while retaining a low and tolerable level of class I HDAC inhibition. The pharmacokinetics of ricolinostat and lenalidomide were not affected by co-administration. In a preliminary assessment of antitumour activity, 21 (55% [95% CI 38-71]) of 38 patients had an overall response.

INTERPRETATION

The findings from this study provide preliminary evidence that ricolinostat is a safe and well tolerated selective HDAC6 inhibitor, which might partner well with lenalidomide and dexamethasone to enhance their efficacy in relapsed or refractory multiple myeloma.

FUNDING

Acetylon Pharmaceuticals.

A clinical update on the role of carfilzomib in the treatment of relapsed or refractory multiple myeloma

Even though the prognosis of patients with multiple myeloma is continuing to improve, all patients eventually develop relapsed refractory disease. Several novel therapeutics have been developed in the last few years including the second-generation proteasome inhibitor carfilzomib which has been approved for patients with relapsed and refractory multiple myeloma in the United States since 2012. Recently data from several phase III studies have become available showing the promising efficacy of carfilzomib in combination with lenalidomide, which led to the renewed approval of carfilzomib in combination with lenalidomide and dexamethasone for relapsed myeloma in 2015. Furthermore carfilzomib showed superiority over bortezomib on both efficacy and toxicity profiles, especially a profoundly lower incidence in polyneuropathy. Carfilzomib has been shown to partially overcome the negative effects of high-risk cytogenetics. Promising combinations of carfilzomib with histone deacetylase (HDAC) inhibitors, pomalidomide and several other novel therapeutics have been presented in early studies. The optimal dosing regimen and sequence of treatment regimens remain important questions for the future.

HDAC inhibitor AR-42 decreases CD44 expression and sensitizes myeloma cells to lenalidomide

Multiple myeloma (MM) is a hematological malignancy of plasma cells in the bone marrow. Despite multiple treatment options, MM is inevitably associated with drug resistance and poor outcomes. Histone deacetylase inhibitors (HDACi's) are promising novel chemotherapeutics undergoing evaluation in clinical trials for the potential treatment of patients with MM. Although in preclinical studies HDACi's have proven anti-myeloma activity, but in the clinic single-agent HDACi treatments have been limited due to low tolerability. Improved clinical outcomes were reported only when HDACi's were combined with other drugs. Here, we show that a novel pan-HDACi AR-42 downregulates CD44, a glycoprotein that has been associated with lenalidomide and dexamethasone resistance in myeloma both in vitro and in vivo. We also show that this CD44 downregulation is in part mediated by miR-9–5p, targeting insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3), which directly binds to CD44 mRNA and increases its stability. Importantly, we also demonstrate that AR-42 enhances anti-myeloma activity of lenalidomide in primary MM cells isolated from lenalidomide resistant patients and in in vivo MM mouse model. Thus, our findings shed light on potential novel combinatorial therapeutic approaches modulating CD44 expression, which may help overcome lenalidomide resistance in myeloma patients.

NF-κB dysregulation in multiple myeloma

The nuclear factor-κB (NF-κB) transcription factor family plays critical roles in the pathophysiology of hematologic neoplasias, including multiple myeloma. The current review examines the roles that this transcription factor system plays in multiple myeloma cells and the nonmalignant accessory cells of the local microenvironment; as well as the evidence indicating that a large proportion of myeloma patients harbor genomic lesions which perturb diverse genes regulating the activity of NF-κB. This article also discusses the therapeutic targeting of the NF-κB pathway using proteasome inhibitors, a pharmacological class that has become a cornerstone in the therapeutic management of myeloma; and reviews some of the future challenges and opportunities for NF-κB-related research in myeloma.

Salvage therapies in relapsed and/or refractory myeloma: what is current and what is the future?

The treatment landscape for multiple myeloma (MM) is evolving with our understanding of its pathophysiology. However, given the inevitable cohort heterogeneity in salvage therapy, response to treatment and overall prognoses tend to vary widely, making meaningful conclusions about treatment efficacy difficult to derive. Despite the hurdles in current research, progress is underway toward more targeted therapeutic approaches. Several new drugs with novel mechanism of action and less toxic profile have been developed in the past decade, with the potential for use as single agents or in synergy with other treatment modalities in MM therapy. As our discovery of these emerging therapies progresses, so too does our need to reshape our knowledge on knowing how to apply them. This review highlights some of the recent landmark changes in MM management with specific emphasis on salvage drugs available for relapsed and refractory MM and also discusses some of the upcoming cutting-edge therapies that are currently in various stages of clinical development.

Novel agents in the treatment of multiple myeloma: a review about the future

Multiple myeloma (MM) is a disease that affects plasma cells and can lead to devastating clinical features such as anemia, lytic bone lesions, hypercalcemia, and renal disease. An enhanced understanding of MM disease mechanisms has led to new more targeted treatments. There is now a plethora of treatments available for MM. In this review article, our aim is to discuss many of the novel agents that are being studied or have recently been approved for the treatment of MM. These agents include the following: immunomodulators (pomalidomide), proteasome inhibitors (carfilzomib, marizomib, ixazomib, oprozomib), alkylating agents (bendamustine), AKT inhibitors (afuresertib), BTK inhibitors (ibrutinib), CDK inhibitors (dinaciclib), histone deacetylase inhibitors (panobinostat, rocilinostat, vorinostat), IL-6 inhibitors (siltuximab), kinesin spindle protein inhibitors (filanesib), monoclonal antibodies (daratumumab, elotuzumab, indatuximab, SAR650984), and phosphoinositide 3-kinase (PI3K) inhibitors.

