Rebecca Elstrom

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.

The glucose dependence of Akt-transformed cells can be reversed by pharmacologic activation of fatty acid β -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. AICARs 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 Akts 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.

Bortezomib Plus CHOP-Rituximab for Previously Untreated Diffuse Large B-Cell Lymphoma and Mantle Cell Lymphoma

PURPOSE The proteasome inhibitor bortezomib may enhance activity of chemoimmunotherapy in lymphoma. We evaluated dose-escalated bortezomib plus standard cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) plus rituximab (R) in patients with diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma (MCL). PATIENTS AND METHODS Seventy-six subjects with untreated DLBCL (n = 40) and MCL (n = 36) received standard CHOP every 21 days (CHOP-21) with R plus bortezomib at 0.7 mg/m(2) (n = 4), 1.0 mg/m(2) (n = 9), or 1.3 mg/m(2) (n = 63) on days 1 and 4 for six cycles. RESULTS Median age was 63 years (range, 20 to 87), and International Prognostic Index (IPI) scores were generally unfavorable (39% with IPI of 2, and 49% with IPI of 3 to 5), as were Mantle Cell Lymphoma International Prognostic Index scores in patients with MCL (28% intermediate risk and 39% high risk). Toxicity was manageable, including neuropathy in 49 subjects (8% grade 2 and 4% grade 3) and grade 3/4 anemia (13%), neutropenia (41%), and thrombocytopenia (25%). For DLBCL, the evaluable overall response rate (ORR) was 100% with 86% complete response (CR)/CR unconfirmed (CRu; n = 35). Intent-to-treat (ITT, n = 40) ORR was 88% with 75% CR/CRu, 2-year progression-free survival (PFS) of 64% (95% CI, 47% to 77%) and 2-year overall survival (OS) of 70% (95% CI, 53% to 82%). For MCL, the evaluable ORR was 91% with 72% CR/CRu (n = 32). The ITT (n = 36) ORR was 81% with 64% CR/CRu, 2-year PFS 44% (95% CI, 27% to 60%) and 2-year OS 86% (95% CI, 70% to 94%). IPI and MIPI correlated with survival in DLBCL and MCL, respectively. Unlike in DLBCL treated with R-CHOP alone, nongerminal center B cell (non-GCB) and GCB subtypes had similar outcomes. CONCLUSION Bortezomib with R-CHOP-21 can be safely administered and may enhance outcomes, particularly in non-GCB DLBCL, justifying randomized studies.

Treatment of PTLD with Rituximab or Chemotherapy

Information regarding treatment of post‐transplant lymphoproliferative disease (PTLD) beyond reduction in immunosuppression (RI) is limited. We retrospectively evaluated patients receiving rituximab and/or chemotherapy for PTLD for response, time to treatment failure (TTF) and overall survival (OS). Thirty‐five patients met inclusion criteria. Twenty‐two underwent rituximab treatment, with overall response rate (ORR) 68%. Median TTF was not reached at 19 months and estimated OS was 31 months. In univariable analysis, Epstein‐Barr virus (EBV) positivity predicted response and TTF. LDH elevation predicted shorter OS. No patient died of rituximab toxicity and all patients who progressed underwent further treatment with chemotherapy. Twenty‐three patients received chemotherapy. ORR was 74%, median TTF was 10.5 months and estimated OS was 42 months. Prognostic factors for response included stage, LDH and allograft involvement by tumor. These factors and lack of complete response (CR) predicted poor survival. Twenty‐six percent of the patients receiving chemotherapy died of toxicity. Rituximab and chemotherapy are effective in patients with PTLD who fail or do not tolerate RI. While rituximab is well tolerated, toxicity of chemotherapy is marked. PTLD patients requiring therapy beyond RI should be considered for rituximab, especially with EBV‐positive disease. Chemotherapy should be reserved for patients who fail rituximab, have EBV‐negative tumors or need a rapid response.

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.

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.

