Preliminary results of a phase I trial of FT516, an off-the-shelf natural killer (NK) cell therapy derived from a clonal master induced pluripotent stem cell (iPSC) line expressing high-affinity, non-cleavable CD16 (hnCD16), in patients (pts) with relapsed/refractory (R/R) B-cell lymphoma (BCL)

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Background: FT516 is an investigational, NK cell cancer immunotherapy derived from a clonal master iPSC line. FT516 is engineered with a novel hnCD16 Fc receptor, demonstrated preclinically to maximize antibody-dependent cellular cytotoxicity (Zhu et al. Blood 2020). FT516 can be mass produced and made available off-the-shelf for broad pt access and multi-dose administration. Methods: This is a Phase I trial of FT516 combined with rituximab (R) in pts with R/R BCL. Treatment consists of 2 cycles, each with 3 days lympho-conditioning (fludarabine 30 mg/m2 and cyclophosphamide 500 mg/m2) and 1 dose of R followed by 3 weekly infusions of FT516 (planned doses 30-900 million/dose) with IL-2 (6 MIU after each FT516 dose). The primary objective is to identify the incidence of dose-limiting toxicity (DLT)/dose cohort and the recommended Phase II dose using a standard 3+3 design. Additional objectives include safety, tolerability, preliminary activity, pharmacokinetics, and immunogenicity. Results: Six pts (5 DLBCL, 1 FL, median age 65.5 y) have completed (5) or discontinued (1) study treatment after the DLT period (data cutoff 9 Dec 2020): 2 received 30 million cells/dose, 3 received 90 million cells/dose, and 1 received 300 million cells/dose. All pts received > 1 prior R-containing regimen, and median number of prior therapies was 3 (range 2-6), including CAR-T in 3 pts. FT516 was primarily administered in the outpatient setting. No FT516-related Grade ≥3 adverse events (AEs) or serious AEs, and no events of cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), or graft-versus-host disease (GvHD) of any grade were reported. DLT (Grade 4 neutrophil count decreased, not recovered to baseline by D29) was reported in the first pt at 30 million cells/dose and R dosing of 375 mg/m2 weekly x 4/cycle, resulting in modification of R dosing to once/cycle; no DLTs were observed with modified R dosing. Most common all grade AEs in ≥3 pts: fatigue (4 pts) and decreased appetite, nausea, neutrophil count decreased, and headache (3 pts each). Grade ≥3 AEs in ≥2 pts: neutrophil count decreased (3 pts) and febrile neutropenia and platelet count decreased (2 pts each); none considered related to FT516. Host anti-product B- or T-cell immunogenicity was not observed. Three of 4 pts treated at ≥90 million cells/dose achieved objective response (2 complete responses [CRs] and 1 partial response). Conclusions: Administration of up to 6 doses of FT516 cells, including up to 300 million cells/dose, appears to be safe and tolerable, without CRS, ICANS, or GvHD. Activity was observed, including CRs, in heavily pretreated pts. Dose escalation is ongoing. Updated clinical and translational data will be presented. Clinical trial information: NCT04023071.

Trial in progress: A phase III, randomized, open-label study comparing zanubrutinib plus rituximab versus bendamustine plus rituximab in patients with previously untreated mantle cell lymphoma (MCL)

