Tanya M. Spektor

Combined TRAF6 Targeting and Proteasome Blockade has Anti-tumor and Anti-bone Resorptive Effects

TNF receptor–associated factor 6 (TRAF6) has been implicated in polyubiquitin-mediated IL1R/TLR signaling through activation of IκB kinase (IKK) to regulate the NF-κB and JNK signaling pathways. Here, TRAF6 protein was determined to be overexpressed in bone marrow mononuclear cells (BMMC) from patients with multiple myeloma. TRAF6 expression in BMMCs from patients with progressive disease is significantly elevated as compared with individuals in complete remission, with monoclonal gammopathy of undetermined significance, or healthy subjects. Furthermore, TRAF6 dominant–negative (TRAF6dn) peptides were constructed which specifically reduced TRAF6 signaling and activation of IKK. TRAF6 not only reduced cellular growth but also increased the apoptosis of multiple myeloma tumor cells in a concentration-dependent fashion. Because TRAF6 activates IKK through polyubiquitination, independent of its proteasome activity, a TRAF6dn peptide was combined with the proteasome inhibitors bortezomib or carfilzomib to treat multiple myeloma. Importantly, targeting of TRAF6 in the presence of proteasome inhibition enhanced anti–multiple myeloma effects and also decreased TLR/TRAF6/NF-κB–related signaling. Finally, TRAF6dn dose dependently inhibited osteoclast cell formation from CD14+ monocytes, induced with RANKL and mCSF, and markedly reduced bone resorption in dentin pits. In all, these data demonstrate that blocking TRAF6 signaling has anti–multiple myeloma effects and reduces bone loss. Implications: The ability to target TRAF6 signaling and associated pathways in multiple myeloma suggests a promising new therapeutic approach. Mol Cancer Res; 15(5); 598–609. ©2017 AACR.

Serum B-cell maturation antigen: a novel biomarker to predict outcomes for multiple myeloma patients

B-cell maturation antigen is expressed on plasma cells. In this study, we have identified serum B-cell maturation antigen as a novel biomarker that can monitor and predict outcomes for multiple myeloma patients. Compared to healthy donors, patients with multiple myeloma showed elevated serum B-cell maturation antigen levels (P<0.0001). Serum B-cell maturation antigen levels correlated with the proportion of plasma cells in bone marrow biopsies (Spearman’s rho = 0.710; P<0.001), clinical status (complete response vs. partial response, P=0.0374; complete response vs. progressive disease, P<0.0001), and tracked with changes in M-protein levels. Among patients with non-secretory disease, serum B-cell maturation antigen levels correlated with bone marrow plasma cell levels and findings from positron emission tomography scans. Kaplan-Meier analysis demonstrated that serum B-cell maturation antigen levels above the median levels were predictive of a shorter progression-free survival (P=0.0006) and overall survival (P=0.0108) among multiple myeloma patients (n=243). Specifically, patients with serum B-cell maturation antigen levels above the median level at the time of starting front-line (P=0.0043) or a new salvage therapy (P=0.0044) were found to have shorter progression-free survival. Importantly, serum B-cell maturation antigen levels did not show any dependence on renal function and maintained independent significance when tested against other known prognostic markers for multiple myeloma such as age, serum β2 microglobulin, hemoglobin, and bone disease. These data identify serum B-cell maturation antigen as a new biomarker to manage multiple myeloma patients.

Outcomes of multiple myeloma patients receiving bortezomib, lenalidomide, and carfilzomib

New classes of drugs including the proteasome inhibitors (PI) bortezomib and, more recently, carfilzomib and the immunomodulatory agent lenalidomide have shown improved outcomes for multiple myeloma (MM) patients during the past decade. However, most of the studies reporting outcomes for patients receiving these drugs have relied on older data sets derived from large institutions that included patients not receiving their treatment at those facilities and represented only those eligible for clinical trials or were from sites where treatment options were limited. We have analyzed data from 258 MM patients who have received treatment with at least one of three agents: bortezomib, carfilzomib, and lenalidomide in a single clinic specializing in MM with respect to their responses and other outcomes to treatment regimens including these agents. Response rates were similar between these three drugs when used for the first time and again during subsequent treatment regimens. As expected, the clinical benefit rates (CBRs) were better for patients receiving their first treatment when compared to their use in subsequent treatment regimens. The CBRs were similar during their 2nd, 3rd, and 4th treatments containing these agents. Many patients refractory to these agents showed responses to regimens containing these same drugs when used in different combinations. In addition, patients refractory to one PI often responded to the other PI. The results of this study demonstrate that novel agents can be used repeatedly in novel combinations with significant clinical benefit for patients with MM.

Safety and efficacy of pomalidomide, dexamethasone and pegylated liposomal doxorubicin for patients with relapsed or refractory multiple myeloma

Immunomodulatory drugs including thalidomide, lenalidomide (LEN) and pomalidomide (POM), are effective for treating multiple myeloma (MM). POM has shown enhanced efficacy with dexamethasone (DEX). Pegylated liposomal doxorubicin (PLD) with bortezomib is US Food and Drug Administration‐approved for treating MM. PLD with LEN or thalidomide has shown efficacy for MM patients. LEN with DEX, PLD and bortezomib achieves high response rates. We evaluated the combination of POM with DEX 40 mg and PLD 5 mg/m2 with the latter two drugs administered on days 1, 4, 8 and 11 on a 28‐day cycle for the treatment of relapsed/refractory MM patients. During Phase 1, the maximum tolerated dose of POM was 4 mg, and was used in Phase 2, which also required patients to be refractory to LEN. However, neutropenia ≥ grade 3 was observed in 10/17 (59%) patients, and the dose was lowered to 3 mg. Median PFS was 5·4 months (range, 0·3–29·0 + months). Overall response rates for patients in Phase 2 were 39% and 31% among subjects receiving POM at 3 mg and 4 mg, respectively, and clinical benefit rates were 51% and 44%, respectively. POM, PLD and DEX is a treatment option for relapsed/refractory MM patients including those who are refractory to LEN.

