Phase Ib dose-escalation study (PX-171-006) of carfilzomib, lenalidomide, and low-dose dexamethasone in relapsed or progressive multiple myeloma

Management of Relapsed and Refractory Multiple Myeloma: Recent advances

Multiple myeloma (MM) accounts for ∼10% of total hematologic malignancies worldwide. In India, the incidence of MM has increased two-fold with marked heterogeneity. Significant improvements in terms of clinical outcomes have been observed in the management of MM in recent years. However, most patients develop a disease relapse with the first or subsequent treatments. A combination of immunomodulatory drugs (thalidomide and lenalidomide) and proteasome inhibitors (PIs; bortezomib) has been the mainstay for the therapeutic management of relapsed/refractory multiple myeloma (RRMM). This review highlights the management of RRMM with newer agents such as belantamab, carfilzomib, daratumumab, elotuzumab, ixazomib, mafadotin, selinexor, panobinostat, and venetoclax, with more focus on PIs. As a single agent and in combination with other drugs including dexamethasone and carfilzomib has been studied extensively and approved by the United States, European Union, and India. Clinical trials of these newer agents, either alone or in combination, for the treatment of RRMM in Western countries indicate survival, improved outcomes, and overall well-being. However, evidence in Indian patients is evolving from ongoing studies on carfilzomib and daratumumab, which will ascertain their efficacy and safety. Currently, several guidelines recommend carfilzomib-based, daratumumab-based, and panobinostat-based regimens in RRMM patients. Currently, with more accessible generic versions of these drugs, more Indian patients may attain survival benefits and improved quality of life.

Carfilzomib: A Promising Proteasome Inhibitor for the Treatment of Relapsed and Refractory Multiple Myeloma

The proteasome is crucial for the degradation of intracellular proteins and plays an important role in mediating a number of cell survival and progression events by controlling the levels of key regulatory proteins such as cyclins and caspases in both normal and tumor cells. However, compared to normal cells, cancer cells are more dependent on the ubiquitin proteasome pathway (UPP) due to the accumulation of proteins in response to uncontrolled gene transcription, allowing proteasome to become a potent therapeutic target for human cancers such as multiple myeloma (MM). Up to date, three proteasome inhibitors namely bortezomib (2003), carfilzomib (2012) and ixazomib (2015) have been approved by the US Food and Drug Administration (FDA) for the treatment of patients with relapsed and/or refractory MM. This review mainly focuses on the biochemical properties, mechanism of action, toxicity profile and pivotal clinical trials related to carfilzomib, a second-generation proteasome inhibitor that binds irreversibly with proteasome to overcome the major toxicities and resistance associated with bortezomib.

Incidence and Management of Carfilzomib-induced Cardiovascular Toxicity; A Systematic Review and Meta-analysis

BACKGROUND

The ASPIRE and ENDEAVOUR trials have shown cardiovascular adverse effects in patients treated with carfilzomib-based regimens. Therefore, we conducted this meta-analysis of published clinical trials to identify the cumulative incidence and risk of cardiovascular adverse effects due to carfilzomib.

METHODS

A systematic search of PubMed, Embase, Web of Science, and Cochrane library was performed, and we identified 45 prospective trials of carfilzomib with data on 5583 patients. Among all patients being treated with carfilzomib (N=5,583), 8.9% sustained all grade cardiotoxicity, while 4.4% sustained high-grade cardiotoxicity. All-grade hypertension was present in 13.2%, while the incidence of high-grade hypertension was 5.3%.

RESULT

The observed incidences of all-grade heart failure, edema, and ischemia were 5.1%, 20.7%, and 4.6% respectively. Likewise, for high-grade heart failure and edema observed incidence was 3.2%, and 2.7% respectively. There was no difference in the event rate of all and high-grade cardiotoxicity between newly diagnosed multiple myeloma and relapsed/refractory (p-value 0.42 and 0.86 respectively). Likewise, we did not observe any difference in the event rate of all and high-grade cardiotoxicity when carfilzomib was used as a single agent versus when used in combination therapy with other agents (p-value 0.43 and 0.73 respectively).

CONCLUSION

Carfilzomib is associated with a significant risk of cardiovascular toxicity and hypertension. With the increasing utilization of carfilzomib, it is critical for primary care physicians, oncologists and cardiologists to be aware of the risk of cardiotoxicity associated with the use of carfilzomib to recognize and treat baseline cardiovascular risk factors in such patients.

KRD (carfilzomib and lenalidomide plus dexamethasone) for the treatment of relapsed or refractory multiple myeloma in the real-life: a retrospective survey in 123 patients

From April 2016, carfilzomib, in combination with lenalidomide and dexamethasone (KRD), became available for use in the daily practice in Italy for patients with relapsed or refractory multiple myeloma (RRMM). We performed a retrospective survey at 14 different institutions from Southern Italy in order to evaluate patient characteristics and treatment results from an unselected series of patients treated accordingly so far. One hundred and twenty-three consecutive patients were included, with a median of 2 previous lines of therapy (range 1-9) and a median age of 63 years (range 39-82). At the time of analysis, median number of courses administered is 11 (range 1-34), and all patients are evaluable for response. Overall response rate including complete remission, very good partial remission, and partial remission is 85%. After a median follow-up of 27 months, median overall and progression-free survival are 33 and 23 months, respectively. Sixty-three patients are alive and between them, 45 (37%) are in continuous remission. Sixty patients have died (49%), mainly from progressive disease. There were 6 treatment-related deaths (5% of the whole patient population). Overall, hematological and non-hematological toxicity were manageable, mostly on outpatient basis. Arterial hypertension has been observed in 43 cases (35%) but did not lead to treatment interruption. Our data demonstrate that in real life, KRD is highly effective and well tolerated in the majority of patients with RRMM.

Anti-VEGF Drugs in the Treatment of Multiple Myeloma Patients

The interaction between the bone marrow microenvironment and plasma cells plays an essential role in multiple myeloma progression and drug resistance. The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) pathway in vascular endothelial cells activates and promotes angiogenesis. Moreover, VEGF activates and promotes vasculogenesis and vasculogenic mimicry when it interacts with VEGF receptors expressed in precursor cells and inflammatory cells, respectively. In myeloma bone marrow, VEGF and VEGF receptor expression are upregulated and hyperactive in the stromal and tumor cells. It has been demonstrated that several antiangiogenic agents can effectively target VEGF-related pathways in the preclinical phase. However, they are not successful in treating multiple myeloma, probably due to the vicarious action of other cytokines and signaling pathways. Thus, the simultaneous blocking of multiple cytokine pathways, including the VEGF/VEGFR pathway, may represent a valid strategy to treat multiple myeloma. This review aims to summarize recent advances in understanding the role of the VEGF/VEGFR pathway in multiple myeloma, and mainly focuses on the transcription pathway and on strategies that target this pathway.

