Proteomic markers with prognostic impact on outcome of chronic lymphocytic leukemia patients under chemo-immunotherapy: results from the HOVON 109 study

Despite recent identification of several prognostic markers, there is still a need for new prognostic parameters able to predict clinical outcome in chronic lymphocytic leukemia (CLL) patients. Here, we aimed to validate the prognostic ability of known (proteomic) markers measured pretreatment and to search for new proteomic markers that might be related to treatment response in CLL. To this end, baseline serum samples of 51 CLL patients treated with chemo-immunotherapy were analyzed for 360 proteomic markers, using Olink technology. Median event-free survival (EFS) was 23 months (range: 1.25-60.9). Patients with high levels of sCD23 (>11.27, p = 0.026), sCD27 (>11.03, p = 0.04), SPINT1 (>1.6, p = 0.001), and LY9 (>8.22, p = 0.0003) had a shorter EFS than those with marker levels below the median. The effect of sCD23 on EFS differed between immunoglobulin heavy chain variable gene-mutated and unmutated patients, with the shortest EFS for unmutated CLL patients with sCD23 levels above the median. Taken together, our results validate the prognostic impact of sCD23 and highlight SPINT1 and LY9 as possible promising markers for treatment response in CLL patients.

Feasibility and efficacy of addition of individualized-dose lenalidomide to chlorambucil and rituximab as first-line treatment in elderly and FCR-unfit patients with advanced chronic lymphocytic leukemia

Lenalidomide has been proven to be effective but with a distinct and difficult to manage toxicity profile in the context of chronic lymphocytic leukemia, potentially hampering combination treatment with this drug. We conducted a phase 1-2 study to evaluate the efficacy and safety of six cycles of chlorambucil (7 mg/m² daily), rituximab (375 mg/m² cycle 1 and 500 mg/m² cycles 2-6) and individually-dosed lenalidomide (escalated from 2.5 mg to 10 mg) (induction-I) in first-line treatment of patients with chronic lymphocytic leukemia unfit for treatment with fludarabine, cyclophosphamide and rituximab. This was followed by 6 months of 10 mg lenalidomide monotherapy (induction-II). Of 53 evaluable patients in phase 2 of the study, 47 (89%) completed induction-I and 36 (68%) completed induction-II. In an intention-to-treat analysis, the overall response rate was 83%. The median progression-free survival was 49 months, after a median follow-up time of 27 months. The 2- and 3-year progression-free survival rates were 58% and 54%, respectively. The corresponding rates for overall survival were 98% and 95%. No tumor lysis syndrome was observed, while tumor flair reaction occurred in five patients (9%, 1 grade 3). The most common hematologic toxicity was grade 3-4 neutropenia, which occurred in 73% of the patients. In conclusion, addition of lenalidomide to a chemotherapy backbone followed by a fixed duration of lenalidomide monotherapy resulted in high remission rates and progression-free survival rates, which seem comparable to those observed with novel drug combinations including novel CD20 monoclonal antibodies or kinase inhibitors. Although lenalidomide-specific toxicity remains a concern, an individualized dose-escalation schedule is feasible and results in an acceptable toxicity profile. EuraCT number: 2010-022294-34.

Rituximab maintenance improves overall survival of patients with follicular lymphoma-Individual patient data meta-analysis

BACKGROUND

Randomised trials of rituximab maintenance (MR) for patients with follicular lymphoma support improved progression-free survival (PFS), but the effect on overall survival has been inconclusive. To evaluate the effect of MR on overall survival according to patient and disease characteristics, and to explore certain adverse events, we performed an individual patient data (IPD) meta-analysis.

METHODS

All investigators of randomised controlled trials that compared MR therapy with observation or treatment only at relapse (no MR) for patients with follicular lymphoma were invited to participate in an IPD meta-analysis. We obtained baseline patient and disease characteristics and time to progression and death for each patient. All analyses took into account the trial and original randomised treatment group. We analysed data in two ways: a two-stage analysis and a multivariate model including patient and disease characteristics.

