Mechanisms of activity of the TORC1 inhibitor everolimus in Waldenstrom macroglobulinemia

PURPOSE

The TORC1 inhibitor everolimus has previously shown significant activity as a single agent in hematologic malignancies, with reported responses of 30% to 70% in Waldenstrom macroglobulinemia. However, the specific mechanisms by which this class of mTOR inhibitors exerts anti-Waldenstrom macroglobulinemia activity have not been fully investigated. We therefore sought to dissect the mechanisms of everolimus-dependent modulation of Waldenstrom macroglobulinemia cell survival.

EXPERIMENTAL DESIGN

We confirmed that everolimus targets mTOR in patients treated with everolimus and responding to therapy. We evaluated the effect of everolimus on proliferation and survival of primary Waldenstrom macroglobulinemia cells, as well as of other IgM-secreting lymphoma cell lines. Everolimus-dependent mechanisms of induced apoptosis and its effect on Waldenstrom macroglobulinemia cells in the context of bone marrow microenvironment have been also evaluated. miRNA-155 loss-of-function studies were conducted. Moreover, the combinatory effect of bortezomib and rituximab has been tested.

RESULTS

We showed that everolimus targeted mTOR downstream signaling pathways, ex vivo, in patients responding to everolimus treatment. Everolimus induced toxicity in primary Waldenstrom macroglobulinemia cells, as well as in other IgM-secreting lymphoma cells, supported by cell-cycle arrest and caspase-dependent and -independent induction of apoptosis. Importantly, everolimus targeted Waldenstrom macroglobulinemia cells even in the context of bone marrow milieu, where it affected migration, adhesion, and angiogenesis. Everolimus-dependent anti-Waldenstrom macroglobulinemia activity was partially driven by miRNA-155. Moreover, everolimus synergized with bortezomib and rituximab in targeting Waldenstrom macroglobulinemia cells, as shown by synergistic inhibition of p65/ and p50/NF-κB activities.

CONCLUSIONS

These findings provide a better understanding of the mechanisms that are responsible for everolimus-induced anti-Waldenstrom macroglobulinemia activity.

[Waldenström macroglobulinemia complicated with chylothorax]

An 81-year-old male had been diagnosed with Waldenström macroglobulinemia (WM) eight years previously and had thus been administered appropriate treatment. Left chylothorax later developed at 3 years and 8 months after the initial diagnosis. He was hospitalized with severe anemia, general fatigue, and appetite loss one year prior to this presentation and died due to a severe fungal infection. Autopsy revealed the presence of 1,300 ml chylothorax and infiltration of lymphoplasmacytic lymphoma (LPL) cells throughout his entire body. LPL cells were found to have invaded the excitation conducting system in the heart. In an evaluation of a resected lung tissue specimen of pneumothorax, subpleural infiltrated lymphoid cells were observed to show immunohistochemical positivity for IgM and bcl-2. Although these lymphoid cells were initially considered to be non-neoplastic lymphocytes, they were later determined to be LPL cells, which thus induced dilatation and proliferation of the lymph vessels. Chylothorax complications in patients with WM are rare events and only six such cases have so far been reported. The present case is considered to be an instructive one in which autopsy suggested the invasion of LPL cells to be involved in the development of arrhythmia, pneumothorax, and chylothorax before death.

Molecular pathogenesis of Waldenstrom's macroglobulinemia

Waldenström's macroglobulinemia is an indolent, lymphoproliferative disease, characterized by a heterogeneous lymphoplasmacytic bone marrow infiltrate and high immunoglobulin M production. While technological advances over the past several decades have dramatically improved the possibilities of studying the molecular basis of Waldenström's macroglobulinemia, the pathogenesis of the disease remains fragmented. Undoubtedly, research has been successful in uncovering underlying aberrations and deregulated mechanisms in this disease, providing useful information for identifying biomarkers for disease diagnosis, risk stratification and therapeutic intervention, but there is still a long way to go before the pathogenesis of Waldenström's macroglobulinemia is fully revealed. In addition, the low number of in vitro or in vivo models significantly challenges extensive analysis. In this manuscript, we review the molecular basis of this disease.