KRD-PACE Mobilization for Multiple Myeloma Patients With Significant Residual Disease Before Autologous Stem-Cell Transplantation

BACKGROUND

Bortezomib has been incorporated into thalidomide and dexamethasone provided with cisplatin, doxorubicin, cyclophosphamide, and etoposide (PACE) as an intensive regimen before autologous stem-cell transplantation for multiple myeloma (MM). We examined MM patients at our center who received chemomobilization with a regimen that substituted carfilzomib and lenalidomide for bortezomib and thalidomide (KRD-PACE).

PATIENTS AND METHODS

This was a retrospective study of 27 MM patients who received KRD-PACE for chemomobilization. Our analysis included patients who had circulating plasma cells (CPCs) by flow cytometry, ≥ 10% bone marrow plasma cells (BMPC), a monoclonal protein ≥ 1 g/dL, or an involved serum free light chain ≥ 10 mg/dL.

RESULTS

The most common indication for KRD-PACE was BMPC ≥ 10% in 16 patients (60%), followed by CPCs in 11 (41%). The median (range) age was 61 (35-69) years, and the median (range) BMPC before treatment was 10% (5%-47%). The overall response rate was 43%, and a median (range) of 20.24 (8.08-69.88) × 10⁶ CD34⁺ cells/kg were collected. CPC clearance rate was 50%, and the median reduction in BMPC was 75%. Two patients had sinus bradycardia and 5 (19%) had neutropenic fever.

CONCLUSION

KRD-PACE is an effective therapy to mobilize peripheral blood stem cells in MM patients with residual disease burden. This regimen was successful at clearing CPCs and reducing BMPC burden, with an overall response rate of 43%. Despite theoretical concern regarding the combination of 3 cardiotoxic agents, we observed a low frequency of cardiac issues.

Proteasome Inhibitors for the Treatment of Multiple Myeloma

Use of proteasome inhibitors (PIs) has been the therapeutic backbone of myeloma treatment over the past decade. Many PIs are being developed and evaluated in the preclinical and clinical setting. The first-in-class PI, bortezomib, was approved by the US food and drug administration in 2003. Carfilzomib is a next-generation PI, which selectively and irreversibly inhibits proteasome enzymatic activities in a dose-dependent manner. Ixazomib was the first oral PI to be developed and has a robust efficacy and favorable safety profile in patients with multiple myeloma. These PIs, together with other agents, including alkylators, immunomodulatory drugs, and monoclonal antibodies, have been incorporated into several regimens. This review summarizes the biological effects and the results of clinical trials investigating PI-based combination regimens and novel investigational inhibitors and discusses the future perspective in the treatment of multiple myeloma.

Venous thromboembolism risk with contemporary lenalidomide-based regimens despite thromboprophylaxis in multiple myeloma: A systematic review and meta-analysis

BACKGROUND

Thromboprophylaxis is routinely used with lenalidomide-based regimens in multiple myeloma because of a substantial risk of venous thromboembolism (VTE). However, little is known about the incidence of VTE with contemporary lenalidomide-based regimens. The objective of the current study was to estimate the incidence of VTE despite thromboprophylaxis with currently used lenalidomide-based regimens in patients with myeloma.

METHODS

The Ovid MEDLINE, Embase, and Cochrane databases were queried from study inception to January 2019 for keywords to cover the following concepts: "lenalidomide," "venous thromboembolism," and "multiple myeloma." Phase 1, 2, and 3 clinical trials evaluating lenalidomide-based regimens with thromboprophylaxis were included. The pooled incidence rate of VTE was estimated using a random-effects model.

RESULTS

The search generated 1372 citations, with 51 clinical trials and 9069 patients included for analysis. The most common thromboprophylaxis agents were aspirin, low-molecular-weight heparin or warfarin, administered either per risk-stratification or at investigators' discretion. The pooled incidence of VTE in trials of patients who had newly diagnosed and relapsed/refractory myeloma was 6.2% (95% CI, 5.4%-7.1%) over median treatment durations ranging from 2 to 34 cycles, which translated into 1.2 VTE events per 100 patient-cycles (95% CI, 0.9-1.7 VTE events per 100 patient-cycles). Among contemporary regimens, the risk of VTE was low with combined lenalidomide and low-dose dexamethasone (0.2 [95% CI, 0.1-0.6] events/100 patient-cycles) and lenalidomide maintenance (0.0 [95% CI, 0.0-0.7] events per 100 patient-cycles). VTE risk was higher with combined lenalidomide and low-dose dexamethasone plus proteasome inhibitors (1.3 [95% CI, 0.7-2.3] events per 100 patient-cycles).

CONCLUSIONS

Despite adequate thromboprophylaxis, lenalidomide-based regimens have a substantial risk of VTE in controlled clinical trial settings. Further studies are needed on new thromboprophylaxis strategies with regimens that have a high VTE risk.

Isatuximab plus carfilzomib/dexamethasone versus carfilzomib/dexamethasone in patients with relapsed/refractory multiple myeloma: IKEMA Phase III study design

Although the treatment of relapsed/refractory multiple myeloma has improved dramatically over the past decade, the disease remains incurable; therefore, additional therapies are needed. Novel combination therapies incorporating monoclonal antibodies have shown significant promise. Here we describe the design of a Phase III study (NCT03275285, IKEMA), which is evaluating isatuximab plus carfilzomib and low-dose dexamethasone, versus carfilzomib/dexamethasone in relapsed/refractory multiple myeloma. The primary end point is progression-free survival. Responses are being determined by an independent review committee using 2016 International Myeloma Working Group criteria, and safety will be assessed throughout. The first patient was recruited in November 2017, and the last patient was recruited in March 2019; 302 patients have been randomized, and the study is ongoing. Clinical trial registration: NCT03275285.