FINDINGS

Seven trials including 2315 patients were analysed. Overall survival of patients improved with MR compared with no MR (hazard ratio [HR] 0.79, 95% CI 0.66-0.96). We could not detect any patient or disease characteristics that were associated with a survival benefit with MR. In all of the models, MR had a beneficial effect on overall survival compared with observation for all types of patients, which was not shown in a particular subgroup in which the patient had already received rituximab in the induction phase and received first-line therapy. MR improved PFS compared with observation (HR 0.57, 95% CI 0.51-0.64). The risk of adverse events was higher with MR, specifically infection of any grade and grade 3-4 infections.

INTERPRETATION

Based on IPD from randomised controlled trials, MR improves overall survival consistently in all patients, regardless of patient and disease characteristics when compared with observation, and should be prescribed after a successful induction with R-CVP or R-CHOP for patients with follicular lymphoma. It is still uncertain if that holds when the patient has already received rituximab in his/hers first induction. The effect of MR after bendamustine-rituximab induction compared with rituximab at progression should be further explored.

Soluble CD52 is an indicator of disease activity in chronic lymphocytic leukemia

CD52 is a glycoprotein expressed on normal as well as leukemic immune cells and shed as soluble CD52 (sCD52). We studied sCD52 levels in three CLL cohorts: the 'early', the 'high-risk', and the 'ibrutinib-treated'. The 'high-risk' patients had significantly higher sCD52 levels than the 'early' patients. For the 'early' patients, high sCD52 levels were associated with a significantly shorter time to first treatment. Regarding prognostic factors, no clear correlations with stage, IGHV, or beta-2-microglobulin were found; in a cox multivariate analysis of the 'early' patients, sCD52 and IGHV both had independent prognostic value. Following chemo-immunotherapy, sCD52 decreased in parallel with leukocytes while during ibrutinib treatment and ibrutinib-induced ymphocytosis, sCD52 decreased along with lymph node reductions. In vitro IgM stimulation of CLL cells led to increased sCD52 levels in the medium. Our findings indicate that sCD52 reflects disease activity and potentially treatment efficacy in CLL.

The HOVON68 CLL trial revisited: performance status and comorbidity affect survival in elderly patients with chronic lymphocytic leukemia

In the HOVON68 CLL trial, patients 65 to 75 years of age had no survival benefit from the addition of low-dose alemtuzumab to fludarabine and cyclophosphamide (FC) in contrast to younger patients. The reasons are explored in this 5-year trial update using both survival analysis and competing risk analysis on non-CLL-related mortality. Elderly FCA patients died more frequently from causes not related to CLL, and more often related to comorbidity (mostly cardiovascular) than to infection. In a Cox multivariate analysis, del(17p), performance status >0, and comorbidity were associated with a higher non-CLL-related mortality in the elderly independent of the treatment modality. Thus, while the 'fit' elderly with no comorbidity or performance status of 0 might potentially benefit from chemo-immunotherapy with FC, caution is warranted, when considering alemtuzumab treatment in elderly patients with cardiovascular comorbidity.

Ofatumumab maintenance versus observation in relapsed chronic lymphocytic leukaemia (PROLONG): an open-label, multicentre, randomised phase 3 study

BACKGROUND

Ofatumumab is a human anti-CD20 monoclonal antibody that has proven efficacy as monotherapy in refractory chronic lymphocytic leukaemia. We assessed the efficacy and safety of ofatumumab maintenance treatment versus observation for patients in remission after re-induction treatment for relapsed chronic lymphocytic leukaemia.

METHODS

This open-label, multicentre, randomised phase 3 study enrolled patients aged 18 years or older from 130 centres in 24 countries who had chronic lymphocytic leukaemia in complete or partial remission after second-line or third-line treatment. Eligible patients had a WHO performance status of 0-2, had a response assessment within the previous 3 months, did not have refractory disease, autoimmune haemolytic anaemia requiring treatment, chronic or active infection requiring treatment, and had not previously received maintenance treatment or autologous or allogeneic stem-cell transplant. Using a randomisation list generated by a central computerised system and an interactive voice recognition system, we randomly assigned (1:1) patients to receive ofatumumab (300 mg followed by 1000 mg 1 week later and every 8 weeks for up to 2 years) or undergo observation. Randomisation was stratified by number and type of previous treatment and remission status after induction treatment (block size of four). Treatment assignment was open label. The primary endpoint was investigator-assessed progression-free survival in the intention-to-treat population. We report the results of a prespecified interim analysis after two-thirds of the planned study events (disease progression or death) had happened. This trial is closed to accrual but follow-up is ongoing. This trial is registered with ClinicalTrials.gov, number NCT00802737.

