Phase I Study of the CD47 Blocker TTI-621 in Patients with Relapsed or Refractory Hematologic Malignancies

PURPOSE

TTI-621 (SIRPα-IgG1 Fc) is a novel checkpoint inhibitor that activates antitumor activity by blocking the CD47 "don't eat me" signal. This first-in-human phase I study (NCT02663518) evaluated the safety and activity of TTI-621 in relapsed/refractory (R/R) hematologic malignancies.

PATIENTS AND METHODS

Patients with R/R lymphoma received escalating weekly intravenous TTI-621 to determine the maximum tolerated dose (MTD). During expansion, patients with various malignancies received weekly single-agent TTI-621 at the MTD; TTI-621 was combined with rituximab in patients with B-cell non-Hodgkin lymphoma (B-NHL) or with nivolumab in patients with Hodgkin lymphoma. The primary endpoint was the incidence/severity of adverse events (AEs). Secondary endpoint included overall response rate (ORR).

RESULTS

Overall, 164 patients received TTI-621: 18 in escalation and 146 in expansion (rituximab combination, n = 35 and nivolumab combination, n = 4). On the basis of transient grade 4 thrombocytopenia, the MTD was determined as 0.2 mg/kg; 0.1 mg/kg was evaluated in combination cohorts. AEs included infusion-related reactions, thrombocytopenia, chills, and fatigue. Thrombocytopenia (20%, grade ≥3) was reversible between doses and not associated with bleeding. Transient thrombocytopenia that determined the initial MTD may not have been dose limiting. The ORR for all patients was 13%. The ORR was 29% (2/7) for diffuse large B-cell lymphoma (DLBCL) and 25% (8/32) for T-cell NHL (T-NHL) with TTI-621 monotherapy and was 21% (5/24) for DLBCL with TTI-621 plus rituximab. Further dose optimization is ongoing.

CONCLUSIONS

TTI-621 was well-tolerated and demonstrated activity as monotherapy in patients with R/R B-NHL and T-NHL and combined with rituximab in patients with R/R B-NHL.

Phase I Alexander study of AUTO3, the first CD19/22 dual targeting CAR T cell therapy, with pembrolizumab in patients with relapsed/refractory (r/r) DLBCL

8001

Background: CD19 directed CAR T cells are effective in patients with r/r DLBCL, however relapses due to CD19 loss or PDL1 upregulation are common. In this study, we evaluate the safety and efficacy of AUTO3, a CAR T targeting CD19/22 with limited duration of PD-1 blockade. Methods: We constructed a bicistronic retroviral vector encoding both an anti-CD19 (OX40 co-stim) and an anti-CD22 (41BB co-stim) CAR with humanized binders. The cell product was manufactured in a semi-automated and closed process using CliniMACS Prodigy. Patients (≥ 18 years) with r/r DLBCL (NOS) or transformed (tDLBCL); ECOG <2, adequate organ function are eligible. Lymphodepletion was Flu/Cy prior to AUTO3. Bridging therapy was allowed. The three dose levels explored are 50, 150, and 450 x 10^6 CAR T cells. Patients received AUTO3 alone, or with 3 doses of pembrolizumab (pem) 200 mg q 3 wks starting on D14 (regimen A), or with a single dose of pem 200 mg on D-1 (regimen B). The primary endpoint is frequency of DLTs and grade (G) 3-5 adverse events (AE) and secondary endpoints included ORR, CRR, and biomarkers. Results: As of Jan 21, 2020, 28 patients underwent leukapheresis, 27 successfully manufactured, 1 being manufactured, and 19 patients treated with AUTO3. The median age was 57 (28 - 71) and median number of prior therapies was 3 (2 - 10). 89% had refractory disease, 74% were DLBCL NOS, and 26% were tDLBCL. Dose escalation from 50 to 450 x 106 cells with pem regimen A and B have been completed without DLTs. G > 3 treatment emergent AEs that occurred > 15% were neutropenia (89%), thrombocytopenia (58%), anemia (47%), febrile neutropenia (16%), and hypophosphataemia (16%). Across all dose levels, there were 0% sCRS with primary infusion and 5% severe neurotoxicity (sNT) (1/19), which resolved. There were no cases of sCRS and no neurotoxicity of any grade at > 50 x 106 cells. Eighteen patients were evaluable for efficacy. Among the 11 treated at dose > 50 x 106, the ORR and CRR were 64% and 55%, and all CRs are ongoing (1-12 mth). Two out of 3 patients achieved CR at 450 x 106 cells on pem regimen B. Additional patients and longer follow up, as well as biomarkers, will be presented. Conclusions: AUTO3 at > 50 x 106 CAR T cells with pembrolizumab induces CRs without severe CRS or neurotoxicities of any grade. Clinical trial information: NCT03287817 .

New and emerging Bruton tyrosine kinase inhibitors for treating mantle cell lymphoma - where do they fit in?

INTRODUCTION

Despite recent prognostic improvements, mantle cell lymphoma (MCL) remains incurable. Bruton tyrosine kinase (BTK) is a key receptor in B-cell tumorigenesis, and the benefits of the first BTK inhibitor, ibrutinib, are becoming clear in MCL. However, off-target activities, which contribute to ibrutinib-related adverse events, suggest potential for further improvement of this drug class. Areas covered: The authors systematically interrogated ClinicalTrials.gov for trials containing keywords for BTK and MCL. Published literature for new and emerging BTK inhibitors being investigated in MCL was then identified (PubMed and Embase), summarized, and placed in the context of treatment guidelines. Expert commentary: Reduced off-target effects of new and emerging covalent, irreversible BTK inhibitors under investigation in patients with MCL offer the potential of improved safety compared with ibrutinib. Efficacy may also be favorable based on trial data for acalabrutinib, which has just been approved in the USA as second-line therapy for MCL. The role of BTK inhibitors in treating MCL will evolve substantially over the coming years as results from a number of trials become available, particularly in relation to potential upfront use and possible synergy with other targeted therapies such as B-cell lymphoma 2, phosphoinositide 3-kinase and checkpoint inhibitors.

Multi-center phase II trial of bortezomib and rituximab maintenance combination therapy in patients with mantle cell lymphoma after consolidative autologous stem cell transplantation

Background

Mantle cell lymphoma (MCL) is an aggressive and incurable lymphoma. Standard of care for younger patients with MCL is induction chemotherapy followed by autologous stem cell transplantation (auto-HCT). Rituximab maintenance after auto-HCT has been shown to improve progression-free survival (PFS) and overall survival (OS) in MCL. Bortezomib maintenance therapy has also been shown to be tolerable and feasible in this setting. However, the combination of bortezomib and rituximab as maintenance therapy post-auto-HCT has not been studied.

