Citations

Everolimus is an oral raptor mTOR inhibitor and has shown activity in patients with Waldenstrom's macroglobulinemia (WM). This study examines a large cohort of patients with relapsed/refractory WM with long‐term follow up for survival. Patients were eligible if they had measurable disease, a platelet count >75,000 × 106/L, an absolute neutrophil count >1,000 × 106/L. Patients received everolimus 10 mg PO daily and were evaluated monthly. A success was defined as a complete or partial response (PR); minor responses (MR) were recorded and considered to be of clinical benefit. Sixty patients were enrolled and treated. The overall response rate (ORR) was 50% (all PR); the clinical benefit rate including MR or better was 73% (95% CI: 60–84%) with 23% MR. The median time to response for patients who achieved PR was 2 months (range, 1–26). The median duration of response has not been reached and median progression‐free survival (PFS) was 21 months. Grade 3 or higher toxicities (at least possibly related to everolimus) were observed in 67% of patients. The most common grade 3 or 4 toxicities were anemia (27%), leukopenia (22%), and thrombocytopenia (20%). Other nonhematological toxicities were diarrhea (5%), fatigue (8%), stomatitis (8%) and pulmonary toxicity (5%). Everolimus has a high single‐agent activity of 73% including MR, with a progression free survival of 21 months, indicating that this agent is active in relapsed/refractory WM. Am. J. Hematol. 89:237–242, 2014. © 2013 Wiley Periodicals, Inc

Purpose The phosphatidylinositol 3-kinase/mammalian target of rapamycin (mTOR) signal transduction pathway controls cell proliferation and survival. Everolimus is an oral agent targeting raptor mTOR (mTORC1). The trial's goal was to determine the antitumor activity and safety of single-agent everolimus in patients with relapsed/refractory Waldenström macroglobulinemia (WM). Patients and Methods Eligible patients had measurable disease (immunoglobulin M monoclonal protein > 1,000 mg/dL with > 10% marrow involvement or nodal masses > 2 cm), a platelet count more than 75,000 × 10 6 /L, a neutrophil count more than 1,000 × 10 6 /L, and a creatinine and bilirubin less than 2 × the laboratory upper limit of normal. Patients received everolimus 10 mg orally daily and were evaluated monthly. Tumor response was assessed after cycles 2 and 6 and then every three cycles until progression. Results Fifty patients were treated. The median age was 63 years (range, 43 to 85 years). The overall response rate (complete response plus partial remission [PR] plus minimal response [MR]) was 70% (95% CI, 55% to 82%), with a PR of 42% and 28% MR. The median duration of response and median progression-free survival (PFS) have not been reached. The estimated PFS at 6 and 12 months is 75% (95% CI, 64% to 89%) and 62% (95% CI, 48% to 80%), respectively. Grade 3 or higher related toxicities were observed in 56% of patients. The most common were hematologic toxicities with cytopenias. Pulmonary toxicity occurred in 10% of patients. Dose reductions due to toxicity occurred in 52% of patients. Conclusion Everolimus has high single-agent activity with an overall response rate of 70% and manageable toxicity in patients with relapsed WM and offers a potential new therapeutic strategy for this patient group.

Abstract Recently, many new drugs have been developed for the treatment of Waldenström macroglobulinemia (WM). To optimize the treatment according to the prognosis and to facilitate the comparison of trials, we developed an International Prognostic Scoring System for WM in a series of 587 patients with clearly defined criteria for diagnosis and for initiation of treatment. The median survival after treatment initiation was 87 months. Five adverse covariates were identified: advanced age (>65 years), hemoglobin less than or equal to 11.5 g/dL, platelet count less than or equal to 100 × 109/L, β2-microglobulin more than 3 mg/L, and serum monoclonal protein concentration more than 7.0 g/dL. Low-risk patients (27%) presented with no or 1 of the adverse characteristics and advanced age, intermediate-risk patients (38%) with 2 adverse characteristics or only advanced age, and high-risk patients (35%) with more than 2 adverse characteristics. Five-year survival rates were 87%, 68%, and 36%, respectively (P < .001). The ISSWM retained its prognostic significance in subgroups defined by age, treatment with alkylating agent, and purine analog. Thus, the ISSWM may provide a means to design risk-adapted studies. However, independent validation and new biologic markers may enhance its significance.