Familial aggregation of lymphoplasmacytic lymphoma/Waldenström macroglobulinemia with solid tumors and myeloid malignancies

Lymphoplasmacytic lymphoma (LPL)/Waldenström macroglobulinemia (WM) is a B-cell disorder resulting from the accumulation, predominantly in the bone marrow, of clonally related lymphoplasmacytic cells. LPL/WM is a very rare disease, with an incidence rate of 3-4 cases per million people per year.Currently, the causes of LPL/WM are poorly understood; however, there are emerging data to support a role for immune-related factors in the pathogenesis of LPL/WM. In addition, data show that genetic factors are of importance in the etiology of LPL/WM. In this paper, we will review the current knowledge about familiality of LPL/WM and provide novel data on solid tumors and myeloid malignancies in first-degree relatives of LPL/WM patients.

Eph-B2/ephrin-B2 interaction plays a major role in the adhesion and proliferation of Waldenstrom's macroglobulinemia

PURPOSE

The ephrin receptors (Eph) are found in a wide range of cancers and correlate with metastasis. In this study, we characterized the role of Eph-B2 receptor in the interaction of Waldenstrom's macroglobulinemia (WM) cells with the bone marrow microenvironment.

EXPERIMENTAL DESIGN

We screened the activity of different receptor tyrosine kinases in WM patients and found that Eph-B2 was overexpressed compared with control. Also, we tested the expression of ephrin-B2 ligand on endothelial cells and bone marrow stromal cells (BMSC) isolated from WM patients. We then tested the role of Eph-B2/Ephrin-B2 interaction in the adhesion of WM cells to endothelial cells and BMSCs; the cell signaling induced by the coculture in both the WM cells and the endothelial cells; WM cell proliferation, apoptosis, and cell cycle in vitro and tumor progression in vivo; and in angiogenesis.

RESULTS

Eph-B2 receptor was found to be activated in WM patients compared with control, with a 5-fold increase in CD19(+) WM cells, and activated cell adhesion signaling, including focal adhesion kinase, Src, P130, paxillin, and cofilin, but decreased WM cell chemotaxis. Ephrin-B2 ligand was highly expressed on endothelial cells and BMSCs isolated from WM patients and on human umbilical vein endothelial cells and induced signaling in the endothelial cells promoting adhesion and angiogenesis. Blocking of ephrin-B2 or Eph-B2 inhibited adhesion, cytoskeletal signaling, proliferation, and cell cycle in WM cells, which was induced by coculture with endothelial cells and decreased WM tumor progression in vivo.

CONCLUSION

Ephrin-B2/Eph-B2 axis regulates adhesion, proliferation, cell cycle, and tumor progression in vivo through the interaction of WM with the cells in the bone marrow microenvironment.

Recovery of kidney function by rituximab-based therapy in a patient with Waldenström's macroglobulinemia-related nephropathy presenting cast nephropathy and interstitial lymphocytic infiltration

A 60-year-old man with Waldenström's macroglobulinemia (WM) was admitted to our hospital for evaluation of rapid progressive renal deterioration despite 3 cycles of oral melphalan and prednisolone (MP) therapy. Renal biopsy just before introducing hemodialysis revealed cast nephropathy and severe tubulo-interstitial infiltration of B lymphocytes. After 6 cycles of rituximab, cyclophosphamide, vincristine and prednisolone (R-COP) therapy, his renal function improved enough to discontinue hemodialysis. This is a rare case of WM-related renal involvement caused by both monoclonal protein and tumor infiltration and, to our knowledge, the second report on improved renal function by rituximab-based therapy.

