Bortezomib, low-dose intravenous melphalan, and dexamethasone for patients with relapsed multiple myeloma

Weekly carfilzomib plus cyclophosphamide and dexamethasone in the treatment of relapsed/refractory multiple myeloma: Final results from the MCRN-003/MYX.1 single arm phase II trial

The MCRN-003/CCTGMYX.1 is a single arm phase II trial of weekly carfilzomib, cyclophosphamide and dexamethasone (wKCd), exploring a convenient immunomodulator (IMiD)-free regimen in relapsed myeloma. Weekly carfilzomib (20/70 mg/m² ), dexamethasone 40 mg and cyclophosphamide 300 mg/m² was delivered over 28-day cycles. The primary endpoint was overall response after four cycles. Secondary endpoints included toxicity, response depth, PFS and OS. Exploratory endpoints included the impact of cytogenetics, prior therapy exposure and serum free light chain (sFLC) escape; 76 patients were accrued. The ORR was 85% (68% ≥very good partial response [VGPR] and 29% ≥complete response [CR]). The median OS and PFS were 27 and 17 months respectively. High-risk cytogenetics conferred a worse ORR (75% vs. 97%, p = .013) and median OS (18 months vs. NR, p = .002) with a trend toward a worse median PFS (14 vs. 22 months, p = .06). Prior proteasome inhibitor (PI) or lenalidomide did not influence OS or PFS. The sFLC was noted in 15% of patients with a median PFS of 17 months when included as a progression event. The most common ≥ grade 3 non-hematologic adverse events were infectious (40%), vascular (17%) and cardiac (15%). The wKCD is a safe and effective regimen in relapse, especially for patients ineligible for lenalidomide-based therapies.

DNA Damage Response in Multiple Myeloma: The Role of the Tumor Microenvironment

Multiple myeloma (MM) is an incurable plasma cell malignancy characterized by genomic instability. MM cells present various forms of genetic instability, including chromosomal instability, microsatellite instability, and base-pair alterations, as well as changes in chromosome number. The tumor microenvironment and an abnormal DNA repair function affect genetic instability in this disease. In addition, states of the tumor microenvironment itself, such as inflammation and hypoxia, influence the DNA damage response, which includes DNA repair mechanisms, cell cycle checkpoints, and apoptotic pathways. Unrepaired DNA damage in tumor cells has been shown to exacerbate genomic instability and aberrant features that enable MM progression and drug resistance. This review provides an overview of the DNA repair pathways, with a special focus on their function in MM, and discusses the role of the tumor microenvironment in governing DNA repair mechanisms.

Bortezomib and other proteosome inhibitors-induced peripheral neurotoxicity: From pathogenesis to treatment

Proteasome inhibitors (PIs), especially bortezomib (BTZ), have come to the forefront over the last years because of their unprecedented efficacy mainly against multiple myeloma (MM). Unfortunately, peripheral neuropathy (PN) secondary to treatment of MM with PIs has emerged as a clinically relevant complication, which negatively impacts the quality of life of MM survivors. Bortezomib-induced peripheral neuropathy (BIPN) is a dose-limiting toxicity, which develops in 30% to 60% of patients during treatment. Typically, BIPN is a length-dependent sensory axonopathy characterized by numbness, tingling, and severe neuropathic pain in stocking and glove distribution. BIPN mechanisms have not yet been fully elucidated. Experimental studies suggest that aggresome formation, endoplasmic reticulum stress, myotoxicity, microtubule stabilization, inflammatory response, and DNA damage could contribute to this neurotoxicity. A new generation of structurally distinct PIs has been developed, being increasingly used in clinical settings. Carfilzomib exhibits a much lower neurotoxicity profile, with a significantly lower incidence of PN compared to BTZ. Pre-existing PN increases the risk of developing BIPN. Besides, BIPN is related to dose, schedule and mode of administration and modifications of these factors have lowered the incidence of PN. However, to date there is no cure for PIs-induced PN (PIIPN), and a careful neurological monitoring and dose adjustment is a key strategy for preserving quality of life. This review critically looks at the pathogenesis, incidence, risk factors, both clinical and pharmacogenetics, clinical phenotype and management of PIIPN. We also make recommendations for further elucidating the whole clinical spectrum of PIIPN.

Subcutaneous bortezomib might be standard of care for patients with multiple myeloma: a systematic review and meta-analysis

Background: Administration of subcutaneous (SC) bortezomib in patients with multiple myeloma (MM) has increased in recent years. Yet, it is unclear whether there is sufficient evidence to support the use of SC bortezomib as a standard of care.