Augmenting Autologous Stem Cell Transplantation to Improve Outcomes in Myeloma

Consolidation with high-dose chemotherapy and autologous stem cell transplantation (ASCT) is the standard of care for transplantation-eligible patients with multiple myeloma, based on randomized trials showing improved progression-free survival with autologous transplantation after combination chemotherapy induction. These trials were performed before novel agents were introduced; subsequently, combinations of immunomodulatory drugs and proteasome inhibitors as induction therapy have significantly improved rates and depth of response. Ongoing randomized trials are testing whether conventional autologous transplantation continues to improve responses after novel agent induction. Although these results are awaited, it is important to review strategies for improving outcomes after ASCT. Conditioning before ASCT with higher doses of melphalan and combinations of melphalan with other agents, including radiopharmaceuticals, has been explored. Tandem ASCT, consolidation, and maintenance therapy after ASCT have been investigated in phase III trials. Experimental cellular therapies using ex vivo-primed dendritic cells, ex vivo-expanded autologous lymphocytes, Killer Immunoglobulin Receptor (KIR)-mismatched allogeneic natural killer cells, and genetically modified T cells to augment ASCT are also in phase I trials. This review summarizes these strategies and highlights the importance of exploring strategies to augment ASCT, even in the era of novel agent induction.

Therapeutic Targeting of miR-29b/HDAC4 Epigenetic Loop in Multiple Myeloma

Epigenetic abnormalities are common in hematologic malignancies, including multiple myeloma, and their effects can be efficiently counteracted by a class of tumor suppressor miRNAs, named epi-miRNAs. Given the oncogenic role of histone deacetylases (HDAC) in multiple myeloma, we investigated whether their activity could be antagonized by miR-29b, a well-established epi-miRNA. We demonstrated here that miR-29b specifically targets HDAC4 and highlighted that both molecules are involved in a functional loop. In fact, silencing of HDAC4 by shRNAs inhibited multiple myeloma cell survival and migration and triggered apoptosis and autophagy, along with the induction of miR-29b expression by promoter hyperacetylation, leading to the downregulation of prosurvival miR-29b targets (SP1, MCL-1). Moreover, treatment with the pan-HDAC inhibitor SAHA upregulated miR-29b, overcoming the negative control exerted by HDAC4. Importantly, overexpression or inhibition of miR-29b, respectively, potentiated or antagonized SAHA activity on multiple myeloma cells, as also shown in vivo by a strong synergism between miR-29b synthetic mimics and SAHA in a murine xenograft model of human multiple myeloma. Altogether, our results shed light on a novel epigenetic circuitry regulating multiple myeloma cell growth and survival and open new avenues for miR-29b-based epi-therapeutic approaches in the treatment of this malignancy. Mol Cancer Ther; 15(6); 1364-75. ©2016 AACR.

Clinical use and applications of histone deacetylase inhibitors in multiple myeloma

The incorporation of various novel therapies has resulted in a significant survival benefit in newly diagnosed and relapsed patients with multiple myeloma (MM) over the past decade. Despite these advances, resistance to therapy leads to eventual relapse and fatal outcomes in the vast majority of patients. Hence, there is an unmet need for new safe and efficacious therapies for continued improvement in outcomes. Given the role of epigenetic aberrations in the pathogenesis and progression of MM and the success of histone deacetylase inhibitors (HDACi) in other malignancies, many HDACi have been tried in MM. Various preclinical studies helped us to understand the antimyeloma activity of different HDACi in MM as a single agent or in combination with conventional, novel, and immune therapies. The early clinical trials of HDACi depicted only modest single-agent activity, but recent studies have revealed encouraging clinical response rates in combination with other antimyeloma agents, especially proteasome inhibitors. This led to the approval of the combination of panobinostat and bortezomib for the treatment of relapsed/refractory MM patients with two prior lines of treatment by the US Food and Drug Administration. However, it remains yet to be defined how we can incorporate HDACi in the current therapeutic paradigms for MM that will help to achieve longer disease control and significant survival benefits. In addition, isoform-selective and/or class-selective HDAC inhibition to reduce unfavorable side effects needs further evaluation.

Histone deacetylase inhibitors in multiple myeloma: from bench to bedside

Histone deacetylases (HDACs) deacetylate the lysine residues of both histones and non-histone proteins. Histone acetylation results in a loose local chromatin structure that regulates gene-specific transcription. Non-histone proteins can also be acetylated, leading to dynamic changes in their activity and stability. For these reasons, HDAC inhibition has emerged as a potential approach for the treatment of MM. Specifically, combination treatment with HDAC inhibitors and proteasome inhibitors or immunomodulatory drugs shows remarkable anti-MM activity in both preclinical and clinical settings. However, the clinical studies using non-selective HDAC inhibitors also cause unfavorable side effects in patients, leading us to develop more isoform- and/or class-selective HDAC inhibitors to enhance tolerability without diminishing anti-MM activity, thereby improving patient outcome in MM.

