Targeting B cell receptor signaling with ibrutinib in diffuse large B cell lymphoma.

The two major subtypes of diffuse large B cell lymphoma (DLBCL)--activated B cell-like (ABC) and germinal center B cell-like (GCB)--arise by distinct mechanisms, with ABC selectively acquiring mutations that target the B cell receptor (BCR), fostering chronic active BCR signaling. The ABC subtype has a ∼40% cure rate with currently available therapies, which is worse than the rate for GCB DLBCL, and highlights the need for ABC subtype-specific treatment strategies. We hypothesized that ABC, but not GCB, DLBCL tumors would respond to ibrutinib, an inhibitor of BCR signaling. In a phase 1/2 clinical trial that involved 80 subjects with relapsed or refractory DLBCL, ibrutinib produced complete or partial responses in 37% (14/38) of those with ABC DLBCL, but in only 5% (1/20) of subjects with GCB DLBCL (P = 0.0106). ABC tumors with BCR mutations responded to ibrutinib frequently (5/9; 55.5%), especially those with concomitant myeloid differentiation primary response 88 (MYD88) mutations (4/5; 80%), a result that is consistent with in vitro cooperation between the BCR and MYD88 pathways. However, the highest number of responses occurred in ABC tumors that lacked BCR mutations (9/29; 31%), suggesting that oncogenic BCR signaling in ABC does not require BCR mutations and might be initiated by non-genetic mechanisms. These results support the selective development of ibrutinib for the treatment of ABC DLBCL.

Phase 1 study of radiosensitization using bortezomib in patients with relapsed non-Hodgkin lymphoma receiving radioimmunotherapy with 131I-tositumomab.

Radioimmunotherapy (RIT) is effective treatment for indolent non-Hodgkin lymphomas (NHLs), but response durations are usually limited, especially in aggressive NHL. We hypothesized that administration of bortezomib as a radiosensitizer with RIT would be tolerable and improve efficacy in NHL. This phase 1 dose-escalation study evaluated escalating doses of bortezomib combined with 131I-tositumomab in patients with relapsed/refractory NHL. Twenty-five patients were treated. Treatment was well tolerated, with primarily hematologic toxicity. The maximum tolerated dose (MTD) was determined to be 0.9 mg/m2 bortezomib, in combination with a standard dose of 75 cGy 131I-tositumomab. Sixteen patients responded (64%), including 44% complete responses (CRs), with 82% CR in patients with follicular lymphoma (FL). At a median follow-up of 7 months, median progression-free survival was 7 months, and seven of 11 patients with FL remained in remission at a median of 22 months. In conclusion, bortezomib can be safely administered in combination with 131I-tositumomab with promising response rates.

Rituximab and three dexamethasone cycles provide responses similar to splenectomy in women and those with immune thrombocytopenia of less than two years duration.

Adults with newly diagnosed or persistent immunothrombocytopenia frequently relapse upon tapering steroids; adults and children with chronic disease have an even lower likelihood of lasting response. In adults with newly-diagnosed immunothrombocytopenia, two studies showed that dexamethasone 40 mg/day × four days and 4 rituximab infusions were superior to dexamethasone alone. Studies have also shown three cycles of dexamethasone are better than one and patients with persistent/chronic immunothrombocytopenia respond less well to either dexamethasone or rituximab. Therefore, 375 mg/m(2) × 4 rituximab was combined with three 4-day cycles of 28 mg/m(2) (max. 40 mg) dexamethasone at 2-week intervals and explored in 67 ITP patients. Best long-term response was assessed as complete (platelet count ≥ 100 × 10(9)/L) or partial (50-99 × 10(9)/L). Only 5 patients had not been previously treated. Fifty achieved complete (n=43, 64%) or partial (n=7, 10%) responses. Thirty-five of 50 responders maintained treatment-free platelet counts over 50 × 10(9)/L at a median 17 months (range 4-67) projecting 44% event-free survival. Duration of immunothrombocytopenia less than 24 months, achieving complete responses, and being female were associated with better long-term response (P<0.01). Adverse events were generally mild-moderate, but 3 patients developed serum sickness and 2 colitis; there were no sequelae. Dexamethasone could be difficult to tolerate. Fourteen patients became hypogammaglobulinemic and half had increased frequency of minor infections; 9 of 12 evaluable patients recovered their IgG levels. Rituximab combined with three cycles of dexamethasone provides apparently better results to reported findings with rituximab alone, dexamethasone alone, or the combination with one cycle of dexamethasone. The results suggest medical cure may be achievable in immunothrombocytopenia, especially in women and in patients within two years of diagnosis. (clinicaltrials.gov identifier:02050581).

