Anuj Mahindra

Latest advances and current challenges in the treatment of multiple myeloma

Effectively treating patients with multiple myeloma is challenging. The development of therapeutic regimens over the past decade that incorporate the proteasome inhibitor bortezomib and the immunomodulatory drugs thalidomide and lenalidomide has been the cornerstone of improving the outcome of patients with myeloma. Although these treatment regimens have improved patient survival, nearly all patients eventually relapse. Our improved understanding of the biology of the disease and the importance of the microenvironment has translated into ongoing work to help overcome the challenge of relapse. Several classes of agents including next-generation proteasome inhibitors, immunomodulatory agents, selective histone-deacetylase inhibitors, antibody and antitumor immunotherapy approaches are currently undergoing preclinical and clinical evaluation. This Review provides an update on the latest advances in the treatment of multiple myeloma. In particular, we focus on novel therapies including modulating protein homeostasis, kinases inhibitors, targeting accessory cells and cytokines, and immunomodulatory agents. A discussion of the challenges associated with these therapeutic approaches is also presented.

Plasma cell leukemia: consensus statement on diagnostic requirements, response criteria and treatment recommendations by the International Myeloma Working Group

Plasma cell leukemia (PCL) is a rare and aggressive variant of myeloma characterized by the presence of circulating plasma cells. It is classified as either primary PCL occurring at diagnosis or as secondary PCL in patients with relapsed/refractory myeloma. Primary PCL is a distinct clinic-pathological entity with different cytogenetic and molecular findings. The clinical course is aggressive with short remissions and survival duration. The diagnosis is based upon the percentage (⩾20%) and absolute number (⩾2 × 109/l) of plasma cells in the peripheral blood. It is proposed that the thresholds for diagnosis be re-examined and consensus recommendations are made for diagnosis, as well as, response and progression criteria. Induction therapy needs to begin promptly and have high clinical activity leading to rapid disease control in an effort to minimize the risk of early death. Intensive chemotherapy regimens and bortezomib-based regimens are recommended followed by high-dose therapy with autologous stem cell transplantation if feasible. Allogeneic transplantation can be considered in younger patients. Prospective multicenter studies are required to provide revised definitions and better understanding of the pathogenesis of PCL.

Multiple myeloma: biology of the disease

Multiple myeloma (MM) is a clonal B-cell malignancy characterized by the aberrant expansion of plasma cells within the bone marrow, as well as at extramedullary sites. Decades of scientific research are now beginning to unravel the intricate biology that underlies the pathophysiology of MM. In particular, the roles of cellular differentiation, molecular pathogenesis, and oncogenes involved in the natural history of MM are becoming clearer. This has enabled the identification of specific cytokines, adhesion molecules, and stromal cells that affect MM cell development, disease progression, and treatment responses. This review describes our current understanding regarding the biology of MM, and how this has led to a robust pipeline of novel therapeutic agents with the potential to overcome resistance to existing MM therapies and, therefore, further improve outcomes in patients with MM.

The use of novel agents in the treatment of relapsed and refractory multiple myeloma.

Although outcomes for patients with multiple myeloma (MM) have improved over the past decade, the disease remains incurable and even patients who respond well to induction therapy ultimately relapse and require additional treatment. Conventional chemotherapy and high-dose therapy with stem cell transplantation (SCT) have historically been utilized in the management of relapsed MM, but in recent years the immunomodulatory drugs (IMiDs) thalidomide and lenalidomide, as well as the proteasome inhibitor bortezomib, have assumed a primary role in this setting. This review focuses on the role of thalidomide, lenalidomide and bortezomib in relapsed and refractory MM, with additional discussion dedicated to emerging drugs in relapsed MM that may prove beneficial to patients with this disease.

Management of relapsed multiple myeloma: Recommendations of the international myeloma working group

The prognosis for patients multiple myeloma (MM) has improved substantially over the past decade with the development of new, more effective chemotherapeutic agents and regimens that possess a high level of anti-tumor activity. In spite of this important progress, however, nearly all MM patients ultimately relapse, even those who experience a complete response to initial therapy. Management of relapsed MM thus represents a vital aspect of the overall care for patients with MM and a critical area of ongoing scientific and clinical research. This comprehensive manuscript from the International Myeloma Working Group provides detailed recommendations on management of relapsed disease, with sections dedicated to diagnostic evaluation, determinants of therapy, and general approach to patients with specific disease characteristics. In addition, the manuscript provides a summary of evidence from clinical trials that have significantly impacted the field, including those evaluating conventional dose therapies, as well as both autologous and allogeneic stem cell transplantation. Specific recommendations are offered for management of first and second relapse, relapsed and refractory disease, and both autologous and allogeneic transplant. Finally, perspective is provided regarding new agents and promising directions in management of relapsed MM.