Treatment of relapsed and refractory multiple myeloma

The approach to the patient with relapsed or relapsed/refractory multiple myeloma (RRMM) requires a careful evaluation of the results of previous treatments, the toxicities associated with them and an assessment of prognostic factors. Since the majority of patients will have received prior therapy with drug combinations including a proteasome inhibitor and/or an immunomodulatory drug (IMiD), it is the physician's task to choose the right moment for the start of therapy and define with the patient which goals need to be achieved. The choice of regimen is usually based on prior responsiveness, drugs already received, prior adverse effects, the condition of the patient and expected effectiveness and tolerability. Many double and triple drug combinations are available. In addition, promising new drugs like pomalidomide, carfilzomib and monoclonal antibodies are, or will be, available shortly, while other options can be tried in clinical studies. Finally, supportive care and palliative options need to be considered in some patients. It is becoming increasingly more important to consider the therapeutic options for the whole duration of the disease rather than take a step by step approach, and to develop a systematic approach for each individual patient.

In vivo treatment with epigenetic modulating agents induces transcriptional alterations associated with prognosis and immunomodulation in multiple myeloma

Histone deacetylase inhibitors (HDACi) and DNA methyltransferase inhibitors (DNMTi) are in early clinical development for multiple myeloma (MM) therapy. Despite all encouraging pre-clinical data, clinical activity of HDACi and DNMTi is mostly lacking. To optimize the trials, characterization of the in vivo response towards HDACi and DNMTi will be crucial. Therefore, we investigated the transcriptional response after in vivo treatment with the HDACi quisinostat or DNMTi decitabine using the murine 5T33MM model. We identified 504 and 154 genes deregulated by quisinostat and decitabine, respectively. Of interest, MM patients' gene expression levels of 62 quisinostat- and 25 decitabine-deregulated genes were predictive for overall survival of patients. This prognostic information was implemented in a DNA methylation and histone acetylation score. A high score was related to a high proliferative and immature phenotype of MM cells. Furthermore, highly scored MM patients had an adverse overall survival. Interestingly, bio-informatic prediction tools revealed an association of quisinostat-deregulated genes with lymphocyte activation, proliferation, immune-effector mechanisms and T-helper-1 development. Overall, treatment of 5T33MM mice with epigenetic modulating agents led to the translation of gene signatures to predict overall survival of MM patients. HDACi mainly deregulated tumoral immunomodulatory pathways, supporting the rationale to combine HDACi with immunomodulatory therapies.

VANTAGE 095: An International, Multicenter, Open-Label Study of Vorinostat (MK-0683) in Combination With Bortezomib in Patients With Relapsed and Refractory Multiple Myeloma

BACKGROUND

The present global, open-label, single-arm, multicenter, phase IIb study was designed to determine the efficacy and tolerability of oral vorinostat combined with standard doses of bortezomib in patients with multiple myeloma considered refractory to novel myeloma agents.

PATIENTS AND METHODS

Eligible patients were age ≥ 18 years, had received ≥ 2 previous regimens, had disease refractory to ≥ 1 previous bortezomib-containing regimen, and had received ≥ 1 dose of an immunomodulatory drug (thalidomide or lenalidomide)-based regimen. The patients received 21-day cycles of bortezomib (1.3 mg/m(2) intravenously on days 1, 4, 8, and 11) plus oral vorinostat (400 mg/d on days 1-14). Oral dexamethasone, 20 mg, on the day of and the day after each dose of bortezomib could be added for patients with progressive disease after 2 cycles or no change after 4 cycles. The primary endpoint was the objective response rate.

RESULTS

The objective response rate was 11.3% (95% confidence interval, 6.6%-17.7%), and the median duration of response was 211 days (range, 64-550 days). The median overall survival duration was 11.2 months (95% confidence interval, 8.5-14.4 months), with a 2-year survival rate of 32%. The frequently reported adverse events were thrombocytopenia (69.7%), nausea (57.0%), diarrhea (53.5%), anemia (52.1%), and fatigue (48.6%); the overall safety profile was consistent with that of bortezomib and vorinostat.

CONCLUSION

The combination of vorinostat and bortezomib is active in patients with multiple myeloma refractory to novel treatment modalities and offers a new therapeutic option for this difficult-to-treat patient population (ClinicalTrials.gov identifier, NCT00773838).

Histone Deacetylase Inhibitors Enhance the Therapeutic Potential of Reovirus in Multiple Myeloma

Multiple myeloma remains incurable and the majority of patients die within 5 years of diagnosis. Reolysin, the infusible form of human reovirus (RV), is a novel viral oncolytic therapy associated with antitumor activity likely resulting from direct oncolysis and a virus-mediated antitumor immune response. Results from our phase I clinical trial investigating single agent Reolysin in patients with relapsed multiple myeloma confirmed tolerability, but no objective responses were evident, likely because the virus selectively entered the multiple myeloma cells but did not actively replicate. To date, the precise mechanisms underlying the RV infectious life cycle and its ability to induce oncolysis in patients with multiple myeloma remain unknown. Here, we report that junctional adhesion molecule 1 (JAM-1), the cellular receptor for RV, is epigenetically regulated in multiple myeloma cells. Treatment of multiple myeloma cells with clinically relevant histone deacetylase inhibitors (HDACi) results in increased JAM-1 expression as well as increased histone acetylation and RNA polymerase II recruitment to its promoter. Furthermore, our data indicate that the combination of Reolysin with HDACi, potentiates RV killing activity of multiple myeloma cells in vitro and in vivo This study provides the molecular basis to use these agents as therapeutic tools to increase the efficacy of RV therapy in multiple myeloma. Mol Cancer Ther; 15(5); 830-41. ©2016 AACR.

