Carfilzomib enhances natural killer cell-mediated lysis of myeloma linked with decreasing expression of HLA class I

Addition of Elotuzumab to Backbone Treatment Regimens for Multiple Myeloma: An Updated Meta-Analysis of Randomized Clinical Trials

BACKGROUND

The efficacy of elotuzumab, an anti-SLAMF7 monoclonal antibody, in treating relapsed/refractory multiple myeloma (RRMM) and newly-diagnosed multiple myeloma (NDMM) has varied in randomized controlled trials (RCTs). Moreover, there is limited data on its real-world application.

PATIENTS AND METHODS

We conducted a systematic review and meta-analysis of RCTs investigating the addition of elotuzumab to backbone antimyeloma regimens. The primary outcome of interest was progression-free survival (PFS). Secondary efficacy outcomes included overall survival (OS), overall response rate (ORR), and rates of very good partial response or better (VGPR). Key toxicities were also evaluated.

RESULTS

Three RRMM trials (n = 915) and 5 NDMM trials (n = 1790) were included, with 50% of the 2705 patients receiving elotuzumab-containing triplets or quadruplets. In RRMM settings, elotuzumab use significantly improved PFS (hazard ratio [HR], 0.70; 95% confidence interval [CI], 0.60-0.82; P < .001; I² = 0%). This benefit was consistent among patients with high-risk cytogenetics (HR, 0.62; 95% CI, 0.43-0.90; P = .01; I² = 0%) and was particularly evident in those previously treated with proteasome inhibitors (PIs) or immunomodulatory drugs (IMiDs). The RRMM cohort also demonstrated better OS, ORR, and ≥VGPR rate. However, the NDMM cohort showed no significant improvements in any efficacy outcomes. Despite an increase in severe (grade ≥3) infections, elotuzumab use did not adversely affect rates of severe cytopenias, severe cardiac disorders, or second primary malignancies.

CONCLUSION

Our results suggest that elotuzumab-containing regimens represent valuable therapeutic options for PI/IMiD-exposed patients with RRMM. In contrast, elotuzumab's role in frontline settings remains limited.

Proteasome inhibition enhances the anti-leukemic efficacy of chimeric antigen receptor (CAR) expressing NK cells against acute myeloid leukemia

BACKGROUND

Relapsed and refractory acute myeloid leukemia (AML) carries a dismal prognosis. CAR T cells have shown limited efficacy in AML, partially due to dysfunctional autologous T cells and the extended time for generation of patient specific CAR T cells. Allogeneic NK cell therapy is a promising alternative, but strategies to enhance efficacy and persistence may be necessary. Proteasome inhibitors (PI) induce changes in the surface proteome which may render malignant cells more vulnerable to NK mediated cytotoxicity. Here, we investigated the potential benefit of combining PIs with CAR-expressing allogeneic NK cells against AML.

METHODS

We established the IC50 concentrations for Bortezomib and Carfilzomib against several AML cell lines. Surface expression of class-I HLA molecules and stress-associated proteins upon treatment with proteasome inhibitors was determined by multiparameter flow cytometry. Using functional in vitro assays, we explored the therapeutic synergy between pre-treatment with PIs and the anti-leukemic efficacy of NK cells with or without expression of AML-specific CAR constructs against AML cell lines and primary patient samples. Also, we investigated the tolerability and efficacy of a single PI application strategy followed by (CAR-) NK cell infusion in two different murine xenograft models of AML.

RESULTS

AML cell lines and primary AML patient samples were susceptible to Bortezomib and Carfilzomib mediated cytotoxicity. Conditioned resistance to Azacitidine/Venetoclax did not confer primary resistance to PIs. Treating AML cells with PIs reduced the surface expression of class-I HLA molecules on AML cells in a time-and-dose dependent manner. Stress-associated proteins were upregulated on the transcriptional level and on the cell surface. NK cell mediated killing of AML cells was enhanced in a synergistic manner. PI pre-treatment increased effector-target cell conjugate formation and Interferon-γ secretion, resulting in enhanced NK cell activity against AML cell lines and primary samples in vitro. Expression of CD33- and CD70-specific CARs further improved the antileukemic efficacy. In vivo, Bortezomib pre-treatment followed by CAR-NK cell infusion reduced AML growth, leading to prolonged overall survival.