Mechanism-based epigenetic chemosensitization therapy of diffuse large B-cell lymphoma.

UNLABELLED: Although aberrant DNA methylation patterning is a hallmark of cancer, the relevance of targeting DNA methyltransferases (DNMT) remains unclear for most tumors. In diffuse large B-cell lymphoma (DLBCL) we observed that chemoresistance is associated with aberrant DNA methylation programming. Prolonged exposure to low-dose DNMT inhibitors (DNMTI) reprogrammed chemoresistant cells to become doxorubicin sensitive without major toxicity in vivo. Nine genes were recurrently hypermethylated in chemoresistant DLBCL. Of these, SMAD1 was a critical contributor, and reactivation was required for chemosensitization. A phase I clinical study was conducted evaluating azacitidine priming followed by standard chemoimmunotherapy in high-risk patients newly diagnosed with DLBCL. The combination was well tolerated and yielded a high rate of complete remission. Pre- and post-azacitidine treatment biopsies confirmed SMAD1 demethylation and chemosensitization, delineating a personalized strategy for the clinical use of DNMTIs. SIGNIFICANCE: The problem of chemoresistant DLBCL remains the most urgent challenge in the clinical management of patients with this disease. We describe a mechanism-based approach toward the rational translation of DNMTIs for the treatment of high-risk DLBCL.

Metronomic therapy for refractory/relapsed lymphoma: the PEP-C low-dose oral combination chemotherapy regimen.

BACKGROUND: Metronomic therapy is the application of continuous, low dose chemotherapy. The doses of chemotherapy are usually not sufficient to destroy neoplastic cells, but impact the milieu, particularly angiogenesis. OBJECTIVE: To determine if the oral PEP-C regimen, consisting of prednisone 20 mgm, etoposide 50 mgm, procarbazine 50 mgm, and cyclophosphamide 50 mgm given in either a daily, alternate day, or fractionated basis, is effective in a variety of lymphomas. METHODS: One hundred twenty two patients were studied although the majority had low grade or mantle cell lymphoma. All had received at least two or more prior therapies. RESULTS: Overall, 75% achieved an objective response (OR) with 38% complete responses (CRs) or CRs unconfirmed, and 37% partial responses. ORs were achieved in mantle cell (85%), follicular (88%), marginal zone (71%), and small lymphocytic (67%) lymphomas. Chemosensitive disease was more responsive. Toxicity was minimal. CONCLUSION: The PEP-C regimen is an easily administered highly effective treatment for heavily pretreated mantle cell and low grade lymphomas.

Bortezomib in combination with rituximab, dexamethasone, ifosfamide, cisplatin and etoposide chemoimmunotherapy in patients with relapsed and primary refractory diffuse large B-cell lymphoma.

Patients with relapsed or refractory diffuse large B-cell lymphoma may experience extended survival with second-line chemotherapy and autologous stem cell transplant (ASCT). Since a major determinant of outcome after ASCT is responsiveness to second-line therapy, the development of more effective second-line treatments is desirable. We investigated the addition of bortezomib to rituximab, dexamethasone, ifosfamide, cisplatin and etoposide (VIPER). Fifteen patients were enrolled, of whom seven were refractory to first-line chemotherapy and only three had maintained first response for 1 year. Nine (60%) patients achieved objective responses, of which three (20%) were IWC-PET (International Workshop Criteria positron emission tomography) complete responses. Median progression-free survival was 3 months, and median overall survival was 10 months. At a median follow-up of 26 months, five patients (33%) remained alive. Treatment was well tolerated with no unexpected toxicity. Although response rates did not meet predefined criteria, activity was at least comparable to other second-line approaches despite a poor-prognosis patient population.

Response to second-line therapy defines the potential for cure in patients with recurrent diffuse large B-cell lymphoma: implications for the development of novel therapeutic strategies.