Methods

We conducted a multicenter, phase II trial of bortezomib given in combination with rituximab as maintenance in MCL patients after consolidative auto-HCT. Enrolled patients (n = 23) received bortezomib 1.3 mg/m² subcutaneously weekly for 4 weeks every 3 months (up to 24 months) and rituximab 375 mg/m² intravenously weekly for 4 weeks every 6 months (up to 24 months) for a total duration of 2 years. The primary study endpoint was disease-free survival (DFS).

Results

With a median follow-up of 35.9 months, the 2-year DFS probability was 90.2% (95% CI 66–97), and 2-year OS was 94.7% (95% CI 68–99). The most frequent grade 3/4 toxic events were neutropenia (in 74% of patients) and lymphopenia (in 35%). The incidence of peripheral neuropathy was 48% for grade 1, 9% for grade 2, and 0% for grade 3/4. We also examined the role of quantitative cyclin D1 (CCND1) mRNA in monitoring minimal residual disease.

Conclusion

Combined bortezomib and rituximab as maintenance therapy in MCL patients following auto-HCT is an active and well-tolerated regimen.

Trial registration

ClinicalTrials.govNCT01267812, registered Dec 29, 2010.

Long-Term Results of High-Dose Therapy and Autologous Stem Cell Transplantation for Mantle Cell Lymphoma: Effectiveness of Maintenance Rituximab

High-dose therapy followed by autologous stem cell transplantation (ASCT) can improve outcomes for mantle cell lymphoma (MCL) but is associated with a high incidence of relapse. A retrospective study of 191 MCL patients who underwent ASCT at City of Hope was performed to examine prognostic factors for outcomes after ASCT. For all patients the 5-year overall survival (OS) was 71% (95% confidence interval [CI], 63% to 77%) and progression-free survival (PFS) was 53% (95% CI, 45% to 60%). The 5-year cumulative incidence of relapse was 41% (95% CI, 34% to 48%) with a continuous pattern of relapse events occurring at a median of 2.1 years (range, .2 to 13.4) after ASCT. In multivariate analysis, post-transplant maintenance rituximab was the factor most significantly associated with both OS (relative risk [RR], .17; 95% CI, .07 to .38) and PFS (RR, .25; 95% CI, .14 to .44). For the subset of patients who had positron emission tomography (PET) data available and were in a PET-negative first complete remission at ASCT (n = 105), maintenance rituximab was significantly associated with superior OS (RR, .17; 95% CI, .05 to .59) and PFS (RR, .20; 95% CI, .09 to .43). These results support a benefit with maintenance rituximab for all MCL patients treated with ASCT.

Phase 1b/3 study of avelumab-based combination regimens in patients with relapsed or refractory diffuse large B-cell lymphoma (R/R DLBCL)

TPS7575

Background: Approximately 50% of patients (pts) with advanced DLBCL are refractory to or relapse following first line R-CHOP therapy. Pts with R/R DLBCL have limited treatment options and a poor prognosis. This study assesses immunotherapy-based regimens containing avelumab (a fully human IgG1 anti–PD-L1 antibody) in combination with utomilumab (a novel 4-1BB agonist), azacitidine, rituximab, and/or conventional chemotherapy (CT; bendamustine) in pts with R/R DLBCL. Methods: JAVELIN DLBCL (NCT02951156) is a global, multicenter, randomized, open-label, 2-component(phase 1b followed by phase 3) study of avelumab-based combination regimens in R/R DLBCL. In phase 1b, up to 84 pts will be randomized 1:1:1 to receive avelumab/rituximab/utomilumab, or avelumab/azacitidine/utomilumab, or avelumab/rituximab/bendamustine. The primary phase 1b objectives are preliminary assessments of dose-limiting toxicities (n = 6 per arm) and efficacy (objective response [OR]; n = 28 per arm). One regimen from phase 1b will be selected for phase 3 evaluation in 220 additional pts randomized 1:1 to the chosen regimen or investigator’s choice CT (rituximab/bendamustine or rituximab/gemcitabine/oxaliplatin). The primary phase 3 objective is to demonstrate progression-free survival (PFS) superiority of the avelumab-based regimen over CT. Overall survival is a key secondary endpoint. Eligible pts have completed up to 4 lines of prior rituximab/multiagent CT, and/or have failed autologous stem cell transplantation (ASCT), or are not eligible for intensive CT or ASCT. Other eligibility criteria include ECOG PS ≤1 and no prior therapy with a checkpoint inhibitor. Treatment with avelumab, utomilumab, and azacitidine will be continued until the pt no longer receives clinical benefit; rituximab and bendamustine are limited to 8 and 6 cycles, respectively. OR and PFS will be assessed per Lugano disease classification criteria. Other secondary efficacy endpoints include disease control, duration of response, time to response, and minimal residual disease burden. Safety, PK, immunogenicity, pt-reported outcomes, and biomarkers will also be evaluated. Clinical trial information: NCT02951156.

A multicenter, randomized, double-blind, placebo-controlled phase III study of the Bruton's tyrosine kinase (BTK) inhibitor, ibrutinib, in combination with rituximab versus placebo in combination with rituximab in patients with treatment-naive follicular lymphoma (PERSPECTIVE)

TPS7576

Background: Follicular lymphoma (FL) is the most common subtype of indolent non-Hodgkin lymphoma. A limited number of chemotherapy-free options exist for patients with treatment-naïve (TN) FL who are older or who have comorbidities. Single-agent rituximab is considered a treatment option for elderly or infirm patients. In a phase 2 study, frontline treatment with ibrutinib in combination with rituximab for 4 weekly doses without maintenance resulted in an ORR of 85% (CR, 35%) with a median follow-up of 22 months and an 18-month PFS rate of 87% (Fowler Blood 2016). The phase 2 study serves as the basis for the randomized, double-blind, placebo-controlled phase 3 PERSPECTIVE (PCYC-1141-CA) trial. PERSPECTIVE will be conducted in two parts and will uniquely test (1) whether frontline treatment with ibrutinib in combination with rituximab results in prolongation of PFS compared to rituximab alone, and (2) whether continuous versus finite treatment with ibrutinib affects PFS outcomes. Methods: In the ongoing PERSPECTIVE trial, approximately 440 patients with TN FL meeting at least one Groupe d'Etude des Lymphomes Folliculaires (GELF) criterion will be randomized if they also meet one of the following criteria: age ≥70 years or age 60 to 69 with one or more comorbidities (creatinine clearance 30-59 mL/min or ECOG performance status of 2). Patients will be randomized to receive either ibrutinib or oral placebo once daily. All patients will be given rituximab for 4 weekly doses followed by maintenance. After at least 2 years of treatment in Part 1, patients randomized to ibrutinib who still remain on ibrutinib will be re-randomized in Part 2 to continue ibrutinib or switch to placebo. Key exclusion criteria include any prior treatment for FL, evidence of CNS involvement, or transformation. Analyses will be conducted in two distinct parts, both with a primary endpoint of PFS. The study is open for enrollment with sites planned in the US, EU, and Asia Pacific. Clinical trial information: NCT02947347.

