Deep and sustained response after venetoclax therapy in a patient with very advanced refractory myeloma with translocation t(11;14)

Integrated epigenetic and transcriptional single-cell analysis of t(11;14) multiple myeloma and its BCL2 dependency

ABSTRACT

The translocation t(11;14) occurs in 20% of patients with multiple myeloma (MM) and results in the upregulation of CCND1. Nearly two-thirds of t(11;14) MM cells are BCL2 primed and highly responsive to the oral BCL2 inhibitor venetoclax. Although it is evident that this unique sensitivity to venetoclax depends on the Bcl-2 homology domain 3- proapoptotic protein priming of BCL2, the biology underlying t(11;14) MM dependency on BCL2 is poorly defined. Importantly, the epigenetic regulation of t(11;14) transcriptomes and its impact on gene regulation and clinical response to venetoclax remain elusive. In this study, by integrating assay for transposase-accessible chromatin by sequencing (ATAC-seq) and RNA-seq at the single-cell level in primary MM samples, we have defined the epigenetic regulome and transcriptome associated with t(11;14) MM. A B-cell-like epigenetic signature was enriched in t(11;14) MM, confirming its phylogeny link to B-cell rather than plasma cell biology. Of note, a loss of a B-cell-like epigenetic signature with a gain of canonical plasma cell transcription factors was observed at the time of resistance to venetoclax. In addition, MCL1 and BCL2L1 copy number gains and structural rearrangements were linked to venetoclax resistance in patients with t(11;14) MM. To date, this is the first study in which both single-cell (sc) ATAC-seq and scRNA-seq analysis are integrated into primary MM cells to obtain a deeper resolution of the epigenetic regulome and transcriptome associated with t(11;14) MM biology and venetoclax resistance.

Effective venetoclax-based treatment in relapsed/refractory multiple myeloma patients with translocation t(6;14)

Introduction: The selective Bcl-2 inhibitor venetoclax has shown promising therapeutic potential in multiple myeloma, particularly in cases associated with t(11;14) IGH::CCND1 translocation. However, the efficacy of venetoclax in myeloma patients with the t(6;14) IGH::CCND3 translocation remains less investigated. Methods: In this study, we conducted a retrospective analysis to investigate the efficacy of venetoclax-based therapy in relapsed/refractory myeloma patients with t(6;14) translocation. The treatment courses of three patients, that included previous therapies and responses to venetoclax, were assessed. Clinical data, laboratory results, and adverse events were analyzed to evaluate treatment outcomes. Results: Our findings demonstrated remarkable therapeutic responses in three consecutive patients with t(6;14) translocation-associated myeloma who received venetoclax-based therapy. Patient 1, a lenalidomide-bortezomib-daratumumab and alkylator treatment refractory patient, achieved sustained stringent complete remission (sCR) after combining carfilzomib-dexamethasone with venetoclax, which was his best response ever. Similarly, Patient 2, refractory to frontline bortezomib-thalidomide-dexamethasone therapy, attained CR following a transition to bortezomib-dexamethason-venetoclax treatment. Patient 3, who was immunomodulatory (IMID)-intolerant, showed a highly favorable response to venetoclax-dexamethasone therapy after his first relapse following autologous stem cell transplantation. No significant adverse effects were observed in any of the patients. Discussion: Our study provides compelling preliminary evidence for the efficacy of venetoclax in t(6;14) translocation-associated myeloma. The outcomes observed in our patients suggest that venetoclax-based therapy holds substantial promise as an effective treatment option for this specific genetic subgroup. Furthermore, the similarities in treatment response between t(11;14) and t(6;14) translocation subgroups highlight the importance of personalized approaches targeting specific genetic abnormalities to optimize therapeutic outcomes.

AL amyloidosis clonal plasma cells are regulated by microRNAs and dependent on anti-apoptotic BCL2 family members

BACKGROUND

Noncoding RNAs such as microRNAs (miRNAs) have attracted attention as biological pathway regulators, which differ from chromosomal translocations and gene point mutations. Their involvement in the molecular mechanisms underlying light chain (AL) amyloidosis pathogenesis is yet to be elucidated.

AIMS

To decipher specific miRNA expression profile in AL-amyloidosis and to examine how miRNAs are involved in AL pathogenesis.

METHODS

The expression profile of miRNAs and mRNA from bone marrow (BM)-derived CD138+ cells were determined using the NanoString nCounter assay and RNA-Seq, respectively. The effect of aberrantly expressed miRNAs on potential molecular targets was analyzed by qRT-PCR, Western blot, Mito-potential assay, and Annexin-PI staining.