Surveillance CT scans are a source of anxiety and fear of recurrence in long-term lymphoma survivors

BACKGROUND We aimed to assess anxiety and the psychological impact of routine surveillance scans in long-term survivors of adult aggressive lymphoma. PATIENTS AND METHODS In this cross-sectional observational study of 70 survivors of curable adult aggressive lymphoma, we measured anxiety and the doctor-patient relationship and performed a qualitative interview (n = 30) focused on patient perception of routine follow-up imaging studies. RESULTS Participants were diagnosed with aggressive lymphoma a median of 4.9 years (2.4-38.0 years) before enrollment. Thirty-seven percent of patients were found to meet criteria for clinically significant anxiety, which was not associated with years since diagnosis. In multivariate analysis, history of relapse and a worse doctor-patient relationship were independently associated with higher anxiety levels. Despite representing a largely cured population, in qualitative interviews patients reported fear of recurrence as a major concern and considerable anxiety around the time of a follow-up imaging scan. CONCLUSIONS Routine surveillance scans exacerbate underlying anxiety symptoms and fear of recurrence in survivors of aggressive lymphoma. Strategies to minimize follow-up imaging and to improve doctor-patient communication should be prospectively evaluated to address these clinically significant issues.

Combined PET and low-dose, noncontrast CT scanning obviates the need for additional diagnostic contrast-enhanced CT scans in patients undergoing staging or restaging for lymphoma

BACKGROUND Positron emission tomography (PET) is more accurate than computed tomography (CT) in staging and restaging of lymphoma, but both are considered necessary. Increasingly, PET is carried out with a low-dose CT scan. Many patients undergo both PET/CT and standard diagnostic CT. The clinical utility of performing both studies in patients with lymphoma was evaluated. PATIENTS AND METHODS Patients with lymphoma who underwent concurrent PET/CT and diagnostic CT (a scan pair) were identified, and findings detected in either scan but not both were documented. Discrepancies were considered significant if they were related to either lymphoma or another disease process which potentially required intervention. RESULTS Eighty-seven scan pairs were identified. PET/CT detected additional lesions over diagnostic CT in 30 patients, of which 11 demonstrated increased clinical stage. Lymphoma therapy changed based on PET/CT in two patients, and one occult rectal cancer was detected. In contrast, diagnostic CT detected five relevant findings, including two incidental findings (venous thrombosis) and three patients with splenic lesions, none of which could be confirmed as lymphoma. No patient had change of stage or lymphoma therapy based on diagnostic CT. CONCLUSION In our series, diagnostic CT did not add value to staging or restaging of lymphoma when carried out concurrently with PET/CT.

Prognostic value of FDG-PET scan imaging in lymphoma patients undergoing autologous stem cell transplantation

We conducted a retrospective analysis of 50 lymphoma patients (Hodgkins disease and non-Hodgkins lymphoma) who had an 18F-fluoro-deoxyglucose positron emission tomography (FDG-PET) scan after at least two cycles of salvage chemotherapy and before autologous stem cell transplantation (ASCT) at our institution. The patients were categorized into FDG-PET negative (N=32) and positive (N=18) groups. The median follow-up after ASCT was 19 months (range: 3–59). In the FDG-PET-negative group, the median progression-free survival (PFS) was 19 months (range: 2–59) with 15 (54%) patients without progression at 12 months after ASCT. The median overall survival (OS) for this group was not reached. In the FDG-PET-positive group, the median PFS was 5 months (range: 1–19) with only one (7%) patient without progression at 12 months after ASCT. The median OS was 19 months (range: 1–34). In the FDG-PET-negative group, chemotherapy-resistant patients by CT-based criteria had a comparable outcome to those with chemotherapy-sensitive disease. A positive FDG-PET scan after salvage chemotherapy and prior ASCT indicates an extremely poor chance of durable response after ASCT.

Intensive treatment strategies may not provide superior outcomes in mantle cell lymphoma: overall survival exceeding 7 years with standard therapies

BACKGROUND Reported median overall survival (OS) in patients with mantle cell lymphoma (MCL) has been reported to be just 3-4 years. As a consequence, first-line treatment has become more aggressive. Single-center studies with R-Hyper-CVAD and/or autologous stem-cell transplant (ASCT) have produced 3-year OS rates >80%, prompting many to adopt their use. We evaluated outcomes from a single-center cohort managed in a more traditional fashion. METHODS We identified patients with MCL evaluated at Weill Cornell Medical Center since 1997, and included those with known date of diagnosis. An online social security database was used to verify survival. RESULTS We identified 181 patients with MCL, and date of diagnosis could be determined in 111. Three-year OS from diagnosis was 86% [95% confidence interval (CI) 78% to 92%]. Median OS was 7.1 years (95% CI 63-98 months). Adequate information on therapy was available for 75 patients. Only five were treated upfront with (R)-Hyper-CVAD or ASCT while an additional four patients received one of these regimens subsequently. Treatment type had no significant effect on OS. CONCLUSION Outcomes with standard approaches can yield similar survival to that achieved with more intensive approaches. Biases may account for the perceived superiority of aggressive strategies.