Methods: A systematic review of 4 randomized controlled trials and 8 retrospective trials comparing SC to intravenous (IV) bortezomib among 1,857 MM patients was performed. Embase, PubMed, Clinical Trials.gov, Cochrane Library and reference lists were searched for relevant studies from inception until August 2018. Outcomes of interest included 1-year overall survival (OS), 1-year progression-free survival (PFS), objective response rate (ORR) and adverse events (AEs). Random events meta-analyses were performed. We also performed sensitivity analysis to examine whether the results of the meta-analysis were robust.

Results: Compared to IV administration, SC bortezomib had a significantly lower incidence of some all-grade or grade 3–4 AE, such as peripheral sensory neuropathy, leukopenia and thrombocytopenia (p<0.05). There was no statistical difference in 1-year OS, 1-year PFS, ORR between SC and IV bortezomib (p>0.05).

Conclusion: The data presented so far consistently show that SC bortezomib has become a standard of care for patients with MM.

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.

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 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.

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.

Modified bortezomib, adriamycin and dexamethasone (PAD) regimen in advanced multiple myeloma

The PAD regime, composed of bortezomib, adriamycin and dexamethasone, improves the outcomes of patients with advanced multiple myeloma (MM), but at the same time produces high frequency of serious toxic side effects. For the first time, we evaluated the efficacy and safety of a bortezomib-dose-reduced PAD regime in the treatment of relapsed/refractory MM in this clinical study. Forty-five patients were treated with two to six 21-day cycles of PAD, comprising bortezomib at 1.3 mg/m(2) (P1AD, n = 21) or 1.0 mg/m(2) (P2AD, n = 24) (days 1, 4, 8, 11), adriamycin at 9 mg/m(2) (days 1-4) and dexamethasone at 40 mg/day (days 1-4). Overall, 36 patients (80 %) showed at least partial remission (PR), in which 9 cases (20 %) showed complete remission (CR) and 10 cases (22 %) showed very good partial remission (VGPR). The efficacy of PAD regimen in advanced MM patients was not related to the traditional prognostic factors. There was no significant difference between P1AD and P2AD in the rates of PR, CR or VGPR, 1.5-year progression-free survival (PFS), and overall survival (OS) (81 % vs. 79 %, 48 % vs. 38 %, 64 % vs. 59 %, and 85 % vs. 73 %, respectively). However, the grade 3-4 toxic effects, including thrombocytopenia (13 % vs. 38 %), peripheral neuropathy (8 % vs. 33 %) and 3-4 grade gastrointestinal reaction (13 % vs. 43 %), were markedly inhibited after P2AD compared to P1AD (P < 0.05). The bortezomib-dose-reduced PAD regime reduced the incidence of adverse reactions without affecting the treatment efficacy in patients with advanced MM.

Incidence and risk of cardiotoxicity associated with bortezomib in the treatment of cancer: a systematic review and meta-analysis

Background

We conducted a systematic review and meta-analysis to clarify the incidence and risk of cardiotoxicity associated with bortezomib in cancer patients.

Methods

Databases from PubMed, Web of Science and abstracts presented at ASCO meeting up to July 31, 2013 were searched to identify relevant studies. Eligible studies included prospective phase II and III trials evaluating bortezomib in cancer patients with adequate data on cardiotoxicity. Statistical analyses were conducted to calculate the summary incidence, odds ratio (OR) and 95% confidence intervals (CIs) by using either random effects or fixed effect models according to the heterogeneity of included studies.

Results

A total of 5718 patients with a variety of malignancies from 25 clinical trials were included in our analysis. The incidence of all-grade and high-grade cardiotoxicity associated with bortezomib was 3.8% (95%CI: 2.6–5.6%) and 2.3% (1.6–3.5%), with a mortality of 3.0% (1.4–6.5%). Patients treated with bortezomib did not significantly increase the risk of all-grade (OR 1.15, 95%CI: 0.82–1.62, p = 0.41) and high-grade (OR 1.13, 95%CI: 0.58–2.24, p = 0.72) cardiotoxicity compared with patients treated with control medication. Sub-group analysis showed that the incidence of cardiotoxicity varied with tumor types, treatment regimens and phases of trials. No evidence of publication bias was observed.

Conclusions

The use of bortezomib does not significantly increase the risk of cardiotoxicity compared to control patients. Further studies are recommended to investigate this association and risk differences among different tumor types, treatment regimens and phases of trials.

