Efficacy and safety of carfilzomib regimens in multiple myeloma patients relapsing after autologous stem cell transplant: ASPIRE and ENDEAVOR outcomes

Proteomic Alteration in the Progression of Multiple Myeloma: A Comprehensive Review

Multiple myeloma (MM) is an incurable hematologic malignancy. Most MM patients are diagnosed at a late stage because the early symptoms of the disease can be uncertain and nonspecific, often resembling other, more common conditions. Additionally, MM patients are commonly associated with rapid relapse and an inevitable refractory phase. MM is characterized by the abnormal proliferation of monoclonal plasma cells in the bone marrow. During the progression of MM, massive genomic alterations occur that target multiple signaling pathways and are accompanied by a multistep process involving differentiation, proliferation, and invasion. Moreover, the transformation of healthy plasma cell biology into genetically heterogeneous MM clones is driven by a variety of post-translational protein modifications (PTMs), which has complicated the discovery of effective treatments. PTMs have been identified as the most promising candidates for biomarker detection, and further research has been recommended to develop promising surrogate markers. Proteomics research has begun in MM, and a comprehensive literature review is available. However, proteomics applications in MM have yet to make significant progress. Exploration of proteomic alterations in MM is worthwhile to improve understanding of the pathophysiology of MM and to search for new treatment targets. Proteomics studies using mass spectrometry (MS) in conjunction with robust bioinformatics tools are an excellent way to learn more about protein changes and modifications during disease progression MM. This article addresses in depth the proteomic changes associated with MM disease transformation.

Canagliflozin mitigates carfilzomib-induced endothelial apoptosis via an AMPK-dependent pathway

Carfilzomib (CFZ) is a proteasome inhibitor approved for relapsed/refractory multiple myeloma (MM) but its clinical use is limited by cardiovascular toxicity. The mechanisms of CFZ-induced cardiovascular toxicity are not fully understood but endothelial dysfunction may be a common denominator. Here, we first characterized the direct toxic effects of CFZ on endothelial cells (HUVECs and EA.hy926 cells) and tested whether SGLT2 inhibitors, known to have cardioprotective effects, can protect against CFZ-induced toxicity. To determine the chemotherapeutic effect of CFZ in the presence of SGLT2 inhibitors, MM and lymphoma cells were treated with CFZ with or without canagliflozin. CFZ decreased cell viability and induced apoptotic cell death in endothelial cells in a concentration-dependent manner. CFZ also upregulated ICAM-1 and VCAM-1 and downregulated VEGFR-2. These effects were associated with the activation of Akt and MAPK pathways, inhibition of p70s6k, and downregulation of AMPK. Canagliflozin, but not empagliflozin or dapagliflozin, protected endothelial cells from CFZ-induced apoptosis. Mechanistically, canagliflozin abrogated CFZ-induced JNK activation and AMPK inhibition. AICAR (an AMPK activator) protected from CFZ-induced apoptosis, and compound C (an AMPK inhibitor) abrogated the protective effect of canagliflozin, strongly suggesting that AMPK mediates these effects. Canagliflozin did not interfere with the anticancer effect of CFZ in cancer cells. In conclusion, our findings demonstrate for the first time the direct toxic effects of CFZ in endothelial cells and the associated signaling changes. Canagliflozin abrogated the apoptotic effects of CFZ in endothelial cells in an AMPK-dependent mechanism, without interfering with its cytotoxicity in cancer cells.

Carfilzomib, lenalidomide, and dexamethasone in relapsed refractory multiple myeloma: a prospective real-life experience of the Regional Tuscan Myeloma Network

Introduction

Carfilzomib, a potent, irreversible, selective proteasome inhibitor has demonstrated consistent results in relapsed/refractory multiple myeloma (RRMM) combined with lenalidomide and dexamethasone (KRd). No prospective studies are yet available that analyzed the efficacy of the KRd combination.

Methods

Herein, we report a multicenter prospective observational study on 85 patients who were treated with KRd combination as the second or third line of treatment, according to standard practice.