Effects of TTI-621 (SIRPαFc) on CD47 and serum cytokines associated with phagocytosis in subjects with relapsed, refractory hematologic malignancies: Pharmacodynamic findings from a first-in-human clinical trial

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Background: CD47 delivers an anti-phagocytic (“do not eat”) signal by binding SIRPα on macrophages and is overexpressed on many cancers enabling immune surveillance evasion. TTI-621 is a decoy receptor that promotes phagocytosis of tumors by blocking CD47 and engaging activating FcR on macrophages. A first-in-human, phase 1a, open label, multicenter study (NCT02663518) evaluating safety and tolerability of weekly, intravenous infusions of TTI-621 was conducted. As of October 12, 2016, 18 subjects were treated with TTI-621 with doses of 0.05-0.3 mg/kg. Multiple pharmacodynamic and hematologic assessments were performed to characterize the effects of TTI-621 and better understand the mechanism of action. Methods: Serial blood draws were analyzed for CD47 receptor occupancy (RO), complete blood counts, cytokines, T cell repertoire changes and CD47, SIRPα and FcR sequences. CD47 expression, macrophage and T cell infiltration was assessed on biopsies by IHC. Results: Peripheral CD47 levels varied considerably between subjects and were inversely correlated with RO. A maximum of 80% RO was achieved on peripheral leukocytes. Circulating monocytes, neutrophils, and lymphocytes were transiently decreased at the end of the TTI-621 infusion and generally returned to baseline levels by 24 to 72 hours. Platelet counts decreased immediately after TTI-621 infusions, typically recovering to baseline levels prior to the subsequent treatment cycle. Hemoglobin levels did not meaningfully change during treatment. Cytokines associated with macrophage activation or phagocytosis, notably MIP-1α, MIP-1β, TNF-α and IP-10 were elevated in a dose dependent manner. Conclusions: Systemic administration of TTI-621 leads to CD47 blockade and dose dependent increases in cytokines associated with phagocytosis, temporally associated with reversible thrombocytopenia, suggesting enhanced macrophage mediated clearance of circulating platelets followed by a robust marrow regenerative response. Enrollment into multiple expansion cohorts addressing a wide range of hematopoietic cancers is ongoing. Clinical trial information: NCT02663518.

RB but not R-HCVAD is a feasible induction regimen prior to auto-HCT in frontline MCL: results of SWOG Study S1106

Aggressive induction chemotherapy followed by autologous haematopoietic stem cell transplant (auto-HCT) is effective for younger patients with mantle cell lymphoma (MCL). However, the optimal induction regimen is widely debated. The Southwestern Oncology Group S1106 trial was designed to assess rituximab plus hyperCVAD/MTX/ARAC (hyperfractionated cyclophosphamide, vincristine, doxorubicin and dexamethasone, alternating with high dose cytarabine and methotrexate) (RH) versus rituximab plus bendamustine (RB) in a randomized phase II trial to select a pre-transplant induction regimen for future development. Patients had previously untreated stage III, IV, or bulky stage II MCL and received either 4 cycles of RH or 6 cycles of RB, followed by auto-HCT. Fifty-three of a planned 160 patients were accrued; an unacceptably high mobilization failure rate (29%) on the RH arm prompted premature study closure. The estimated 2-year progression-free survival (PFS) was 81% vs. 82% and overall survival (OS) was 87% vs. 88% for RB and RH, respectively. RH is not an ideal platform for future multi-centre transplant trials in MCL. RB achieved a 2-year PFS of 81% and a 78% MRD negative rate. Premature closure of the study limited the sample size and the precision of PFS estimates and MRD rates. However, RB can achieve a deep remission and could be a platform for future trials in MCL.

Online Selection of Alternating Subsequences from a Random Sample

We consider sequential selection of an alternating subsequence from a sequence of independent, identically distributed, continuous random variables, and we determine the exact asymptotic behavior of an optimal sequentially selected subsequence. Moreover, we find (in a sense we make precise) that a person who is constrained to make sequential selections does only about 12 percent worse than a person who can make selections with full knowledge of the random sequence.

A secretary problem with two decision makers

n applicants of similar qualification are on an interview list and their salary demands are from a known and continuous distribution. Two managers, I and II, will interview them one at a time. Right after each interview, manager I always has the first opportunity to decide to hire the applicant or not unless he has hired one already. If manager I decides not to hire the current applicant, then manager II can decide to hire the applicant or not unless he has hired one already. If both managers fail to hire the current applicant, they interview the next applicant, but both lose the chance of hiring the current applicant. If one of the managers does hire the current one, then they proceed with interviews until the other manager also hires an applicant. The interview process continues until both managers hire an applicant each. However, at the end of the process, each manager must have hired an applicant. In this paper, we first derive the optimal strategies for them so that the probability that the one he hired demands less salary than the one hired by the other does is maximized. Then we derive an algorithm for computing manager II's winning probability when both managers play optimally. Finally, we show that manager II's winning probability is strictly increasing in n, is always less than c, and converges to c as n →∞, where c = 0.3275624139 · ·· is a solution of the equation ln(2) + x ln(x) = x.

Synchronous service on a circle

In this paper, we study a synchronous computer network model which may be described as follows. There are n service stations around a circle and there are k people to be serviced with at most one person per station. Time is slotted and in each time slot b adjacent people with an empty station ahead can move synchronously and simultaneously to the next counterclockwise station with probability pb. We show that the stationary distribution is uniform on all possible states, and using the Descartes' rule of signs we find the optimal value of k (fixed p and n) that yields maximal ‘throughput', i.e., the expected number of people served per time slot in equilibrium. We also briefly study an asynchronous model (introduced by D. Sarkar) where in each time slot a person moves with probability p to the next counterclockwise station if it is empty. We find, among other results, the new stationary distribution (Ramakrishnan et al. (1989) also find independently the stationary distribution and they also find the optimal value of k (fixed p and n) that yields maximal throughput in this model). We give tables comparing the synchronous and asynchronous models. Some applications which motivate this study are briefly presented.