CONCLUSIONS

PIs enhance the anti-leukemic efficacy of CAR-expressing allogeneic NK cells against AML in vitro and in vivo, warranting further exploration of this combinatorial treatment within early phase clinical trials.

Different evasion strategies in multiple myeloma

Multiple myeloma is the second most common malignant hematologic malignancy which evolved different strategies for immune escape from the host immune surveillance and drug resistance, including uncontrolled proliferation of malignant plasma cells in the bone marrow, genetic mutations, or deletion of tumor antigens to escape from special targets and so. Therefore, it is a big challenge to efficiently treat multiple myeloma patients. Despite recent applications of immunomodulatory drugs (IMiDS), protease inhibitors (PI), targeted monoclonal antibodies (mAb), and even hematopoietic stem cell transplantation (HSCT), it remains hardly curable. Summarizing the possible evasion strategies can help design specific drugs for multiple myeloma treatment. This review aims to provide an integrative overview of the intrinsic and extrinsic evasion mechanisms as well as recently discovered microbiota utilized by multiple myeloma for immune evasion and drug resistance, hopefully providing a theoretical basis for the rational design of specific immunotherapies or drug combinations to prevent the uncontrolled proliferation of MM, overcome drug resistance and improve patient survival.

Natural killer cells affect the natural course, drug resistance, and prognosis of multiple myeloma

Multiple myeloma (MM), a stage-developed plasma cell malignancy, evolves from monoclonal gammopathy of undetermined significance (MGUS) or smoldering MM (SMM). Emerging therapies including immunomodulatory drugs, proteasome inhibitors, monoclonal antibodies, chimeric antigen-T/natural killer (NK) cells, bispecific T-cell engagers, selective inhibitors of nuclear export, and small-molecule targeted therapy have considerably improved patient survival. However, MM remains incurable owing to inevitable drug resistance and post-relapse rapid progression. NK cells with germline-encoded receptors are involved in the natural evolution of MGUS/SMM to active MM. NK cells actively recognize aberrant plasma cells undergoing malignant transformation but are yet to proliferate during the elimination phase, a process that has not been revealed in the immune editing theory. They are potential effector cells that have been neglected in the therapeutic process. Herein, we characterized changes in NK cells regarding disease evolution and elucidated its role in the early clinical monitoring of MM. Additionally, we systematically explored dynamic changes in NK cells from treated patients who are in remission or relapse to explore future combination therapy strategies to overcome drug resistance.

A Clinical and Correlative Study of Elotuzumab, Carfilzomib, Lenalidomide, and Dexamethasone (Elo-KRd) for Lenalidomide Refractory Multiple Myeloma in First Relapse

INTRODUCTION

Treatment of patients with multiple myeloma (MM) in first relapse remains a challenge. This phase II study combined elotuzumab (Elo) with carfilzomib, lenalidomide, and dexamethasone (KRd) for treatment of MM in first relapse with the aim of improving efficacy.

METHODS

Enrolled patients received Elo-KRd induction for 4 cycles, and Elo-lenalidomide maintenance until progression. The primary endpoint was VGPR or better (≥VGPR) postinduction. Secondary endpoints were MRD by flow cytometry, OS, PFS, and safety. Correlatives included characterization of the impact of Elo-KRd on NK and T cell subsets via flow cytometry. Target accrual of 40 patients was not met due to COVID-19 pandemic.

RESULTS

Of 15 patients enrolled, 10 (67%) had high-risk features (del17p, t[4;14], t[14;16], 1q gain/amplification, plasma cell leukemia, extramedullary MM, or functional high risk), 12 (80%) were lenalidomide-refractory, and 5 (33.3%) bortezomib-refractory. Postinduction ≥VGPR was 7/15 (46.7%) and MRD-negative (10^-5) rate 20%. Overall response during study was 80%, including ≥VGPR as best response of 53.3%. At median follow-up of 28.2 (range, 3.8 to 44.2) months, the median PFS was 11.5 months (95% CI 1.9, 18), and median OS not reached (95% CI 10.1, NA). No new safety concerns were reported. Elo-KRd treatment did not augment NK cell distribution or activity in blood or bone marrow. Effector CD4+ and CD8+ T cells significantly decreased postinduction, with concomitant acquisition of T central memory phenotype, particularly at a high rate in ≥VGPR group.