[Pathology, diagnostics, and treatment of Waldenström's macroglobulinaemia]

Waldenström's macroglobulinaemia is a rare non-Hodgkin lymphoma with bone marrow involvement and serum immunoglobulin M monoclonal protein component. The most important risk factor is immunoglobulin M monoclonal gammopathy of undetermined significance. Clinical features vary but may include anaemia, neuropathy, infections and elevated serum viscosity. Diagnosis is confirmed by flow-cytometry made on bone marrow aspirate. Not all patients require treatment at diagnosis. The main therapeutic options include alkylating agents, nucleoside analogues and rituximab used in different combination regimens.

Waldenstrom macroglobulinemia with CD5+ expression presented as cryoglobulinemic glomerulonephropathy: a case report

Waldenstrom macroglobulinemia (WM) is a B-cell lymphoproliferative disorder associated with bone marrow involvement of lymphoplasmacytic lymphoma (LPL) and an IgM monoclonal gammopathy. Generally B-lymphocytes in LPL do not express CD5 that is important for differential diagnosis of B-cell lymphoproliferative disorders. In WM, various renal diseases and type I cryoglobulinemia are well described separately, but cryoglobulinemic glomerulonephropathy is very rarely reported. A 61-yr-old woman complained of generalized edema, cyanosis of the extremities in cold weather, visual disturbance, and pancytopenia. Bone marrow and renal biopsy showed CD5+ expressing B-cells and cryoglobulinemic glomerulonephropathy. With the diagnosis of WM, she received cyclophosphamide, doxorubicin, vincristine and prednisolone chemotherapy and got complete remission. Here, we report a rare case of WM associated with unusual expression of CD5+ B-lymphocytes and cryoglobulinemic glomerulonephropathy, and emphasize the importance of the clinical features in differentiating CD5+ B-cell lymphoproliferative disorders.

[Clinical features of 16 cases of lymphoplasmacytic lymphoma/Waldenström macroglobulinemia]

In order to investigate the clinical manifestations, diagnosis, therapy and prognosis of lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM), 16 patients with LPL/WM were analyzed retrospectively. The results showed that the average age of 16 patients with LPL/WM was 65.1 years old, the most common syndromes were anemia and hyperviscosity syndrome, bone marrows were composed of small lymphocyte, admixed with variable numbers of plasma cells and plasmacytoid lymphocytes. And lymph node biopsy revealed that most cells expressed B-cell-associated antigen. Among the 16 cases, complete remission was 25%, overall response rate (ORR) was 81.3%, overall survival time was 6 to 108 months. 3 patients died and survival rate was 81.3 %. It is concluded that the clinical course of LPL/WM is typically indolent. These patients can acquire remission in clinic, but can not be cured, some of them can transform into patients with more malignant lymphoma.

[Clinicopathologic features of lymphoplasmacytic lymphoma]

OBJECTIVE

To explore the clinicopathologic features of lymphoplasmacytic lymphomas (LPL).

METHODS

Routine histological examination was performed on hematoxylin-eosin stained sections of 24 bone marrow biopsies and available 6 concurrent lymph node specimens. Immunohistochemistry study was performed using EliVision methods.

RESULTS

Among 24 cases, the male-to-female ratio was 2.4:1 and the median age was 59.5 years (42 - 75). The most common symptom was weakness (83.3%, 20/24). Hyperviscosity and "B" symptoms occurred in 20.8% (5/24) and 8.3% (2/24) respectively. 41.7% (10/24) patients presented with lymphadenopathy. Anemia, leukocytosis and thrombocytopenia were seen in 79.2% (19/24), 8.3% (2/24) and 37.5% (9/24) respectively. Monoclonal Ig light chain expression was detected by serum immunofixation electrophoresis in 23 cases (95.8%), including IgM (20 cases), IgG (2 cases) and IgA (1 case). Basing on the histology and immunohistochemistry findings, the diagnosis was made in 22 bone marrow and 2 lymph node biopsies, respectively. Histologically, the bone marrow and lymph node specimens composed of small lymphocytes, plasmacytoid lymphocytes and plasma cells. The most frequent pattern of bone marrow involvement was diffuse in appearance (63.6%, 14/22), while nodular and interstitial patterns were less common (22.7%, 5/22 and 13.6%, 3/22, respectively). Lymph node involvement was also to be diffuse in pattern. The proliferative cells expressed Pax5, CD20, CD38 and CD138, but were negative for CD5, CD10, CD23, CyclinD1, CD3, CD7 and MPO.