RESULTS

Genes which were significantly differentially expressed between AL-amyloidosis and MM, were found to be involved in cell growth and apoptotic mechanisms. Specifically, BCL2L1, MCL1, and BCL2 were upregulated in AL-amyloidosis compared with MM and controls. The levels of miR-181a-5p and miR-9-5p, which regulate the above-mentioned genes, were lower in BM samples from AL-amyloidosis compared with controls, providing a mechanism for BCL2 family gene upregulation. When miR-9-5p and miR-181a-5p were overexpressed in ALMC1 cells, BCL2L1, MCL1, and BCL2 were downregulated and induced apoptosis. Treatment of ALMC-1 cells with venetoclax, (BCL-2 inhibitor), resulted in the upregulation of those miRNAs, the downregulation of BCL2, MCL1, and BCL2L1 mRNA and protein levels, and subsequent apoptosis.

CONCLUSION

Our findings suggest that miR-9-5p and miR-181a-5p act as tumor-suppressors whose downregulation induces anti-apoptotic mechanisms underlying the pathogenesis of AL-amyloidosis. The study highlights the post-transcriptional regulation in AL-amyloidosis and provides pathogenetic evidence for the potential use of BCL-2 inhibitors in this disease.

Efficacy and safety of venetoclax-based regimens for the treatment of relapsed/refractory multiple myeloma: a systemic review and meta-analysis

BACKGROUND

Patients with relapsed/refractory multiple myeloma (RRMM) usually have dismal prognostic outcomes. Venetoclax, a selective inhibitor of antiapoptotic protein B-cell lymphoma-2 (BCL-2), demonstrates antimyeloma activity in plasma cells with t(11;14) or high BCL-2 expression.

OBJECTIVES

This meta-analysis aimed to investigate the efficacy and safety of venetoclax-based therapy in RRMM.

DESIGN

This is a meta-analysis study.

DATA SOURCES AND METHODS

PubMed, Embase, and Cochrane were searched for studies published up to 20 December 2021. Overall response rate (ORR), rate of very good partial response or better (≧VGPR), and complete response (CR) rate were pooled with the random-effects model. Safety was evaluated by the incidences of grade ≧3 adverse events. Subgroup analysis and meta-regression were performed to identify the causes of heterogeneities. All the analyses were conducted by STATA 15.0 software.

RESULTS

A total of 14 studies with 713 patients were included for analysis. The pooled ORR, rate of ≧VGPR, and CR for all patients were 59% [95% confidence interval (CI) = 45-71%], 38% (95% CI = 26-51%), and 17% (95% CI = 10-26%), respectively. The median progression-free survival (PFS) ranged from 2.0 months to not reached (NR), and the median overall survival (OS) ranged from 12.0 months to NR. Meta-regression showed that patients treated with more drugs combined or less heavily pretreated had higher response rates. Patients with t(11;14) had superior ORR [relative risk (RR) = 1.47, 95% CI = 1.05-2.07], ≧VGPR (RR = 1.71, 95% CI = 1.12-2.60), CR (RR = 1.86, 95% CI = 1.34-2.57), PFS [hazard ratio (HR) = 0.47, 95% CI = 0.30-0.65], and OS (HR = 0.30, 95% CI = 0.08-0.52) compared with patients without t(11;14). Most grade ≧3 adverse events were hematologic, gastrointestinal, and infectious related and were manageable.

CONCLUSION

Venetoclax-based therapy is an effective and safe option for RRMM patients, especially those with t(11;14).

Exploiting endogenous and therapy-induced apoptotic vulnerabilities in immunoglobulin light chain amyloidosis with BH3 mimetics

Immunoglobulin light chain (AL) amyloidosis is an incurable hematologic disorder typically characterized by the production of amyloidogenic light chains by clonal plasma cells. These light chains misfold and aggregate in healthy tissues as amyloid fibrils, leading to life-threatening multi-organ dysfunction. Here we show that the clonal plasma cells in AL amyloidosis are highly primed to undergo apoptosis and dependent on pro-survival proteins MCL-1 and BCL-2. Notably, this MCL-1 dependency is indirectly targeted by the proteasome inhibitor bortezomib, currently the standard of care for this disease and the related plasma cell disorder multiple myeloma, due to upregulation of pro-apoptotic Noxa and its inhibitory binding to MCL-1. BCL-2 inhibitors sensitize clonal plasma cells to multiple front-line therapies including bortezomib, dexamethasone and lenalidomide. Strikingly, in mice bearing AL amyloidosis cell line xenografts, single agent treatment with the BCL-2 inhibitor ABT-199 (venetoclax) produces deeper remissions than bortezomib and triples median survival. Mass spectrometry-based proteomic analysis reveals rewiring of signaling pathways regulating apoptosis, proliferation and mitochondrial metabolism between isogenic AL amyloidosis and multiple myeloma cells that divergently alter their sensitivity to therapies. These findings provide a roadmap for the use of BH3 mimetics to exploit endogenous and induced apoptotic vulnerabilities in AL amyloidosis.