CONCLUSION

A short course of Elo-KRd induction followed by Elo-lenalidomide maintenance demonstrated activity in predominantly lenalidomide-refractory and / or high-risk MM. The results with this well-tolerated combination are comparable to other contemporary approved triplet combinations.

NK cell therapy in relapsed refractory multiple myeloma

Recent advances in adoptive cell therapy have considerably changed the paradigm of cancer immunotherapy. Although current immunotherapies could cure many patients with multiple myeloma (MM), relapsed/refractory MM (RR/MM) is still challenging in some cases. Natural killer (NK) cells are innate immune cells that exert effective cytotoxic activity against malignant cells like myeloma cells. In addition to their antitumor properties, NK cells do not induce graft versus host disease following transplantation. Therefore, they provide a promising approach to treating RR/MM patients. Currently, attempts have been made to produce large-scale and good manufacturing practices (GMP) of NK cells. Ex vivo expanded/activated NK cells derived from the own patient or allogenic donors are potential options for NK cell therapy in MM. Besides, novel cell-based products such as NK cell lines and chimeric antigen receptor (CAR)-NK cells may provide an off-the-shelf source for NK cell therapy. Here, we summarized NK cell activity in the MM microenvironment and focused on different NK cell therapy methods for MM patients.

Carfilzomib usage patterns and outcomes in patients with relapsed multiple myeloma: A multi-institutional report from the Canadian Myeloma Research Group (CMRG) Database

Carfilzomib is an active and commonly used treatment in patients with multiple myeloma (MM). Using the Canadian Myeloma Research Group Database, we performed a retrospective observational study of patients treated with carfilzomib for relapse of MM in a real-world setting in Canada between years 2007 and 2020. A total of 445 patients were included in this study: the doublet (Kd/p, n = 218) and triplets (KCd, n = 88; KRd, n = 99; KPd/p, n = 40). One hundred and twenty-two (27%) received carfilzomib-based treatment in line 2, 133 (30%) in line 3, 90 (20%) in line 4, and 100 (23%) in line 5 or higher. Carfilzomib was dosed weekly in 40% of patients and twice weekly in 60%. The overall response rate of the entire cohort was 57.7%, with 33.6% of patients achieving very good partial response or better. Median progression-free survival for the overall cohort was 6.3 months with overall survival 19.7 months. This study provides a benchmark for carfilzomib-based regimens in the real world, demonstrating that these regimens are effective in treating patients with relapsed MM.

Harnessing Unconventional T Cells and Innate Lymphoid Cells to Prevent and Treat Hematological Malignancies: Prospects for New Immunotherapy

Unconventional T cells and innate lymphoid cells (ILCs) make up a heterogeneous set of cells that characteristically show prompt responses toward specific antigens. Unconventional T cells recognize non-peptide antigens, which are bound and presented by diverse non-polymorphic antigen-presenting molecules and comprise γδ T cells, MR1-restricted mucosal-associated invariant T cells (MAITs), and natural killer T cells (NKTs). On the other hand, ILCs lack antigen-specific receptors and act as the innate counterpart to the T lymphocytes found in the adaptive immune response. The alteration of unconventional T cells and ILCs in frequency and functionality is correlated with the onset of several autoimmune diseases, allergy, inflammation, and tumor. However, depending on the physio-pathological framework, unconventional T cells may exhibit either protective or pathogenic activity in a range of neoplastic diseases. Nonetheless, experimental models and clinical studies have displayed that some unconventional T cells are potential therapeutic targets, as well as prognostic and diagnostic markers. In fact, cell-mediated immune response in tumors has become the focus in immunotherapy against neoplastic disease. This review concentrates on the present knowledge concerning the function of unconventional T cell sets in the antitumor immune response in hematological malignancies, such as acute and chronic leukemia, multiple myeloma, and lymphoproliferative disorders. Moreover, we discuss the possibility that modulating the activity of unconventional T cells could be useful in the treatment of hematological neoplasms, in the prevention of specific conditions (such as graft versus host disease), and in the formulation of an effective anticancer vaccine therapy. The exact knowledge of the role of these cells could represent the prerequisite for the creation of a new form of immunotherapy for hematological neoplasms.