Results

The median age was 61 years; high-risk cytogenetic was found in 26% and renal impairment (estimated glomerular filtration rate (eGFR) <60 ml/min) in 17%. After a median follow-up of 40 months, patients received a median number of 16 cycles of KRd, with a median duration of treatment (DoT) of 18 months (range, 16.1-19.2 months). The overall response rate was 95%, with a high-quality response (≥very good partial remission [VGPR]) in 57% of the patients. The median progression-free survival (PFS) was 36 months (range, 29.1-43.2 months). Achievement of at least VGPR and a previous autologous stem cell transplantation (ASCT) were associated with longer PFS. The median overall survival (OS) was not reached (NR); the 5-year OS rate was 73%. Nineteen patients underwent KRd treatment as a bridge to autologous transplantation, obtaining a post-transplant minimal residual disease (MRD) negativity in 65% of cases. The most common adverse events were hematological, followed by infection and cardiovascular events, rarely G3 or higher, with a discontinuation rate for toxicities of 6%. Our data confirmed the feasibility and safety of the KRd regimen in real life.

Isatuximab Plus Carfilzomib and Dexamethasone Versus Carfilzomib and Dexamethasone in Patients with Relapsed Multiple Myeloma: IKEMA Subgroup Analysis by Prior Transplantation

In the era of highly active novel agents for multiple myeloma (MM), the role, ideal timing, and impact of transplantation on further therapy after relapse remains a matter of debate. The impact of prior transplantation on treatment benefit from monoclonal antibodies in patients with relapsed/refractory MM (RRMM) is largely unknown. Few Phase 3 studies of monoclonal antibody combinations with proteasome inhibitors or immunomodulatory agents have reported outcomes according to transplantation status. This subgroup analysis examined efficacy and safety in patients from the Phase 3 IKEMA study with and without previous transplantation. IKEMA (NCT03275285) was a randomized, open-label, multinational, parallel-group Phase 3 study that investigated isatuximab (Isa), an anti-CD38 monoclonal antibody, combined with carfilzomib and dexamethasone (Isa-Kd; experimental group) versus Kd (control group) in 302 patients with RRMM and 1 to 3 prior lines of therapy. Patients were randomized in a 3:2 ratio to either Isa-Kd or Kd, with stratification by number of prior lines (1 versus more than 1) and Revised International Staging System (R-ISS) stage (I or II versus III versus not classified). Treatment was given until progressive disease, unacceptable adverse events, or patient choice. Of the 302 randomized patients in IKEMA, 185 (61.3%) had received a prior transplant, comprising 116 of 179 (64.8%) patients in the Isa-Kd arm and 69 of 123 (56.1%) patients in the Kd arm. After a median follow-up of 20.6 months, median progression-free survival (PFS) in patients with prior transplant was not reached with Isa-Kd versus 19.15 months with Kd (hazard ratio [HR] = 0.60; 99% confidence interval [CI], 0.31-1.16). After a median follow-up of 20.8 months, median PFS in patients without prior transplant was not reached with Isa-Kd versus 18.99 months with Kd (HR = 0.44; 99% CI, 0.18-1.05). The overall response rate in patients with prior transplant was 87.9% (Isa-Kd) versus 85.5% (Kd). More patients in the Isa-Kd arm achieved a complete response or better compared with the Kd arm (43.1% versus 29.0%). The overall response rate in patients without prior transplant was 84.1% (Isa-Kd) versus 79.6% (Kd). More patients in the Isa-Kd arm achieved a complete response or better compared with the Kd arm (33.3% versus 25.9%). The minimal residual disease negativity rate was higher with Isa-Kd versus Kd in patients with (31.9% versus 13.0%) and without prior transplantation (25.4% versus 13.0%). In patients with prior transplant, Grade 3 or higher treatment-emergent adverse events (TEAEs) were more common with Isa-Kd; however, no increases in serious TEAEs or definitive treatment discontinuations were seen versus Kd. Among patients without prior transplant, serious treatment-related TEAEs were similar, and there were fewer TEAEs leading to definitive discontinuation with Isa-Kd. The most common Grade 3 or higher TEAEs in patients with and without prior transplant were hypertension and pneumonia. For patients who underwent prior transplantation, Isa-Kd is an effective treatment option. Overall, these data demonstrate that Isa-Kd represents a standard of care for patients with RRMM, regardless of prior transplant status.