Pharmacodynamics and pharmacokinetics of proteasome inhibitors for the treatment of multiple myeloma

Introduction: Multiple myeloma (MM) is the second most commonly diagnosed hematologic malignancy and has an increasing incidence and prevalence globally, and proteasome inhibitors (PIs) form the backbone of some of our most effective regimens for all phases of this disease in fit and frail patients. Areas covered: Strong understanding of the proteasome complex is increasingly important as the rapid development of new PIs and innovative myeloma therapies complicate the use of old and new combination regimens. We focus herein on the pharmacodynamics and pharmacokinetics of the approved PIs and others in development, including their safety and efficacy in corresponding clinical studies. Expert opinion: Advancements such as the first oral PI, ixazomib, with a more convenient route of administration and improved toxicity profile led to an improved quality of life, patient compliance, and all-oral combination regimens which are efficacious for long-term management of standard and high-risk MM. Novel pan-PIs, such as marizomib, hold the promise of superior clinical activity due to irreversible targeting of all multicatalytic proteinase complex subunits. Development of clinically validated biomarkers of PI sensitivity/resistance is required to inform utilization of the most optimal and effective, rationally targeted PI treatments for all MM patients.

Carfilzomib for relapsed and refractory multiple myeloma

Although the prognosis of multiple myeloma (MM) patients has dramatically improved during recent years, virtually all patients eventually develop relapsed refractory disease. Several new therapeutics have been developed in the last few years, including carfilzomib, a second-generation proteasome inhibitor (PI) that has been approved by the US Food and Drug Administration (FDA) in the setting of relapsed and/or refractory MM, as a single agent with or without dexamethasone, and in combination with lenalidomide in 2012 and 2015, respectively. Other promising combinations with carfilzomib are being investigated. Carfilzomib has shown superiority over the first-generation PI bortezomib on both efficacy and toxicity. In particular, profoundly lower incidence in polyneuropathy compared to bortezomib has been described. However, carfilzomib has a different toxicity profile, with more cardiovascular adverse events. Therefore, caution should be taken with the use of carfilzomib for elderly and cardiovascularly compromised patients. The once-weekly administration of carfilzomib, recently approved by the FDA in combination with dexamethasone, will lead to a lower burden for the patient and caregivers compared to the twice-weekly schemes that were routinely used until recently. This review has a focus on clinical trial data that has led to drug approval, as well as new promising combination studies, and provides advice for treating physicians who are now prescribing this drug to patients.

Lenalidomide and Low Dose Dexamethasone Plus Elotuzumab or Carfilzomib for Relapsed or Refractory Multiple Myeloma: A Comparison of Progression-Free Survival with Reconstructed Individual Participant Data

Background

Refractory and relapsed multiple myeloma (RRMM) remains a clinical challenge. We compared the progression-free survival (PFS) of RRMM patients treated with lenalidomide and low dose dexamethasone plus elotuzumab or carfilzomib (ELD vs. CLD), using reconstructed individual patient data (IPD) based on two published trials reports.

Methods

We extracted data of study-level characteristics from original trial reports. We evaluated the comparability between the two treatment groups in terms of baseline status. Digitization of PFS Kaplan-Meier curves, reconstruction of IPD data, and subsequent survival analysis were performed. Distribution of progression and death events over time was visualized as histograms and corresponding kernel density lines, and Kaplan-Meier survival curves were plotted. Hazard ratio (HR) and corresponding 95% confidence interval (95% CI) were calculated.

Results

Significant difference in race and disease stage distribution was found (P < 0.0001). Higher proportion of white patients and patients with advanced disease in the carfilzomib group was identified. Survival analysis revealed better PFS in the carfilzomib group (elotuzumab group vs. carfilzomib group: HR = 1.36, 95% CI = [1.11-1.67]).

Conclusion

The CLD regimen may result in better PFS as compared with the ELD regimen in RRMM patients.

Analysis of carfilzomib cardiovascular safety profile across relapsed and/or refractory multiple myeloma clinical trials

Carfilzomib is a selective proteasome inhibitor approved for the treatment of relapsed and/or refractory multiple myeloma (RRMM). It has significantly improved outcomes, including overall survival (OS), and shown superiority vs standard treatment with lenalidomide plus dexamethasone and bortezomib plus dexamethasone. The incidence rate of cardiovascular (CV) events with carfilzomib treatment has varied across trials. This analysis evaluated phase 1-3 trials with >2000 RRMM patients exposed to carfilzomib to describe the incidence of CV adverse events (AEs). In addition, the individual CV safety data of >1000 patients enrolled in the carfilzomib arm of phase 3 studies were compared with the control arms to assess the benefit-risk profile of carfilzomib. Pooling data across carfilzomib trials, the CV AEs (grade ≥3) noted included hypertension (5.9%), dyspnea (4.5%), and cardiac failure (4.4%). Although patients receiving carfilzomib had a numeric increase in the rates of any-grade and grade ≥3 cardiac failure, dyspnea, and hypertension, the frequency of discontinuation or death due to these cardiac events was low and comparable between the carfilzomib and control arms. Serial echocardiography in a blinded cardiac substudy showed no objective evidence of cardiac dysfunction in the carfilzomib and control arms. Moreover, carfilzomib had no significant effect on cardiac repolarization. Our results, including the OS benefit, showed that the benefit of carfilzomib treatment in terms of reducing progression or death outweighed the risk for developing cardiac failure or hypertension in most patients. Appropriate carfilzomib administration and risk factor management are recommended for elderly patients and patients with underlying risk factors.

Update on the role of lenalidomide in patients with multiple myeloma

Lenalidomide is a derivative of thalidomide and belongs to the class of drugs known as the immunomodulatory drugs (IMiDs). The IMiDs have played a large role in improving the survival outcomes of patients with multiple myeloma. In particular, lenalidomide is currently standard of care in the newly diagnosed setting, in the maintenance setting post-autologous stem cell transplant, as well as in the relapsed/refractory setting. While the combination of lenalidomide and various proteasome inhibitors has proven particularly effective, there are emerging data demonstrating the effectiveness of lenalidomide in combination with other important classes of drugs including the monoclonal antibodies. Recent studies have provided insight into the molecular target of lenalidomide and the other IMiDs, although there is still much to be learned regarding the mechanisms by which lenalidomide affects the myeloma cell and the immune system. Here we review the molecular mechanisms of action, side effects, and the results of the clinical trials which have led to the widespread incorporation of lenalidomide into the myeloma therapeutic armamentarium.