CONCLUSIONS

LPL has distinct clinicopathological features. Histological and immunohistochemistry findings are important for its differential diagnosis with chronic lymphocytic leukemia/small lymphocytic lymphoma, splenic marginal zone lymphoma and follicular lymphoma. Waldenström macroglobulinemia is LPL.

[Skin abnormalities as first sign of Waldenström macroglobulinaemia]

Small-vessel vasculitis was found in a 56-year-old female patient as the first sign of Waldenström macroglobulinemia. After the diagnosis was made by immunological investigation, she was treated successfully by combination therapy with rituximab, cyclophosphamide, vincristine en prednisone. Leukocytoclastic vasculitis occurs in only 5% of patients with Waldenström macroglobulinaemia as the first manifestation of this condition.

[Lymphoplasmacytic lymphoma with Waldenström's macroglobulinemia: a clinicopathological and immunophenotypic study of 40 Chinese patients]

OBJECTIVE

To investigate the clinicopathologic features of lymphoplasmacytic lymphoma (LPL) with Waldenström's macroglobulinemia (WM) and to evaluate the usefulness of immunophenotype analysis in diagnosis and differential diagnosis of the tumor.

METHODS

A total of 40 cases of LPL with WM diagnosed according to the 2008 World Health Organization classification of tumors of hematopoietic and lymphoid tissues were analyzed using immunophenotype and follow-up information.

RESULTS

The mostly common initial clinical presentations were non-specific symptoms, such as fatigue, anemia and hemorrhage. Lymphadenopathy, splenomegaly and hepatomegaly were found in 42.5%, 20.0% and 12.5% of the patients respectively. The pattern of bone marrow involvement included mixed type (47.2%), diffuse type (41.7%) and interstitial type (11.1%). The nodal architecture was completely destroyed in one case and partially effaced with residual germinal centers and dilated sinuses in 8 cases. All of the neoplastic cells expressed CD20 and CD79a. Neoplastic plasma cells were positive for CD138 and CD79a. No cases expressed CD5. Four cases weakly expressed CD23. No significant prognosis related factors were identified in the survival analysis.

CONCLUSIONS

LPL with WM is a rare indolent small B-cell lymphoma, which is commonly seen, in older male patients. The tumor frequently involves bone marrow and shows various clinical manifestations. Combination analyses of the bone marrow biopsy histology, immunophenotypic study and clinical data, especially the serum examination are important for the diagnosis of LPL with WM.

Waldenstrom's macroglobulinemia: Recent advances in biology and therapy

Waldenstrom's macroglobulinemia (WM) is a B-cell disorder characterized by bone marrow infiltration with clonal lymphoplasmacytic cells (LPCs), along with an immunoglobulin M monoclonal gammopathy. Recent studies have led to several insights into disease biology as well as the development of an international staging system. Patients with asymptomatic macroglobulinemia should be observed without therapy. Options for frontline therapy include alkylating agents, nucleoside analogs, and rituximab, either as monotherapy or in combination. Although objective responses are common, complete remissions are infrequent. Several novel agents including proteasome inhibitors and thalidomide, as well as high-dose chemotherapy and stem cell transplantation are being incorporated into the therapeutic armamentarium in WM and show promising activity. This report provides an update on recent advances in biology and treatment of this disease.