Novel Approaches Outside the Setting of Immunotherapy for the Treatment of Multiple Myeloma: The Case of Melflufen, Venetoclax, and Selinexor

Although the survival rate of patients with multiple myeloma has significantly improved in the last years thanks to the introduction of various classes of new drugs, such as proteasome inhibitors, immunomodulatory agents, and monoclonal antibodies, the vast majority of these subjects relapse with a more aggressive disease due to the acquisition of further genetic alterations that may cause resistance to current salvage therapies. The treatment of these often "triple" (or even more) refractory patients remains challenging, and alternative approaches are required to overcome the onset of that resistance. Immunotherapies with novel monoclonal, drug-conjugated, or bi-specific antibodies, as well as the use of chimeric antigen receptor T cells, have been recently developed and are currently investigated. However, other non-immunologic therapeutic regimens based on melfluflen, venetoclax, or selinexor, three molecules with new mechanisms of action, have also shown promising results in the setting of relapsed/refractory myeloma. Here we report the most recent literature data regarding these three drugs, focusing on their efficacy and safety in multiple myeloma.

Venetoclax for the treatment of multiple myeloma: Outcomes outside of clinical trials

Multiple myeloma (MM) remains an incurable disease despite incorporation of novel agents. Venetoclax, a B-cell lymphoma 2 (BCL-2) inhibitor is approved for some hematologic malignancies but not yet for MM, although clinical trials have shown efficacy in patients with MM, particularly those harboring t(11;14). We reviewed the medical records of relapsed and/or refractory MM patients to study the efficacy and safety of venetoclax used outside of clinical trials at Mayo Clinic between December, 2016 and March, 2019. The data cut-off date was August 06, 2020. We identified 56 patients of whom 42 (75%) harbored t(11;14). The median number of prior therapies was six (range 1-15) and 14% of patients had received ≥10 prior lines of therapy. Fifty-three (95%) patients were refractory to an immunomodulatory drug and proteasome inhibitor. Venetoclax was used as monotherapy or doublet, in combination with dexamethasone in 55% (n = 31) and a triplet or quadruplet in 45% of patients. No patient experienced tumor lysis syndrome. Overall response rate in 52 evaluable patients was 44%. The median time to best response was 2 months and median duration of response was 13.6 months. The median PFS for the entire cohort was 5.8 (95% CI 4.9-10.3) months and median OS was 28.4 (95% CI 14.6-not reached) months. The presence of t(11;14) was associated with improved PFS (median 9.7 months vs. 4.2 months, p = 0.019) and OS (median not reached vs. 10.8 9 months, p = 0.015). Venetoclax demonstrates encouraging activity in heavily-treated patients with relapsed/refractory MM, particularly the t(11;14) patient-population.

Genetic pathogenesis of immunoglobulin light chain amyloidosis: basic characteristics and clinical applications

Immunoglobulin light chain amyloidosis (AL) is an indolent plasma cell disorder characterized by free immunoglobulin light chain (FLC) misfolding and amyloid fibril deposition. The cytogenetic pattern of AL shows profound similarity with that of other plasma cell disorders but harbors distinct features. AL can be classified into two primary subtypes: non-hyperdiploidy and hyperdiploidy. Non-hyperdiploidy usually involves immunoglobulin heavy chain translocations, and t(11;14) is the hallmark of this disease. T(11;14) is associated with low plasma cell count but high FLC level and displays distinct response outcomes to different treatment modalities. Hyperdiploidy is associated with plasmacytosis and subclone formation, and it generally confers a neutral or inferior prognostic outcome. Other chromosome abnormalities and driver gene mutations are considered as secondary cytogenetic aberrations that occur during disease evolution. These genetic aberrations contribute to the proliferation of plasma cells, which secrete excess FLC for amyloid deposition. Other genetic factors, such as specific usage of immunoglobulin light chain germline genes and light chain somatic mutations, also play an essential role in amyloid fibril deposition in AL. This paper will propose a framework of AL classification based on genetic aberrations and discuss the amyloid formation of AL from a genetic aspect.

