Treatment of relapsed and refractory myeloma

Clinical and Sociodemographic Characteristics of Patients With Relapsed and/or Refractory Multiple Myeloma and Their influence on Treatment in the Real-World Setting in Spain: The CharisMMa Study

INTRODUCTION

Treatment of relapsed and/or refractory multiple myeloma (RRMM) should be established based on multiple factors, including previous treatment and the sociodemographic/clinical characteristics of the patients. However, patients enrolled in randomized-controlled trials often do not mirror the scenario encountered in real-world practice, thus challenging therapeutic decisions in day-to-day practice.

PATIENTS AND METHODS

This observational, cross-sectional, multicenter study aimed to investigate the sociodemographic and clinical characteristics of patients with RRMM treated in routine practice in Spain and their influence on treatment regimens.

RESULTS

The study included 276 RRMM patients (median age 69 years; no gender predominance). Seventy-four percent of patients had CRAB features at the time of study inclusion, 65.9% bone lesions, 28.7% high-risk cytogenetics, and 27.0% were at ISS stage III; 65.1% were retired and lived in urban areas (75.7%) with their relatives (85.8%); 28.7% had some dependence degree. Patients had experienced their last relapse in a median of 1.61 months before enrollment and had received a median of 2 treatment lines (range 1-10). Second-and third-line therapies were mostly based on immunomodulatory drugs, followed by proteasome inhibitors (PIs), whereas monoclonal antibodies prevailed in later treatment lines. The presence of extramedullary plasmacytomas, the absence of osteopenia, and being in the second or third treatment line (vs. later lines) significantly increased the odds of receiving PIs.

CONCLUSIONS

RRMM treatment in the real-world setting is highly heterogeneous and is primarily influenced by the number of previous lines. The consideration of patients' clinical and sociodemographic characteristics may support clinicians in making therapeutic decisions.

Multidrug resistance 1 (MDR1/ABCB1) gene polymorphism (rs1045642 C > T) and susceptibility to multiple myeloma: a systematic review and meta-analysis

INTRODUCTION

Several studies have evaluated the association between the multidrug resistance 1 (MDR1) polymorphism (rs1045642 C > T) and multiple myeloma (MM). However, the results were not consistent. Therefore, to reach a comprehensive and reliable answer we determined the association of the MDR1 (rs1045642 C > T) polymorphism and MM in the context of meta-analysis.

METHODS

All eligible studies published in EMBASE, PubMed, and Web of Science databases before July 2017 were reviewed. Subsequently, to assess the strength of association in the dominant model, recessive model, allelic model, homozygotes contrast, and heterozygotes contrast, pooled odds ratios and 95% confidence intervals (CIs) were calculated by the fixed effects model.

RESULTS

A total of four case-control studies with 395 MM cases and 418 healthy controls were included in the meta-analysis. The overall results showed no significant association between the MDR1 (rs1045642 C > T) polymorphism and the risk of MM in genetic models (dominant model: OR = 1.04, 95% CI = 0.78-1.38; recessive model: OR = 0.74, 95% CI = 0.52-1.06; allelic model: OR = 0.90, 95% CI = 0.73-1.11; TT vs. CC: OR = 0.80, 95% CI = 0.51-1.25; and CT vs. CC: OR = 1.12, 95% CI = 0.77-1.62). No evidence of publication bias was detected except for the analysis of the recessive model.

CONCLUSION

This meta-analysis suggests that the MDR1 C > T polymorphism was not associated with the risk of MM. To confirm these findings, further comprehensive and well-designed studies are needed.

Overexpression of survivin via activation of ERK1/2, Akt, and NF-κB plays a central role in vincristine resistance in multiple myeloma cells

The acquisition of anti-cancer drug resistance is a major limitation of chemotherapy for multiple myeloma (MM) and it is thus important to identify the mechanisms by which MM cells develop such drug resistance. In a previous study, we showed that multidrug resistance (MDR) involves the overexpression of MDR1 and survivin in vincristine-resistant RPMI8226/VCR cells. However, the underlying mechanism of MDR remains unclear. In this study, we investigated the mechanism of MDR in RPMI8226/VCR cells, and found that RPMI8226/VCR cells exhibit increased levels of activated ERK1/2, Akt, and NF-κB, while the levels of activated mTOR, p38MAPK, and JNK do not differ between RPMI8226/VCR cells and their vincristine-susceptible counterparts. In addition, the inhibition of ERK1/2, Akt, or NF-κB by inhibitors reversed the drug-resistance of RPMI8226/VCR cells via the suppression of survivin expression, but did not affect MDR1 expression; RNA silencing of survivin expression completely reversed vincristine resistance, while MDR1 silencing only weakly suppressed vincristine resistance in RPMI8226/VCR cells. These results indicate that enhanced survivin expression via the activation of ERK1/2, Akt, and NF-κB plays a critical role in vincristine resistance in RPMI8226/VCR cells. Our findings suggest that ERK1/2, Akt, and NF-κB inhibitors are potentially useful as anti-MDR agents for the treatment of vincristine-resistant MM.