FINDINGS

Between May 6, 2010, and June 19, 2014, we enrolled 474 patients: 238 patients were randomly assigned to receive ofatumumab maintenance treatment and 236 to undergo observation. One (<1%) patient in the ofatumumab group did not receive the allocated intervention (withdrawal of consent). The median follow-up was 19·1 months (IQR 10·3-28·8). Progression-free survival was improved in patients assigned to the ofatumumab group (29·4 months, 95% CI 26·2-34·2) compared with those assigned to observation (15·2 months, 11·8-18·8; hazard ratio 0·50, 95% CI 0·38-0·66; p<0·0001). The most common grade 3 or higher adverse events up to 60 days after last treatment were neutropenia (56 [24%] of 237 patients in the ofatumumab group vs 23 [10%] of 237 in the observation group) and infections (31 [13%] vs 20 [8%]). 20 (8%) of 237 patients in the ofatumumab group and three (1%) of 237 patients in the observation group had adverse events that led to permanent discontinuation of treatment. Up to 60 days after last treatment, two deaths related to adverse events occurred in the ofatumumab treatment group and five deaths related to adverse events occurred in the observation group; no deaths were attributed to the study drug.

INTERPRETATION

These data are important for the development of optimum maintenance strategies in patients with relapsed chronic lymphocytic leukaemia, notably in the present era of targeted drugs, many of which are to be used until progression.

Induction of TAp73 by platinum-based compounds to overcome drug resistance in p53 dysfunctional chronic lymphocytic leukemia

In chronic lymphocytic leukemia (CLL), strategies to overcome drug resistance due to p53 dysfunction are highly needed. Platinum-based compounds such as cisplatinum (CDDP) are active in fludarabine-refractory CLL through a largely unknown mechanism. We analyzed the mechanism of action of CDDP in the context of p53 dysfunctionality. In vitro treatment with CDDP did not induce death in quiescent CLL cells, but did induce apoptosis in CD40-ligand (and CpG) stimulated and proliferating cells, irrespective of p53 function. In the p53 dysfunctional prolymphocytic cell-line MEC1, CDDP treatment resulted in apoptosis, cell cycle arrest and ABL1-dependent expression of TAp73, CDKN1A, PUMA and BID. TAp73 RNA-interference decreased sensitivity to CDDP. Finally, both in vitro stimulated CLL cells and lymph node (LN) derived CLL cells showed increased TAp73 expression in comparison with quiescent peripheral blood derived cells. Activity of CDDP may therefore be mediated by TAp73, especially in the context of activation such as occurs in the LN microenvironment.

Early discharge after high dose chemotherapy is safe and feasible: a prospective evaluation of 6 years of home care

A single-center, prospective, non-randomized clinical study was performed to examine the safety and feasibility of early discharge in patients undergoing consolidation chemotherapy for acute leukemia, or autologous stem cell transplant for lymphoma or multiple myeloma. Patients were discharged into ambulatory care the day after the last chemotherapy administration and were subsequently seen at the ambulatory care unit three times a week. One hundred and one of 224 patients were ineligible for the program, mostly because of their medical situation, the lack of a caregiver or the travel time to the hospital. The remaining 123 patients were able to spend more than 70% of the time at home. In 44% of cycles they were never readmitted. This study demonstrates the safety, feasibility and benefits of managing carefully selected patients. Patients and their caregivers felt safe and comfortable at home, and the vast majority preferred home care to in-hospital treatment.