Abstract The nuclear factor-κB (NF-κB) path-way has been implicated in tumor B-cell survival, growth, and resistance to therapy. Because tumor cells overcome single-agent antitumor activity, we hypothesized that combination of agents that target differentially NF-κB pathway will induce significant cytotoxicity. Therapeutic agents that target proteasome and Akt pathways should induce significant activity in B-cell malignancies as both pathways impact NF-κB activity. We demonstrated that perifosine and bortezomib both targeted NF-κB through its recruitment to the promoter of its target gene IκB using chromatin immunoprecipitation assay. This combination led to synergistic cytotoxicity in Waldenstrom macroglobulinemia (WM) cells that was mediated through a combined reduction of the PI3K/Akt and ERK signaling pathways, found to be critical for survival of WM cells. Moreover, a combination of these drugs with the CD20 monoclonal antibody rituximab further increased their cytotoxic activity. Thus, effective WM therapy may require combination regimens targeting the NF-κB pathway.

Abstract To better understand the molecular changes that occur in Waldenstrom macroglobulinemia (WM), we employed antibody-based protein microarrays to compare patterns of protein expression between untreated WM and normal bone marrow controls. Protein expression was defined as a &gt;2-fold or 1.3-fold change in at least 67% of the tumor samples. Proteins up-regulated by &gt;2-fold included Ras family proteins, such as Rab-4 and p62DOK, and Rho family proteins, such as CDC42GAP and ROKα. Other proteins up-regulated by &gt;1.3-fold included cyclin-dependent kinases, apoptosis regulators, and histone deacetylases (HDAC). We then compared the samples of patients with symptomatic and asymptomatic WM and showed similar protein expression signatures, indicating that the dysregulation of signaling pathways occurs early in the disease course. Three proteins were different by &gt;2-fold in symptomatic versus asymptomatic, including the heat shock protein HSP90. Elevated protein expression was confirmed by immunohistochemistry and immunoblotting. Functional significance was validated by the induction of apoptosis and inhibition of proliferation using specific HDAC and HSP90 inhibitors. This study, therefore, identifies, for the first time, multiple novel proteins that are dysregulated in WM, which both enhance our understanding of disease pathogenesis and represent targets of novel therapeutics. [Cancer Res 2007;67(8):3777–8]

AbstractWaldenström macroglobulinemia (WM) is an incurable lymphoplasmacytic lymphoma with limited options of therapy. Protein kinase Cβ (PKCβ) regulates cell survival and growth in many B-cell malignancies. In this study, we demonstrate up-regulation of PKCβ protein in WM using protein array techniques and immunohistochemistry. Enzastaurin, a PKCβ inhibitor, blocked PKCβ activity and induced a significant decrease of proliferation at 48 hours in WM cell lines (IC50, 2.5-10 μM). Similar effects were demonstrated in primary CD19+ WM cells, without cytotoxicity on peripheral blood mononuclear cells. In addition, enzastaurin overcame tumor cell growth induced by coculture of WM cells with bone marrow stromal cells. Enzastaurin induced dose-dependent apoptosis at 48 hours mediated via induction of caspase-3, caspase-8, caspase-9, and PARP cleavage. Enzastaurin inhibited Akt phosphorylation and Akt kinase activity, as well as downstream p-MARCKS and ribosomal p-S6. Furthermore, enzastaurin demonstrated additive cytotoxicity in combination with bortezomib, and synergistic cytotoxicity in combination with fludarabine. Finally, in an in vivo xenograft model of human WM, significant inhibition of tumor growth was observed in the enzastaurin-treated mice (P = .028). Our studies therefore show that enzastaurin has significant antitumor activity in WM both in vitro and in vivo, providing the framework for clinical trials to improve patient outcome in WM.

Purpose To review the diagnostic criteria, prognostic factors, response criteria, and treatment options of patients with Waldenstrom's macroglobulinemia (WM). Methods A review of published reports was facilitated by the use of a MEDLINE computer search and by manual search of the Index Medicus. Results WM should be regarded as a distinct clinicopathologic entity and confined to those patients with lymphoplasmacytoid lymphoma who have demonstrable serum immunoglobulin M monoclonal protein. Treatment decisions should rely on specific clinical and laboratory criteria. Initiation of therapy should not be based on serum monoclonal protein levels per se. The three main choices for systemic primary treatment of symptomatic patients with WM include alkylating agents (chlorambucil), nucleoside analogs (fludarabine and cladribine), and the monoclonal antibody rituximab. There are no data from prospective randomized studies to recommend the use of one first-line agent over another, although consideration of a patient's candidacy for autologous stem-cell transplantation (ASCT) should be taken into account to avoid stem cell–damaging agents. There are preliminary data to suggest that combinations of nucleoside analogs and alkylating agents with or without rituximab may improve response rates at the expense of higher toxicity. Conclusion WM is a distinct low-grade lymphoproliferative disorder. When therapy is indicated, alkylating agents, nucleoside analogs, and rituximab are reasonable choices. Several factors, including the presence of cytopenias, need for rapid disease control, candidacy for ASCT, age, and comorbidities, should be taken into consideration when choosing the most appropriate primary treatment.