Response and progression-free survival according to planned treatment duration in patients with relapsed multiple myeloma treated with carfilzomib, lenalidomide, and dexamethasone (KRd) versus lenalidomide and dexamethasone (Rd) in the phase III ASPIRE study

Background

In ASPIRE, carfilzomib, lenalidomide, and dexamethasone (KRd) significantly improved progression-free survival (PFS) and response rates versus lenalidomide and dexamethasone (Rd) in patients with relapsed multiple myeloma. Per protocol, patients received KRd for a maximum of 18 cycles followed by Rd to progression, so the benefit/risk profile of KRd to progression was not established.

Methods

This post hoc analysis evaluated the efficacy and safety of KRd versus Rd at 18 months from randomization. Cumulative rates of complete response (CR) or better over time and PFS hazard ratio (HR) at 18 months were evaluated for KRd versus Rd. PFS HRs were also assessed according to cytogenetic risk, prior lines of therapy, and prior bortezomib treatment. Cox regression analysis was used to evaluate PFS HRs.

Results

The hazard ratio (HR) for PFS at 18 months was 0.58 versus 0.69 for the overall ASPIRE study. Patients with high-risk cytogenetics, ≥ 1 prior lines of therapy, and prior bortezomib exposure benefited from KRd up to 18 months versus Rd. The HRs for PFS at 18 months in the pre-defined subgroups were lower than those in the overall study. The difference in the proportion of KRd and Rd patients achieving at least a complete response (CR) increased dramatically over the first 18 months and then remained relatively constant. The safety profile at 18 months was consistent with previous findings.

Conclusions

The improved PFS HR at 18 months and the continued increase in CR rates for KRd through 18 cycles suggest that there may be a benefit of continued carfilzomib treatment.

Trial registration

Clinical trials.gov NCT01080391. Registered 2 March 2010.

Carfilzomib-Associated Cardiovascular Adverse Events: A Systematic Review and Meta-analysis

Importance

Cardiovascular adverse events (CVAE) with carfilzomib in patients with multiple myeloma can be potentially life-threatening and remain incompletely characterized. We performed the first systematic review and meta-analysis of carfilzomib-associated CVAE.

Objective

To determine the incidence of carfilzomib-associated CVAE and to compare the rates of carfilzomib CVAE among different doses and companion therapies.

Data Sources

PubMed, EMBASE, Web of Science, and clinicaltrials.gov were queried for the keywords "carfilzomib," "Kyprolis," and "PX-171" through January 1, 2017.

Study Selection

Phase 1 to 3 prospective clinical trials of carfilzomib in patients with multiple myeloma with evaluable toxic effects data were eligible for meta-analysis.

Data Extraction and Synthesis

Data were independently extracted by 2 reviewers following Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Pooled incidence rates and relative risks (for randomized trials) and 95% confidence intervals were calculated using a random effects model. Subgroup analyses were performed to assess study-level characteristics associated with CVAE.

Main Outcomes and Measures

Cardiovascular adverse events were defined as heart failure, hypertension, ischemia, and arrhythmia. All-grade and grades 3 or higher AEs and study characteristics were recorded.

Results

A total of 514 studies were assessed for eligibility. Of those, 24 studies were eligible, including a total of 2594 patients with multiple myeloma. All-grade and grades 3 and higher CVAE were seen in 617 (18.1%) and 274 (8.2%), respectively. Phase 2 or 3 studies and carfilzomib doses of 45 mg/m2 or higher were associated with high-grade CVAE. Median age older than 65 years, prior myeloma therapies, and concurrent myeloma therapies were not associated with CVAE. For the 3 randomized clinical trials, the summary relative risk of all-grade and grade 3 or higher CVAE for patients receiving carfilzomib compared with noncarfilzomib-receiving control patients were 1.8 and 2.2, respectively.

Conclusions and Relevance

Carfilzomib was associated with a significant incidence of CVAE, with higher rates seen with higher doses of carfilzomib. Phase 1 studies may be underdetecting CVAE. Future studies are needed to identify patients at high risk for CVAE, develop optimal monitoring strategies, and explore strategies to mitigate these risks.

Proteasome inhibitors for the treatment of multiple myeloma

INTRODUCTION

Multiple Myeloma (MM) management is rapidly evolving, with a spectrum of novel treatments that have changed our approach to the therapy. Proteasome inhibitors (PIs) have revolutionized the scenario of both relapsed/refractory and newly diagnosed patients. The efficacy of bortezomib, the first PI approved, followed by carfilzomib and, the oral ixazomib, have been tested in several trials as single agents or in combination.

AREAS COVERED

In this review, the authors summarize mechanism of action, efficacy and safety of proteasome inhibitors in MM and focus on data derived from clinical trials, analyzing adverse events and their relative management.

EXPERT OPINION

The authors believe that, currently, the best course of action in the treatment of MM is to use PIs in combination with immunomodulatory drugs (IMiDs) and/or with monoclonal antibodies for all patients. However, based on the patient-specific characteristics, it is important to avoid inappropriate discontinuation by knowing the single side effects of every agent in order to balance their efficacy and safety.

The activity and safety of novel proteasome inhibitors strategies (single, doublet and triplet) for relapsed/refractory multiple myeloma

PURPOSE

We sought to evaluate the activity and safety of these novel proteasome inhibitors (PIs) (carfilzomib, ixazomib, oprozomib and marizomib) containing regimens (single, doublet and triplet) for relapsed/refractory multiple myeloma (R/RMM).

METHODS

We searched published reports including these novel PIs containing regimens for R/RMM.

RESULTS

Finally, we identified 28 prospective studies that evaluated 4123 patients. Pooled analysis showed that novel PIs doublet combinations attained an impressive overall response rate (ORR) of 67%, which was higher than that of 22% from novel PIs single-agent (p < .001). And, the same trends favoring novel PIs doublet combinations were also shown in at least very good partial response (≥VGPR) and clinical benefit rate (CBR) analysis. Meanwhile, the ORR of 70% from novel PIs triplet regimens seemed to be similar to that of 67% from novel PIs doublet combinations (p = .54). And, there were no difference between them in ≥VGPR and CBR analysis. Compared to standard therapy, novel PIs combinations clearly benefited patients with R/RMM in terms of overall survival (HR, 0.79; p= .01), progression free survival(HR, 0.64; p = .01), overall response rate (RR = 1.21 p < .001).

CONCLUSIONS

Novel PIs doublet combinations attained superior response outcomes over novel PIs single-agent in patients with R/RMM. Meanwhile, novel PIs triplet combinations had similar response outcomes with novel PIs doublet combinations. Compared to standard therapy, novel PIs combinations clearly prolonged survival for patients with R/RMM.