Genome Instability in Multiple Myeloma: Facts and Factors

Multiple myeloma (MM) is a malignant neoplasm of terminally differentiated immunoglobulin-producing B lymphocytes called plasma cells. MM is the second most common hematologic malignancy, and it poses a heavy economic and social burden because it remains incurable and confers a profound disability to patients. Despite current progress in MM treatment, the disease invariably recurs, even after the transplantation of autologous hematopoietic stem cells (ASCT). Biological processes leading to a pathological myeloma clone and the mechanisms of further evolution of the disease are far from complete understanding. Genetically, MM is a complex disease that demonstrates a high level of heterogeneity. Myeloma genomes carry numerous genetic changes, including structural genome variations and chromosomal gains and losses, and these changes occur in combinations with point mutations affecting various cellular pathways, including genome maintenance. MM genome instability in its extreme is manifested in mutation kataegis and complex genomic rearrangements: chromothripsis, templated insertions, and chromoplexy. Chemotherapeutic agents used to treat MM add another level of complexity because many of them exacerbate genome instability. Genome abnormalities are driver events and deciphering their mechanisms will help understand the causes of MM and play a pivotal role in developing new therapies.

Carfilzomib, Lenalidomide, and Dexamethasone Followed by Salvage Autologous Stem Cell Transplant with or without Maintenance for Relapsed or Refractory Multiple Myeloma

Salvage high-dose chemotherapy and autologous stem cell transplantation (HDCT/ASCT) is a treatment option for relapsed and/or refractory multiple myeloma (RRMM). No data are available on salvage HDCT/ASCT following re-induction treatment with state-of-the-art triplet regimens. We retrospectively report on 44 patients receiving salvage HDCT/ASCT following re-induction with carfilzomib/lenalidomide/dexamethasone (KRd). All patients received frontline HDCT/ASCT with median time to progression (TTP1) of 2.9 (1.2-13.5) years, enabling paired comparison of frontline and salvage HDCT/ASCT. After re-induction and before salvage transplant, 25/44 patients (57%) attained ≥ very good partial response (VGPR), which increased to 34/44 (77%) at best response after salvage HDCT/ASCT. Median progression-free survival (PFS) was 23.3 months from salvage HDCT/ASCT. Patients with ≥ VGPR at the time of salvage HDCT/ASCT and those receiving maintenance treatment post salvage HDCT/ASCT had significantly superior PFS (hazard ratio (HR) 0.19, p = 0.001 and HR 0.20, p = 0.009). In patients achieving at least an equal depth of response before salvage HDCT/ASCT as before frontline HDCT/ASCT, PFS after salvage HDCT/ASCT was comparable to the frontline situation (p = 0.3). This is the first report of state-of-the-art triplet re-induction and salvage HDCT/ASCT for RRMM after frontline transplantation. Deep remissions achieved with KRd translate into prolonged PFS following salvage HDCT/ASCT and are enhanced by maintenance treatment.

Copy number evolution and its relationship with patient outcome-an analysis of 178 matched presentation-relapse tumor pairs from the Myeloma XI trial

