Sheeba K. Thomas

Impairment of Filgrastim-Induced Stem Cell Mobilization after Prior Lenalidomide in Patients with Multiple Myeloma

Lenalidomide is an agent that has shown great activity in patients with multiple myeloma (MM). However, studies have suggested that this drug negatively affects subsequent stem cell collection. To investigate whether lenalidomide impairs stem cell mobilization and collection, we reviewed data for patients with MM who underwent mobilization with filgrastim. Predictors of mobilization failure were evaluated using logistic regression analysis. In 26 (9%) of 302 myeloma patients, stem cell mobilization failed. Mobilization failed in 25% of patients who had previously received lenalidomide, compared with 4% of patients who had not received lenalidomide (P < .001). In a multivariate analysis, prior lenalidomide use (odds ratio: 5.9; 95% confidence interval [CI]: 2.4-14.3) and mobilization more than 1 year after diagnosis (odds ratio: 4.6; 95% CI: 1.9-11.1) were significantly associated with failed mobilization. Twenty-one of 26 patients in whom mobilization with filgrastim failed underwent remobilization with chemotherapy and filgrastim; in 18 (86%) of these 21 patients, stem cells were successfully mobilized and collected. In patients with multiple myeloma, prior lenalidomide therapy is associated with failure of stem cell mobilization with filgrastim. Remobilization with chemotherapy and filgrastim is usually successful in these patients.

Targeting the insulin-like growth factor-1 receptor to overcome bortezomib resistance in preclinical models of multiple myeloma

Proteasome inhibition with bortezomib is a validated approach to the treatment of multiple myeloma, but drug resistance often emerges and limits its utility in the retreatment setting. To begin to identify some of the mechanisms involved, we developed bortezomib-resistant myeloma cell lines that, unlike previously reported models, showed no β5 subunit mutations. Instead, up-regulation of the insulin-like growth factor (IGF)-1 axis was identified, with increased autocrine and paracrine secretion of IGF-1, leading to increased activation of the IGF-1 receptor (IGF-1R). Exogenous IGF-1 reduced cellular sensitivity to bortezomib, whereas pharmacologic or small hairpin RNA-mediated IGF-1R suppression enhanced bortezomib sensitivity in cell lines and patient samples. In vitro studies with OSI-906, a clinically relevant dual IGF-1R and insulin receptor inhibitor, showed it acted synergistically with bortezomib, and potently resensitized bortezomib-resistant cell lines and patient samples to bortezomib. Importantly, OSI-906 in combination with bortezomib also overcame bortezomib resistance in an in vivo model of myeloma. Taken together, these data support the hypothesis that signaling through the IGF-1/IGF-1R axis contributes to acquired bortezomib resistance, and provide a rationale for combining bortezomib with IGF-1R inhibitors like OSI-906 to overcome or possibly prevent the emergence of bortezomib-refractory disease in the clinic.

A phase 2 multicentre study of siltuximab, an anti-interleukin-6 monoclonal antibody, in patients with relapsed or refractory multiple myeloma

Interleukin‐6 (IL6) plays a central role in multiple myeloma pathogenesis and confers resistance to corticosteroid‐induced apoptosis. We therefore evaluated the efficacy and safety of siltuximab, an anti‐IL6 monoclonal antibody, alone and in combination with dexamethasone, for patients with relapsed or refractory multiple myeloma who had ≥2 prior lines of therapy, one of which had to be bortezomib‐based. Fourteen initial patients received siltuximab alone, 10 of whom had dexamethasone added for suboptimal response; 39 subsequent patients were treated with concurrent siltuximab and dexamethasone. Patients received a median of four prior lines of therapy, 83% were relapsed and refractory, and 70% refractory to their last dexamethasone‐containing regimen. Suppression of serum C‐reactive protein levels, a surrogate marker of IL6 inhibition, was demonstrated. There were no responses to siltuximab but combination therapy yielded a partial (17%) + minimal (6%) response rate of 23%, with responses seen in dexamethasone‐refractory disease. The median time to progression, progression‐free survival and overall survival for combination therapy was 4·4, 3·7 and 20·4 months respectively. Haematological toxicity was common but manageable. Infections occurred in 57% of combination‐treated patients, including ≥grade 3 infections in 18%. Further study of siltuximab in modern corticosteroid‐containing myeloma regimens is warranted, with special attention to infection‐related toxicity.