Isatuximab plus pomalidomide/dexamethasone versus pomalidomide/dexamethasone in relapsed/refractory multiple myeloma: ICARIA Phase III study design

Treatment for relapsed/refractory multiple myeloma (RRMM) remains an unmet need. Isatuximab, an anti-CD38 monoclonal antibody has shown efficacy and tolerability as a monotherapy and combination therapy in Phase I/II studies in RRMM. Here, we describe the design of the Phase III ICARIA-MM study (NCT02990338) which will evaluate isatuximab in combination with pomalidomide (Pom) and low-dose dexamethasone (dex) (Pom/dex) versus Pom/dex alone in RRMM. Patients will be randomized in a 1:1 ratio. The primary endpoint is progression-free survival. Response will be determined by an independent response review committee using IMWG criteria (2016) and safety will be assessed throughout. Approximately 300 patients (150 in each arm) are expected to enroll. The first patient was recruited in January 2017 and accrual is ongoing.

Emerging drugs and combinations to treat multiple myeloma

In the past few years, multiple targeted therapies and immunotherapies including second generation immunomodulatory drugs (pomalidomide) and proteasome inhibitors (carfilzomib, ixazomib), monoclonal antibodies and checkpoint inhibitors were approved for the treatment of myeloma or entered advanced phases of clinical testing. These agents showed significant activity in advanced myeloma and increased the available treatment strategies. Pomalidomide is well-tolerated and effective in patients with relapsed/refractory multiple myeloma who have exhausted any possible treatment with lenalidomide and bortezomib. Carfilzomib, a second-generation proteasome inhibitor, is active as a single agent and in combination with other anti-myeloma agents. Ixazomib is the first oral proteasome inhibitor to be evaluated in myeloma and is associated with a good safety profile and anti-myeloma activity in relapsed/refractory patients, even in those refractory to bortezomib. Monoclonal antibodies and immune checkpoint inhibitors are likely to play a major role in the treatment of myeloma over the next decade. In phase 3 studies, triplet regimens based on these agents combined with a backbone therapy (including lenalidomide, pomalidomide or bortezomib) were more efficacious than doublet regimens in patients with relapsed/refractory multiple myeloma, with limited additional toxic effects. This paper aims to provide an overview of the recent use of these agents for the treatment of myeloma, in particular focusing on the role of multi-agent combinations.

Carfilzomib/pomalidomide single-agent or in combination with other agents for the management of relapsed/refractory multiple myeloma: a meta-analysis of 37 trials

PURPOSE

The use of carfilzomib/pomalidomide single-agent or in combination with other agents in patients with refractory/relapsed multiple myeloma (RRMM) was not clearly clarified in clinical practice. We sought to compile the available clinical reports to better understand the efficacy and safety of carfilzomib (CFZ) and pomalidomide (POM).

RESULTS

Based on our research criteria, we identified 37 prospective studies that evaluated 1160 patients. Analysis of subgroup differences between carfilzomib single-agent and CFZ/DEX dual combination showed significantly(P < 0.001, I2 = 96.3%), suggesting the overall response rate (ORR) of 66% attained from CFZ/DEX dual combination seemed to be higher than that of 28% from carfilzomib single-agent. And, the same trend favoring CFZ/DEX dual combination was found in ≥VGPR and CBR analysis. The ORR of 31% attained from POM/DEX dual combination was superior to that of 19% from pomalidomide single-agent(P < 0.001, I2 = 94.4%). And, the same trend favoring POM/DEX dual combination was found in ≥VGPR and CBR analysis. However, the ORR of 83% attained from POM/BOR/DEX triplet combination was superior to that of 31% from POM/DEX dual combination(P < 0.001, I2 = 99.1%). And, the same trend favoring POM/BOR/DEX triplet combination was found in ≥VGPR analysis.

METHODS

We searched published reports including carfilzomib and (or) pomalidomide therapy for RRMM who had received bortezomib and (or) lenalidomide.

CONCLUSION

Pomalidomide/Carfilzomib plus dexamethasone seemed to attain a superior response rate compared with pomalidomide/carfilzomib single-agent. Furthermore, the combination of pomalidomide, bortezomib and dexamethasone resulted in a much higher response rate compared with pomalidomide plus dexamethasone regimen. These results needed more validation in future trials.

Immunomodulatory Drugs in Multiple Myeloma: Mechanisms of Action and Clinical Experience

Over the last two decades, the outcomes for patients with multiple myeloma, a plasma cell malignancy, have dramatically improved. The development of the immunomodulatory drugs (IMiDs), which include thalidomide, lenalidomide, and pomalidomide, has contributed significantly to these improved outcomes. While thalidomide is now less commonly prescribed, lenalidomide is widely used in the treatment of newly diagnosed transplant-eligible and transplant-ineligible patients, in the maintenance setting post-transplant and in the relapsed/refractory setting, while pomalidomide is currently utilized in the relapsed/refractory setting. The IMiDs have been reported to have a multitude of activities, including anti-angiogenic, cytotoxic, and immunomodulatory. However, the more recent discoveries that the IMiDs bind to cereblon and thus regulate the ubiquitination of key transcription factors including IKZF1 and IKZF3 have provided greater insight into their mechanism of action. Here, the clinical efficacy of these agents in myeloma is reviewed and the structure-function relationship, the molecular mechanisms of action, and the association of IMiDs with second primary malignancies and thrombosis are discussed.

Carfilzomib Triple Combination Therapy: A Review in Relapsed Multiple Myeloma

Carfilzomib (Kyprolis®) is a proteasome inhibitor that binds selectively and irreversibly to the 20S proteasome (the proteolytic core particle within the 26S proteasome), inducing growth arrest and apoptosis. This intravenous drug is approved in the EU and the USA as combination therapy with oral lenalidomide and intravenous or oral dexamethasone for the treatment of patients with multiple myeloma who have received at least one prior therapy. In the multinational, phase III ASPIRE study in this patient population, carfilzomib triple combination therapy significantly prolonged progression-free survival (PFS), reflecting a clinically relevant gain in PFS of 8.7 months, compared with lenalidomide plus dexamethasone. Improvements in overall response rate and patients' global health status were also observed with carfilzomib triple combination therapy. A significant improvement in overall survival (OS) is yet to be demonstrated, with the prespecified stopping boundary not crossed at the time of the prespecified interim analysis, although OS data were not mature by the cut-off date. Carfilzomib triple combination therapy had a manageable tolerability profile. The incidences of the most frequently reported grade 3 or higher adverse events of special interest (with the exception of neutropenia, anaemia and thrombocytopenia) were low in both the carfilzomib triple combination therapy and lenalidomide plus dexamethasone groups. Although final OS data are awaited, current evidence suggests carfilzomib in combination with lenalidomide and dexamethasone is a welcome addition to the treatment options currently available for patients with relapsed multiple myeloma.