Combination strategies to overcome resistance to the BCL2 inhibitor venetoclax in hematologic malignancies

Venetoclax has been approved by the United States Food and Drug Administration since 2016 as a monotherapy for treating patients with relapsed/refractory chronic lymphocytic leukemia having 17p deletion. It has led to a breakthrough in the treatment of hematologic malignancies in recent years. However, unfortunately, resistance to venetoclax is inevitable. Multiple studies confirmed that the upregulation of the anti-apoptotic proteins of the B-cell lymphoma 2 (BCL2) family mediated by various mechanisms, such as tumor microenvironment, and the activation of intracellular signaling pathways were the major factors leading to resistance to venetoclax. Therefore, only targeting BCL2 often fails to achieve the expected therapeutic effect. Based on the mechanism of resistance in specific hematologic malignancies, the combination of specific drugs with venetoclax was a clinically optional treatment strategy for overcoming resistance to venetoclax. This study aimed to summarize the possible resistance mechanisms of various hematologic tumors to venetoclax and the corresponding clinical strategies to overcome resistance to venetoclax in hematologic malignancies.

Multiple Myeloma Presenting in Patients Younger than 50 Years of Age: A Single Institution Experience

INTRODUCTION

Multiple myeloma (MM) is uncommon in persons younger than 50 years of age. The presenting features in this age group are unclear.

METHODS

We analyzed a cohort of patients <50 years of age with MM treated in our center.

RESULTS

Twenty-three patients at a median age of 41.5 years (range 27-49) were analyzed. Patients presented at International Staging System (ISS) I-II (79%), had high frequency of bone lytic lesions (89%), extramedullary disease (26%), light-chain myeloma (45%), and translocation t(11;14) (68%). The subpopulation of patients carrying t(11;14) were younger (p = 0.025). This subgroup had higher bone marrow infiltration of plasma cells (75 vs. 47.5%), higher incidence of proteinuria (2.9 vs. 0.19 g/day), and poorer response to therapy: 85.7% of patients achieving complete/very good partial remission after induction therapy did not have t(11;14). A trend toward inferior progression-free survival (PFS) was observed in patients with t(11; 14) compared to patients without this translocation (median PFS 18 and 36 months, respectively).

DISCUSSION/CONCLUSION

Translocation t(11; 14) seems to be more prevalent in young myeloma patients. Young myeloma patients and especially those who harbor translocation t(11; 14) may represent a distinct clinical entity that confers a poor outcome.

Dual targeting of BCL2 and MCL1 rescues myeloma cells resistant to BCL2 and MCL1 inhibitors associated with the formation of BAX/BAK hetero-complexes

Multiple myeloma is a plasma cell malignancy that escapes from apoptosis by heterogeneously over-expressing anti-apoptotic BCL2 proteins. Myeloma cells with a t(11;14) translocation present a particular vulnerability to BCL2 inhibition while a majority of myeloma cells relies on MCL1 for survival. The present study aimed to determine whether the combination of BCL2 and MCL1 inhibitors at low doses could be of benefit for myeloma cells beyond the single selective inhibition of BCL2 or MCL1. We identified that half of patients were not efficiently targeted neither by BCL2 inhibitor nor MCL1 inhibitor. Seventy percent of these myeloma samples, either from patients at diagnosis or relapse, presented a marked increase of apoptosis upon low dose combination of both inhibitors. Interestingly, primary cells from a patient in progression under venetoclax treatment were not sensitive ex vivo to neither venetoclax nor to MCL1 inhibitor, whereas the combination of both efficiently induced cell death. This finding suggests that the combination could overcome venetoclax resistance. The efficacy of the combination was also confirmed in U266 xenograft model resistant to BCL2 and MCL1 inhibitors. Mechanistically, we demonstrated that the combination of both inhibitors favors apoptosis in a BAX/BAK dependent manner. We showed that activated BAX was readily increased upon the inhibitor combination leading to the formation of BAK/BAX hetero-complexes. We found that BCLXL remains a major resistant factor of cell death induced by this combination. The present study supports a rational for the clinical use of venetoclax/S63845 combination in myeloma patients with the potential to elicit significant clinical activity when both single inhibitors would not be effective but also to overcome developed in vivo venetoclax resistance.

A single-center retrospective cohort analysis of venetoclax in relapsed/refractory multiple myeloma

Venetoclax, a small molecule inhibitor of BCL-2, has promising pre-clinical and early clinical activity in relapsed refractory multiple myeloma (RRMM). However, the clinical use of venetoclax remains under evaluation. We performed a single-center, retrospective analysis of patients with RRMM treated with off-label venetoclax. Forty-seven patients with a median of seven lines of prior therapy were identified. Most patients (87%) received venetoclax plus proteasome inhibitor, though there was heterogeneity in the venetoclax-containing regimen patients received, and 38% had known t(11;14). The overall response rate (ORR) was 39%, with 17% achieving ≥ very good partial response (VGPR). In the t(11;14) cohort, the ORR was 71%, with 24% achieving ≥ VGPR. The median progression-free survival was 2.1 months and overall survival was 15.6 months. One treatment-related death (related to infection) occurred. Venetoclax appears safe and efficacious in patients with RRMM, especially in those with t(11;14). Prospective trials are ongoing to further evaluate this treatment.