Quisinostat, bortezomib, and dexamethasone combination therapy for relapsed multiple myeloma

The maximum tolerated dose (MTD) of quisinostat + bortezomib + dexamethasone in patients with relapsed multiple myeloma was evaluated in a phase-1b, open-label, multicenter, '3 + 3' dose-escalation study. Patients received escalating doses of oral quisinostat (6 mg [n = 3], 8 mg [n = 3], 10 mg [n = 6], and 12 mg [n = 6] on days 1, 3, and 5/week) plus subcutaneous bortezomib (1.3 mg/m(2)) and oral dexamethasone (20 mg) in cycles of 21 (cycles 1-8) or 35 d (cycles 9-11) until MTD was determined. No dose-limiting toxicities were reported in 6/8 mg groups except ventricular fibrillation (Grade 4 cardiac arrest, n = 1 [10 mg] cycle 6) and clinically significant cardiac toxicities (Grade 3 QTc prolongation, Grade 3 atrial fibrillation, n = 2 [12 mg]). Thrombocytopenia (n = 11), asthenia (n = 10), and diarrhea (n = 12) were most common adverse events. Overall, 88.2% patients achieved treatment response, median duration of response, and median progression-free survival were 9.4 and 8.2 months, respectively. The MTD of quisinostat was established as 10 mg thrice weekly oral dose with bortezomib + dexamethasone.

Multiple myeloma in the marrow: pathogenesis and treatments

Multiple myeloma (MM) is a B cell malignancy resulting in osteolytic lesions and fractures. In the disease state, bone healing is limited owing to increased osteoclastic and decreased osteoblastic activity, as well as an MM-induced forward-feedback cycle where bone-embedded growth factors further enhance tumor progression as bone is resorbed. Recent work on somatic mutation in MM tumors has provided insight into cytogenetic changes associated with this disease; the initiating driver mutations causing MM are diverse because of the complexity and multitude of mutations inherent in MM tumor cells. This manuscript provides an overview of MM pathogenesis by summarizing cytogenic changes related to oncogenes and tumor suppressors associated with MM, reviewing risk factors, and describing the disease progression from monoclonal gammopathy of undetermined significance to overt MM. It also highlights the importance of the bone marrow microenvironment (BMM) in the establishment and progression of MM, as well as associated MM-induced bone disease, and the relationship of the bone marrow to current and future therapeutics. This review highlights why understanding the basic biology of the healthy and diseased BMM is crucial in the quest for better treatments and work toward a cure for genetically diverse diseases such as MM.

Treatment of Relapsed/Refractory Multiple Myeloma

Survival outcomes of patients with Multiple Myeloma (MM) have improved over the last decade due to the introduction of novel agents such as the immunomodulatory drugs thalidomide, lenalidomide (Len) and pomalidomide, and the proteasome inhibitors bortezomib (BTZ) and carfilzomib [1, 2]. However, despite these major advances, MM remains largely incurable and almost all patients relapse and require additional therapy [3]. The successful introduction of next generation novel agents including oral proteasome inhibitors, deacetylase inhibitors, and especially monoclonal antibodies as part of immunotherapy promises to further improve outcome.

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.

Role of Histone Deacetylase Inhibitors in Relapsed Refractory Multiple Myeloma: A Focus on Vorinostat and Panobinostat

Multiple myeloma is a neoplastic plasma cell disorder that is characterized by clonal proliferation of plasma cells in the bone marrow, monoclonal protein in the blood and/or urine, and associated organ dysfunction and biomarkers. There have been multiple recent advances in the relapsed and refractory setting. Major steps forward include the introduction of proteasome inhibitors (bortezomib and carfilzomib) and immunomodulatory drugs (thalidomide, lenalidomide, and pomalidomide) in various combinations. These drugs have changed the management of multiple myeloma and have extended overall survival in the past decade. Established curative therapy is not yet available for patients diagnosed with multiple myeloma, supporting the development of new treatment targets. Histone deacetylase inhibitors have multiple proposed mechanisms of action in the treatment of multiple myeloma. Both vorinostat and panobinostat have demonstrated some activity against multiple myeloma, and due to the benefits reported with panobinostat, the U.S. Food and Drug Administration has recently approved the drug for the treatment of relapsed and refractory multiple myeloma. In this article, we describe the pharmacology, efficacy, and toxicity profile of vorinostat and panobinostat and their possible place in therapy.