Managing Risk in Hodgkin Lymphoma

Approximately 90% of patients with limited-stage Hodgkin lymphoma are cured. The cure rate in advanced-stage Hodgkin lymphoma is dramatically better than it once was, but it is still lower than the rate in patients with limited disease. The choice of treatment is based on several factors, including symptoms, disease stage, extent of tumor burden, and prognosis. Positron emission tomography scanning can be used to assess the patient's stage of disease, which can allow further individualization of therapy. Traditional frontline treatment options include doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) and, for high-risk patients, bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (BEACOPP). Autologous stem cell transplantation cures approximately 50% of patients. The antibody-drug conjugate brentuximab vedotin is very active in relapsed/refractory Hodgkin lymphoma. Data presented at the 2014 meeting of the American Society of Hematology (ASH) showed that brentuximab vedotin was beneficial in several settings, including as consolidation therapy posttransplant in patients at high risk for relapse, as first-line salvage therapy in relapsed/refractory Hodgkin lymphoma prior to autologous hematopoietic cell transplantation, and in combination with bendamustine in relapsed/refractory disease. The ASH meeting also offered promising data on novel agents, such as the programmed cell death 1 (PD-1) inhibitors. In this monograph, 4 experts in the management of Hodgkin lymphoma discuss various aspects of the disease and provide their perspectives on the new data presented at the ASH meeting.

Brentuximab vedotin in the front-line treatment of patients with CD30+ peripheral T-cell lymphomas: results of a phase I study

PURPOSE

Front-line treatment of peripheral T-cell lymphomas (PTCL) involves regimens such as cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) and results in a 5-year overall survival (OS) rate of less than 50%. This phase I open-label study evaluated the safety and activity of brentuximab vedotin administered sequentially with CHOP or in combination with CHP (CHOP without vincristine) as front-line treatment in patients with CD30(+) PTCL.

PATIENTS AND METHODS

Patients received sequential treatment (once every 3 weeks) with brentuximab vedotin 1.8 mg/kg (two cycles) followed by CHOP (six cycles) or brentuximab vedotin 1.8 mg/kg plus CHP (BV+CHP) for six cycles (once every 3 weeks). Responders received single-agent brentuximab vedotin for eight to 10 additional cycles (for a total of 16 cycles). The primary objective was assessment of safety; secondary end points included objective response rate, complete remission (CR) rate, progression-free survival rate (PFS), and OS. There were no prespecified comparisons of the two treatment approaches.

RESULTS

After sequential treatment, 11 (85%) of 13 patients achieved an objective response (CR rate, 62%; estimated 1-year PFS rate, 77%). Grade 3/4 adverse events occurred in eight (62%) of 13 patients. At the end of combination treatment, all patients (n = 26) achieved an objective response (CR rate, 88%; estimated 1-year PFS rate, 71%). All seven patients without anaplastic large-cell lymphoma achieved CR. Grade 3/4 adverse events (≥ 10%) in the combination-treatment group were febrile neutropenia (31%), neutropenia (23%), anemia (15%), and pulmonary embolism (12%).

CONCLUSION

Brentuximab vedotin, administered sequentially with CHOP or in combination with CHP, had a manageable safety profile and exhibited substantial antitumor activity in newly diagnosed patients with CD30(+) PTCL. A randomized phase III trial is under way, comparing BV+CHP with CHOP (clinical trial No. NCT01777152).

Irradiated compared with nonirradiated NSG mice for the development of a human B-cell lymphoma model

NOD.Cg-Prkdc(scid)Il2rg(tm1Wjl)/SzJ (NSG) mice are a superior strain for the engraftment of human tumors, as they provide an ideal model to explore the potency, toxicity, and dosage of therapeutic drugs. Although whole-body nonlethal irradiation is often performed to enhance engraftment, the need for irradiation to establish a human B-cell lymphoma model using the NSG strain has not been addressed. In the current study, a mouse model of B-cell lymphoma was established by intravenous injection of human B-cell lymphoma Z138 cells into mice with and without irradiation. Tumor development, signs of engraftment, survivability of engrafted mice, histopathology, and immunohistochemistry were evaluated. Potential sex-associated variations in the model were assessed also. Irradiation of NSG mice did not enhance tumor cell engraftment, and nonirradiated animals had increased survivability. Mice with irradiation survived for a median of 27 d before being euthanized due to signs of morbidity, whereas those without irradiation had a median survival of 35 d. Both irradiated and nonirradiated mice were normal in activity until 3 wk after the injection of cells. At that time, the mice started to show signs of lymphoma including ruffled fur, decreased activity, and hindlimb paralysis. There were no significant differences in evaluated parameters between male and female mice. Therefore, we conclude that a model of B-cell lymphoma can successfully be established by using Z138 cells in nonirradiated male and female NSG mice.

Retreatment with brentuximab vedotin in CD30‑positive hematologic malignancies: A phase II study

8027

Background: Brentuximab vedotin comprises an anti-CD30 antibody conjugated by a protease-cleavable linker to a microtubule-disrupting agent, MMAE. In pivotal phase 2 studies in patients (pts) with relapsed/refractory Hodgkin lymphoma (HL) or systemic anaplastic large cell lymphoma (sALCL), objective response rates were 75% and 86% and median durations of response were 6.7 and 12.6 mo, respectively. A phase 2 study was initiated to investigate if pts who have previously responded to brentuximab vedotin could achieve another remission with retreatment (ClinicalTrials.gov #NCT00947856). Methods: Pts had a CD30-positive hematologic malignancy, achieved an objective response (per Cheson 2007) with prior brentuximab vedotin treatment, and experienced relapse after discontinuing treatment. Brentuximab vedotin was administered IV 1.8 mg/kg every 21 days; antitumor activity was assessed by the investigator. Results: 14 HL pts and 8 sALCL (5 ALK-negative) pts were enrolled (median age 34 yr, range 16–72). Pts had received a median of 4 prior chemotherapy regimens (range 2–12). Median time since the previous brentuximab vedotin treatment was 6.9 mo (range 1–44). Median number of retreatment cycles was 7 (range 1+ to 32+). Adverse events (AEs) in >25% of pts were nausea (41%), fatigue (36%), peripheral sensory neuropathy (36%), and diarrhea (27%). The most common Grade 3/4 AEs were anemia, fatigue, and hyperglycemia (3 pts each). Of the 11 pts who had pre-existing peripheral neuropathy, 3 (27%) had worsening with retreatment. Best clinical responses in pts with HL were 3 CR, 5 PR, 3 SD, 3 PD. Among pts with sALCL, 5 achieved a CR, 1 had PD, and 2 were not yet evaluated. Of the 8 pts with CR in retreatment, previous best responses to brentuximab vedotin treatment were 4 PR and 4 CR. Median duration of retreatment response was 10.8 mo (range 0+ to 10.8), and in pts who achieved CR, the median duration of response was not reached (range 0+ to 10.5 mo); 11 pts remain on retreatment. Conclusions: Retreatment with brentuximab vedotin was generally well tolerated. Objective responses were observed (13 of 20; 65%) in this heavily pretreated population. Enrollment to the phase 2 retreatment study is ongoing.