The evaluation of monoclonal gammopathy of renal significance: a consensus report of the International Kidney and Monoclonal Gammopathy Research Group

The term monoclonal gammopathy of renal significance (MGRS) was introduced by the International Kidney and Monoclonal Gammopathy Research Group (IKMG) in 2012. The IKMG met in April 2017 to refine the definition of MGRS and to update the diagnostic criteria for MGRS-related diseases. Accordingly, in this Expert Consensus Document, the IKMG redefines MGRS as a clonal proliferative disorder that produces a nephrotoxic monoclonal immunoglobulin and does not meet previously defined haematological criteria for treatment of a specific malignancy. The diagnosis of MGRS-related disease is established by kidney biopsy and immunofluorescence studies to identify the monotypic immunoglobulin deposits (although these deposits are minimal in patients with either C3 glomerulopathy or thrombotic microangiopathy). Accordingly, the IKMG recommends a kidney biopsy in patients suspected of having MGRS to maximize the chance of correct diagnosis. Serum and urine protein electrophoresis and immunofixation, as well as analyses of serum free light chains, should also be performed to identify the monoclonal immunoglobulin, which helps to establish the diagnosis of MGRS and might also be useful for assessing responses to treatment. Finally, bone marrow aspiration and biopsy should be conducted to identify the lymphoproliferative clone. Flow cytometry can be helpful in identifying small clones. Additional genetic tests and fluorescent in situ hybridization studies are helpful for clonal identification and for generating treatment recommendations. Treatment of MGRS was not addressed at the 2017 IKMG meeting; consequently, this Expert Consensus Document does not include any recommendations for the treatment of patients with MGRS.

This Expert Consensus Document from the International Kidney and Monoclonal Gammopathy Research Group includes an updated definition of monoclonal gammopathy of renal significance (MGRS) and recommendations for the use of kidney biopsy and other modalities for evaluating suspected MGRS

Overview of Current Targeted Anti-Cancer Drugs for Therapy in Onco-Hematology

The upgraded knowledge of tumor biology and microenviroment provides information on differences in neoplastic and normal cells. Thus, the need to target these differences led to the development of novel molecules (targeted therapy) active against the neoplastic cells' inner workings. There are several types of targeted agents, including Small Molecules Inhibitors (SMIs), monoclonal antibodies (mAbs), interfering RNA (iRNA) molecules and microRNA. In the clinical practice, these new medicines generate a multilayered step in pharmacokinetics (PK), which encompasses a broad individual PK variability, and unpredictable outcomes according to the pharmacogenetics (PG) profile of the patient (e.g., cytochrome P450 enzyme), and to patient characteristics such as adherence to treatment and environmental factors. This review focuses on the use of targeted agents in-human phase I/II/III clinical trials in cancer-hematology. Thus, it outlines the up-to-date anticancer drugs suitable for targeted therapies and the most recent finding in pharmacogenomics related to drug response. Besides, a summary assessment of the genotyping costs has been discussed. Targeted therapy seems to be an effective and less toxic therapeutic approach in onco-hematology. The identification of individual PG profile should be a new resource for oncologists to make treatment decisions for the patients to minimize the toxicity and or inefficacy of therapy. This could allow the clinicians to evaluate benefits and restrictions, regarding costs and applicability, of the most suitable pharmacological approach for performing a tailor-made therapy.

BCL2-Family Dysregulation in B-Cell Malignancies: From Gene Expression Regulation to a Targeted Therapy Biomarker

BCL2-family proteins have a central role in the mitochondrial apoptosis machinery and their expression is known to be deregulated in many cancer types. Effort in the development of small molecules that selectively target anti-apoptotic members of this family i.e., Bcl-2, Bcl-xL, Mcl-1 recently opened novel therapeutic opportunities. Among these apoptosis-inducing agents, BH3-mimetics (i.e., venetoclax) led to promising preclinical and clinical activity in B cell malignancies. However, several mechanisms of intrinsic or acquired resistance have been described ex vivo therefore predictive markers of response as well as mechanism-based combinations have to be designed. In the present study, we analyzed the expression of the BCL2-family genes across 10 mature B cell malignancies through computational normalization of 21 publicly available Affimetrix datasets gathering 1,219 patient samples. To better understand the deregulation of anti- and pro-apoptotic members of the BCL2-family in hematological disorders, we first compared gene expression profiles of malignant B cells to their relative normal control (naïve B cell to plasma cells, n = 37). We further assessed BCL2-family expression according to tissue localization i.e., peripheral blood, bone marrow, and lymph node, molecular subgroups or disease status i.e., indolent to aggressive. Across all cancer types, we showed that anti-apoptotic genes are upregulated while pro-apoptotic genes are downregulated when compared to normal counterpart cells. Of interest, our analysis highlighted that, independently of the nature of malignant B cells, the pro-apoptotic BH3-only BCL2L11 and PMAIP1 are deeply repressed in tumor niches, suggesting a central role of the microenvironment in their regulation. In addition, we showed selective modulations across molecular subgroups and showed that the BCL2-family expression profile was related to tumor aggressiveness. Finally, by integrating recent data on venetoclax-monotherapy clinical activity with the expression of BCL2-family members involved in the venetoclax response, we determined that the ratio (BCL2+BCL2L11+BAX)/BCL2L1 was the strongest predictor of venetoclax response for mature B cell malignancies in vivo.