TPS8071

Background: Bruton tyrosine kinase (BTK) mediates B-cell proliferation, migration, and adhesion. BTK inhibition has emerged as a strategy for targeting B-cell malignancies, including MCL. Zanubrutinib is a next-generation BTK inhibitor that was designed to maximize BTK occupancy and minimize off-target inhibition of TEC- and EGFR-family kinases, with favorable pharmacokinetic and pharmacodynamic properties. Zanubrutinib monotherapy has been evaluated in 118 patients (pts) with relapsed/refractory MCL in 2 single-arm studies: BGB-3111-206 [NCT03206970] and BGB-3111-AU-003 [NCT02343120]. The overall response rate (ORR) by independent review committee (IRC) in both trials was 84% with median durations of response of 19.5 and 18.5 months, respectively. First-line treatment for MCL has failed to cure most pts, particularly elderly or transplant-ineligible groups, and chemotherapy-based approaches result in cumulative, long-term risks. The study described herein is designed to evaluate the safety and efficacy of zanubrutinib plus rituximab versus bendamustine plus rituximab in elderly pts and pts with comorbidities with previously untreated MCL who are ineligible for stem cell transplant. Methods: This ongoing phase 3, open-label study will enroll ≈500 pts to be randomized 1:1, stratified by MCL International Prognostic Index score (low vs intermediate/high), age ( < 70 vs ≥70 years), and geographic region (North America/Europe vs Asia-Pacific). In arm A, pts will receive up to six 28-day cycles of oral zanubrutinib 160 mg twice daily in combination with intravenous (IV) rituximab 375 mg/m2 on day 1 of each cycle. After 6 cycles, zanubrutinib will continue as a monotherapy until progressive disease, unacceptable toxicity, or withdrawal of consent. In arm B, pts will receive up to six 28-day cycles of IV bendamustine 90 mg/m2 on days 1 and 2 of each cycle and rituximab 375 mg/m2 on day 1 of each cycle, followed by observation. Eligible pts must have histologically confirmed MCL and be aged ≥70 years, or 65-69 years with defined comorbidities. Disease response will be assessed per the 2014 Lugano Classification for non-Hodgkin lymphoma. The primary endpoint is progression-free survival (PFS) determined by IRC. Key secondary end points include PFS by investigator assessment, ORR, time to and duration of response, overall survival, and safety. Recruitment is ongoing. Clinical trial information: NCT04002297 .

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

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.

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.

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.

Final results of phase I/II trial of vorinostat in combination with cyclophosphamide, etoposide, prednisone, and rituximab (R-CVEP) for elderly patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL)

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Background: Standard treatment of relapsed/refractory DLBCL in elderly patients who are not candidates for autologous stem cell transplantation (auSCT) has not been established. Cyclophosphamide (C), etoposide (E), prednisone (P) and procarbazine (CEPP) has been used by many clinicians based on limited data (Blood 76: 1293-98, 1990). Vorinostat (V) is a histone deacetylase inhibitor that is approved for relapsed cutaneous T-cell lymphoma and has activity in B-cell lymphomas. This trial defined the maximum tolerated dose (MTD) of V added to standard therapy and determined the response rate of this combination. Methods: Patients ≥age 60 with relapsed/refractory DLBCL not candidates for auSCT were enrolled on R-CVEP (R 375mg/m2 IV, d1; C 600mg/m2 d1 and 8, E 70mg/m2 IV d1, 140mg/m2 d2 and 3; V PO and Pred 60mg/m2 PO d1-10) every 28 days for 6 cycles. In the phase I component V was administered at doses of 300mg/d or 400mg/d for 10 days. The phase I was a 3 + 3 design and the phase II a two stage design requiring 8/20 complete responses (CR) for expansion. Assessment of response utilized end-of-treatment positron emission tomography (PET) (JCO 25: 579-86, 2007). Quality of life (QOL) was measured with the FACT-Lym v.4. Results: 27 pts. were enrolled. 1 died before treatment. For 26 pts: median age 76 yrs. (69-88), 14 females and 12 males, baseline PS (ECOG) 1 (0-2). Median follow-up for survivors: 9.2 mo. Phase I: 6 pts. at 300mg/d (no dose-limiting toxicity-DLT), 6 pts. at 400mg/d (2 grade 3 neutropenia = DLT). MTD 300mg/d x 10d. For 20 pts. at V 300mg/m2 (6 phase I + 14 phase II): 2 off study for toxicity, 1 withdrew consent, 6 CR (30%), 5 partial response (PR) (25%), 6 progressed (30%). Phenotypic overall responses (OR): germinal center (GC) 4/8 (2 CR), non-GC 6/10 (3 CR), transformed CLL 1/2 (1 CR). Median progression-free survival: 10 mo. QOL results will be presented. Conclusions: OR rate for V added to conventional chemotherapy and R was 55% (CR 30%, PR 25%) in relapsed/refractory DLBCL in elderly pts. not candidates for auSCT. This could provide a baseline for comparison with future clinical trials in this understudied 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 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.