A phase I study of vorinostat combined with bortezomib in Japanese patients with relapsed or refractory multiple myeloma

This study was undertaken to evaluate safety and pharmacokinetics and to determine treatment doses of vorinostat plus bortezomib in Japanese patients with relapsed or refractory multiple myeloma (MM). Of 9 originally enrolled patients, 2 were refractory to bortezomib, and both experienced dose-limiting toxicity (DLT), prompting a protocol amendment to exclude bortezomib-refractory individuals. Patients not considered bortezomib refractory (N = 7) received 21-day cycles of 1.3 mg/m(2) intravenous bortezomib (Days 1, 4, 8, and 11) and oral vorinostat 400 mg (Days 1 through 14) and were further evaluated. Vorinostat and bortezomib treatment doses were determined by DLT and safety, tolerability, and treatment response were assessed. Of 7 enrolled patients, 6 were evaluated, and one developed DLTs. The most common adverse events were leukopenia, neutropenia, thrombocytopenia, diarrhea, nausea, decreased appetite, and vomiting. Combination of vorinostat plus bortezomib did not increase vorinostat exposure at Day 11 [AUC0-24 h ratio (95% CI) = 1.08 (0.80, 1.45)]; geometric mean AUC0-24 h ratio for bortezomib (90% CI) was 1.96 (1.24-3.12). Objective therapeutic response occurred in 3 patients, including 1 complete response and 2 partial responses. Vorinostat 400 mg plus bortezomib 1.3 mg/m(2) was safe and well-tolerated in Japanese patients with relapsed or refractory MM not considered bortezomib refractory (NCT00858234).

VEGF-mediated cell survival in non-small-cell lung cancer: implications for epigenetic targeting of VEGF receptors as a therapeutic approach

Aims: To evaluate the potential therapeutic utility of histone deacetylase inhibitors (HDACi) in targeting VEGF receptors in non-small-cell lung cancer. Materials & methods: Non-small-cell lung cancer cells were screened for the VEGF receptors at the mRNA and protein levels, while cellular responses to various HDACi were examined. Results: Significant effects on the regulation of the VEGF receptors were observed in response to HDACi. These were associated with decreased secretion of VEGF, decreased cellular proliferation and increased apoptosis which could not be rescued by addition of exogenous recombinant VEGF. Direct remodeling of the VEGFR1 and VEGFR2 promoters was observed. In contrast, HDACi treatments resulted in significant downregulation of the Neuropilin receptors. Conclusion: Epigenetic targeting of the Neuropilin receptors may offer an effective treatment for lung cancer patients in the clinical setting.

Evolving Paradigms in the Management of Multiple Myeloma: Novel Agents and Targeted Therapies

Multiple myeloma (MM) is a clonal plasma cell disorder defined by bone marrow infiltration and osteolytic bone lesions and is the second most common hematologic malignancy after non-Hodgkin lymphoma. The landscape of MM treatment was transformed at the dawn of the twenty-first century by the introduction of novel agents including proteasome inhibitors (bortezomib) and immunomodulatory drugs (thalidomide, lenalidomide), which have prolonged the survival of MM patients. The recently revised International Myeloma Working Group diagnostic criteria for MM added validated biomarkers (clonal bone marrow plasma cell ≥60%, involved:uninvolved serum free light chain ratio ≥100, or >1 focal lesion on magnetic resonance imaging) to identify near inevitable progression to symptomatic MM requiring therapy. In addition, the definition of myeloma-defining CRAB features (hypercalcemia, renal failure, anemia, and bone lesions) has been refined based on advances in imaging and laboratory techniques since the 2003 IMWG consensus. Despite expanded treatment options, MM remains an incurable disease. Drug resistance and clonal evolution remain problematic, and novel therapeutic agents are needed. New approaches to myeloma treatment include anti-CD38 antibodies, next generation proteasome inhibitors, epigenetic modulation with histone deacetylase inhibitors, and targeting the tumor microenvironment. In this article, the diagnosis, staging, and prognostic stratification of newly diagnosed MM will be reviewed. Clinical data pertaining to the emerging targeted agents will be discussed, and a suggested framework for integration of these new therapeutic options will be provided.

Clinical characteristics of patients with relapsed multiple myeloma

Although survival outcomes have improved over the last decade for patients with multiple myeloma (MM), few patients remain free of disease and most inevitably relapse. Selecting a treatment for patients with relapsed MM is challenging given the number and diversity of regimens patients may have previously received, which can affect subsequent therapeutic choices. Importantly, a number of patient- and disease-related factors can also have an effect on treatment choice, treatment efficacy, and tolerability; thus, an understanding of the heterogeneity of patients in the setting of relapsed MM is important for appropriate treatment selection. Here, we review select patient and disease characteristics reported in key interventional and observational studies in relapsed MM (including age, sex, race, and the presence of high-risk disease, renal impairment, or peripheral neuropathy at baseline) to examine common and disparate features of patients with relapsed MM. As therapeutic regimens can have varying efficacy and/or tolerability in patients depending on these factors, we also provide treatment recommendations for patients with select baseline characteristics.