Clinical Implications of t(11;14) in Patients with Multiple Myeloma Undergoing Autologous Stem Cell Transplantation

Conventional cytogenetic analyses and fluorescent in situ hybridization (FISH) are helpful for stratifying patients with multiple myeloma (MM) into high-risk [t(4;14), t(14;16), and/or del 17p] and standard-risk [t(11;14)] categories. However, the prognosis of patients with MM treated with autologous stem cell transplantation (ASCT) stratified according to these categories remains unclear. This retrospective observational study analyzed 97 patients with MM who received a single, planned ASCT after treatment with 200 mg/m² melphalan between 2001 and 2011. The patients were grouped according to chromosomal abnormality, including t(11;14) (n = 45), t(4;14) (n = 31), del 17p (n = 10), t(11;14) with del 17p (n = 7), and t(4;14) with del 17p (n = 4). Median overall survival (OS) of the t(11;14) group (64.1 months) was not significantly different from that of the t(4;14) group (not reached), but it was significantly longer than that of the del 17p group (23.0 months; P = .002). G-banding revealed that the median OS of the t(11;14) group with additional chromosomal abnormalities (ACAs) (46.2 months) was significantly shorter than that of the t(11;14) group without ACAs (not reached; P = .005) and the t(4;14) group (not reached; P = .010). These findings highlight the importance of G-banding in patients with t(11;14) MM.

BH3-mimetic toolkit guides the respective use of BCL2 and MCL1 BH3-mimetics in myeloma treatment

BH3 mimetics are promising drugs for hematologic malignancies that trigger cell death by promoting the release of proapoptotic BCL2 family members from antiapoptotic proteins. Multiple myeloma is considered to be a disease dependent mainly on MCL1 for survival, based mostly on studies using cell lines. We used a BH3-mimetic toolkit to study the dependency on BCL2, BCLXL, or MCL1 in malignant plasma cells from 60 patients. Dependencies were analyzed using an unbiased BH3 mimetics cell-death clustering by k-means. In the whole cohort of patients, BCL2 dependency was mostly found in the CCND1 subgroup (83%). Of note, MCL1 dependence significantly increased from 33% at diagnosis to 69% at relapse, suggesting a plasticity of the cellular dependency favoring MCL1 dependencies at relapse. In addition, 35% of overall patient samples showed codependencies on either BCL2/MCL1 or BCLXL/MCL1. Finally, we identified a group of patients not targeted by any of the BH3 mimetics, predominantly at diagnosis in patients not presenting the common recurrent translocations. Mechanistically, we demonstrated that BAK is crucial for cell death induced by MCL1 mimetic A1210477, according to the protection from cell death observed by BAK knock-down, as well as the complete and early disruption of MCL1/BAK complexes on A1210477 treatment. Interestingly, this complex was also dissociated in A1210477-resistant cells, but free BAK was simultaneously recaptured by BCLXL, supporting the role of BCLXL in A1210477 resistance. In conclusion, our study opens the way to rationally use venetoclax and/or MCL1 BH3 mimetics for clinical evaluation in myeloma at both diagnosis and relapse.

Venetoclax: A new wave in hematooncology

Inhibitors of antiapoptotic proteins of the BCL2 family can successfully restart the deregulated process of apoptosis in malignant cells. Whereas nonselective agents have been limited by their affinity to different BCL2 members, thus inducing excessive toxicity, the highly selective BCL2 inhibitor venetoclax (ABT-199, Venclexta™) has an acceptable safety profile. To date, it has been approved in monotherapy for the treatment of relapsed or refractory chronic lymphocytic leukemia (CLL) with 17p deletion. Extension of indications can be expected in monotherapy and in combination regimens. Sensitivity to venetoclax is not common in lymphomas, but promising outcomes have been achieved in the mantle cell lymphoma group. Venetoclax is also active in multiple myeloma patients, especially in those with translocation t(11;14), even if high-risk features such as del17p are also present. Surprisingly, positive results are being obtained in elderly acute myeloid leukemia patients, in whom inhibition of BCL2 is able to substantially increase the efficacy of low-dose cytarabine or hypomethylating agents. Here, we provide a summary of available results from clinical trials and describe a specific mechanism of action that stands behind the efficacy of venetoclax in hematological malignancies.