Carfilzomib boosted combination therapy for relapsed multiple myeloma

Carfilzomib is a proteasome inhibitor that binds selectively and irreversibly to the 20S proteasome, the proteolytic core particle within the 26S proteasome, resulting in the accumulation of proteasome substrates and ultimately growth arrest and apoptosis of tumor cells. The development and ultimate approval of this medication by regulatory agencies has been an important step toward improving clinical outcomes in multiple myeloma. Although initially approved as a single agent for the treatment of multiply relapsed and/or refractory myeloma, in the USA, it is now widely used in the early relapse setting in combination with lenalidomide and dexamethasone. Carfilzomib has also been studied in combination with second-generation immunomodulatory drugs, histone deacetylase inhibitors, alkylating agents and other novel medications. In this review article, we will discuss the efficacy, safety, tolerability and quality of life of carfilzomib-based combination therapies, as well as novel agents, for relapsed multiple myeloma.

Triplet combinations in relapsed/refractory myeloma: update on recent phase 3 trials

INTRODUCTION

Multiple myeloma (MM) is a rare hematologic disease of antibody-secreting plasma cells. Our understanding of the pathogenesis of this malignancy has improved greatly, and at the same time, we have access to new and more effective treatments options. Over the last 5 years, a spectrum of novel therapies with different mechanisms of action, including third-generation immunomodulatory drugs (pomalidomide), second generation proteasome inhibitors (carfilzomib and ixazomib), a histone deacetylase inhibitor (panobinostat) and monoclonal antibodies (mAbs) (elotuzumab and daratumumab) has transformed our approach to the treatment of patients with relapsed/refractory MM (RRMM). Areas covered: In this review, we will summarize the characteristics of the new drugs used in RRMM with a specific focus on recent phase 3 trials of triplet combinations in this setting and the rationale behind the selection of one regimen over another. Expert commentary: Several recent phase III trials conducted with patients with RRMM have demonstrated that triplet combinations are associated with a deeper response and an increased duration of response compared to standard treatments. These effective regimens may control the emerging drug resistant clones leading to progression. However, they have distinct toxicity profiles, which need to be taken into account by patients and care givers. The landscape of RRMM is changing rapidly, and new standards of care are proposed.

Population Pharmacokinetics and Exposure-Response Relationship of Carfilzomib in Patients With Multiple Myeloma

A population pharmacokinetic (PK) model and exposure-response (E-R) analysis was developed using data collected from 5 phase 1b/2 and 2 phase 3 studies in subjects with multiple myeloma. Subjects receiving intravenous infusion on 2 consecutive days each week for 3 weeks (days 1, 2, 8, 9, 15, and 16) in each cycle at doses ranging from 15 to 20/56 mg/m² (20 mg/m² in cycle 1 and, if tolerated, escalated to 56 mg/m² on day 8 of cycle 1). The population PK analysis indicated that among all the covariates tested, the only statistically significant covariate was body surface area on carfilzomib clearance; however, this covariate was unlikely to be clinically significant. Despite inclusion of different populations (relapsed or relapsed/refractory), treatments (carfilzomib monotherapy or combination therapy), infusion lengths (2 to 10 minutes or 30 minutes), and different doses, the E-R analysis of efficacy showed that after adjusting for baseline characteristics, higher area under the concentration-time curve was associated with improved overall response rate (ORR), from 15 to 20/56 mg/m² . No positive relationships between maximum concentration and ORR were identified, indicating that ORR would not be expected to be impacted by infusion length. For safety end points, no statistically significant relationship between exposure and increasing risk of adverse events was identified. The results of an E-R analysis provided strong support for a carfilzomib dose at 20/56 mg/m² as a 30-minute infusion for monotherapy and combination therapy. This article illustrates an example of application of E-R analysis to support labeling dose recommendation in the absence of extensive clinical data.

Integration of Novel Agents into the Care of Patients with Multiple Myeloma

The pace of therapeutic drug development in multiple myeloma has reached unprecedented levels, with five regulatory approvals for relapsed and/or refractory disease of either new drugs or new drug regimens in 2015, one already in 2016, and still others anticipated. This has provided a wide array of options to be considered by patients and their health care providers in the event of relapse after or progression on front-line therapy. Most of these agents are currently being evaluated in earlier patient populations, including as parts of induction, consolidation, and maintenance therapy approaches, where their benefits may be even greater. Moreover, additional randomized studies have been completed with our previous stable of novel agents that inform their use in these settings as well. In the current contribution to this CCR Focus on multiple myeloma, we will present an overview of some of the key recent data that have supported the addition of these new therapeutics to our armamentarium against multiple myeloma. Also, we will provide some guidelines about possible best practices in applying these regimens and attempt to extrapolate how they will be used as parts of our future standards of care. Clin Cancer Res; 22(22); 5443-52. ©2016 AACR SEE ALL ARTICLES IN THIS CCR FOCUS SECTION, "MULTIPLE MYELOMA MULTIPLYING THERAPIES".

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.

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.

Specificity of Protein Covalent Modification by the Electrophilic Proteasome Inhibitor Carfilzomib in Human Cells

Carfilzomib (CFZ) is a second-generation proteasome inhibitor that is Food and Drug Administration and European Commission approved for the treatment of relapsed or refractory multiple myeloma. CFZ is an epoxomicin derivative with an epoxyketone electrophilic warhead that irreversibly adducts the catalytic threonine residue of the β5 subunit of the proteasome. Although CFZ produces a highly potent, sustained inactivation of the proteasome, the electrophilic nature of the drug could potentially produce off-target protein adduction. To address this possibility, we synthesized an alkynyl analog of CFZ and investigated protein adduction by this analog in HepG2 cells. Using click chemistry coupled with streptavidin based IP and shotgun tandem mass spectrometry (MS/MS), we identified two off-target proteins, cytochrome P450 27A1 (CYP27A1) and glutathione S-transferase omega 1 (GSTO1), as targets of the alkynyl CFZ probe. We confirmed the adduction of CYP27A1 and GSTO1 by streptavidin capture and immunoblotting methodology and then site-specifically mapped the adducts with targeted MS/MS methods. Although CFZ adduction of CYP27A1 and GSTO1 in vitro decreased the activities of these enzymes, the small fraction of these proteins modified by CFZ in intact cells should limit the impact of these off-target modifications. The data support the high selectivity of CFZ for covalent modification of its therapeutic targets, despite the presence of a reactive electrophile. The approach we describe offers a generalizable method to evaluate the safety profile of covalent protein-modifying therapeutics.