Risk of skin cancer in multiple myeloma patients: a retrospective cohort study.

Immunosuppressed patients are known to have an increased incidence of skin cancer. Patients with multiple myeloma (MM) show impaired immune function. In the past, because of poor survival, the incidence of specific secondary primary malignancies such as skin cancer among these patients was difficult to establish. With more effective MM therapies that have emerged in recent years, these patients are living markedly longer, and therefore, it becomes of increasing importance to determine whether their risk of developing other medical problems such as skin cancer is increased. We performed a retrospective cohort study of 205 myeloma patients and 193 age‐, race‐, and gender‐matched control subjects to assess the incidence of skin cancers among patients with MM and determine the specific types of and risk factors for skin cancer. We found that there is an increased occurrence of skin cancer among patients with MM compared to control subjects (26.8% vs. 16.1% in controls; P = 0.009). Among specific types of skin cancer, the proportion of patients with squamous cell carcinoma (SCC) was higher than controls (P = 0.016). In addition to MM diagnosis, older age and Caucasian ethnicity were predictors of skin cancer of any type. Furthermore, older age was also a predictor of SCC.

Venetoclax in combination with bortezomib, dexamethasone and daratumumab for multiple myeloma

Introduction Multiple myeloma (MM) is an incurable plasma cell (PC) dyscrasia with a 5-year overall survival of 50.7% that is estimated to currently affect 124,733 people in the United States. Despite recent advances that have improved outcomes, MM inevitably becomes refractory to therapy, so clinicians must rely on a variety of treatment options for long-term disease management. Venetoclax is an oral BCL-2 (B-cell lymphoma 2) inhibitor that has been demonstrated to show activity in the treatment of MM. Members of the BCL-2 family of proteins are critical regulators of apoptosis and include both antiapoptotic (eg, BCL-2, MCL-1, BCL-XL) and proapoptotic (eg, BAK, BAX) elements. The upregulation of antiapoptotic proteins has been reported for most cancers, but high BCL-2 levels have been especially prevalent in human lymphoid malignancies, including chronic lymphocytic leukemia, for which venetoclax is currently indicated. BCL-2 is also overexpressed especially in the subset of MM patients with t(11;14) translocations, a cytogenetic abnormality found in about 20% of all MM patients. Venetoclax as a single agent has been shown to induce apoptosis not only in human MM cell lines and primary samples but also in relapsed/refractory (RR) MM patients. Single-agent activity was

Circulating proteasomes: circling myeloma with a new potential biomarker

Since the early 1990s, the generation and subsequent use of small molecule inhibitors targeting the ubiquitin proteasome pathway have transformed the treatment and improved the outcomes for patients with multiple myeloma (MM). Specifically, agents in this drug class such as the first FDA-approved proteasome inhibitor (PI) bortezomib (Velcade) [1,2] have become common components of many standard anti-myeloma treatment regimens during the past decade. Although most patients respond to bortezomib when used in combination with other active anti-MM agents, some of them do not benefit from treatment with this PI. Others, who were initially sensitive to this treatment, develop resistance to the drug after repeated exposure. These observations have encouraged the development of the next generation of PIs, including carfilzomib which has also been FDA-approved for the treatment of previously treated patients with MM. Since its development, clinical studies have shown that treatment with carfilzomib can overcome bortezomib resistance in MM [3]. Patients treated with carfilzomib experience less peripheral neuropathy and show superior anti-myeloma effects compared with bortezomib [4]. A number of clinical trials have also documented the ability of bortezomib to overcome the poor prognosis conferred by the diverse clinical, biochemical, and cytogenetic factors that have been identified for patients undergoing conventional anti-MM therapies [5–8]. This evidence suggested that sensitivity to bortezomib occurred among patients previously identified as likely to be resistant to standard treatments available in the pre-PI era, thereby implying that different biomarkers may be indicative of responsiveness to treatment with PIs. Because of this, efforts were undertaken to identify possible new prognostic factors for patients treated with PIs. However, until now no markers have been found and validated in a manner that would allow for their routine clinical use to identify patients who are more likely to respond to treatment with bortezomib or other PIs as opposed to those who would not. Because of the constitutively increased activity of proteasomes in myeloma cells and these being the target of PI’s anti-MM effects, assessment of the proteasome complex captured interest as a potential biomarker for defining the likelihood of response to treatment with bortezomib. Early evidence supporting this idea derived from the higher levels of free circulating proteasomes found in patients with a variety of autoimmune diseases and cancers. These results suggested that the circulating proteasomes were generated from pathologic processes that were occurring in these patients [9]. Investigation of the enzymatic activity of circulating proteasome components among patients with hematologic disorders such as acute myeloid leukemia, lymphocytic leukemias, and myelodysplastic syndrome had shown that the levels of proteasome components and their enzymatic activities could be successfully detected in plasma samples from patients as well as healthy individuals [10]. Plasma samples from patients with the above diseases had significantly higher proteasome enzymatic activities when compared with those from healthy controls. Furthermore, changes in proteasome levels and enzymatic activity highly correlated with changes in the clinical status of these diseases [10]. In MM, the first study to examine circulating proteasome levels as an independent prognostic indicator for survival was reported by Jakob et al. for patients