Inhibition of bromodomain and extra-terminal proteins (BET) as a potential therapeutic approach in haematological malignancies: emerging preclinical and clinical evidence

Post-translational modifications of the nucleosomal histone proteins orchestrate chromatin organization and gene expression in normal and cancer cells. Among them, the acetylation of N-terminal histone tails represents the fundamental epigenetic mark of open structure chromatin and active gene transcription. The bromodomain and extra-terminal (BET) proteins are epigenetic readers which utilize tandem bromodomains (BRD) modules to recognize and dock themselves on the acetylated lysine tails. The BET proteins act as scaffolds for the recruitment of transcription factors and chromatin organizers required in transcription initiation and elongation. The recent discovery of small molecules capable of blocking their lysine-binding pocket is the first paradigm of successful pharmacological inhibition of epigenetic readers. JQ1 is a prototype benzodiazepine molecule and a specific BET inhibitor with antineoplastic activity both in solid tumours and haematological malignancies. The quinolone I-BET151 and the suitable for clinical development I-BET762 benzodiazepine were introduced in parallel with JQ1 and have also shown potent antitumour activity in preclinical studies. I-BET762 is currently being tested in early phase clinical trials, along with a rapidly growing list of other BET inhibitors. Unlike older epigenetic therapies, the study of BET inhibitors has offered substantial, context-specific, mechanistic insights of their antitumour activity, which will facilitate optimal therapeutic targeting in future. Here, we review the development of this novel class of epigenetic drugs, the biology of BET protein inhibition, the emerging evidence from preclinical work and early phase clinical studies and we discuss their potential role in the treatment of haematological malignancies.

Novel therapeutic strategies for multiple myeloma

Multiple myeloma (MM) is a plasma-cell malignancy which remains incurable despite the recent emergence of multiple novel agents. Importantly, recent genetic and molecular analyses have revealed the complexity and heterogeneity of this disease, highlighting the need for therapeutic strategies to eliminate all clones. Moreover, the bone marrow microenvironment, including stromal cells and immune cells, plays a central role in MM pathogenesis, promoting tumor cell growth, survival, and drug resistance. New classes of agents including proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, and histone deacetylase inhibitors have shown remarkable efficacy; however, novel therapeutic approaches are still urgently needed to further improve patient outcomes. In this review, we discuss the recent advances and future strategies to ultimately develop MM therapies with curative potential.

Lenalidomide and vorinostat maintenance after autologous transplant in multiple myeloma

Single-agent post-autologous transplant maintenance therapy with lenalidomide is standard of care for patients with multiple myeloma. The tolerability and effectiveness of combination post-transplant maintenance therapy is unknown, so we investigated lenalidomide and vorinostat (suberoylanilide hydroxamic acid) in this setting, hypothesizing that the regimen would be well tolerated and associated with an improved post-transplant response. This trial followed a standard 3 × 3 dose escalation phase 1 design. Vorinostat was administered beginning day +90 post-haematopoietic stem cell transplantation for days 1-7 and 15-21, and lenalidomide was started at 10 mg days 1-21, both on a 28-d cycle. The primary endpoint was maximum tolerated dose and dose limiting toxicities were assessed during the first cycle. Treatment was well tolerated in 16 enrolled patients. During Cycle 1, the most common toxicities included cytopenias, gastrointestinal complaints and fatigue. Seven patients improved their transplant response after starting combination therapy. The median follow-up was 38·4 months, and the median progression-free survival and overall survival have yet to be reached. This oral post-transplant maintenance regimen was well tolerated. This is the first trial to publish results on the use of a histone deacetylase inhibitor in the maintenance setting, and it provides rationale for the ongoing randomized trial in maintenance (ISRCTN 49407852).

TRIAL REGISTRATION

NCT00729118.

Phase I study of carfilzomib, lenalidomide, vorinostat, and dexamethasone in patients with relapsed and/or refractory multiple myeloma

Research has shown that proteasome inhibitors (e.g., carfilzomib), immunomodulatory agents (e.g., lenalidomide), histone deacetylase inhibitors (e.g., vorinostat) and corticosteroids (e.g., dexamethasone) have synergistic anti-multiple myeloma (MM) activity. This phase I dose-escalation study evaluated a regimen combining carfilzomib, lenalidomide, vorinostat and dexamethasone (QUAD) in patients with relapsed and/or refractory MM. Seventeen patients received carfilzomib (15, 20, or 20/27 mg/m(2) ; 30-min infusion; days 1, 2, 8, 9, 15, 16), lenalidomide (15 or 25 mg; days 1-21), vorinostat (300 or 400 mg; days 1-7, 15-21), and dexamethasone (40 mg; days 1, 8, 15, 22) in 28-d cycles. No dose-limiting toxicities were observed; the maximum tolerated dose was not reached. The maximum administered dose was carfilzomib 20/27 mg/m(2) , lenalidomide 25 mg, vorinostat 400 mg, and dexamethasone 40 mg. Common grade ≥3 adverse events included neutropenia (53%), thrombocytopenia (53%) and anaemia (41%). The overall response rate was 53%: 12% of patients achieved a very good partial response (PR) and 41% of patients achieved a PR. At a median follow-up of 10 months, median progression-free survival was 12 months and median overall survival was not reached. Treatment with QUAD was feasible and had encouraging activity in patients with relapsed and/or refractory MM.