Pooled analysis of the reports of carfilzomib, panobinostat, and elotuzumab combinations in patients with refractory/relapsed multiple myeloma

Purpose

The purpose of this study was to better understand the efficacy and safety of carfilzomib, panobinostat, and elotuzumab combinations in patients with refractory/relapsed multiple myeloma(R/RMM).

Methods

We retrieved and reviewed published reports including carfilzomib, panobinostat, and elotuzumab combination regimens for patients with R/RMM.

Results

We identified 20 prospective studies that evaluated 2220 patients. Carfilzomib combination regimens produced an overall response rate (ORR ≥ PR) of 61 % in the 1211 relapsed/refractory patients. At least very good partial response (VGPR) was 29 % in patients with carfilzomib combinations. Finally, 49 % of the 597 patients achieved ORR in patients receiving panobinostat-containing combinations. At least VGPR was 16 % in patients with panobinostat combinations. Three hundred twenty-eight of these 449 patients (73 %) receiving elotuzumab-containing combinations achieved ORR. And at least VGPR was 37 %. And, the vital nonhematologic adverse events (AEs) were cardiac events and pneumonia.

Conclusion

Carfilzomib, panobinostat, and elotuzumab combination regimens produced clinical benefits in patients with R/RMM.

The MUK five protocol: a phase II randomised, controlled, parallel group, multi-centre trial of carfilzomib, cyclophosphamide and dexamethasone (CCD) vs. cyclophosphamide, bortezomib (Velcade) and dexamethasone (CVD) for first relapse and primary refractory multiple myeloma

Background

Multiple myeloma is a plasma cell tumour with an annual incidence in the UK of approximately 40–50 per million i.e. about 4500 new cases per annum. The triple combination cyclophosphamide, bortezomib (Velcade®) and dexamethasone (CVD) is an effective regimen at relapse and has emerged in recent years as the standard therapy at first relapse in the UK. Carfilzomib has good activity as a single agent in the relapsed setting, and it is expected that efficacy will be improved when used in combination with dexamethasone and cyclophosphamide.

Methods

MUK Five is a phase II open label, randomised, controlled, parallel group, multi-centre trial that will compare the activity of carfilzomib, cyclophosphamide and dexamethasone (CCD) with that of CVD, given over an equivalent treatment period (24 weeks), in participants with multiple myeloma at first relapse, or refractory to no more than 1 line of treatment. In addition, the study also aims to assess the utility of a maintenance schedule of carfilzomib in these participants. The primary objective of the trial is to assess whether CCD provides non-inferior activity in terms of ≥ VGPR rates at 24 weeks, and whether the addition of maintenance treatment with carfilzomib to CCD provides superior activity in terms of progression-free survival, as compared to CCD with no maintenance. Secondary objectives include comparing toxicity profiles, further summarizing and comparing the activity of the different treatment arms and analysis of the effect of each treatment arm on minimal residual disease status.

Discussion

The development of carfilzomib offers the opportunity to further explore the anti-tumour efficacy of proteasome inhibition and, based on the available evidence, it is important and timely to obtain data on the activity, toxicity and tolerability of this drug. In contrast to ongoing phase III trials, this phase II trial has a unique subset of participants diagnosed with multiple myeloma at first relapse or refractory to no more than 1 line of treatment and will also evaluate the utility of maintenance with carfilzomib for up to 18 months and investigate minimal residual disease status to provide information on depth of response and the prognostic impact thereof.

Trial registration

The trial is registered under ISRCTN17354232, December 2012.

Clinical activity of carfilzomib correlates with inhibition of multiple proteasome subunits: application of a novel pharmacodynamic assay

While proteasome inhibition is a validated therapeutic approach for multiple myeloma (MM), inhibition of individual constitutive proteasome (c20S) and immunoproteasome (i20S) subunits has not been fully explored owing to a lack of effective tools. We utilized the novel proteasome constitutive/immunoproteasome subunit enzyme‐linked immunosorbent (ProCISE) assay to quantify proteasome subunit occupancy in samples from five phase I/II and II trials before and after treatment with the proteasome inhibitor carfilzomib. Following the first carfilzomib dose (15–56 mg/m²), dose‐dependent inhibition of c20S and i20S chymotrypsin‐like active sites was observed [whole blood: ≥67%; peripheral blood mononuclear cells (PBMCs): ≥75%]. A similar inhibition profile was observed in bone marrow–derived CD138⁺ tumour cells. Carfilzomib‐induced proteasome inhibition was durable, with minimal recovery in PBMCs after 24 h but near‐complete recovery between cycles. Importantly, the ProCISE assay can be used to quantify occupancy of individual c20S and i20S subunits. We observed a relationship between MM patient response (n = 29), carfilzomib dose and occupancy of multiple i20S subunits, where greater occupancy was associated with an increased likelihood of achieving a clinical response at higher doses. ProCISE represents a new tool for measuring proteasome inhibitor activity in clinical trials and relating drug action to patient outcomes.

A phase 1/2 study of carfilzomib in Japanese patients with relapsed and/or refractory multiple myeloma

We conducted a phase 1/2 study of single-agent carfilzomib in Japanese patients with relapsed/refractory multiple myeloma. Safety, pharmacokinetics and pharmacodynamics of carfilzomib were examined in phase 1. The primary endpoint in phase 2 was the overall response rate (ORR). Carfilzomib was administered in a twice-weekly, consecutive-day dosing schedule. In Phase 1, doses of 15 or 20 mg/m(2) were administered on this schedule or 20 mg/m(2) on Days 1 and 2 of Cycle 1 and then 27 mg/m(2) in the 20/27 mg/m(2) cohort. Patients had a median of five prior therapies, including bortezomib and an immunomodulatory agent. The dose level did not reach the maximum tolerated dose. The most common adverse events were haematological. Notably, carfilzomib either induced new hypertension (n = 4) or aggravated previously existing hypertension (n = 6) in 10 of 50 patients. Four of the eight patients who previously experienced peripheral neuropathy (PN) experienced a recurrence with carfilzomib use, but no new cases of PN occurred. The ORR of the 20/27 mg/m(2) 40 patient cohort was similar to that in the pivotal US study. The dose was efficacious and tolerable in heavily pre-treated Japanese patients; however, meticulous control of hypertension may be necessary for further carfilzomib use.