Natural Killer Cells in the Malignant Niche of Multiple Myeloma

Natural killer (NK) cells represent a subset of CD3- CD7+ CD56+/dim lymphocytes with cytotoxic and suppressor activity against virus-infected cells and cancer cells. The overall potential of NK cells has brought them to the spotlight of targeted immunotherapy in solid and hematological malignancies, including multiple myeloma (MM). Nonetheless, NK cells are subjected to a variety of cancer defense mechanisms, leading to impaired maturation, chemotaxis, target recognition, and killing. This review aims to summarize the available and most current knowledge about cancer-related impairment of NK cell function occurring in MM.

HLA genotyping in Japanese patients with multiple myeloma receiving bortezomib: An exploratory biomarker study of JCOG1105 (JCOG1105A1)

Bortezomib (Btz) shows robust efficacy in patients with multiple myeloma (MM); however, some patients experience suboptimal responses and show specific toxicities. Therefore, we attempted to identify specific HLA alleles associated with Btz-related toxicities and response to treatment. Eighty-two transplant-ineligible patients with newly diagnosed MM enrolled in a phase II study (JCOG1105) comparing two less intensive melphalan, prednisolone, plus Btz (MPB) regimens were subjected to HLA typing. The frequency of each allele was compared between the groups, categorized based on toxicity grades and responses to MPB therapy. Among 82 patients, the numbers of patients with severe peripheral neuropathy (PN; grade 2 or higher), skin disorders (SD; grade 2 or higher), and pneumonitis were 16 (19.5%), 15 (18.3%), and 6 (7.3%), respectively. Complete response was achieved in 10 (12.2%) patients. Although no significant HLA allele was identified by multiple comparisons, several candidates were identified. HLA-B*40:06 was more prevalent in patients with severe PN than in those with less severe PN (odds ratio [OR] = 6.76). HLA-B*40:06 and HLA-DRB1*12:01 were more prevalent in patients with SD than in those with less severe SD (OR = 7.47 and OR = 5.55, respectively). HLA-DRB1*08:02 clustered in the group of patients with pneumonitis (OR = 11.34). Complete response was achieved in patients carrying HLA-DQB1*03:02, HLA-DQB1*05:01, and HLA-DRB1*01:01 class II alleles. HLA genotyping could help predict Btz-induced toxicity and treatment efficacy in patients with MM, although this needs further validation.

Carfilzomib, dexamethasone, and daratumumab in Asian patients with relapsed or refractory multiple myeloma: post hoc subgroup analysis of the phase 3 CANDOR trial

BACKGROUND

Due to increasing use of frontline lenalidomide, effective and safe lenalidomide-free therapies for relapsed/refractory multiple myeloma (RRMM) are needed in Asia. This subgroup analysis of phase 3 CANDOR study evaluated efficacy and safety of KdD vs Kd in Asian patients with RRMM.

METHODS

Self-identified Asian patients with RRMM (KdD = 46; Kd = 20) with 1‒3 prior therapies were included. The primary endpoint of progression-free survival was estimated by stratified Cox regression.

RESULTS

Baseline demographics and patient characteristics were balanced in both arms. KdD reduced the risk of progression or death by 25% vs Kd [hazard ratio (HR) = 0.75; 95% CI 0.259, 2.168] in the Asian subgroup, compared with 37% vs Kd (0.63; 0.464, 0.854) in the overall CANDOR population. Percentage of patients who reported grade ≥ 3 treatment-emergent adverse events (TEAEs) in the KdD and Kd arms was 95.7 and 90.0%, respectively. Serious AEs were observed in 58.7 and 40.0% of patients in the KdD and Kd arms, respectively. There were two (4.3%) fatal TEAEs in the KdD arm due to infections.

CONCLUSIONS

There was a trend toward better efficacy and a favorable benefit-risk profile for KdD vs Kd in Asian patients with RRMM. Cautious interpretation is warranted due to small patient size.