Rational combination treatment with histone deacetylase inhibitors and immunomodulatory drugs in multiple myeloma

Immunomodulatory drugs (IMiDs) thalidomide, lenalidomide (Len) and pomalidomide trigger anti-tumor activities in multiple myeloma (MM) by targetting cereblon and thereby impacting IZF1/3, c-Myc and IRF4. Histone deacetylase inhibitors (HDACi) also downregulate c-Myc. We therefore determined whether IMiDs with HDACi trigger significant MM cell growth inhibition by inhibiting or downregulating c-Myc. Combination treatment of Len with non-selective HDACi suberoylanilide hydroxamic acid or class-I HDAC-selective inhibitor MS275 induces synergic cytotoxicity, associated with downregulation of c-Myc. Unexpectedly, we observed that decreased levels of cereblon (CRBN), a primary target protein of IMiDs, was triggered by these agents. Indeed, sequential treatment of MM cells with MS275 followed by Len shows less efficacy than simultaneous treatment with this combination. Importantly ACY1215, an HDAC6 inhibitor with minimal effects on class-I HDACs, together with Len induces synergistic MM cytotoxicity without alteration of CRBN expression. Our results showed that only modest class-I HDAC inhibition is able to induce synergistic MM cytotoxicity in combination with Len. These studies may provide the framework for utilizing HDACi in combination with Len to both avoid CRBN downregulation and enhance anti-MM activities.

Treatment options for relapsed and refractory multiple myeloma

Over the last few decades, significant improvement in outcomes has been observed for myeloma patients, mainly as a result of the use of currently available approved antimyeloma agents, along with combining autologous stem cell transplantation in the treatment of myeloma. With more targeted agents in development, the treatment of a myeloma patient at relapse has become complicated and, as a consequence, results in vast heterogeneity in treatment patterns. Although a consensus on the timing of initiation of treatment, the choice of agents to be used, and the role of transplant is less clear, we describe an evidence-based approach and the factors to consider upon relapse. We describe additional newer agents and targets that are under development, with the goal of achievement of durable remissions for myeloma patients.

Trial Watch: Proteasomal inhibitors for anticancer therapy

The so-called "ubiquitin-proteasome system" (UPS) is a multicomponent molecular apparatus that catalyzes the covalent attachment of several copies of the small protein ubiquitin to other proteins that are generally (but not always) destined to proteasomal degradation. This enzymatic cascade is crucial for the maintenance of intracellular protein homeostasis (both in physiological conditions and in the course of adaptive stress responses), and regulates a wide array of signaling pathways. In line with this notion, defects in the UPS have been associated with aging as well as with several pathological conditions including cardiac, neurodegenerative, and neoplastic disorders. As transformed cells often experience a constant state of stress (as a result of the hyperactivation of oncogenic signaling pathways and/or adverse microenvironmental conditions), their survival and proliferation are highly dependent on the integrity of the UPS. This rationale has driven an intense wave of preclinical and clinical investigation culminating in 2003 with the approval of the proteasomal inhibitor bortezomib by the US Food and Drug Administration for use in multiple myeloma patients. Another proteasomal inhibitor, carfilzomib, is now licensed by international regulatory agencies for use in multiple myeloma patients, and the approved indications for bortezomib have been extended to mantle cell lymphoma. This said, the clinical activity of bortezomib and carfilzomib is often limited by off-target effects, innate/acquired resistance, and the absence of validated predictive biomarkers. Moreover, the antineoplastic activity of proteasome inhibitors against solid tumors is poor. In this Trial Watch we discuss the contribution of the UPS to oncogenesis and tumor progression and summarize the design and/or results of recent clinical studies evaluating the therapeutic profile of proteasome inhibitors in cancer patients.

Synergistic effects of valproic acid and arsenic trioxide on RPMI8226 cells in vitro and the possible underlying mechanisms

The aim of the present study was to investigate the synergistic effects of valproic acid (VPA) and arsenic trioxide (ATO) on the proliferation of RPMI8226 cells and the possible underlying mechanisms. Cell apoptosis was assessed by flow cytometry. The mRNA expression levels were analyzed by semi-quantitative polymerase chain reaction, and the protein expression levels were analyzed by western blotting. The histone acetylation and methylation states of the gene promoters were detected using a chromatin immunoprecipitation technique. The apoptotic rates of the RPMI8226 cells in the combined drug groups were significantly increased compared with those of the single drug groups (P<0.05). The mRNA and protein expression levels of Bcl-2 and the expression levels of HDAC1 mRNA and H3K9me2 protein decreased significantly in the combined groups compared with the single drug groups. The mRNA and protein expression levels of Bax, Caspase 8, Caspase 9 and LSD1, and the protein expression of acetylated H3 increased significantly in the combination groups compared with the single drug groups. Histone methylation and acetylation of the Bcl-2 and bax gene promoters were increased in the combination groups compared with the single drug groups. VPA and ATO had synergistic effects on the proliferation of RPMI8226 cells, which may have been associated with the decreased expression of Bcl-2 and the increased expression levels of Bcl-2-associated X protein, Caspase 8 and Caspase 9. Therefore, the expression levels of the Bcl-2 gene family may have been regulated by the levels of gene promoter methylation and acetylation.