Structural chromosomal changes including copy number aberrations (CNAs) are a major feature of multiple myeloma (MM), however their evolution in context of modern biological therapy is not well characterized. To investigate acquisition of CNAs and their prognostic relevance in context of first-line therapy, we profiled tumor diagnosis-relapse pairs from 178 NCRI Myeloma XI (ISRCTN49407852) trial patients using digital multiplex ligation-dependent probe amplification. CNA profiles acquired at relapse differed substantially between MM subtypes: hyperdiploid (HRD) tumors evolved predominantly in branching pattern vs. linear pattern in t(4;14) vs. stable pattern in t(11;14). CNA acquisition also differed between subtypes based on CCND expression, with a marked enrichment of acquired del(17p) in CCND2 over CCND1 tumors. Acquired CNAs were not influenced by high-dose melphalan or lenalidomide maintenance randomization. A branching evolution pattern was significantly associated with inferior overall survival (OS; hazard ratio (HR) 2.61, P = 0.0048). As an individual lesion, acquisition of gain(1q) at relapse was associated with shorter OS, independent of other risk markers or time of relapse (HR = 2.00; P = 0.021). There is an increasing need for rational therapy sequencing in MM. Our data supports the value of repeat molecular profiling to characterize disease evolution and inform management of MM relapse.

Emerging agents and regimens for multiple myeloma

The outcomes of multiple myeloma (MM) have been improved significantly with the therapies incorporating proteasome inhibitors (PI), immunomodulatory drugs, monoclonal antibodies (MoAb) and stem cell transplantation. However, relapsed and refractory MM (RRMM) remains a major challenge. Novel agents and regimens are under active clinical development. These include new PIs such as ixazomib, marizomib, and oprozomib; new MoAbs such as isatuximab and MOR202; novel epigenetic agent ricolinostat and novel cytokines such as siltuximab. Recently, the first XPO-1 inhibitor, selinexor, was approved for RRMM. BCMA-targeted BiTE, antibody-drug conjugates and CAR-T cells have the potential to revolutionize the therapy for RRMM. In this review, we summarized the latest clinical development of these novel agents and regimens.

Carfilzomib, lenalidomide, and dexamethasone in relapsed/refractory multiple myeloma patients: the real-life experience of Rete Ematologica Pugliese (REP)

Carfilzomib, lenalidomide, and dexamethasone (KRd) have been approved for the treatment of relapsed and refractory multiple myeloma (RRMM) based on ASPIRE clinical trial. However, its effectiveness and safety profile in real clinical practice should be further assessed. We retrospectively evaluated 130 consecutive RRMM patients treated with KRd between December 2015 and August 2018, in 9 Hematology Departments of Rete Ematologica Pugliese (REP). The overall response rate (ORR) was 79%, with 37% complete response (CR). Treatment with KRd led to an improvement in response regardless of age, refractory disease, and number and type of previous therapies. After a median follow-up of 18 months, median PFS was 24 months and 2y-PFS was 54%. PFS was longer in patients achieving a very good partial response (VGPR) with median PFS of 32.4 months. The relapses after prior autologous transplant (ASCT) positively impact median PFS. Several baseline disease characteristics, such as III ISS scoring or elevated LDH, and prior exposure to lenalidomide were found to negatively impact PFS. Primary refractory or relapsed myeloma patients have been treated with KRd as bridge to ASCT with a great benefit. Thirty-four (83%) reached at least a partial response after KRd and 21 (61%) performed ASCT. In transplanted patients, median PFS was not reached and 2y-PFS was 100%. The treatment discontinuation rate due to adverse events (AEs) was 18%, most commonly for lenalidomide (11%). Overall, in 10% of patients, a KRd dose reduction was necessary at least once (2.5% for carfilzomib and 8% for lenalidomide). The most frequent AE was neutropenia (44%) and anemia (41%). Infections occurred in 14% of patients. Cardiovascular events occurred in 11% of patients. Elderly patients have tolerated therapy very well, without additional side effects compared to younger patients, except for cardiac impairment. Our analysis confirmed that KRd is effective in RRMM patients. It is well tolerated and applicable to the majority of patients outside clinical trials. A longer PFS was shown in patients achieving VGPR, in those lenalidomide naïve and in patients relapsing after previous ASCT. Previous ASCT should not hamper the option for KRd therapy. Accordingly, KRd should be used as bridge regimen to ASCT with remarkable improvement in response and PFS rates. Further clinical studies are needed.