The Nuclear Factor (Erythroid-derived 2)-like 2 and Proteasome Maturation Protein Axis Mediate Bortezomib Resistance in Multiple Myeloma

Resistance to the proteasome inhibitor bortezomib is an emerging clinical problem whose mechanisms have not been fully elucidated. We considered the possibility that this could be associated with enhanced proteasome activity in part through the action of the proteasome maturation protein (POMP). Bortezomib-resistant myeloma models were used to examine the correlation between POMP expression and bortezomib sensitivity. POMP expression was then modulated using genetic and pharmacologic approaches to determine the effects on proteasome inhibitor sensitivity in cell lines and in vivo models. Resistant cell lines were found to overexpress POMP, and while its suppression in cell lines enhanced bortezomib sensitivity, POMP overexpression in drug-naive cells conferred resistance. Overexpression of POMP was associated with increased levels of nuclear factor (erythroid-derived 2)-like (NRF2), and NRF2 was found to bind to and activate the POMP promoter. Knockdown of NRF2 in bortezomib-resistant cells reduced POMP levels and proteasome activity, whereas its overexpression in drug-naive cells increased POMP and proteasome activity. The NRF2 inhibitor all-trans-retinoic acid reduced cellular NRF2 levels and increased the anti-proliferative and pro-apoptotic activities of bortezomib in resistant cells, while decreasing proteasome capacity. Finally, the combination of all-trans-retinoic acid with bortezomib showed enhanced activity against primary patient samples and in a murine model of bortezomib-resistant myeloma. Taken together, these studies validate a role for the NRF2/POMP axis in bortezomib resistance and identify NRF2 and POMP as potentially attractive targets for chemosensitization to this proteasome inhibitor.

Carfilzomib, pomalidomide, and dexamethasone for relapsed or refractory myeloma

Treatment options for patients with heavily pretreated relapsed and/or refractory multiple myeloma remain limited. We evaluated a novel therapeutic regimen consisting of carfilzomib, pomalidomide, and dexamethasone (CPD) in an open-label, multicenter, phase 1, dose-escalation study. Patients who relapsed after prior therapy or were refractory to the most recently received therapy were eligible. All patients were refractory to prior lenalidomide. Patients received carfilzomib IV on days 1, 2, 8, 9, 15, and 16 (starting dose of 20/27 mg/m(2)), pomalidomide once daily on days 1 to 21 (4 mg as the initial dose level), and dexamethasone (40 mg oral or IV) on days 1, 8, 15, and 22 of 28-day cycles. The primary objective was to evaluate the safety and determine the maximum tolerated dose (MTD) of the regimen. A total of 32 patients were enrolled. The MTD of the regimen was dose level 1 (carfilzomib 20/27 mg/m(2), pomalidomide 4 mg, dexamethasone 40 mg). Hematologic adverse events (AEs) occurred in ≥60% of all patients, including 11 patients with grade ≥3 anemia. Dyspnea was limited to grade 1/2 in 10 patients. Peripheral neuropathy was uncommon and limited to grade 1/2. Eight patients had dose reductions during therapy, and 7 patients discontinued treatment due to AEs. Two deaths were noted on study due to pneumonia and pulmonary embolism (n = 1 each). The combination of CPD is well-tolerated and highly active in patients with relapsed/refractory multiple myeloma. This trial was registered at www.clinicaltrials.gov as #NCT01464034.

Monoclonal antibodies in the treatment of multiple myeloma: current status and future perspectives

The treatment landscape for patients with multiple myeloma (MM) is constantly evolving. Over the past decade, the introduction of novel agents such as proteasome inhibitors and immunomodulatory drugs has led to notable changes in therapeutic strategy, and improvements in survival, yet MM remains incurable in the vast majority of cases. More recently, a targeted approach to MM treatment has emerged, using monoclonal antibodies (mAbs) to target antigens expressed on the surface of MM cells. MAbs tested to date kill MM cells via the host's immune system and/or by promoting apoptosis, and appear to have generally improved tolerability compared with currently available treatments. Due to their distinct mode of action, mAbs are promising both for patients who have exhausted current regimens, and as part of first-line treatments in newly diagnosed patients. This review examines the recent developments in mAb-based therapy for MM, primarily focused on those agents in ongoing clinical testing.

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.

Carfilzomib for the treatment of patients with relapsed and/or refractory multiple myeloma

Carfilzomib is a proteasome inhibitor that irreversibly binds to its target, resulting in sustained proteasomal inhibition with minimal off-target effects. As a single agent, carfilzomib has demonstrated durable antimyeloma activity with manageable toxicities, which has resulted in its approval in Argentina, Israel, Mexico and the USA for the treatment of patients with relapsed and refractory multiple myeloma. Data from ongoing Phase III studies that are evaluating carfilzomib in earlier lines of therapy may facilitate an expanded indication for this agent, as well as for regulatory approval in the EU. This article summarizes the chemistry, pharmacokinetics, pharmacodynamics and available clinical data for carfilzomib in the treatment of patients with multiple myeloma.

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.

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.

New approaches to management of multiple myeloma

Multiple myeloma is still an incurable disease with pattern of regression and remission followed by multiple relapses raising from the residual myeloma cells surviving even in the patients who achieve complete clinical response to treatment. New antimyeloma drugs such as thalidomide, lenalidomide, and bortezomib have dramatically changed treatment paradigm leading to both tumor reduction and tumor suppression. Much progress has been made, but still many unsolved questions remain. In the mode of sequencing treatment for patients with multiple myeloma, we are still using old drugs such as the alkylating agent melphalan, which continues to play a central role in the transplantation setting. Newer drugs are now emerging and are being tested: monoclonal antibodies, histone deacetylase (romidespsin), MLN9708 (ixazomib) a new oral proteasome inhibitor, carfilzomib, signal transduction modulator perifosine. Many advances have been made, but there is still a long way to go.