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.

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.

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.

Long-term event-free survivors after high-dose therapy and autologous stem-cell transplantation for low-grade follicular lymphoma

Although follicular lymphoma (FL) is generally responsive to conventional-dose chemotherapy, improved survival in patients with this disease has been difficult to demonstrate. High-dose chemo/radiotherapy followed by autologous stem-cell transplantation (ASCT) can improve response rates, although its effects on survival remain controversial. Between 1990 and 2003, we transplanted 49 patients with low-grade FL at our institution. Twenty-two patients (45%) had undergone histologic transformation at the time of ASCT. In all, 44 patients (90%) had relapsed disease and five patients (10%) were resistant to chemotherapy at the time of transplantation. After ASCT, 30 patients (61%) were in complete remission (CR). The median overall survival (OS) has not been reached, while the median event-free survival (EFS) is 2.4 years. At a median follow-up of 5.5 years (longest 12.4 years), a plateau has been reached with 56% of patients remaining alive, and 35% event-free. ASCT was well tolerated except for two (4%) treatment-related deaths. In multivariable analysis, CR after ASCT and age less than 60 years are the best predictors of EFS and OS. ASCT is thus a safe therapeutic approach in FL, resulting in long-term EFS and OS for some patients, even with transformed disease.

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.

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.

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.

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.

Analysis of immunoglobulin and T-cell receptor gene rearrangements in human fetal bone marrow B lineage cells

Fetal bone marrow B lineage cells representing multiple stages of B cell development were isolated by two-color cell sorting and analyzed for immunoglobulin H and T-cell receptor (TCR) gamma and delta gene rearrangements. Analysis of CD10+/surface mu- cells using a JH probe revealed a high frequency of rearrangements; some of these rearrangements used the 3' D region gene DQ52. Analysis of CD10+/surface mu- cells revealed no detectable TCR-gamma or -delta rearrangements, nor were TCR-delta rearrangements detected in CD10+/surface mu+ cells, despite the limited repertoire of these genes. These observations are surprising given the high frequency of TCR delta/gamma rearrangements in B cell precursor acute lymphoblastic leukemia, and identify a potential difference in patterns of gene rearrangement that distinguish normal and leukemic B cell precursors.

Differentiation of normal human pre-B cells in vitro

The differentiation of surface Ig- pre-B cells into surface Ig+ B cells is a critical transition in mammalian B cell ontogeny. Elucidation of the growth factor requirements and differentiative potential of human pre-B cells has been hampered by the absence of a reproducible culture system that supports differentiation. Fluorescence-activated cell sorting and magnetic bead depletion were used to purify fetal bone marrow CD10+/surface mu- cells, which contain 60-70% cytoplasmic mu+ pre-B cells. CD10+/surface mu- cells cultured for 2 d were observed to differentiate into surface mu+ cells. Analysis by Southern blotting provided direct evidence that rearrangement of kappa light chain genes occurs in culture, and flow cytometric analysis revealed the appearance of surface Ig+ B cells expressing mu/kappa or mu/lambda. Unexpectedly, the kappa/lambda ratio in differentiated cells was the inverse of what is normally observed in adult peripheral blood. Differentiation occurs in the absence of exogenous growth factors or cytokines, suggesting that a stimulus-independent differentiative inertia might characterize pre-B cells in vivo. Future use of this model will facilitate our understanding of normal and abnormal human pre-B cell differentiation.