Small interfering RNAs targeting cyclin D1 and cyclin D2 enhance the cytotoxicity of chemotherapeutic agents in mantle cell lymphoma cell lines

Cyclin D1 (CCND1) is a known cell cycle regulator whose overexpression is a hallmark of mantle cell lymphoma (MCL). Although molecular techniques have unified the diagnostic approach to MCL, no therapeutic advances have been made to target this particular pathway. The significance of CCND1 in the pathogenesis and treatment of MCL has yet to be defined. We have taken advantage of RNA interference (RNAi) to down-regulate CCND1 expression in two MCL cell lines (Granta-519 and Jeko-1) to investigate the cytotoxic effect of combining RNAi with conventional chemotherapeutic agents. We designed four small interfering RNAs (siRNAs) specific to CCND1, one specific to CCND2, and one dual-targeting siRNA that simultaneously down-regulates CCND1 and CCND2. Etoposide and doxorubicin were used as chemotherapeutics in combination with the siRNAs. The transfected siRNAs in MCL cell lines triggered 40-60% reduction in target mRNA and protein levels. Importantly, the siRNA-mediated reduction in cyclins resulted in decreased IC(50) (50% inhibitory concentration) values for both doxorubicin and etoposide. The combination of siRNA-mediated inhibition of the cyclins along with chemotherapeutic agents could potentially be used to lower the effective doses of the chemotherapeutic agents and reduce drug-related toxicities.

On Optimality of Bold Play for Primitive Casinos in the Presence of Inflation

Mr. G owes $100 000 to a loan shark, and will be killed at dawn if the loan is not repaid in full. Mr. G has $20 000, but partial payments are not accepted, and he has no other source of income or credit. The loan shark owns a primitive casino where one can stake any amount in one's possession, gaining r times the stake with probability w and losing the stake with probability 1 - w (r > 0, 0 < w < 1). Mr. G is permitted to gamble at the casino, but each time he places a bet, the amount of his debt is increased by a factor of 1 + α (α ≥ 0). How should Mr. G gamble to maximize his chance of reaching his (moving) target and thereby surviving? Dubins and Savage showed that an optimal strategy is to stake boldly if the primitive casino is subfair or fair (i.e. w(1 + r) ≤ 1) and the inflation rate α is 0. Intuitively, a positive inflation rate would motivate Mr. G to try to reach his goal as quickly as possible, so it seems plausible that the bold strategy is optimal. However, Chen, Shepp, and Zame found that, surprisingly, the bold strategy is no longer optimal for subfair primitive casinos with inflation if both r > 1 and α satisfies 1/r ≤ α < r. They also conjectured that the bold strategy is optimal for subfair primitive casinos with inflation if r < 1. It is shown in the present paper that this conjecture is true provided that w ≤ ½. Furthermore, by introducing an interesting notion of sharp strategy, additional results are obtained on optimality of the bold strategy.

A bold strategy is not always optimal in the presence of inflation

A gambler, with an initial fortune less than 1, wants to buy a house which sells today for 1. Due to inflation, the price of the house tomorrow will be 1 + α, where α is a nonnegative constant, and will continue to go up at this rate, becoming (1 + α)n on the nth day. Once each day, he can stake any amount of fortune in his possession, but no more than he possesses, on a primitive casino. It is well known that, in a subfair primitive casino without the presence of inflation, the gambler should play boldly. The presence of inflation would motivate the gambler to recognize the time value of his fortune and to try to reach his goal as quickly as possible; intuitively, we would conjecture that the gambler should again play boldly. However, in this note we will show that, unexpectedly, bold play is not necessarily optimal.

[Immunostimulatory activity elicited by CpG sequences in Cysticercus cellulosae paramyosin cDNA]

OBJECTIVE

To analyse the immunostimulatory activity of CpG sequences in cysticercus cellulosae paramyosin (also named Antigen B, AgB) cDNA.

METHODS

C57BL/6 mice were immunized with pcDNA3-AgB plasmid, pcDNA3-AgB' (CpG sequences were mutated), pcDNA3 or AgB protein and two weeks later, immune response was assayed by ELISA.

RESULTS

IgG and IgG2a were detectable at week 2 after immunization and continually increased until week 4. The antibody levels elicited by pcDNA3-AgB were significantly higher(P < 0.05) than those elicited by others.

CONCLUSION

After pcDNA3-AgB plasmid inoculation, the immune response of mouse was elicited not only by the AgB protein but also by the CpG immunostimulatory sequences in the AgB cDNA.

[Cloning and expression of Cysticercus cellulosae antigen cC1 in E. coli]

OBJECTIVE

To clone and express Cysticercus Cellulosae antigen cC1 in E. coli.

METHODS

cC1 cDNA fragment was cloned to BamHI and PstI sites of pGEM-3Z vector. After alteration of the restriction sites, the fragment was cloned to EcoRI and XhoI sites of pGEX-5T with a synthetic linker to construct recombinant expression vector pGEX-5T-cC1.

RESULTS

The clone produced the largest yield of cC1 protein expression when incubated in 2YT culture medium for 3 h or induced by IPTG for 6 h. Detected by scanning optical densitometry, cC1 constituted 57% of the total bacterial proteins. Western blotting analysis revealed that the GST-cC1 fusion protein exhibited a specific reactive band.

CONCLUSION

High level expression of Cysticercus cellulosae antigen cC1 was obtained in E. coli.

Establishment and characterisation of human papillomavirus type 16 DNA immortalised human tonsillar epithelial cell lines

Oncogenic human papillomavirus (HPV) plays a possible aetiological role in a subset of head and neck cancers, particularly in tonsillar carcinomas. For establishing a model to study mechanisms involved in HPV-associated tonsillar carcinogenesis, normal human tonsillar epithelial (HTE) cells were transfected with full-length HPV-16 DNA. The transfections produced four immortalised cell lines, designated HTE-114/K1, HTE-114/K2, HTE-114/K3 and HTE-114/B. All transfected HTE cell lines were cytogenetically abnormal. They exhibited altered morphology and impaired expression of cytokeratins in organotypic cultures. They failed to form colonies in soft agarose and formed no tumours in nude mice within 6 months. Each of them contained integrated viral DNA in a distinctive pattern as shown by Southern blot hybridisation. Early viral transcripts containing the E7 gene were detected by northern blot hybridisation. In conclusion, primary HTE cells can be immortalised following transfection with full-length HPV-16 DNA; the immortalised cell lines had partially retained epithelial characteristics in their morphology and function. They seem to represent early stages of premalignant epithelial cells and thus provide a useful model for studying further the multistep molecular events of HPV-16-associated tonsillar carcinogenesis.