Dasatinib in combination with fludarabine in patients with refractory chronic lymphocytic leukemia: a multicenter phase 2 study

Resistance to chemotherapy-induced apoptosis in CLL is associated with overexpression of antiapoptotic proteins induced by signals from the microenvironment. In vitro, dasatinib effectively inhibits expression of anti-apoptotic regulators and restores fludarabine sensitivity in activated CLL. The aim of this study was to evaluate efficacy of one cycle of dasatinib monotherapy (100mg/day, days 1-28) followed by combination of dasatinib with fludarabine (40mg/m²/day, days 1-3 every 28 day) for a total of 6 cycles in fludarabine-refractory CLL. The primary endpoint was overall response rate according to the IWCLL'08 criteria. 20 patients were enrolled: 18 completed at least one cycle of treatment of which 67% finished at least 2 cycles of combination treatment. 3 of these 18 patients reached a formal PR (16.7%). Majority of patients obtained some reduction in lymph node (LN) size. Most frequent toxicity was related to myelosuppression. NF-κB RNA expression levels of circulating CLL cells decreased whereas the levels of pro-apoptotic NOXA increased during treatment. In conclusion, dasatinib/fludarabine combination has modest clinical efficacy in fludarabine-refractory patients.

Tipping the Noxa/Mcl-1 balance overcomes ABT-737 resistance in chronic lymphocytic leukemia

PURPOSE

Chronic lymphocytic leukemia (CLL) cells in lymph nodes (LN), from which relapses are postulated to originate, display an antiapoptotic profile in contrast to CLL cells from peripheral blood (PB). The BH3 mimetic ABT-737 antagonizes the antiapoptotic proteins Bcl-X(L) and Bcl-2 but not Mcl-1 or Bfl-1. Previously, it was shown that CD40-stimulated CLL cells were resistant to ABT-737. We aimed to define which antiapoptotic proteins determine resistance to ABT-737 in CLL and whether combination of known antileukemia drugs and ABT-737 was able to induce apoptosis of CD40-stimulated CLL cells.

EXPERIMENTAL DESIGN

To mimic the LN microenvironment, PB lymphocytes of CLL patients were cultured on feeder cells expressing CD40L and treated with ABT-737 with or without various drugs. In addition, we carried out overexpression or knockdown of pro- and antiapoptotic proteins in immortalized primary B cells.

RESULTS

Upon CD40 stimulation patient-specific variations in ABT-737 sensitivity correlated with differences in levels of Mcl-1 and its antagonist Noxa. Knockdown of Noxa, as well as Mcl-1 overexpression, corroborated the importance of the Noxa/Mcl-1 ratio in determining the response to ABT-737. Inhibition of NF-κB resulted in increased Noxa levels and enhanced sensitivity to ABT-737. Interestingly, increasing the Noxa/Mcl-1 ratio, by decreasing Mcl-1 (dasatinib and roscovitine) or increasing Noxa levels (fludarabine and bortezomib), resulted in synergy with ABT-737.

CONCLUSIONS

Thus, the Noxa/Mcl-1 balance determines sensitivity to ABT-737 in CD40-stimulated CLL cells. These data provide a rationale to investigate the combination of drugs which enhance the Noxa/Mcl-1 balance with ABT-737 to eradicate CLL in chemoresistant niches.

Long-term follow-up of autologous hematopoietic stem cell transplantation for severe refractory Crohn's disease

BACKGROUND

Although new therapeutic strategies have been developed to control Crohn's disease, medical treatment for refractory cases is not able to prevent extensive and/or repeat surgery. Recently, several cases have been reported of successful remission induction in Crohn's disease patients by means of hematopoietic stem cell transplantation (HSCT). Here we report our long-term (4 to 6 years) outcome in three patients.

PATIENTS

Three patients (two male, one female) with active severe Crohn's disease were planned to undergo autologous HSCT. All patients were intolerant or refractory to conventional therapies, including anti-TNFα antibodies. Patients either refused surgery or surgery was considered not to be a feasible alternative due to the extensive disease involvement of the small intestine.

METHODS

Peripheral blood stem cells were mobilized using a single infusion of cyclophosphamide 4 g/m(2), followed on day 4 by subcutaneous injections with G-CSF 5 μg/kg twice daily until leukapheresis. CD34+ cells were isolated after leukapheresis by magnetic cell sorting. In two of the three patients a second round of stem cell mobilization using G-CSF only was required, either because of low yield or because of insufficient recovery after CD34 selection. Prior to transplantation, immune ablation was achieved using cyclophosphamide 50mg/kg/day (4 days), antithymocyte globulin 30 mg/kg/day (3 days) and prednisolone 500 mg (3 days). Endoscopy, barium small bowel enteroclysis and MRI enterography were performed.