Class IIa HDAC inhibition enhances ER stress-mediated cell death in multiple myeloma

Histone deacetylase (HDAC) inhibitors have been extensively investigated as therapeutic agents in cancer. However, the biological role of class IIa HDACs (HDAC4, 5, 7 and 9) in cancer cells, including multiple myeloma (MM), remains unclear. Recent studies show HDAC4 interacts with activating transcription factor 4 (ATF4) and inhibits activation of endoplasmic reticulum (ER) stress-associated proapoptotic transcription factor C/EBP homologous protein (CHOP). In this study, we hypothesized that HDAC4 knockdown and/or inhibition could enhance apoptosis in MM cells under ER stress condition by upregulating ATF4, followed by CHOP. HDAC4 knockdown showed modest cell growth inhibition; however, it markedly enhanced cytotoxicity induced by either tunicamycin or carfilzomib (CFZ), associated with upregulating ATF4 and CHOP. For pharmacological inhibition of HDAC4, we employed a novel and selective class IIa HDAC inhibitor TMP269, alone and in combination with CFZ. As with HDAC4 knockdown, TMP269 significantly enhanced cytotoxicity induced by CFZ in MM cell lines, upregulating ATF4 and CHOP and inducing apoptosis. Conversely, enhanced cytotoxicity was abrogated by ATF4 knockdown, confirming that ATF4 has a pivotal role mediating cytotoxicity in this setting. These results provide the rationale for novel treatment strategies combining class IIa HDAC inhibitors with ER stressors, including proteasome inhibitors, to improve patient outcome in MM.

Multiple myeloma: Updates for pharmacists in the treatment of relapsed and refractory disease

There have been a number of recent advances in the treatment of patients with relapsed and refractory multiple myeloma. However, despite additional FDA-approved therapies including carfilzomib and pomalidomide as well as clinical trials investigating new combinations of existing treatments, multiple myeloma remains an incurable disease. New therapies currently in the drug development pipeline for relapsed and refractory disease include additional proteasome inhibitors (oprozomib, marizomib, ixazomib), histone deacetylase inhibitors (panobinostat, ricolinostat, quisinostat), monoclonal antibodies (daratumumab, elotuzumab, SAR650984), Bruton's tyrosine kinase inhibitors (ibrutinib), a selective inhibitor of nuclear export, and others. This review will focus on these newly developing therapies as well as the ever expanding role of the pharmacist in supportive care for patients with relapsed and refractory multiple myeloma.

Meta-analysis of incidence and risk of peripheral neuropathy associated with intravenous bortezomib

BACKGROUND

Bortezomib is a proteasome inhibitor which has demonstrated activity against recurrent or newly diagnosed multiple myeloma (MM) and mantle cell lymphoma. Peripheral neuropathy has been described with this agent, although the overall incidence and relative risk remain unclear. We performed a meta-analysis to calculate the incidence of peripheral neuropathy associated with the use of intravenous bortezomib in MM and lymphoma and to compare the relative risk compared with placebo.

METHODS

We searched PubMed, Embase, Cochrane databases, and meeting proceedings from the American Society of Clinical Oncology (ASCO) for relevant clinical trials. Eligible studies included prospective phase 2 and 3 clinical trials with toxicity profile on peripheral neuropathy associated with intravenous bortezomib in patients with MM and lymphoma. Statistical analyses were done to calculate summary incidences, relative risks (RRs), and 95 % confidence intervals (CIs), employing fixed- or random-effects models depending on the heterogeneity of the included studies.

RESULTS

Altogether, 34 clinical trials were selected for the meta-analysis, yielding a total of 6492 patients. The incidence of peripheral neuropathy (all grades) was 33.9 % (95 % CI, 29.9-38.5 %) and that of high-grade events was 8.1 % (95 % CI, 6.9-9.4 %). The relative risks of bortezomib-induced peripheral neuropathy compared to placebo were increased for all-grade (RR = 4.89; 95 % CI, 2.52-9.51) and high-grade (RR = 4.53; 95 % CI, 2.04-10.07) peripheral neuropathy (for randomized controlled trials only). Our analysis was also stratified by different underlying diseases, and patients with lymphoma had an increased incidence of all-grade peripheral neuropathy than those with MM when treated with intravenous bortezomib.

CONCLUSIONS

Treatment with intravenous bortezomib is associated with an increased risk of developing peripheral neuropathy.

The ubiquitin-proteasome system: opportunities for therapeutic intervention in solid tumors

The destruction of proteins via the ubiquitin-proteasome system is a multi-step, complex process involving polyubiquitination of substrate proteins, followed by proteolytic degradation by the macromolecular 26S proteasome complex. Inhibitors of the proteasome promote the accumulation of proteins that are deleterious to cell survival, and represent promising anti-cancer agents. In multiple myeloma and mantle cell lymphoma, treatment with the first-generation proteasome inhibitor, bortezomib, or the second-generation inhibitor, carfilzomib, has demonstrated significant therapeutic benefit in humans. This has prompted United States Food and Drug Administration (US FDA) approval of these agents and development of additional second-generation compounds with improved properties. There is considerable interest in extending the benefits of proteasome inhibitors to the treatment of solid tumor malignancies. Herein, we review progress that has been made in the preclinical development and clinical evaluation of different proteasome inhibitors in solid tumors. In addition, we describe several novel approaches that are currently being pursued for the treatment of solid tumors, including drug combinatorial strategies incorporating proteasome inhibitors and the targeting of components of the ubiquitin-proteasome system that are distinct from the 26S proteasome complex.