[Intracerebral infiltration by monoclonal plasmacytoid cells in Waldenstrom's macroglobulinemia: a case report and review of the literature]

OBJECTIVE

To sum up the clinical experience of the diagnosis and treatment of intracerebral infiltration by monoclonal plasmacytoid cells in Waldenstrom's macroglobulinemia(Bing-Neel syndrome).

METHODS

The clinical data of the diagnosis and treatment of a case of Bing-Neel syndrome was analyzed.

RESULTS

A 56-year-old male was diagnosed as Waldenstrom's macroglobulinemia one year ago, and presented with persistent headache during the treatment period. Magnetic resonance imaging showed a high intensity area on T2-weighed images in the right frontal lobe which was well enhanced by gadolinium-diethylenetriaminepenta-acetic acid. Infiltration of neoplastic cells was confirmed by biopsy. Immunohistochemical examination showed that mature plasmacytoid cells in the cerebral parenchyma were immunoglobulin M positive.

CONCLUSION

Infiltration in CNS (Bing-Neel syndrome) is uncommon in Waldenstrom's macroglobulinemia. As there is no effective therapy for this Bing-Neel syndrome, combination of radiation and chemotherapy should be considered for this situation.

IgG-lambda secreting B-lymphoplasmacytic lymphoma with disseminated cutaneous infiltration: report of a rare case

We present an 85-year-old female with IgG-lambda lymphoplasmacytic lymphoma (LPL) with disseminated cutaneous infiltration during disease progression, 9 months after initial diagnosis. The patient was voluntarily undertreated, therefore the disease progressed with vast cutaneous involvement. The patient died from severe sepsis and disseminated intravascular coagulation due to acute respiratory bacterial infection, before receiving any kind of treatment.

Primary therapy of Waldenström macroglobulinemia with bortezomib, dexamethasone, and rituximab: WMCTG clinical trial 05-180

PURPOSE

We examined the activity of bortezomib, dexamethasone, and rituximab (BDR) in patients with symptomatic, untreated Waldenström macroglobulinemia (WM).

PATIENTS AND METHODS

A cycle of therapy consisted of bortezomib 1.3 mg/m(2) intravenously; dexamethasone 40 mg on days 1, 4, 8, and 11; and rituximab 375 mg/m(2) on day 11. Patients received four consecutive cycles for induction therapy and then four more cycles, each given 3 months apart, for maintenance therapy. Twenty-three patients received a median of seven cycles of treatment.

RESULTS

Median bone marrow disease involvement declined from 55% to 10% (P = .0004), serum immunoglobulin M levels declined from 4,830 to 1,115 mg/dL (P < .0001), and hematocrit increased from 29.8% to 38.2% (P = .0002) at best response. The overall response rates and major response rates were 96% and 83% with three complete responses, two near complete responses, three very good partial responses, 11 partial responses, and three minor responses. Responses occurred at a median of 1.4 months. With a median follow-up of 22.8 months, 18 of 23 patients remained free of disease progression. Peripheral neuropathy was the most common toxicity, and it resolved to grade < or = 1 in 13 of 16 patients at a median of 6.0 months. Four of the first seven treated patients developed herpes zoster, resulting in the institution of prophylactic antiviral therapy.

CONCLUSION

The results demonstrate that BDR produces rapid and durable responses, along with high rates of response and complete remissions in WM. Herpes zoster prophylaxis is necessary with BDR, and reversible peripheral neuropathy was the most common toxicity leading to premature discontinuation of bortezomib in 61% of patients. Exploration of alternative schedules for bortezomib administration that includes weekly dosing should be pursued.