Choosing treatment options for patients with relapsed/refractory multiple myeloma

Multiple myeloma (MM) is a clonal plasma cell disorder that is still incurable using conventional treatments. Over the last decade, advances in front-line therapy have led to an increase in survival, but there are still some doubts in the case of relapsed/refractory disease. We searched the PubMed database for articles on treatment options for patients with relapsed/refractory MM published between 1996 and 2013. These treatments included hematopoietic cell transplantation (HCT), rechallenges using previous chemotherapy regimens, and trials of new regimens. The introduction of new agents such as the immunomodulatory drugs (IMIDs) thalidomide and lenalidomide, and the first-in-its-class proteasome inhibitor bortezomib, has greatly improved clinical outcomes in patients with relapsed/refractory MM, but not all patients respond and those that do may eventually relapse or become refractory to treatment. The challenge is therefore to select the optimal treatment for each patient by balancing efficacy and toxicity. To do this, it is necessary to consider disease-related factors, such as the quality and duration of responses to previous therapies, and the aggressiveness of the relapse, and patient-related factors such as age, comorbidities, performance status, pre-existing toxicities and cytogenetic patterns. The message from the trials reviewed in this article is that the new agents may be used to re-treat relapsed/refractory disease, and that the sequencing of their administration should be modulated on the basis of the various disease and patient-related factors. Moreover, our understanding of the pharmacology and molecular action of the new drugs will contribute to the possibility of developing tailored treatment.

Current and emerging treatment options for patients with relapsed myeloma

Multiple myeloma (MM) is a neoplastic disorder. It results from proliferation of clonal plasma cells in bone marrow with production of monoclonal proteins, which are detectable in serum or urine. MM is clinically characterized by destructive bone lesions, anemia, hypercalcemia and renal insufficiency. Its prognosis is severe, with a median survival after diagnosis of approximately 3 years due to frequent relapses. Treatments for patients with relapsed/refractory MM include hematopoietic cell transplantation, a rechallenge using a previous chemotherapy regimen or a trial of a new regimen. The introduction of new drugs such as thalidomide, lenalidomide and bortezomib has markedly improved MM outcomes. When relapse occurs, the clinician's challenge is to select the optimal treatment for each patient while balancing efficacy and toxicity. Patients with indolent relapse can be first treated with a 2-drug or a 3-drug combination. Patients with more aggressive relapse often require therapy with a combination of multiple active agents. Autologous stem cell transplantation should be considered as salvage therapy at first relapse for patients who have cryopreserved stem cells early in the disease course. The aim of this review is to provide an overview on the pharmacological and molecular action of treatments used for patients with relapsed/refractory multiple myeloma.

Good clinical activity and favorable toxicity profile of once weekly bortezomib, fotemustine, and dexamethasone (B-MuD) for the treatment of relapsed multiple myeloma

Since multiple myeloma (MM) is still not-curable, the management of relapse remains challenging. Given the known efficacy of alkylating agents in MM, we conducted a phase I/II study to test a new three drug combination in which Fotemustine (Muphoran), an alkylating agent of nitrosurea family, was added to bortezomib + dexamethasone backbone (B-MuD) for the treatment of MM relapsed patients. Fotemustine was administered at two dose levels (80–100 mg/m² i.v.) on day 1. The original 21-day schedule was early amended for extra-hematological toxicity and a 35-day schedule was adopted (Bortezomib 1.3 mg/m² i.v. on days 1, 8, 15, and 22, Dexamethasone 20 mg i.v. on days 1, 8, 15, and 22) for a total of six courses. Twenty-four patients were enrolled. The maximum tolerated dose of Fotemustine was 100 mg/m². The overall response rate was of 62% (CR 8%, VGPR 33%, and PR 21%). The median OS was 28.5 months, the median progression-free survival (PFS) was 19.1 months. B-MuD resulted effective in patients previous exposed to bortezomib without difference of response (P = 0.25) and PFS (P = 0.87) when compared to bortezomib-naive patients. Thrombocytopenia was the most common AE overall. In conclusion, B-MuD is an effective and well tolerated combination in relapsed MM patients even in advanced disease phase. © Am. J. Hematol., 88:102–106, 2013. © 2012 Wiley Periodicals, Inc.

Bortezomib-cyclophosphamide-dexamethasone for relapsing multiple myeloma

OBJECTIVES

In vitro studies have shown synergistic antimyeloma effects with the combination of bortezomib and alkylating agents. Combinations of bortezomib, cyclophosphamide, and dexamethasone are rational with the prospect of superior antitumor activity with independent toxicity.