Oral lenalidomide with rituximab in relapsed or refractory diffuse large cell, follicular and transformed lymphoma: a phase II clinical trial

Lenalidomide–rituximab therapy is effective in grade 1–2 follicular and mantle cell lymphoma, but its efficacy in diffuse large B-cell lymphoma (DLBCL), transformed large cell lymphoma (TL) and grade 3 follicular lymphoma (FLG3) is unknown. In this phase II trial, 45 patients with relapsed or refractory DLBCL (n=32), TL (n=9) or FLG3 (n=4) who had received 1–4 prior lines of treatment were given 20 mg oral lenalidomide on days 1–21 of each 28-day cycle, and intravenous rituximab (375 mg/m2) weekly during cycle 1. Grade 3/4 hematological toxicities included neutropenia (53%), lymphopenia (40%), thrombocytopenia (33%), leukopenia (27%) and anemia (18%), with a median follow-up time of 29.1 months (range 14.7–52.0 months). Overall response (OR) rate was 33%; median response duration was 10.2 months. Median progression-free survival (PFS) and overall survival (OS) were 3.7 and 10.7 months, respectively. Nine of the 15 responding patients (three partial response (PR), six complete response (CR)) proceeded with stem cell transplantation (SCT) and were censored at the time of transplantation. When data were analyzed without censoring, median PFS remained 3.7 months and response duration increased to 30.9 months. Rituximab plus oral lenalidomide is well tolerated and effective for patients with relapsed/refractory DLBCL and TL. SCT after lenalidomide–rituximab is associated with prolonged response duration.

Treatment recommendations for patients with Waldenström macroglobulinemia (WM) and related disorders: IWWM-7 consensus.

Waldenström macroglobulinemia (WM) is a distinct B-cell lymphoproliferative disorder for which clearly defined criteria for the diagnosis, initiation of therapy, and treatment strategy have been proposed as part of the consensus panels of International Workshops on WM (IWWM). As part of the IWWM-7 and based on recently published and ongoing clinical trials, the panels updated treatment recommendations. Therapeutic strategy in WM should be based on individual patient and disease characteristics (age, comorbidities, need for rapid disease control, candidacy for autologous transplantation, cytopenias, IgM-related complications, hyperviscosity, and neuropathy). Mature data show that rituximab combinations with cyclophosphamide/dexamethasone, bendamustine, or bortezomib/dexamethasone provided durable responses and are indicated for most patients. New monoclonal antibodies (ofatumumab), second-generation proteasome inhibitors (carfilzomib), mammalian target of rapamycin inhibitors, and Brutons tyrosine kinase inhibitors are promising and may expand future treatment options. A different regimen is typically recommended for relapsed or refractory disease. In selected patients with relapsed disease after long-lasting remission, reuse of a prior effective regimen may be appropriate. Autologous stem cell transplantation may be considered in young patients with chemosensitive disease and in newly diagnosed patients with very-high-risk features. Active enrollment of patients with WM in clinical trials is encouraged.

Blockade of interleukin-6 signalling with siltuximab enhances melphalan cytotoxicity in preclinical models of multiple myeloma

Signalling through the interleukin (IL)‐6 pathway induces proliferation and drug resistance of multiple myeloma cells. We therefore sought to determine whether the IL‐6‐neutralizing monoclonal antibody siltuximab, formerly CNTO 328, could enhance the activity of melphalan, and to examine some of the mechanisms underlying this interaction. Siltuximab increased the cytotoxicity of melphalan in KAS‐6/1, INA‐6, ANBL‐6, and RPMI 8226 human myeloma cell lines (HMCLs) in an additive‐to‐synergistic manner, and sensitized resistant RPMI 8226.LR5 cells to melphalan. These anti‐proliferative effects were accompanied by enhanced activation of drug‐specific apoptosis in HMCLs grown in suspension, and in HMCLs co‐cultured with a human‐derived stromal cell line. Siltuximab with melphalan enhanced activation of caspase‐8, caspase‐9, and the downstream effector caspase‐3 compared with either of the single agents. This increased induction of cell death occurred in association with enhanced Bak activation. Neutralization of IL‐6 also suppressed signalling through the phosphoinositide 3‐kinase/Akt pathway, as evidenced by decreased phosphorylation of Akt, p70 S6 kinase and 4E‐BP1. Importantly, the siltuximab/melphalan regimen demonstrated enhanced anti‐proliferative effects against primary plasma cells derived from patients with myeloma, monoclonal gammopathy of undetermined significance, and amyloidosis. These studies provide a rationale for translation of siltuximab into the clinic in combination with melphalan‐based therapies.

Solitary plasmacytomas: outcome and prognostic factors after definitive radiation therapy.