Triplet vs. doublet drug regimens for managing multiple myeloma

INTRODUCTION

Multiple Myeloma (MM) is a complex and heterogeneous plasma cell disorder. Sub-clones present before therapy and clonal evolution during therapy make this disease more resistant and finally refractory. These findings make us aware of the difficulty to target MM with few agents. Multi-drugs therapies allow us to target more pathways and more sub-clones both at diagnosis and in advanced disease.

AREAS COVERED

In this review, the authors focus on the effectiveness and tolerability of three drug regimens (triplet) in comparison with two drug regimens (doublet) and discuss their implications in the present and future of MM therapy.

EXPERT OPINION

It has been demonstrated that triplet regimens are better than doublet in terms of response rate and PFS in newly diagnosed, relapsed-refractory MM and in most patient subgroups. Whether this translates into OS improvement needs further demonstration. However, achievement of MRD negativity in most newly diagnosed and, firstly, in a consistent proportion of relapsed-refractory MM patients is very encouraging in this respect. However, not all patients are able to tolerate all triplet combinations; therefore, the choice should be based on patient characteristics, besides disease features. Finally, cost of triplets may be an important limitation in some countries.

Found in Translation: How Preclinical Research Is Guiding the Clinical Development of the BCL2-Selective Inhibitor Venetoclax

Since the discovery of apoptosis as a form of programmed cell death, targeting the apoptosis pathway to induce cancer cell death has been a high-priority goal for cancer therapy. After decades of effort, drug-discovery scientists have succeeded in generating small-molecule inhibitors of antiapoptotic BCL2 family proteins. Innovative medicinal chemistry and structure-based drug design, coupled with a strong fundamental understanding of BCL2 biology, were essential to the development of BH3 mimetics such as the BCL2-selective inhibitor venetoclax. We review a number of preclinical studies that have deepened our understanding of BCL2 biology and facilitated the clinical development of venetoclax.Significance: Basic research into the pathways governing programmed cell death have paved the way for the discovery of apoptosis-inducing agents such as venetoclax, a BCL2-selective inhibitor that was recently approved by the FDA and the European Medicines Agency. Preclinical studies aimed at identifying BCL2-dependent tumor types have translated well into the clinic thus far and will likely continue to inform the clinical development of venetoclax and other BCL2 family inhibitors. Cancer Discov; 7(12); 1376-93. ©2017 AACR.

Promising efficacy and acceptable safety of venetoclax plus bortezomib and dexamethasone in relapsed/refractory MM

The antiapoptotic proteins BCL-2 and myeloid cell leukemia sequence 1 (MCL-1) promote multiple myeloma (MM) cell survival. Venetoclax is a selective, orally bioavailable small-molecule BCL-2 inhibitor; bortezomib can indirectly inhibit MCL-1. In preclinical studies, venetoclax enhanced bortezomib activity, suggesting that cotargeting of BCL-2 and MCL-1 could be an effective treatment strategy in myeloma. This phase 1b trial studied patients with relapsed/refractory MM receiving daily venetoclax (50-1200 mg per designated dose cohort; 800 mg in safety expansion) in combination with bortezomib and dexamethasone. A total of 66 patients were enrolled (54 in the dose-escalation cohorts and 12 in the safety expansion). Patients had received a median of 3 prior therapies (range, 1-13); 26 (39%) were refractory to prior bortezomib and 35 (53%) to lenalidomide; 39 (59%) had prior stem cell transplant. The combination was generally well tolerated, and common adverse events included mild gastrointestinal toxicities (diarrhea [46%], constipation [41%], and nausea [38%]) and grade 3/4 cytopenias (thrombocytopenia [29%] and anemia [15%]). The overall response rate (ORR) was 67% (44/66); 42% achieved very good partial response or better (≥VGPR). Median time to progression and duration of response were 9.5 and 9.7 months, respectively. ORR of 97% and ≥VGPR 73% were seen in patients not refractory to bortezomib who had 1 to 3 prior therapies. Patients with high BCL2 expression had a higher ORR (94% [17/18]) than patients with low BCL2 expression (59% [16/27]). This novel combination of venetoclax with bortezomib and dexamethasone has an acceptable safety profile and promising efficacy in patients with relapsed/refractory MM. This trial was registered at www.clinicaltrials.gov as #NCT01794507.