METHODS

Between December 2004 and April 2007, we treated 44 patients with relapsing multiple myeloma with the combination of bortezomib 1.3 mg/m intravenously on days 1, 4, 8, 11; dexamethasone 20 mg/m orally daily for 4 days beginning on days 1, 9 and 17; and cyclophosphamide 70 mg/m orally twice daily for 4 days. A second course was given 1 month later.

RESULTS

Clinical response was observed in 32 patients (73%) including 26 with disease in partial remission (59%), and 6 with disease in complete remission (14%). Side effects were uncommon and mild, except for grade 3 thrombocytopenia in 15%, infection in 5% and constipation in 2% of patients. The median remission time of responding patients was 10 months that contributed to significantly longer median survival for patients with responsive disease (33 mo) than for those with unresponsive disease (12 mo) (P < 0.01).

CONCLUSION

Bortezomib-cyclophosphamide-dexamethasone was an effective, well-tolerated combination for the treatment of relapsing multiple myeloma.

Intravenous injection of bortezomib, melphalan and dexamethasone in refractory and relapsed multiple myeloma

BACKGROUND

A combination of bortezomib (1.3 mg/m(2)), melphalan (5 mg/m(2)), and dexamethasone (40 mg) (BMD), with all three drugs given as a contemporary intravenous administration, was retrospectively evaluated.

PATIENTS AND METHODS

Fifty previously treated (median 2 previous lines) patients with myeloma (33 relapsed and 17 refractory) were assessed. The first 19 patients were treated with a twice-a-week (days 1, 4, 8, 11, 'base' schedule) administration while, in the remaining 31 patients, the three drugs were administered once a week (days 1, 8, 15, 22, 'weekly' schedule).

RESULTS

Side-effects were predictable and manageable, with prominent haematological toxicity, and a better toxic profile in 'weekly' schedule (36% versus 66% in 'base' schedule). The overall response rate was 62%. After median follow-up of 24.5 months (range 2.7-50 months), the median progression-free survival (PFS) was 21.6 with no difference between the two schedules and the median overall survival (OS) was 33.8 months. Independently from the adopted schedule, we found that also in a cohort of relapsed/refractory patients achieving at least partial remission improved PFS (35.2 versus 9 months) and OS (unreached median versus 18 months).

CONCLUSION

Taken together, our observations suggest that BMD is an effective regimen in advanced myeloma patients with acceptable toxicity.

Management strategies for relapsed/refractory multiple myeloma: current clinical perspectives

In the last decade, the introduction of novel agents including the immunomodulatory drugs thalidomide and lenalidomide, and the first-in-class proteasome inhibitor bortezomib, has dramatically improved clinical outcome in patients with relapsed/refractory multiple myeloma (MM) compared to conventional chemotherapy alone. Although combination treatment approaches with traditional cytotoxic agents and novel agents have led to response rates as high as 85% in patients with relapsed/refractory disease, not all patients will respond to established novel agents, and even those who do respond will ultimately relapse or become refractory to currently available regimens. There is no generally accepted standard treatment for patients with relapsed/refractory disease; however, both disease-related (eg, quality and duration of response to previous therapies and the aggressiveness of the relapse) and patient-related (eg, preexisting toxicities, comorbid conditions, quality of life, age, and performance status) factors should be considered when selecting the best treatment option. This article will review up-to-date approaches for managing patients with relapsed/refractory MM, including the efficacy and safety of established novel agents, the use of adjunctive/supportive care, and strategies for tailored treatment.

Proteasome inhibitors

In May 2003, the US Food and Drug Administration (FDA) granted accelerated approval for the use of the first-in-class proteasome inhibitor bortezomib as a third-line therapy in multiple myeloma, and the European Union followed suit a year later. Bortezomib has subsequently been approved for multiple myeloma as a second-line treatment on its own and as a first-line therapy in combination with an alkylating agent and a corticosteroid. Furthermore, bortezomib has also been approved as a second-line therapy for mantle cell lymphoma. In this chapter, the focus is on the current clinical research on bortezomib, its adverse effects, and the resistance of multiple myeloma patients to bortezomib-based therapy. The various applications of bortezomib in different diseases and recent advances in the development of a new generation of inhibitors that target the proteasome or other parts of the ubiquitin-proteasome system are also reviewed.