The objective of this study was to review the outcome of patients with solitary plasmacytoma (SP) after definitive radiation therapy.

Evidence of a role for CD44 and cell adhesion in mediating resistance to lenalidomide in multiple myeloma: Therapeutic implications

Resistance of myeloma to lenalidomide is an emerging clinical problem, and though it has been associated in part with activation of Wnt/β-catenin signaling, the mediators of this phenotype remained undefined. Lenalidomide-resistant models were found to overexpress the hyaluronan (HA)-binding protein CD44, a downstream Wnt/β-catenin transcriptional target. Consistent with a role of CD44 in cell adhesion-mediated drug resistance (CAM-DR), lenalidomide-resistant myeloma cells were more adhesive to bone marrow stroma and HA-coated plates. Blockade of CD44 with monoclonal antibodies, free HA or CD44 knockdown reduced adhesion and sensitized to lenalidomide. Wnt/β-catenin suppression by FH535 enhanced the activity of lenalidomide, as did interleukin-6 neutralization with siltuximab. Notably, all-trans retinoic acid (ATRA) downregulated total β-catenin, cell-surface and total CD44, reduced adhesion of lenalidomide-resistant myeloma cells and enhanced the activity of lenalidomide in a lenalidomide-resistant in vivo murine xenograft model. Finally, ATRA sensitized primary myeloma samples from patients that had relapsed and/or refractory disease after lenalidomide therapy to this immunomodulatory agent ex vivo. Taken together, our findings support the hypotheses that CD44 and CAM-DR contribute to lenalidomide resistance in multiple myeloma, that CD44 should be evaluated as a putative biomarker of sensitivity to lenalidomide, and that ATRA or other approaches that target CD44 may overcome clinical lenalidomide resistance.

Feasibility of autologous hematopoietic stem cell transplant in patients aged ≥ 70 years with multiple myeloma

Abstract We retrospectively analyzed the outcomes of all consecutive patients with myeloma (n = 84) aged ≥70 years who had received autologous hematopoietic stem cell transplant (auto HCT) between July 1999 and June 2010 at our institution. The median age at auto HCT was 72 years, the median number of prior therapies was 2.5 and the median time from diagnosis to auto HCT was 10.2 months. The conditioning regimen consisted of melphalan at 140 mg/m2 in 10%, 180 mg/m2 in 25% and 200 mg/m2 in 65% of patients. The day-100 non-relapse mortality was 3%. The overall response rate at day 100 was 85% (complete response 18%, very good partial response 12%, partial response 55%). After a median follow-up of 25 months among surviving patients, the estimated progression-free survival and overall survival at 5 years were 27% and 67%, respectively. The incidence of grade II–IV toxicity, response rate and survival were similar across three melphalan dose levels. These results indicate that high-dose melphalan plus auto HCT is safe and feasible for patients with multiple myeloma aged ≥70 years and age alone should not be an exclusion criterion for auto HCT.

Novel phosphatidylinositol 3-kinase inhibitor NVP-BKM120 induces apoptosis in myeloma cells and shows synergistic anti-myeloma activity with dexamethasone.

NVP-BKM120 is a novel phosphatidylinositol 3-kinase (PI3K) inhibitor and is currently being investigated in phase I clinical trials in solid tumors. This study aimed to evaluate the therapeutic efficacy of BKM120 in multiple myeloma (MM). BKM120 induces cell growth inhibition and apoptosis in both MM cell lines and freshly isolated primary MM cells. However, BKM120 only shows limited cytotoxicity toward normal lymphocytes. The presence of MM bone marrow stromal cells, insulin-like growth factor, or interleukin-6 does not affect BKM120-induced tumor cell apoptosis. More importantly, BKM120 treatment significantly inhibits tumor growth in vivo and prolongs the survival of myeloma-bearing mice. In addition, BKM120 shows synergistic cytotoxicity with dexamethasone in dexamethasone-sensitive MM cells. Low doses of BKM120 and dexamethasone, each of which alone has limited cytotoxicity, induce significant cell apoptosis in MM.1S and ARP-1. Mechanistic study shows that BKM120 exposure causes cell cycle arrest by upregulating p27 (Kip1) and downregulating cyclin D1 and induces caspase-dependent apoptosis by downregulating antiapoptotic XIAP and upregulating expression of cytotoxic small isoform of Bim, BimS. In summary, our findings demonstrate the in vitro and in vivo anti-MM activity of BKM120 and suggest that BKM120 alone or together with other MM chemotherapeutics, particularly dexamethasone, may be a promising treatment for MM.