Treatment of Waldenstrom's Macroglobulinemia with Rituximab: Prognostic Factors for Response and Progression

Recent data have suggested that rituximab is an active agent for the treatment of Waldenstrom's macroglobulinemia (WM). However, the patients that are more likely to benefit have not been clearly defined. In order to address this question we evaluated 52 patients who were treated with single-agent rituximab in the context of prospective studies. Several clinical and laboratory variables were assessed for their correlation with response and time to progression. Twenty-three (44%) patients achieved a partial response after treatment with rituximab. Previously untreated and pretreated patients had the same probability for response. Higher response rates were noted in patients with serum monoclonal protein < 40 g/l, with serum albumin > or = 35 g/l and with kappa light chain. The median time to progression for all patients was 13.8 months. A multivariate analysis indicated that elevated serum monoclonal protein levels and low serum albumin were the dominant variables associated with shorter progression. Presence of two, one or none of these adverse prognostic factors was associated with time to progression of 3.6 months, 11 months and more than 40 months, respectively. We conclude that rituximab is an effective treatment modality for patients with WM. Patients with both low levels of monoclonal protein and normal albumin are the best candidates for treatment with standard dose rituximab.

The International Staging System for Multiple Myeloma is Applicable in Symptomatic Waldenstrom's Macroglobulinemia

Several studies have indicated that age, hemoglobin and serum albumin are among the most important prognostic factors for survival of patients with Waldenstrom's macroglobulinemia (WM). Furthermore, recent data indicate that serum b2-microglobulin may be also significant. The recently proposed International Staging System (ISS) for multiple myeloma is based on serum albumin and b2-microglobulin. We designed a study to assess this model in patients with WM. Our analysis included 83 previously untreated patients with WM who required systemic treatment and in whom pretreatment values for both serum albumin and b2-microglobulin were available. Based on these variables the patients were stratified into three ISS stages. Stage I: albumin > or = 3.5 g/dl and b2-microglobulin < 3.5 mg/dl, stage II: albumin < 3.5 g/dl and b2-microglobulin < 3.5 mg/gl or b2-microglobulin 3.5-5.5 mg/dl and stage III: b2-microglobulin > 5.5 mg/dl. Low albumin (< 3.5 g/dl) and high b2-microglobulin (> or = 3.5 mg/dl) were recorded in 45% and 52% of patients respectively. The distribution of patients in the three ISS stages was: stage I: 30%, stage II: 43% and stage III: 27%. The median overall survival from the date of treatment initiation was 115 months. The median survival according to ISS was not reached for stage I, 116 months for stage II and 54 months for stage III (P = 0.02). Our analysis indicated that the recently proposed ISS for multiple myeloma could stratify the patients with WM into three distinct subgroups with significantly different survival times. If this model is validated in independent series, it could provide a new staging system for WM based on readily available and reproducible variables.

microRNA expression in the biology, prognosis, and therapy of Waldenström macroglobulinemia

Multilevel genetic characterization of Waldenström macroglobulinemia (WM) is required to improve our understanding of the underlying molecular changes that lead to the initiation and progression of this disease. We performed microRNA-expression profiling of bone marrow-derived CD19(+) WM cells, compared with their normal cellular counterparts and validated data by quantitative reverse-transcription-polymerase chain reaction (qRT-PCR). We identified a WM-specific microRNA signature characterized by increased expression of microRNA-363*/-206/-494/-155/-184/-542-3p, and decreased expression of microRNA-9* (ANOVA; P < .01). We found that microRNA-155 regulates proliferation and growth of WM cells in vitro and in vivo, by inhibiting MAPK/ERK, PI3/AKT, and NF-kappaB pathways. Potential microRNA-155 target genes were identified using gene-expression profiling and included genes involved in cell-cycle progression, adhesion, and migration. Importantly, increased expression of the 6 miRNAs significantly correlated with a poorer outcome predicted by the International Prognostic Staging System for WM. We further demonstrated that therapeutic agents commonly used in WM alter the levels of the major miRNAs identified, by inducing downmodulation of 5 increased miRNAs and up-modulation of patient-downexpressed miRNA-9*. These data indicate that microRNAs play a pivotal role in the biology of WM; represent important prognostic marker; and provide the basis for the development of new microRNA-based targeted therapies in WM.