Bortezomib as the first proteasome inhibitor anticancer drug: current status and future perspectives

Targeting the ubiquitin-proteasome pathway has emerged as a rational approach in the treatment of human cancer. Based on positive preclinical and clinical studies, bortezomib was subsequently approved for the clinical use as a front-line treatment for newly diagnosed multiple myeloma patients and for the treatment of relapsed/refractory multiple myeloma and mantle cell lymphoma, for which this drug has become the staple of treatment. The approval of bortezomib by the US Food and Drug Administration (FDA) represented a significant milestone as the first proteasome inhibitor to be implemented in the treatment of malignant disease. Bortezomib has shown a positive clinical benefit either alone or as a part of combination therapy to induce chemo-/radio-sensitization or overcome drug resistance. One of the major mechanisms of bortezomib associated with its anticancer activity is through upregulation of NOXA, which is a proapoptotic protein, and NOXA may interact with the anti-apoptotic proteins of Bcl-2 subfamily Bcl-X(L) and Bcl-2, and result in apoptotic cell death in malignant cells. Another important mechanism of bortezomib is through suppression of the NF-κB signaling pathway resulting in the down-regulation of its anti-apoptotic target genes. Although the majority of success achieved with bortezomib has been in hematological malignancies, its effect toward solid tumors has been less than encouraging. Additionally, the widespread clinical use of bortezomib continues to be hampered by the appearance of dose-limiting toxicities, drug-resistance and interference by some natural compounds. These findings could help guide physicians in refining the clinical use of bortezomib, and encourage basic scientists to generate next generation proteasome inhibitors that broaden the spectrum of efficacy and produce a more durable clinical response in cancer patients. Other desirable applications for the use of proteasome inhibitors include the development of inhibitors against specific E3 ligases, which act at an early step in the ubiquitin-proteasome pathway, and the discovery of less toxic and novel proteasome inhibitors from natural products and traditional medicines, which may provide more viable drug candidates for cancer chemoprevention and the treatment of cancer patients in the future.

Emerging role of carfilzomib in treatment of relapsed and refractory lymphoid neoplasms and multiple myeloma

Proteasome inhibition forms the cornerstone of antimyeloma therapy. The first-in-class proteasome inhibitor, bortezomib, either alone or in combination with other chemotherapeutic agents, induces high overall response rates and response qualities in patients with clinically and molecularly defined high-risk disease. However, resistance to bortezomib and neurotoxicity associated with the treatment remain challenging issues. Carfilzomib is a novel, well tolerated, irreversible proteasome inhibitor with minimal neurotoxicity. Carfilzomib demonstrates promising activity in myeloma patients who are refractory to bortezomib and immunomodulatory agents. This review focuses on the pharmacology, safety, and efficacy of carfilzomib for the treatment of multiple myeloma in bortezomib-naïve and bortezomib-exposed populations.

Therapy of relapsed and refractory multiple myeloma

Despite considerable improvements in first line treatment still the majority of patients experience relapse of multiple myeloma. Treatment decisions for relapse or refractory multiple myeloma should be based on a clinical decision path taking response and adverse events to previous therapy, myeloma specific complications and organ dysfunctions, overall clinical condition, age, cytogenetic information and prognostic factors into account. Bortezomib, thalidomide and lenalidomide have improved the therapeutic armentarium for patients with refractory or relapsed disease and are often used in combination with dexamethasone or chemotherapeutic agents. Combination therapies of novel agents in drug combination regimen are currently under investigation as well. For patients with a disease free survival of 12 month or longer after initial single or tandem high dose therapy and autologous stem cell transplantation (ASCT) repeat of high dose therapy with melphalan and ASCT should be considered in case of relapse. Radiotherapy and osteoplastic procedures can be used as adjunct to systemic therapy to treat local complications in particular vertebral pain caused by osteolytic bone disease. Cytogenetic tests, molecular techniques as gene expression profiling and other diagnostic will lead to a more individualized therapy. The integration of novel compounds into established regimen will be a major challenge for future clinical studies.

Proteasome inhibition and its therapeutic potential in multiple myeloma

Due to an unmet clinical need for treatment, the first in class proteasome inhibitor, bortezomib, moved from drug discovery to FDA approval in multiple myeloma in an unprecedented eight years. In the wake of this rapid approval arose a large number of questions about its mechanism of action and toxicity as well as its ultimate role in the treatment of this disease. In this article, we briefly review the preclinical and clinical development of the drug as the underpinning for a systematic review of the large number of clinical trials that are beginning to shed some light on the full therapeutic potential of bortezomib in myeloma. We conclude with our current understanding of the mechanism of action of this agent and a discussion of the novel proteasome inhibitors under development, as it will be progress in these areas that will ultimately determine the true potential of proteasome inhibition in myeloma.