PI3K/Akt Pathway: The Indestructible Role of a Vintage Target as a Support to the Most Recent Immunotherapeutic Approaches

Simple Summary

PI3K/Akt pathway has an impressive story as tumor marker. PI3K-dependent solid tumors have been studied for several years in order to inhibit the pathway at different levels along the signaling. Despite the highly satisfactory results obtained in vitro and in xenograft mouse tumor models, the use of PI3K/Akt inhibitors in clinical trials resulted in being not as efficient as expected. With the emerging role of the tumor microenvironment in the response to therapy and the awareness, increasing in recent years, of the necessity to army the immune system against the tumor, new opportunities have emerged for PI3K/Akt inhibitors. Here, we show that PI3K/Akt, in addition to its function as tumor marker, exerts a pivotal role as an immunomodulator. Recent studies demonstrate that PI3K/Akt pathway is crucial for the regulation of the immune system and that its inhibition in combination with immunomodulatory agents may provide a new therapeutic approach for cancer.

Abstract

Pathologic activation of PI3Ks and the subsequent deregulation of its downstream signaling pathway is among the most frequent events associated with cellular transformation, cancer, and metastasis. PI3Ks are also emerging as critical factors in regulating anti-tumor immunity by either promoting an immunosuppressive tumor microenvironment or by controlling the activity and the tumor infiltration of cells involved in the immune response. For these reasons, significant pharmaceutical efforts are dedicated to inhibiting the PI3K pathway, with the main goal to target the tumor and, at the same time, to enhance the anti-tumor immunity. Recent immunotherapeutic approaches involving the use of adoptive cell transfer of autologous genetically modified T cells or immune check-point inhibitors showed high efficacy. However, mechanisms of resistance to these kinds of therapy are emerging, due in part to the inhibition of effector T cell functions exerted by the immunosuppressive tumor microenvironment. Here, we first describe how inhibition of PI3K/Akt pathway contribute to enhance anti-tumor immunity and further discuss how inhibitors of the pathway are used in combination with different immunomodulatory and immunotherapeutic agents to improve anti-tumor efficacy.

Role and Modulation of NK Cells in Multiple Myeloma

Myeloma tumor cells are particularly dependent on their microenvironment and sensitive to cellular antitumor immune response, including natural killer (NK) cells. These later are essential innate lymphocytes implicated in the control of viral infections and cancers. Their cytotoxic activity is regulated by a balance between activating and inhibitory signals resulting from the complex interaction of surface receptors and their respective ligands. Myeloma disease evolution is associated with a progressive alteration of NK cell number, phenotype and cytotoxic functions. We review here the different therapeutic approaches that could restore or enhance NK cell functions in multiple myeloma. First, conventional treatments (immunomodulatory drugs-IMids and proteasome inhibitors) can enhance NK killing of tumor cells by modulating the expression of NK receptors and their corresponding ligands on NK and myeloma cells, respectively. Because of their ability to kill by antibody-dependent cell cytotoxicity, NK cells are important effectors involved in the efficacy of anti-myeloma monoclonal antibodies targeting the tumor antigens CD38, CS1 or BCMA. These complementary mechanisms support the more recent therapeutic combination of IMids or proteasome inhibitors to monoclonal antibodies. We finally discuss the ongoing development of new NK cell-based immunotherapies, such as ex vivo expanded killer cell immunoglobulin-like receptors (KIR)-mismatched NK cells, chimeric antigen receptors (CAR)-NK cells, check point and KIR inhibitors.

Carfilzomib with immunomodulatory drugs for the treatment of newly diagnosed multiple myeloma