Current and developing synthetic pharmacotherapy for treating relapsed/refractory multiple myeloma

INTRODUCTION

The introduction of novel agents has significantly improved multiple myeloma (MM) patient outcome during the last two decades. MM received the most drug approvals for any one malignancy during this time period, both in the United States as well as in Europe. Areas covered: Proteasome inhibitors, immunomodulatory drugs, and monoclonal antibodies are prototype drug classes, which target both specific MM cell functions, as well as the tumor supportive bone marrow microenvironment, and represent current cornerstones of MM therapy. Importantly, the unprecedented extent and frequency of durable responses, in relapsed/refractory multiple myeloma (RRMM), in particular, is predominantly based on the combinatorial use of these agents with conventional chemotherapeutics or representatives of other drug classes. This article will summarize past landmark discoveries in MM that led to the dramatic progress of today's clinical practice. Moreover, developing strategies will be discussed that are likely to yet improve patient outcome even further. Expert opinion: Despite significant therapeutic advancements, MM remains an incurable disease. With several novel agents in the preclinical and early clinical pipeline, among those novel CD38 and BCMA mAbs, immune checkpoint inhibitors, as well as ricolinostat, selinexor, venetoclax, CAR-T cells, and vaccines, further advances in MM patient outcome are expected in the near future.

How I treat first relapse of myeloma

The standard treatment of relapsed multiple myeloma has been either lenalidomide-dexamethasone (RD) or bortezomib-dexamethasone (VD) but it is changing rapidly for 2 reasons. First, lenalidomide and bortezomib are currently used in frontline treatment and many patients become resistant to these agents early in the course of their disease. Second, 6 second-line new agents have been recently developed and offer new possibilities (pomalidomide, carfilzomib and ixazomib, panobinostat, elotuzumab, and daratumumab). Recent randomized studies have shown that triple combinations adding 1 of these new agents (except pomalidomide) to the RD or VD regimens were superior to the double combinations in terms of response rate and progression-free survival (PFS). Their place in the treatment of first relapse is discussed here. Among these agents, daratumumab is clearly a breakthrough and daratumumab-based combinations might become the preferred option in the near future. However, all of these drugs are expensive and are not available or affordable in all countries. We propose a decision algorithm for first relapse in fit patients with the objective of achieving the best PFS. The choice of salvage regimen is based on lenalidomide/bortezomib resistance, daratumumab availability, and cost. Autologous transplantation should be considered in younger patients if not used upfront.

CXCL12 and CXCR7 are relevant targets to reverse cell adhesion-mediated drug resistance in multiple myeloma

Cell adhesion-mediated drug resistance (CAM-DR) by the bone marrow (BM) is fundamental to multiple myeloma (MM) propagation and survival. Targeting BM protection to increase the efficacy of current anti-myeloma treatment has not been extensively pursued. To extend the understanding of CAM-DR, we hypothesized that the cytotoxic effects of novel anti-myeloma agents may be abrogated by the presence of BM stroma cells (BMSCs) and restored by addition of the CXCL12 antagonist NOX-A12 or the CXCR4 inhibitor plerixafor. Following this hypothesis, we evaluated different anti-myeloma agents alone, with BMSCs and when combined with plerixafor or NOX-A12. We verified CXCR4, CD49d (also termed ITGA4) and CD44 as essential mediators of BM adhesion on MM cells. Additionally, we show that CXCR7, the second receptor of stromal-derived-factor-1 (CXCL12), is highly expressed in active MM. Co-culture proved that co-treatment with plerixafor or NOX-A12, the latter inhibiting CXCR4 and CXCR7, functionally interfered with MM chemotaxis to the BM. This led to the resensitization of MM cells to the anti-myeloma agents vorinostat and pomalidomide and both proteasome inhibitors bortezomib and carfilzomib. Within a multicentre phase I/II study, NOX-A12 was tested in combination with bortezomib-dexamethasone, underlining the feasibility of NOX-A12 as an active add-on agent to antagonize myeloma CAM-DR.

Precision Medicine in Myeloma: Challenges in Defining an Actionable Approach

Recently, large sequencing studies have provided insights into the mutational landscape of multiple myeloma (MM), identifying actionable mutations and giving a precious opportunity for exploring new targeted therapies. The main goal of precision medicine, matching patients with the right drug, seems to be closer than ever. However, no targeted therapies in MM are approved yet. Several clinical trials testing targeted drugs and enrolling patients with MM are currently ongoing and will provide predictive biomarkers that might support clinical decision making. In this review, we evaluate the evidence supporting the implementation of precision medicine in MM and we discuss the challenges that should be dealt with in this imminent and promising new era.