Second autologous transplant as salvage therapy in multiple myeloma

High-dose chemotherapy followed by autologous haematopoetic stem cell transplantation (ASCT) is a standard frontline therapy for multiple myeloma (MM). Unfortunately, there are no randomized clinical studies examining the role of a second ASCT in patients who relapse after the initial autotransplant. Analysing all available retrospective studies, it seems that salvage ASCT can safely be performed in most patients with an overall treatment-related mortality rate <5%. Approximately 65% of patients will achieve an objective response and progression-free and overall survival will be around 12 months and 32 months, respectively. Retrospective data suggest that patients with a progression-free survival of ≥18 months after initial ASCT are most likely to benefit from a salvage autotransplant. However, patients with a <12-month duration of response after initial ASCT should not be considered for a second autograft in the relapsed setting because this group will probably only experience ASCT-related toxicity without any clinical benefit. Quality of response after initial ASCT and number of therapies preceding salvage ASCT may also have a predictive value. Importantly, these findings need to be verified by randomized clinical trials in order to firmly integrate salvage ASCT into a global therapeutic concept for myeloma patients including optimized induction, consolidation, and maintenance approaches.

Overexpression of MDR1 and survivin, and decreased Bim expression mediate multidrug-resistance in multiple myeloma cells

Multidrug resistance represents a major obstacle for the chemotherapy of a wide variety of human tumors. To investigate the underlying mechanisms associated with resistance to anti-cancer drugs, we established anti-cancer drug-resistant multiple myeloma (MM) cell lines RPMI8226/ADM, RPMI8226/VCR, RPMI8226/DEX, and RPMI8226/L-PAM, the 50% inhibitory concentration values of which were 77-, 58-, 79-, and 30-fold higher than their parental cell lines, respectively. The resistant cell lines overexpressed MDR1 and survivin, or showed decreased Bim expression. These results indicated that regulating these factors with inhibitors might be a viable approach to increasing the susceptibility of quiescent MM cells to chemotherapy.

Polymorphisms in the multiple drug resistance protein 1 and in P-glycoprotein 1 are associated with time to event outcomes in patients with advanced multiple myeloma treated with bortezomib and pegylated liposomal doxorubicin

Single nucleotide polymorphisms (SNPs) in the multiple drug resistance protein 1 (MRP1) and P-glycoprotein 1 (MDR1) genes modulate their ability to mediate drug resistance. We therefore sought to retrospectively evaluate their influence on outcomes in relapsed and/or refractory myeloma patients treated with bortezomib or bortezomib with pegylated liposomal doxorubicin (PLD). The MRP1/R723Q polymorphism was found in five subjects among the 279 patient study population, all of whom received PLD + bortezomib. Its presence was associated with a longer time to progression (TTP; median 330 vs. 129 days; p = 0.0008), progression-free survival (PFS; median 338 vs. 129 days; p = 0.0006), and overall survival (p = 0.0045). MDR1/3435(C > T), which was in Hardy-Weinberg equilibrium, showed a trend of association with PFS (p = 0.0578), response rate (p = 0.0782) and TTP (p = 0.0923) in PLD + bortezomib patients, though no correlation was found in the bortezomib arm. In a recessive genetic model, MDR1/3435 T was significantly associated with a better TTP (p = 0.0405) and PFS (p = 0.0186) in PLD + bortezomib patients. These findings suggest a potential role for MRP1 and MDR1 SNPs in modulating the long-term outcome of relapsed and/or refractory myeloma patients treated with PLD + bortezomib. Moreover, they support prospective studies to determine if such data could be used to tailor therapy to the genetic makeup of individual patients.

Combined proteasome and histone deacetylase inhibition: A promising synergy for patients with relapsed/refractory multiple myeloma

Multiple myeloma (MM) is an incurable disease characterized by the accumulation of malignant plasma cells in the bone marrow. Recently, an improved understanding of the biology of the disease has led to the development of targeted agents such as the proteasome inhibitor bortezomib and the immunomodulatory agents thalidomide and lenalidomide; however, MM remains incurable. The combination of bortezomib and an HDAC inhibitor synergistically induces MM cell apoptosis and may be of value in the treatment of patients with relapsed/refractory MM. This review examines the potential of combined proteasome and HDAC inhibition in the treatment of relapsed/refractory MM.

Advances in treatment for relapses and refractory multiple myeloma

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

Novel agents for relapsed and/or refractory multiple myeloma

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

The persisting challenge of selective and specific proteasome inhibition

Since the discovery of the proteasome and its structure elucidation intensive research programs in academic institutions and pharmaceutical industries led to identification of a wide spectrum of synthetic and natural small proteasomal inhibitors. Activity studies with these small molecules helped to deeply understand the complex biochemical organization and functioning of the proteasome. The new structural and biochemical insights placed the proteasome as an important anti-cancer drug target, as revealed by the dipeptide boronate proteasome inhibitor, bortezomib, which is currently used for treatment of multiple myeloma. Serious side effects and partial cell resistance against bortezomib demand creation and discovery of new improved generations of more specific and potent proteasomal inhibitors.