Carfilzomib, a selective proteasome inhibitor (PI), is approved for the treatment of patients with relapsed or refractory multiple myeloma (MM). Combination regimens incorporating a PI and immunomodulatory drug (IMiD) have been associated with deep responses and extended survival in patients with newly diagnosed MM (NDMM). Carfilzomib-based combinations with immunomodulators are being extensively studied in the frontline setting. The objective of this review was to describe efficacy and safety data for carfilzomib-based, PI/immunomodulatory combinations in NDMM. Information sources were articles indexed in PubMed and abstracts from key hematology/oncology congresses published between January 2012 and December 2018. PubMed and congresses were searched for prospective clinical studies assessing the combination of carfilzomib with an IMiD for NDMM treatment. Retrospective and preclinical reports, case reports/series, reviews, and clinical studies not evaluating carfilzomib-immunomodulator combinations in NDMM were excluded based on review of titles and abstracts. A total of nine articles and 72 abstracts were deemed relevant and included in the review. A total of six distinct carfilzomib-based, PI/immunomodulator combination regimens have been evaluated in 12 clinical trials. Overall, treatment with these regimens has resulted in deep responses, including high rates of negativity for minimal residual disease. These deep responses have translated to long progression-free survival and overall survival rates. Efficacy results for these regimens have generally been consistent across subgroups defined by age, transplant eligibility, and cytogenetic risk. The safety profile of carfilzomib in NDMM is consistent with that observed in the relapsed-refractory MM setting. Clinical studies have found that carfilzomib-based combinations with immunomodulators are highly active with a favorable safety profile in NDMM. The carfilzomib, lenalidomide, and dexamethasone (KRd) drug backbone is a promising foundation for treatment strategies aimed at achieving long-term, deep responses (functional cures) in the frontline setting. Several ongoing studies are evaluating KRd, with or without anti-CD38 monoclonal antibodies.

Potential of NK cells in multiple Myeloma therapy

Introduction: Despite rapid advances in myeloma treatment with the development of new drugs, curative therapies remain elusive. Relapsed/refractory disease related to progressive dysregulation of immune system and acquired genetic abnormalities continues to be a major obstacle in achieving cure. Immune-based therapy harnessing the host defense mechanism of natural killer (NK) cells is a promising avenue in the treatment of myeloma. Areas covered: Here, we discuss the biology and cytotoxic activity of NK cells and the potential role of these innate immune cells in defense against cancer and specifically multiple myeloma. We also discuss the role of NK cells in the anti-myeloma effects of autologous and allogeneic stem cell transplantation, various novel drugs, and treatment modalities such as chimeric antigen receptor therapy. Immune evasion, either directly or indirectly involving NK cell dysfunction, may be a key and under-recognized mechanism in myeloma progression. We reviewed extensive literature identified using the keywords immunotherapy, natural killer cells, and multiple myeloma. Expert opinion: Novel treatment approaches in myeloma utilizing the immunomodulatory and cytotoxic properties of NK cells to eradicate resistant and quiescent clones could pave the way for potentially curative interventions.

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.

Tuning Natural Killer Cell Anti-multiple Myeloma Reactivity by Targeting Inhibitory Signaling via KIR and NKG2A

Natural killer (NK) cells are attractive candidates for allogeneic cell-based immunotherapy due to their potent antitumor effector function and good safety profile. NK cells express killer immunoglobulin-like receptors (KIRs) and the NKG2A receptor important for NK cells education as well as providing inhibitory signals upon encountering HLA-expressing target cells. Multiple myeloma (MM) is an example of a tumor expressing relatively high levels of HLA molecules. In this review, we discuss the functional relevance of inhibitory KIRs and NKG2A for NK cells anti-MM response and strategies to lower these inhibitory signaling to enhance clinical efficacy of allogeneic NK cells in MM.

Enhancing the Activation and Releasing the Brakes: A Double Hit Strategy to Improve NK Cell Cytotoxicity Against Multiple Myeloma

Natural killer (NK) cells are innate lymphocytes with a strong antitumor ability. In tumor patients, such as multiple myeloma (MM) patients, an elevated number of NK cells after stem cell transplantation (SCT) has been reported to be correlated with a higher overall survival rate. With the aim of improving NK cell use for adoptive cell therapy, we also addressed the cytotoxicity of patient-derived, cytokine-stimulated NK cells against MM cells at specific time points: at diagnosis and before and after autologous stem cell transplantation. Remarkably, after cytokine stimulation, the patients' NK cells did not significantly differ from those of healthy donors. In a small cohort of MM patients, we were able to isolate autologous tumor cells, and we could demonstrate that IL-2/15 stimulated autologous NK cells were able to significantly improve their killing capacity of autologous tumor cells. With the aim to further improve the NK cell killing capacity against MM cells, we investigated the potential use of NK specific check point inhibitors with focus on NKG2A because this inhibitory NK cell receptor was upregulated following ex vivo cytokine stimulation and MM cells showed HLA-E expression that could even be increased by exposure to IFN-γ. Importantly, blocking of NKG2A resulted in a significant increase in the NK cell-mediated lysis of different MM target cells. Finally, these results let suggest that combining cytokine induced NK cell activation and the specific check point inhibition of the NKG2A-mediated pathways can be an effective strategy to optimize NK cell therapeutic approaches for treatment of multiple myeloma.