Randomized multicenter phase 2 study of pomalidomide, cyclophosphamide, and dexamethasone in relapsed refractory myeloma

Pomalidomide and low-dose dexamethasone (PomDex) is standard treatment of lenalidomide refractory myeloma patients who have received >2 prior therapies. We aimed to assess the safety and efficacy of the addition of oral weekly cyclophosphamide to standard PomDex. We first performed a dose escalation phase 1 study to determine the recommended phase 2 dose of cyclophosphamide in combination with PomDex (arm A). A randomized, multicenter phase 2 study followed, enrolling patients with lenalidomide refractory myeloma. Patients were randomized (1:1) to receive pomalidomide 4 mg on days 1 to 21 of a 28-day cycle in combination with weekly dexamethasone (arm B) or pomalidomide, dexamethasone, and cyclophosphamide (PomCyDex) 400 mg orally on days 1, 8, and 15 (arm C). The primary end point was overall response rate (ORR). Eighty patients were enrolled (10 in phase 1 and 70 randomized in phase 2: 36 to arm B and 34 to arm C). The ORR was 38.9% (95% confidence interval [CI], 23-54.8%) and 64.7% (95% CI, 48.6-80.8%) for arms B and C, respectively (P = .035). As of June 2015, 62 of the 70 randomized patients had progressed. The median progression-free survival (PFS) was 4.4 (95% CI, 2.3-5.7) and 9.5 months (95% CI, 4.6-14) for arms B and C, respectively (P = .106). Toxicity was predominantly hematologic in nature but was not statistically higher in arm C. The combination of PomCyDex results in a superior ORR and PFS compared with PomDex in patients with lenalidomide refractory multiple myeloma. The trial was registered at www.clinicaltrials.gov as #NCT01432600.

Hematopoietic cell transplant comorbidity index is predictive of survival after autologous hematopoietic cell transplantation in multiple myeloma

Autologous hematopoietic stem cell transplantation (AHCT) improves survival in patients with multiple myeloma (MM) but is associated with morbidity and nonrelapse mortality (NRM). Hematopoietic cell transplant comorbidity index (HCT-CI) was shown to predict risk of NRM and survival after allogeneic transplantation. We tested the utility of HCT-CI as a predictor of NRM and survival in patients with MM undergoing AHCT. We analyzed outcomes of 1156 patients of AHCT after high-dose melphalan reported to the Center for International Blood and Marrow Transplant Research. Individual comorbidities were prospectively collected at the time of AHCT. The impact of HCT-CI and other potential prognostic factors, including Karnofsky performance score (KPS), on NRM and survival were studied in multivariate Cox regression models. HCT-CI score was 0, 1, 2, 3, and >3 in 42%, 18%, 13%, 13%, and 14% of the study cohort, respectively. Subjects were stratified into 3 risk groups: HCT-CI score of 0 (42%) versus HCT-CI score of 1 to 2 (32%) versus HCT-CI score > 2 (26%). Higher HCT-CI was associated with lower KPS < 90 (33% of subjects score of 0 versus 50% in HCT-CI score > 2). HCT-CI score > 2 was associated with melphalan dose reduction (22% versus 10% in score 0 cohort). One-year NRM was low at 2% (95% confidence interval, 1% to 4%) and did not correlate with HCT-CI score (P = .9). On multivariate analysis, overall survival was inferior in groups with HCT-CI score of 1 to 2 (relative risk, 1.37, [95% confidence interval, 1.01 to 1.87], P = .04) and HCT-CI score > 2 (relative risk, 1.5 [95% confidence interval, 1.09 to 2.08], P = .01). Overall survival was also inferior with KPS < 90 (P < .001), IgA subtype (P ≤ .001), those receiving >1 pretransplant induction regimen (P = .007), and those with resistant disease at the time of AHCT (P < .001). AHCT for MM is associated with low NRM, and death is predominantly related to disease progression. Although a higher HCT-CI score did not predict NRM, it was associated with inferior survival.