BACKGROUND: Patients with diffuse large B-cell lymphoma (DLBCL) who are not cured by initial therapy sometimes experience disease-free survival after autologous stem cell transplantation. Chemotherapy responsiveness before transplantation is a major predictor of outcome. Patients not responding to second-line regimens may receive third-line therapy in the hopes of achieving response, but outcome data are limited. PATIENTS AND METHODS: We identified patients with relapsed or refractory DLBCL at Weill Cornell Medical Center for whom data on responses to second-line chemotherapy were available. RESULTS: A total of 74 patients with relapsed or refractory DLBCL who underwent second-line chemotherapy between 1996 and 2007 were identified. Of these patients, 27 (36%) did not respond. The median overall survival of nonresponding patients was 4 months, and only 1 patient (4%) survived for 1 year. The choice of third-line aggressive chemotherapy instead of less intensive approaches did not confer a survival benefit. CONCLUSION: Our data demonstrate that patients with recurrent DLBCL not responding to second-line chemotherapy demonstrate dismal outcomes. Trials of novel regimens should be prioritized as management strategies for these patients. Our data provide an important benchmark in the evaluation of the potential clinical value of such approaches.

New biologic agents and immunologic strategies.

The treatment of non-Hodgkin lymphoma has traditionally consisted of cytotoxic chemotherapy, which can frequently induce remissions but less reliably delivers long-term disease-free survival. The last two decades have heralded an era of increasing exploration of therapies derived from improved biologic understanding of tumors and tumor-host interactions, including the development of therapeutic tactics that take advantage of immune mechanisms to target and kill tumors. Foremost among these has been the development of monoclonal antibodies. Currently, an array of novel therapeutics in development may improve outcomes further, including novel monoclonals and other agents that take advantage of or optimize immune system function in the treatment of lymphoma or that provide other mechanisms of antitumor activity.

FDG-PET in prediction of splenectomy findings in patients with known or suspected lymphoma.

Diagnostic splenectomy is frequently performed in patients with suspected or known lymphoma. We evaluated whether preoperative 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) results may correlate with splenic pathology. Of 165 patients undergoing splenectomy at the Weill Cornell Medical Centre/New York Presbyterian Hospital from 2004 to 2006, 10 were identified as being performed to evaluate known or suspected lymphoma and included a pre-splenectomy FDG-PET scan. The scans were assigned to low, intermediate or high splenic metabolic activity based on standardized uptake values (SUV). Low activity was associated with benign findings or mantle cell lymphoma at splenectomy, intermediate activity with marginal zone lymphoma and high activity with DLBCL. This comprises the largest pathologically confirmed series of cases to evaluate splenic FDG-PET uptake in suspected or known lymphoma. Low splenic SUV appears less likely to be associated with splenic involvement of lymphoma; intermediate and high values suggest presence of lymphoma. Our findings support a potential role for preoperative FDG-PET in consideration of the need for splenectomy in these settings.

FDG-PET scans in patients with lymphoma.

Lymphoma comprises a complex set of diseases, including Hodgkin and non-Hodgkin subtypes. An expected goal of management is chronic disease control over decades in most patients with indolent subtypes, and cure is a realistic target for aggressive histologies, including Hodgkin lymphoma. Making methods available to better assess prognosis and to more specifically tailor therapy toward individual subtypes is a priority. Positron emission tomography using the tracer (18)fluoro-2-deoxyglucose (FDG-PET) has become a valuable tool in the care of patients with lymphoma; it contributes information on staging and response assessment that has the potential to affect and improve patient care. This imaging modality is also being explored as an early response assessor, potentially allowing early prediction of an individual's response to a specific therapy. This information ultimately may lead to modifications of treatment to improve efficacy or reduce toxicity. Although FDG-PET offers valuable information, it is important to recognize its limitations as well as areas that require further exploration in order to optimally integrate its use into the clinical management of lymphoma patients.

The glucose dependence of Akt-transformed cells can be reversed by pharmacologic activation of fatty acid beta-oxidation.

Activation of the oncogenic kinase Akt stimulates glucose uptake and metabolism in cancer cells and renders these cells susceptible to death in response to glucose withdrawal. Here we show that 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) reverses the sensitivity of Akt-expressing glioblastoma cells to glucose deprivation. AICAR's protection depends on the activation of AMPK, as expression of a dominant-negative form of AMPK abolished this effect. AMPK is a cellular energy sensor whose activation can both block anabolic pathways such as protein synthesis and activate catabolic reactions such as fatty acid oxidation to maintain cellular bioenergetics. While rapamycin treatment mimicked the effect of AICAR on inhibiting markers of cap-dependent translation, it failed to protect Akt-expressing cells from death upon glucose withdrawal. Compared to control cells, Akt-expressing cells were impaired in the ability to induce fatty acid oxidation in response to glucose deprivation unless stimulated with AICAR. Stimulation of fatty acid oxidation was sufficient to maintain cell survival as activation of fatty acid oxidation with bezafibrate also protected Akt-expressing cells from glucose withdrawal-induced death. Conversely, treatment with a CPT-1 inhibitor to block fatty acid import into mitochondria prevented AICAR from stimulating fatty acid oxidation and promoting cell survival in the absence of glucose. Finally, cell survival did not require reversal of Akt's effects on either protein translation or lipid synthesis as the addition of the cell penetrant oxidizable substrate methyl-pyruvate was sufficient to maintain survival of Akt-expressing cells deprived of glucose. Together, these data suggest that activation of Akt blocks the ability of cancer cells to metabolize nonglycolytic bioenergetic substrates, leading to glucose addiction.