A real-world efficacy and safety analysis of combined carfilzomib, lenalidomide, and dexamethasone (KRd) in relapsed/refractory multiple myeloma

Carfilzomib-lenalidomide-dexamethasone (KRd) has been approved for the treatment of relapsed/refractory multiple myeloma (RRMM). We conducted a retrospective analysis of 197 RRMM patients (pts) between January 2016 and March 2018 in six Italian hematologic centers, with the aim to evaluate efficacy and safety of KRd in real-life. At KRd initiation 27% carried high risk cytogenetic abnormalities (HRCA) [del17p and/or t(4;14) and/or t(14;16)], median number of prior lines of therapy was 2 (1-8), nearly all pts (96%) received prior bortezomib (18% refractory) while 45% were exposed to lenalidomide (R; 22% refractory). At the median of 12.5 months, 52% of the pts had discontinued treatment, mainly (66%) for progression. Main grade 3-4 adverse events were neutropenia (21%), infections (11%), and hypertension (6%). Overall, the response rate was 88%. The median progression-free survival (PFS) was 19.8 months and 1-year overall survival (OS) rate was 80.6%. By subgroup analysis, extended PFS and OS were observed for pts who received ≤2 prior lines of therapy (HR = 0.42, p < 0.001 and HR = 0.35, p = 0.001, respectively), not refractory to prior R (HR = 0.37, p < 0.001, and HR = 0.47, p = 0.024), without HRCA (HR = 0.33, p = 0.005 and HR = 0.26, p = 0.016) and achieving ≥ very good partial response (VGPR; HR = 0.17, p < 0.001 and HR = 0.18, p < 0.001). In conclusion, KRd demonstrated to be effective in RRMM pts treated in real-world setting, without new safety concerns. Better survival outcomes emerged for pts with ≤2 prior lines of therapy, achieving at least a VGPR, and without HRCA.

Improved outcome in patients following autologous stem cell transplantation for multiple myeloma in south eastern Norway 2001-2010: a retrospective, population based analysis

BACKGROUND

With the advent of novel drugs improved overall survival in patients with multiple myeloma, including patients who received up-front autologous stem cell transplantation (ASCT), has been reported from several centers. Here we report on overall survival in a population-based cohort of patients receiving ASCT as first line treatment and in whom novel agents were an option for second and later lines of treatment.

METHODS

Patients with multiple myeloma ≤ 65 years of age who were considered for ASCT from 01.01.2001-31.06.2005 (period 1) and from 01.07.2005 until 31.12.2009 (period 2) at Oslo University Hospital (OUH) were identified. Relevant data were collected from the patients' medical records.

RESULTS

Altogether, 293/355 patients received ASCT. In all, median OS was 82.9 months in patients ≤ 60 years of age and 59.0 months in patients 61-65 years. For patients ≤ 60 years of age median OS increased from 70.6 months to 87.7 months (p = 0. 22) and median survival after start of second line therapy increased from 34.5 months to 46.5 months (p = 0.015) between the two periods. For patients 61-65 years of age median OS increased from 57.3 months to 61.2 months (p = 0. 87) and median survival after start of second line therapy was practically unchanged (32.6 months vs. 33.1 months (p = 0.97) between the periods. In patients ≤ 60 years of age salvage ASCT was used in 34% of the patients while in patients 61-65 years of age salvage ASCT was used in 7.3% of the patients. The use of salvage ASCT and novel drugs, as well as the number of treatment lines, were higher in patients ≤ 60 years of age and increased during the study period.

CONCLUSION

In patients ≤ 60 years of age an increased median OS of 17 months between the two periods were noted, but the difference failed to reach statistical significance. However, a statistically significant difference in median survival of 12 months after start of second line therapy was found in this age group, which may be explained by a more active second line treatment. In patients 61-65 years only a slight increase of survival, not statistically significant, was noted between the periods.

Ixazomib in the management of relapsed multiple myeloma

The development of proteasome inhibitors contributed to the dramatic life expectancy improvement observed in myeloma patients over the past decades. Ixazomib is a boron-containing selective and reversible proteasome inhibitor that demonstrated antimyeloma activity with excellent safety profile. Ixazomib is the first orally available proteasome inhibitor approved in combination with lenalidomide and dexamethasone for the treatment of myeloma patients who received at least one prior therapy. The present review addresses the current knowledge regarding the clinical use of ixazomib in relapsed myeloma 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.