Early genes responsive to abscisic acid during heterophyllous induction in Marsilea quadrifolia

The aquatic fern Marsilea quadrifolia produces different types of leaves in response to changes in natural environment and culture conditions. When the conditions are in favor of producing the submerged-type leaves, exogenous application of the plant hormone abscisic acid (ABA) induces the formation of aerial-type leaves. Tissues responsive to ABA were localized to the shoot apical meristem and the associated organ primordia. From these tissues, at least two tiers of ABA-regulated early genes were identified, including seven primary genes and seventeen secondary genes. These genes, designated ABRH for ABA-responsive heterophylly, showed diverse expression patterns during the course of heterophyllous induction. Changes in the transcript level of ABRH genes started early, within 0.5-1.0 h after the addition of ABA to the culture medium. Some changes were transient while the others were persistent. The ABRHs contain extensive sequence homology to known genes, including those encoding transcription factors, protein kinases, membrane transporters, metabolic enzymes, structural proteins and those encoded by the chloroplast genome. Identification of these ABRHs is a first step toward the understanding of the regulation mechanisms of heterophylly, and the results suggest the involvement of novel metabolic and regulatory pathways in ABA-controlled morphogenesis.

Real-time PCR for detection and quantitation of hepatitis B virus DNA

A sensitive and reproducible real-time PCR assay based on TaqMan technology was developed for the detection and quantitation of hepatitis B virus (HBV) DNA in serum, and compared with an "in-house" qualitative PCR assay. HBV DNA was measured in 125 serum samples from 76 hepatitis B patients, consisting of 22 patients with an acute infection, 20 patients with a previous history of hepatitis B infection, and 34 patients with a chronic hepatitis B. Four patients with a chronic infection were treated with either an IFN-alpha monotherapy or a combination of IFN-alpha and lamivudine. Twenty-nine sera from healthy individuals and non-hepatitis B patients served as negative controls. The assay was validated by using a 10-fold dilution series of the World Virological Quality Control (VQC) sample containing 3.73 x 10(7) genome equivalents per ml. The detection limit for the real-time PCR was 3.73 x 10(2) genome equivalents per ml (geq/ml), while it was 3.73 x 10(3) geq/ml for the in-house PCR. The real-time PCR assay had an 8-logarithm dynamic range spanning from 10(2) to 10(10) geq/ml. In clinical serum samples, the real-time PCR and the in-house PCR detected HBV DNA in 81% (101/125) and 66% (83/125) of samples, respectively. HBV DNA was not detected among the negative controls by either of these assays. In conclusion, real-time PCR is a sensitive, specific, and a reproducible approach for the detection and quantitation of HBV DNA in clinical serum samples, useful also for monitoring the efficacy of antiviral treatment.

Genomic analysis of the Hsp70 superfamily in Arabidopsis thaliana

The Arabidopsis genome contains at least 18 genes encoding members of the 70-kilodalton heat shock protein (Hsp70) family, 14 in the DnaK subfamily and 4 in the Hsp110/SSE subfamily. While the Hsp70s are highly conserved, a phylogenetic analysis including all members of this family in Arabidopsis and in yeast indicates the homology of Hsp70s in the subgroups, such as those predicted to localize in the same subcellular compartment and those similar to the mammalian Hsp110 and Grp170. Gene structure and genome organization suggest duplication in the origin of some genes. The Arabidopsis hsp70s exhibit distinct expression profiles; representative genes of the subgroups are expressed at relatively high levels during specific developmental stages and under thermal stress.

Molecular epidemiology of viral pathogens and tracing of transmission routes: hepatitis-, calici- and hantaviruses

BACKGROUND

The need to rapidly identify new therapeutic drugs and vaccines for clinically important viral infections has resulted in intensive study of the molecular properties of viruses. Modern molecular techniques have provided tools for tracing infections and studying the evolution of viruses. OBJECTIVE STUDY AND DESIGN: Two examples illustrating how modern molecular techniques can be used in clinical virology and molecular epidemiology (hepatitis and caliciviruses), and one example documenting their importance in basic research (hantaviruses) will be discussed.

RESULTS AND CONCLUSIONS

Water- and food-borne outbreaks caused by the faeco-orally spread hepatitis A virus (HAV) are common in areas lacking proper sanitation, but they are possible also in countries with low seroprevalence. In water epidemics, the sequence comparisons between the virus from patients and from water have been used successfully. Hepatitis B virus variants are clinically important and challenge the diagnostic tests and prophylactic measures. Some hepatitis C (HCV) genotypes appear to be associated with more severe pathology and others respond better to antiviral treatment. Nosocomial and occupational infections are not rare, and the source can be identified by phylogenetic analysis of nucleotide sequences obtained from the infected individuals. The overwhelming role of Norwalk-like caliciviruses (NLV) in adult diarrhoea and especially in food- and water-borne epidemics has become apparent during the last decade. Methods are under development for detecting these viruses, not only from patient samples and water, but also from other environmental samples (e.g. foodstuff and surface swabs). The analysis of the genetic variation and evolution of the Old World hantaviruses in their carrier rodents has shown that the extent of genetic diversity correlates with geographical distance. As a rule, phylogenetic relationships of hantaviruses resemble those of their rodent hosts, suggesting virus-host co-evolution. Exceptional host-switch events allow a study on still radiating hantavirus species. There is suggestive evidence that natural reassortant hantaviruses are involved in human infection.

Prostaglandin A(1) protects striatal neurons against excitotoxic injury in rat striatum

Prostaglandin A(1) (PGA1) reportedly inhibits NF-kappaB activation and induces expression of heat shock proteins. Since both these effects could be neuroprotective, the therapeutic potential of PGA1 in neurodegenerative disorders, where excitotoxicity may contribute to pathogenesis, was evaluated in rat striatal neurons exposed to the N-methyl-D-aspartate (NMDA) receptor agonist quinolinic acid (QA). Intrastriatal administration of PGA1 (5-80 nmol) attenuated QA (60 nmol)-induced internucleosomal DNA fragmentation. The inhibitory effects of a single dose of PGA1 (80 nmol) on QA (60 nmol)-induced DNA fragmentation were observed 12 to 48 h after treatment. PGA1 (80 nmol) also attenuated QA-induced DNA fragmentation when administered up to 4 h after QA exposure. PGA1 significantly decreased the loss of D1 dopamine receptors and GAD(67) mRNA in QA-injected striatum as measured by quantitative receptor autoradiography and in situ hybridization histochemistry, suggesting that it reduced the neuronal loss induced by QA. Protection of striatal neurons against QA-induced death by PGA1 was further indicated by Nissl staining 10 days after QA administration. PGA1 (5-80 nmol) significantly inhibited QA-induced NF-kappaB activation by blocking inhibitory kappaB-alpha degradation but had no effect on activator protein-1 binding activity. PGA1 (80 nmol) treatment substantially increased 70- and 72-kDa heat shock protein levels in striatum. These results indicate that PGA1 blunts NMDA receptor-mediated neuronal apoptosis by a mechanism possibly involving the up-regulation of neuroprotective heat shock proteins and inhibition of NF-kappaB activation. In view of its potent neuroprotective activity, PGA1 could prove useful in the treatment of certain neurodegenerative disorders related to excitotoxicity.