Treatment of relapsed and refractory multiple myeloma in the era of novel agents

The introduction of the Immunomodulatory drugs (IMiDs) and proteasome inhibitors, used either as a single-agent or combined with classic anti-myeloma therapies, has improved the outcome for patients with relapsed myeloma. However, there is currently no generally accepted standard treatment for relapsed/refractory myeloma patients, partly because of the absence of trials comparing the efficacy of the novel agents in relapsed/refractory myeloma. Choice of a new treatment regimen depends on both patient and disease-specific characteristics. A lenalidomide-based regimen is the first choice in patients with neuropathy, while bortezomib has the highest efficacy in patients with renal insufficiency and is not associated with increased risk of thromboembolism. A second autologous stem cell transplantation (auto-SCT) can be applied in patients with a progression-free period of ≥ 18-24 months after the first auto-SCT. In high-risk relapse such as occurring early after auto-SCT consolidation with allogeneic SCT can be considered. In this review we provide an overview of the various salvage regimens and give recommendations for treatment of patients with relapsed/refractory myeloma in different clinical settings.

How best to use new therapies in multiple myeloma

Advances in the molecular understanding of myeloma have led to the development of novel agents such as immunomodulatory drugs (IMiDs) and proteasome inhibitors (bortezomib). When used alone, these agents have significant activity against myeloma and responses increase significantly when they are combined with additional agents including glucocorticosteroids and chemotherapeutic agents such as alkylators. There is a drive to use these novel agents in patients with newly diagnosed myeloma, where they lead to impressive response rates with increasing duration of responses. In addition, novel agents are now the mainstays of therapy for relapsed disease. In the following paper, we summarize the key observations from recent completed and ongoing studies that determined the effect of these novel therapies both in the setting of newly diagnosed myeloma and for relapsed disease. We also discuss our approach to the use of these agents in specific myeloma settings.

Advances in treatment for relapses and refractory multiple myeloma

Recent advances in the treatment of multiple myeloma have resulted in improved response rates and overall survival in patients with multiple myeloma. These advances are largely due to thalidomide-, lenalidomide-, and bortezomib-based combinations that have improved response rates, not only in patients with untreated disease, but also in those with relapsed and/or refractory myeloma, in some cases producing response rates up to 85%. Eventually, however, nearly all patients relapse, emphasizing a continuing role for the introduction of investigational agents that overcome drug resistance. This article will review the current role for thalidomide, lenalidomide, and bortezomib-based combinations, as well as some preliminary findings for promising investigational agents currently in clinical trials for patients with relapsed and/or refractory disease.

Evidence-based mini-review: treatment options for patients with relapsed/refractory myeloma previously treated with novel agents and high-dose chemotherapy and autologous stem-cell transplantation

A 64 year-old man with a history of multiple myeloma presents with new back pain. He has a history of International Staging System stage 1, IgG kappa multiple myeloma with normal cytogenetics which was diagnosed 4 years ago when he presented with a pathological fracture of the left humerus. He was initially managed with mechanical stabilization and 4 cycles of bortezomib-dexamethasone, as well as 2 years of bisphosphanates. Following induction therapy he achieved a very good partial response (VGPR). He subsequently received high-dose melphalan and autologous stem cell transplantation (auto-SCT) and achieved a complete reponse (CR) post-transplant. He did not receive maintenance therapy and had been lost-to follow-up for about a year. He now presents 5 years after initial diagnosis with back pain and is noted to have a new lytic lesion with a compression fracture at T8. A serum protein electrophoresis demonstrates reappearance of his original monoclonal protein. After appropriate stabilization he comes to you to discuss additional treatment options.

Novel agents for relapsed and/or refractory multiple myeloma

The introduction of novel agents, such as thalidomide, bortezomib, and lenalidomide, has altered the landscape of therapeutic options for multiple myeloma by offering new mechanisms for targeting this disease. Combinations of these agents, with each other and/or traditional chemotherapeutics, have vastly increased the treatment options for patients both frontline, and at relapse, providing higher response rates, and importantly, increasing median overall survival. In this review, we will discuss the use of these novel agents and their combinations in patients with relapsed and/or refractory multiple myeloma.