The novel deubiquitinase inhibitor b-AP15 induces direct and NK cell-mediated antitumor effects in human mantle cell lymphoma

The first therapeutic proteasome inhibitor bortezomib has clinical efficacy in mantle cell lymphoma (MCL) which resulted in its incorporation in treatment algorithms for this disease. Impairment of proteasomal function by bortezomib is mediated via inhibition of the 20S core particle. However, proteasome function can also be modified by targeting upstream components of the ubiquitin-proteasome system. Recently, b-AP15 has been identified as a small molecule achieving proteasome inhibition by targeting the deubiquitinase (DUB) activity of the 19S regulatory subunit and was found to inhibit cancer cell growth in preclinical analyses. In the present study, both direct antitumor effects and the possibility to induce natural killer group 2 member D ligands (NKG2DL) to reinforce NK cell immunity with b-AP15 were investigated to provide a rational basis for clinical evaluation of this novel DUB inhibitor in MCL. Treatment with b-AP15 resulted in reduced viability as well as induction of apoptosis in a time- and dose-dependent manner, which could be attributed to caspase activation in MCL cells. In addition, treatment with b-AP15 differentially induced NKG2DL expression and subsequent NK cell lysis of MCL cells. These results indicate that the DUB inhibitor b-AP15 displays substantial antitumor activity in human MCL and suggest that b-AP15 might be a novel therapeutic option in the treatment of MCL that warrants clinical investigation.

Low-dose bortezomib increases the expression of NKG2D and DNAM-1 ligands and enhances induced NK and γδ T cell-mediated lysis in multiple myeloma

Multiple myeloma (MM) is an incurable hematological malignancy, although bortezomib has markedly improved its outcomes. Growing clinical evidence indicates that enhancing induced natural killer (NK) or γδ T cells for infusion is useful in the treatment of MM. However, whether combination treatment with bortezomib and induced NK and γδ T cells further improves outcomes in MM, and how the treatments should be combined, remain unclear. Herein, we found that low-dose bortezomib did not suppress the viability of induced NK and γδ T cells, but did induce MM cell apoptosis. Importantly, low-dose bortezomib increased the expression of NKG2D and DNAM-1 ligands on MM cells, which sensitized the multiple myeloma cells to lysis by induced NK and γδ T cells. Our results suggested that combination treatment with low-dose bortezomib and induced NK or γδ T cells had a synergistic cytotoxic effect on MM cells. This study provided a proof of principle for the design of future trials and investigation of this combination therapeutic strategy for MM treatment.

Elotuzumab for the Treatment of Relapsed or Refractory Multiple Myeloma, with Special Reference to its Modes of Action and SLAMF7 Signaling

Elotuzumab, targeting signaling lymphocytic activation molecule family 7 (SLAMF7), has been approved in combination with lenalidomide and dexamethasone (ELd) for relapsed/refractory multiple myeloma (MM) based on the findings of the phase III randomized trial ELOQUENT-2 (NCT01239797). Four-year follow-up analyses of ELOQUENT-2 have demonstrated that progression-free survival was 21% in ELd versus 14% in Ld. Elotuzumab binds a unique epitope on the membrane IgC2 domain of SLAMF7, exhibiting a dual mechanism of action: natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity (ADCC) and enhancement of NK cell activity. The ADCC is mediated through engagement between Fc portion of elotuzumab and FcgRIIIa/CD16 on NK cells. Enhanced NK cell cytotoxicity results from phosphorylation of the immunoreceptor tyrosine-based switch motif (ITSM) that is induced via elotuzumab binding and recruits the SLAM-associated adaptor protein EAT-2. The coupling of EAT-2 to the phospholipase Cg enzymes SH2 domain leads to enhanced Ca²⁺ influx and MAPK/Erk pathway activation, resulting in granule polarization and enhanced exocytosis in NK cells. Elotuzumab does not stimulate the proliferation of MM cells due to a lack of EAT-2. The inhibitory effects of elotuzumab on MM cell growth are not induced by the lack of CD45, even though SHP-2, SHP-1, SHIP-1, and Csk may be recruited to phosphorylated ITSM of SLAMF7. ELd improves PFS in patients with high-risk cytogenetics, i.e. t(4;14), del(17p), and 1q21 gain/amplification. Since the immune state is paralytic in advanced MM, the efficacy of ELd with minimal toxicity may bring forward for consideration of its use in the early stages of the disease.