[Cloning, high level expression and purification of porcine IFN gamma]

Peripheral blood lymphocytes from a single swine were stimulated with Concavadin A for 17 h, and the total RNA was isolated from it. Then, the mRNA specific for porcine IFN gamma was amplified by reverse transcription polymerase chain reaction. After sequencing, the IFN gamma gene has been successfully inserted into vector pJLA-503 and highly expressed in E. coli. Recombinant porcine IFN gamma expressed as inclusion body, which was dissolved in 7 mol/L guanidine chloride and subsequently renatured by dilution in refolding buffer containing 0.5 mol/L L-arginine. In order to obtain pure protein, the renatured IFN gamma was purified by the chromatographies of SP-Sepharose FF and Sephacryl S-200 HR. As a result, the final pure product can been seen as a single band in SDS-PAGE, and the cytokine activity was verified by inhibiting the cytopathic effect.

Neuronal apoptosis induced by pharmacological concentrations of 3-hydroxykynurenine: characterization and protection by dantrolene and Bcl-2 overexpression

We have studied neurotoxicity induced by pharmacological concentrations of 3-hydroxykynurenine (3-HK), an endogenous toxin implicated in certain neurodegenerative diseases, in cerebellar granule cells, PC12 pheochromocytoma cells, and GT1-7 hypothalamic neurosecretory cells. In all three cell types, the toxicity was induced in a dose-dependent manner by 3-HK at high micromolar concentrations and had features characteristic of apoptosis, including chromatin condensation and internucleosomal DNA cleavage. In cerebellar granule cells, the 3-HK neurotoxicity was unaffected by xanthine oxidase inhibitors but markedly potentiated by superoxide dismutase and its hemelike mimetic, MnTBAP [manganese(III) tetrakis(benzoic acid)porphyrin chloride]. Catalase blocked 3-HK neurotoxicity in the absence and presence of superoxide dismutase or MnTBAP. The formation of H(2)O(2) was demonstrated in PC12 and GT1-7 cells treated with 3-HK, by measuring the increase in the fluorescent product, 2',7'-dichlorofluorescein. In both PC12 and cerebellar granule cells, inhibitors of the neutral amino acid transporter that mediates the uptake of 3-HK failed to block 3-HK toxicity. However, their toxicity was slightly potentiated by the iron chelator, deferoxamine. Taken together, our results suggest that neurotoxicity induced by pharmacological concentrations of 3-HK in these cell types is mediated primarily by H(2)O(2), which is formed most likely by auto-oxidation of 3-HK in extracellular compartments. 3-HK-induced death of PC12 and GT1-7 cells was protected by dantrolene, an inhibitor of calcium release from the endoplasmic reticulum. The protection by dantrolene was associated with a marked increase in the protein level of Bcl-2, a prominent antiapoptotic gene product. Moreover, overexpression of Bcl-2 in GT1-7 cells elicited by gene transfection suppressed 3-HK toxicity. Thus, dantrolene may elicit its neuroprotective effects by mechanisms involving up-regulation of the level and function of Bcl-2 protein.

Co-stimulation of cyclic-AMP-linked metabotropic glutamate receptors in rat striatum attenuates excitotoxin-induced nuclear factor-kappaB activation and apoptosis

Interactions between glutamatergic mechanisms mediated by receptors of the ionotropic and metabotropic classes in the central nervous system are complex and incompletely understood. To explore the consequences of these interactions on excitotoxicity, we examined the influence of group II and group III selective metabotropic glutamate receptor agonists on the N-methyl-D-aspartate-induced apoptotic destruction of GABAergic neurons in rat striatum. The intrastriatal administration of a group III metabotropic glutamate receptor agonist (amino-4-phosphonobutyric acid, 900-1800 nmol), but not of a group II agonist [(2S,1'S,2'S)-(carboxycyclopropyl)glycine, 100-1800 nmol] produced internucleosomal DNA fragmentation. Similarly, amino-4-phosphonobutyric acid (600 nmol) but not (2S,1'S,2'S)-(carboxycyclopropyl)glycine (100-1800 nmol) destroyed some striatal neurons as indicated by a loss of D1 dopamine receptors and 67,000 mol. wt glutamate decarboxylase (glutamate decarboxylase-67) messenger RNA. On the other hand, the intensity of internucleosomal DNA fragmentation induced by N-methyl-D aspartate (150 nmol) was substantially decreased by the intrastriatal co-administration of either (2S,1'S,2'S)-(carboxycyclopropyl)glycine or amino-4-phosphonobutyric acid (100-600 nmol). Both (2S, 1'S,2'S)-(carboxycyclopropyl)glycine and amino-4-phosphonobutyric acid also reduced the N-methyl-D-aspartate-induced loss of striatal D1 dopamine receptors by 67% and 68% (both P < 0.001), and glutamate decarboxylase-67 messenger RNA by 68% and 61%, respectively. Furthermore, both (2S,1'S,2'S)-(carboxycyclopropyl)glycine and amino-4-phosphonobutyric acid also attenuated the N-methyl-D-aspartate-induced decline in striatal IKB-alpha protein levels by 62% and 37%, as well as the increase in nuclear transcription factor nuclear factor-kappaB binding activity by 135% and 94% (both P < 0.001), and the subsequent rise in p53 and c-Myc protein levels. These results suggest that stimulation of cyclic-AMP-linked metabotropic glutamate receptors inhibits ionotropic glutamate receptor-mediated activation of apoptotic cascades involving IkappaB-alpha degradation and nuclear factor-kappaB nuclear translocation, as well as p53 and c-Myc induction. Certain selective metabotropic glutamate receptor agonists might thus find utility as adjuncts to N-methyl-D-aspartate antagonists in the protection against the neurotoxicity initiated by excessive ionotropic glutamate receptor stimulation.