Hematopoietic cell transplantation for primary plasma cell leukemia: results from the Center for International Blood and Marrow Transplant Research

There are limited data on hematopoietic cell transplantation (HCT) in primary plasma cell leukemia (pPCL), an aggressive plasma cell disorder. We report outcomes of 147 patients with pPCL receiving autologous (n=97) or allogeneic (n=50) HCT within 18 months after diagnosis between 1995 and 2006. Median age was 56 years and 48 years for autologous HCT and allogeneic HCT, respectively. Progression-free survival (PFS) at 3 years was 34% (95% confidence interval (CI), 23–46%) in the autologous group and 20% (95% CI, 10–34%) in the allogeneic group. Cumulative incidence of relapse at 3 years was 61% (95% CI, 48–72%) in the autologous group and 38% (95% CI, 25–53%) in the allogeneic group. Overall survival (OS) at 3 years was 64% (95% CI, 52–75%) in the autologous group and 39% (95% CI, 26–54%) in the allogeneic group. Non-relapse mortality (NRM) at 3 years was 5% (95% CI, 1–11%) in the autologous group and 41% (95% CI, 28–56%) in the allogeneic group. The encouraging OS after autologous HCT, establishes the safety and feasibility of this consolidative treatment option after initial induction therapy for pPCL. Allogeneic HCT, although associated with a significantly lower relapse rate, carries a much higher risk of NRM and no OS benefit.

Antimyeloma Activity of a Multitargeted Kinase Inhibitor, AT9283, via Potent Aurora Kinase and STAT3 Inhibition Either Alone or in Combination with Lenalidomide

Purpose: Aurora kinases, whose expression is linked to genetic instability and cellular proliferation, are being investigated as novel therapeutic targets in multiple myeloma (MM). In this study, we investigated the preclinical activity of a small-molecule multitargeted kinase inhibitor, AT9283, with potent activity against Aurora kinase A, Aurora kinase B, and Janus kinase 2/3. Experimental Design: We evaluated the in vitro antimyeloma activity of AT9283 alone and in combination with lenalidomide and the in vivo efficacy by using a xenograft mouse model of human MM. Results: Our data showed that AT9283 induced cell-growth inhibition and apoptosis in MM. Studying the apoptosis mechanism of AT9283 in MM, we observed features consistent with both Aurora kinase A and Aurora kinase B inhibition, such as increase of cells with polyploid DNA content, decrease in phospho-histone H3, and decrease in phospho-Aurora A. Importantly, AT9283 also inhibited STAT3 tyrosine phosphorylation in MM cells. Genetic depletion of STAT3, Aurora kinase A, or Aurora kinase B showed growth inhibition of MM cells, suggesting a role of AT9283-induced inhibition of these molecules in the underlying mechanism of MM cell death. In vivo studies showed decreased MM cell growth and prolonged survival in AT9283-treated mice compared with controls. Importantly, combination studies of AT9283 with lenalidomide showed significant synergistic cytotoxicity in MM cells, even in the presence of bone marrow stromal cells. Enhanced cytotoxicity was associated with increased inhibition of phosphorylated STAT3 and phosphorylated extracellular signal–regulated kinase. Conclusions: Demonstration of in vitro and in vivo anti-MM activity of AT9283 provides the rationale for the clinical evaluation of AT9283 as monotherapy and in combination therapy for treating patients with MM. Clin Cancer Res; 17(10); 3259–71. ©2011 AACR.

Lenalidomide in combination with an activin A-neutralizing antibody: preclinical rationale for a novel anti-myeloma strategy

Given the prevalence of osteolytic bone disease in multiple myeloma (MM), novel therapies targeting bone microenvironment are essential. Previous studies have identified activin A to be of critical importance in MM-induced osteolysis. Lenalidomide is a known and approved treatment strategy for relapsed MM. Our findings demonstrate that lenalidomide acts directly on bone marrow stromal cells via an Akt-mediated increase in Jun N-terminal kinase-dependent signaling resulting in activin A secretion, with consequent inhibition of osteoblastogenesis. Here, we attempted to augment the antitumor benefits of lenalidomide while overcoming its effects on osteoblastogenesis by combining it with a neutralizing antibody to activin A. Increased activin A secretion induced by lenalidomide was abrogated by the addition of activin A-neutralizing antibody, which effectively restored osteoblast function and inhibited MM-induced osteolysis without negating the cytotoxic effects of lenalidomide on malignant cells. This provides the rationale for an ongoing clinical trial (NCT01562405) combining lenalidomide with an anti-activin A strategy.