Enhanced marrow [18F]fluorodeoxyglucose uptake related to myeloid hyperplasia in Hodgkin's lymphoma can simulate lymphoma involvement in marrow.

[18F]Fluorodeoxyglucose (FDG) positron emission tomography (PET) is increasingly used for the clinical staging of lymphomas and for assessment of response to therapy. We report the case of a woman with classic Hodgkin's lymphoma who had marked FDG uptake by tumor and bone marrow suggestive of diffuse marrow involvement by lymphoma. However, iliac crest bone marrow examination showed marked myeloid hyperplasia without evidence of lymphoma involvement. We discuss the implications for interpretation of FDG-PET imaging of bone marrow in lymphomas.

Akt stimulates aerobic glycolysis in cancer cells.

Cancer cells frequently display high rates of aerobic glycolysis in comparison to their nontransformed counterparts, although the molecular basis of this phenomenon remains poorly understood. Constitutive activity of the serine/threonine kinase Akt is a common perturbation observed in malignant cells. Surprisingly, although Akt activity is sufficient to promote leukemogenesis in nontransformed hematopoietic precursors and maintenance of Akt activity was required for rapid disease progression, the expression of activated Akt did not increase the proliferation of the premalignant or malignant cells in culture. However, Akt stimulated glucose consumption in transformed cells without affecting the rate of oxidative phosphorylation. High rates of aerobic glycolysis were also identified in human glioblastoma cells possessing but not those lacking constitutive Akt activity. Akt-expressing cells were more susceptible than control cells to death after glucose withdrawal. These data suggest that activation of the Akt oncogene is sufficient to stimulate the switch to aerobic glycolysis characteristic of cancer cells and that Akt activity renders cancer cells dependent on aerobic glycolysis for continued growth and survival.

Activated Akt promotes increased resting T cell size, CD28-independent T cell growth, and development of autoimmunity and lymphoma.

The mechanisms that regulate basal T cell size and metabolic activity are uncertain. Since the phosphatidylinositol-3 phosphate kinase (PI3 K) and Akt (PKB) pathway has been shown in model organisms to regulate both cell size and metabolism, we generated transgenic mice expressing a constitutively active form of Akt (myristoylated Akt, mAkt) in T cells. Naive transgenic T cells were enlarged and had increased rates of glycolysis compared to control T cells. In addition, mAkt transgenic T cells resisted death-by-neglect upon in vitro culture. Upon activation, mAkt-transgenic T cells were less dependent than control cells on costimulation through CD28 and could both grow rapidly and secrete cytokines in the absence of CD28 ligation. In addition, transgenic expression of mAkt led to the accumulation of CD4 T cells and B cells with age. Many aged mAkt-transgenic mice also developed autoimmunity with immunoglobulin deposits on kidney glomeruli and displayed increased incidence of lymphoma. Together, these data show that Akt activation is sufficient to increase basal T cell size and metabolism. Enhancement of T cell metabolism by Akt and more rapid CD28-independent T cell growth may contribute to the accumulation of excess immune cells and the development of lymphoma and autoimmunity.

The CD28 signaling pathway regulates glucose metabolism.

Lymphocyte activation initiates a program of cell growth, proliferation, and differentiation that increases metabolic demand. Although T cells increase glucose uptake and glycolysis during an immune response, the signaling pathways that regulate these increases remain largely unknown. Here we show that CD28 costimulation, acting through phosphatidylinositol 3'-kinase (PI3K) and Akt, is required for T cells to increase their glycolytic rate in response to activation. Furthermore, CD28 controls a primary response pathway, inducing a level of glucose uptake and glycolysis in excess of that needed to maintain cellular ATP/ADP levels or macromolecular synthesis. These data suggest that CD28 costimulation functions to increase glycolytic flux, allowing T cells to anticipate energetic and biosynthetic needs associated with a sustained response.