Involvement of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and p53 in neuronal apoptosis: evidence that GAPDH is upregulated by p53

We recently reported that cytosine arabinoside (AraC)-induced apoptosis of cerebellar neurons involves the overexpression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The present study was undertaken to investigate whether p53 and/or Bax overexpression participates in the AraC-induced apoptosis of cerebellar granule cells and, if so, the relationship between p53 induction and GAPDH overexpression in these cells. AraC-induced apoptosis of cerebellar granule cells was preceded by an increase in levels of p53 mRNA and protein detected between 1 and 8 hr after treatment. The mRNA level for a p53 target gene, Bax, was also increased. The increase in GAPDH mRNA lasted longer than that of either p53 or Bax, and the level of GAPDH protein in the particulate fraction increased after induction of GAPDH mRNA. The antisense oligonucleotide to p53 protected granule cells from AraC-induced chromatin condensation, internucleosomal cleavage, and apoptotic death. The inhibition of p53 expression by the p53 antisense oligonucleotide not only blocked the expression of Bax but also partially suppressed the increased GAPDH mRNA and protein levels. Conversely, the suppression of GAPDH expression and subsequent attenuation of apoptosis of granule cells by GAPDH antisense oligonucleotide did not influence the expression of p53 or Bax. Cerebellar granule cells prepared from p53 knock-out mice were resistant to AraC toxicity, and the p53 gene knock-out suppressed AraC-upregulated GAPDH expression. Moreover, infection of PC12 cells with an adenoviral vector containing p53 gene dramatically increased GAPDH expression and triggered cell apoptosis. These results suggest that AraC-induced apoptosis of cerebellar granule cells involves the expression of both GAPDH and p53 and that, similar to Bax, GAPDH is upregulated by p53 after exposure to the apoptotic insult.

Nuclear factor kappaB nuclear translocation upregulates c-Myc and p53 expression during NMDA receptor-mediated apoptosis in rat striatum

Nuclear factor kappaB (NF-kappaB) appears to participate in the excitotoxin-induced apoptosis of striatal medium spiny neurons. To elucidate molecular mechanisms by which this transcription factor contributes to NMDA receptor-triggered apoptotic cascades in vivo, rats were given the NMDA receptor agonist quinolinic acid (QA) by intrastriatal infusion, and the role of NF-kappaB in the induction of apoptosis-related genes and gene products was evaluated. QA administration induced time-dependent NF-kappaB nuclear translocation. The nuclear NF-kappaB protein after QA treatment was comprised mainly of p65 and c-Rel subunits as detected by gel supershift assay. Levels of c-Myc and p53 mRNA and protein were markedly increased at the time of QA-induced NF-kappaB nuclear translocation. Immunohistochemical analysis showed that c-Myc and p53 induction occurred in the excitotoxin-sensitive medium-sized striatal neurons. NF-kappaB nuclear translocation was blocked in a dose-dependent manner by the cell-permeable recombinant peptide NF-kappaB SN50, but not by the NF-kappaB SN50 control peptide. NF-kappaB SN50 significantly inhibited the QA-induced elevation in levels of c-Myc and p53 mRNA and protein. Pretreatment or posttreatment with NF-kappaB SN50, but not the control peptide, also substantially reduced the intensity of QA-induced internucleosomal DNA fragmentation. The results suggest that NF-kappaB may promote an apoptotic response in striatal medium-sized neurons to excitotoxic insult through upregulation of c-Myc and p53. This study also provides evidence indicating an unique signaling pathway from the cytoplasm to the nucleus, which regulates p53 and c-Myc levels in these neurons during apoptosis.

Long term lithium treatment suppresses p53 and Bax expression but increases Bcl-2 expression. A prominent role in neuroprotection against excitotoxicity

This study was undertaken to investigate the molecular mechanisms underlying the neuroprotective actions of lithium against glutamate excitotoxicity with a focus on the role of proapoptotic and antiapoptotic genes. Long term, but not acute, treatment of cultured cerebellar granule cells with LiCl induces a concentration-dependent decrease in mRNA and protein levels of proapoptotic p53 and Bax; conversely, mRNA and protein levels of cytoprotective Bcl-2 are remarkably increased. The ratios of Bcl-2/Bax protein levels increase by approximately 5-fold after lithium treatment for 5-7 days. Exposure of cerebellar granule cells to glutamate induces a rapid increase in p53 and Bax mRNA and protein levels with no apparent effect on Bcl-2 expression. Pretreatment with LiCl for 7 days prevents glutamate-induced increase in p53 and Bax expression and maintains Bcl-2 in an elevated state. Glutamate exposure also triggers the release of cytochrome c from the mitochondria into the cytosol. Lithium pretreatment blocks glutamate-induced cytochrome c release and cleavage of lamin B1, a nuclear substrate for caspase-3. These results strongly suggest that lithium-induced Bcl-2 up-regulation and p53 and Bax down-regulation play a prominent role in neuroprotection against excitotoxicity. Our results further suggest that lithium, in addition to its use in the treatment of bipolar depressive illness, may have an expanded use in the intervention of neurodegeneration.

Nuclear translocation of glyceraldehyde-3-phosphate dehydrogenase isoforms during neuronal apoptosis

Treatment with cytosine beta-D-arabinoside (AraC; 300 microM) induced a time-dependent accumulation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) protein in nuclei purified from cultured cerebellar granule cells, with a concomitant degradation of lamin B1, a nuclear membrane protein and a substrate of CPP32/caspase-3. Moreover, Asp-Glu-Val-Asp-fluoromethyl ketone (DEVD-fmk), a CPP32-selective antagonist, dose-dependently suppressed AraC-induced apoptosis of these neurons. Nuclear accumulation of GAPDH protein was associated with a progressive decrease in the activity of uracil-DNA glycosylase (UDG), one of the nuclear functions of GAPDH. The nuclear dehydrogenase activity of GAPDH was initially increased after treatment and then decreased parallel to UDG activity. Six GAPDH isoforms were detected in the nuclei of AraC-treated cells. The more alkaline isoforms, 1-3, constituted the bulk of the nuclear GAPDH, and the remaining isoforms, 4-6, were the minor species. Levels of all six isoforms were increased after treatment with AraC for 16 h; a 4-h treatment increased levels of only isoforms 4 and 5. Thus, it appears that various GAPDH isoforms are differentially regulated and may have distinct apoptotic roles. Pretreatment with GAPDH antisense oligonucleotide blocked the nuclear translocation of GAPDH isoforms, and the latter process occurred concurrently with a decrease in cytosolic GAPDH isoforms. Sodium nitroprusside-induced NAD labeling of nuclear GAPDH showed a 60% loss of GAPDH labeling after AraC treatment, suggesting that the active site of GAPDH may be covalently modified, denatured, or improperly folded. The unfolded protein response elicited by denatured GAPDH may contribute to AraC-induced neuronal death.