HLA ligandome analysis of primary chronic lymphocytic leukemia (CLL) cells under lenalidomide treatment confirms the suitability of lenalidomide for combination with T-cell-based immunotherapy

Recent studies suggest that CLL is an immunogenic disease, which might be effectively targeted by antigen-specific T-cell-based immunotherapy. However, CLL is associated with a profound immune defect, which might represent a critical limitation for mounting clinically effective antitumor immune responses. As several studies have demonstrated that lenalidomide can reinforce effector T-cell responses in CLL, the combination of T-cell-based immunotherapy with the immunomodulatory drug lenalidomide represents a promising approach to overcome the immunosuppressive state in CLL. Antigen-specific immunotherapy also requires the robust presentation of tumor-associated HLA-presented antigens on target cells. We thus performed a longitudinal study of the effect of lenalidomide on the HLA ligandome of primary CLL cells in vitro. We showed that lenalidomide exposure does not affect absolute HLA class I and II surface expression levels on primary CLL cells. Importantly, semi-quantitative mass spectrometric analyses of the HLA peptidome of three CLL patient samples found only minor qualitative and quantitative effects of lenalidomide on HLA class I- and II-restricted peptide presentation. Furthermore, we confirmed stable presentation of previously described CLL-associated antigens under lenalidomide treatment. Strikingly, among the few HLA ligands showing significant modulation under lenalidomide treatment, we identified upregulated IKZF-derived peptides, which may represent a direct reflection of the cereblon-mediated effect of lenalidomide on CLL cells. Since we could not observe any relevant influence of lenalidomide on the established CLL-associated antigen targets of anticancer T-cell responses, this study validates the suitability of lenalidomide for the combination with antigen-specific T-cell-based immunotherapies.

Activation of NK cells and disruption of PD-L1/PD-1 axis: two different ways for lenalidomide to block myeloma progression

Natural Killer (NK) cells play a critical role against tumor cells in hematological malignancies. Their activating receptors are essential in tumor cell killing. In Multiple Myeloma (MM) patients, NK cell differentiation, activation and cytotoxic potential are strongly impaired leading to MM escape from immune surveillance in tissues and bone marrow. Mechanisms used by MM to affect NK cell functions are mediated by the release of soluble factors, the expression of activating and inhibitory NK cell ligands, and the expression of immune check-point inhibitors. Lenalidomide represents an efficient clinical approach in MM treatment to improve patients' survival. Lenalidomide does not only promotes tumor apoptosis, but also stimulates T and NK cells, thereby facilitating NK-mediated tumor recognition and killing. This occurs since Lenalidomide acts on several critical points: stimulates T cell proliferation and cytokine secretion; decreases the expression of the immune check-point inhibitor Programmed Death-1 (PD-1) on both T and NK cells in MM patients; decreases the expression of both PD-1 and PD-L1 on MM cells; promotes MM cell death and abrogates MM/stromal microenvironment cross-talk, a process known to promote the MM cell survival and proliferation. This leads to the inhibition of the negative signal induced by PD-1/PD-L1 axis on NK cells, restoring NK cell cytotoxic functions. Given the importance of an effective immune response to counteract the MM progression and the promising approaches using anti-PD-1/PD-L1 strategies, we will discuss in this review how Lenalidomide could represent an adequate approach to re-establish the recognition against MM by exhausted NK cell.

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.