Improvement in Overall Survival With Carfilzomib, Lenalidomide, and Dexamethasone in Patients With Relapsed or Refractory Multiple Myeloma

Purpose

In the ASPIRE study of carfilzomib, lenalidomide, and dexamethasone (KRd) versus lenalidomide plus dexamethasone (Rd) in patients with relapsed or refractory multiple myeloma, progression-free survival was significantly improved in the carfilzomib group (hazard ratio, 0.69; two-sided P < .001). This prespecified analysis reports final overall survival (OS) data and updated safety results.

Patients and Methods

Adults with relapsed multiple myeloma (one to three prior lines of therapy) were eligible and randomly assigned at a one-to-one ratio to receive KRd or Rd in 28-day cycles until withdrawal of consent, disease progression, or occurrence of unacceptable toxicity. After 18 cycles, all patients received Rd only. Progression-free survival was the primary end point; OS was a key secondary end point. OS was compared between treatment arms using a stratified log-rank test.

Results

Median OS was 48.3 months (95% CI, 42.4 to 52.8 months) for KRd versus 40.4 months (95% CI, 33.6 to 44.4 months) for Rd (hazard ratio, 0.79; 95% CI, 0.67 to 0.95; one-sided P = .0045). In patients receiving one prior line of therapy, median OS was 11.4 months longer for KRd versus Rd; it was 6.5 months longer for KRd versus Rd among patients receiving ≥ two prior lines of therapy. Rates of treatment discontinuation because of adverse events (AEs) were 19.9% (KRd) and 21.5% (Rd). Grade ≥ 3 AE rates were 87.0% (KRd) and 83.3% (Rd). Selected grade ≥ 3 AEs of interest (grouped terms; KRd v Rd) included acute renal failure (3.8% v 3.3%), cardiac failure (4.3% v 2.1%), ischemic heart disease (3.8% v 2.3%), hypertension (6.4% v 2.3%), hematopoietic thrombocytopenia (20.2% v 14.9%), and peripheral neuropathy (2.8% v 3.1%).

Conclusion

KRd demonstrated a statistically significant and clinically meaningful reduction in the risk of death versus Rd, improving survival by 7.9 months. The KRd efficacy advantage is most pronounced at first relapse.

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.

Phase 1/2 Trial of Carfilzomib Plus High-Dose Melphalan Preparative Regimen for Salvage Autologous Hematopoietic Cell Transplantation Followed by Maintenance Carfilzomib in Patients with Relapsed/Refractory Multiple Myeloma

We performed a phase 1/2 trial to investigate the safety and activity of the second-generation proteasome inhibitor Carfilzomib (K) on days -3/-2 in combination with melphalan 200 mg/m² (MEL200) on day -2 (K-MEL) in patients with relapsed multiple myeloma (MM) undergoing autologous hematopoietic cell transplantation (phases 1 and 2). Patients without progression received 12 cycles of K maintenance at 36 mg/m² days 1, 8, and 15 (schedule A) or days 1, 2, 15, and 16 (schedule B), with patients being treated for 2 cycles in each schedule and on the patient-preferred schedule for the remaining cycles (phase 2). The patients had received a median of 3 previous lines of therapy, 56% had undergone previous AHCT, and 51% had received previous K therapy. During phase 1 (n = 15), the maximum tolerated dose of K in combination with MEL200 was not reached, so the maximum tested dose of 27 mg/m² (on day -3) and 56 mg/m² (on day -2) was used in phase 2. The rate of very good partial response after K-MEL therapy (n = 44) was 59.2%, compared with 13.7% before K-MEL therapy. Among patients starting maintenance therapy (n = 27), 12-month progression-free survival was 66.7% and 12-month overall survival was 88.1%. There was no strong patient preference for either schedule. Two patients discontinued maintenance due to toxicity. K-MEL followed by K maintenance is safe and active salvage therapy in patients with MM.