RESULTS

All three patients successfully completed stem cell mobilization, and two of them subsequently underwent conditioning and autologous HSCT with CD34+ cell selection. Treatment was well tolerated, with acceptable toxicity. Now, 5 and 6 years post-transplantation, these patients are in remission under treatment. The third patient went into remission after mobilization and therefore she decided not to undergo conditioning and HSCT transplantation. After a successful pregnancy she relapsed two years later. Since then, she suffers from refractory Crohn's disease for which we are now reconsidering conditioning and transplantation.

CONCLUSION

Autologous HSCT appears to be safe and can be an alternative strategy for Crohn's disease patients with severe and therapy resistant disease.

Precursor T-lymphoblastic lymphoma presenting as primary renal lymphoma with acute renal failure

We report a case of acute renal failure (ARF) and bilateral nephromegaly in a patient with a history of Crohn’s disease and treatment with azathioprine. Kidney biopsy revealed diffuse renal infiltration by precursor T-cell lymphoblastic lymphoma (T-LBL). At the time of diagnosis, no extrarenal manifestations of the lymphoma were detectable and therefore the lymphoma was categorized as primary renal lymphoma (PRL). Thus far, precursor T-LBL presenting as PRL has not been described before. We emphasize that in patients with ARF and bilateral renal enlargement, renal lymphoma is an important differential diagnostic consideration.

Postoperative complications associated with transfusion of platelets and plasma in cardiac surgery

BACKGROUND

Studies in cardiac surgery have reported increased postoperative morbidity and mortality after allogeneic red blood cell (RBC) transfusions. Whether platelet (PLT) and/or plasma transfusions are a marker for more concomitant RBC transfusions or are independently associated with complications after cardiac surgery is unknown.

STUDY DESIGN AND METHODS

Data from two randomized controlled studies were combined to analyze the effects of PLT and/or plasma transfusions on postoperative infections, length of stay in the intensive care unit (ICU), all-cause mortality, and mortality in the presence or absence of infections in the postoperative period.

RESULTS

After adjusting for confounding factors, plasma units and not RBC transfusions were associated with all-cause mortality. White blood cell (WBC)-containing RBC transfusions and PLT transfusions were associated with mortality occurring in the presence of or after infections. The number of (WBC-containing) RBC transfusions was also significantly associated with postoperative infections and with ICU stay for 4 or more days.

CONCLUSION

Although it is difficult to separate the effects of blood components, we found that in cardiac surgery, perioperative plasma transfusions are independently associated with all-cause mortality. WBC-containing RBC transfusions and PLT transfusions are independently associated with mortality in the presence of infections in the postoperative period. Future transfusion studies in cardiac surgery should concomitantly consider the possible adverse effects of all the various transfused blood components.

Treatment strategies in advanced stage follicular lymphoma

Although the introduction of anti-CD20 monoclonal antibodies has improved the outcome of patients with follicular lymphoma, a curative treatment is still not available. Many questions still remain to be answered: when should treatment be initiated? Is there an optimal first line treatment and can this treatment be individualized on the basis of prognostic markers? What is the best treatment strategy for relapsed follicular lymphoma and what is the place of the many novel agents? Should maintenance treatment be given to all patients and how? In the present review we will address these questions.

Analysis of efficacy and prognostic factors of lenalidomide treatment as part of a Dutch compassionate use program

BACKGROUND AND METHODS

To obtain efficacy and safety data on lenalidomide treatment outside of clinical trials, we analyzed the clinical data of 114 patients with refractory or relapsed multiple myeloma treated with lenalidomide on a compassionate use basis. The recommended treatment consisted of lenalidomide 25 mg given on days 1-21 of a 28-day cycle, in combination with dexamethasone. A median of 3 previous lines of therapy were given, including thalidomide in 91%. Most patients were treated until progression or intolerable toxicity.

RESULTS

The median number of cycles was 7 (range, 1-21+ cycles) with a maximum response after a median of 3 cycles (range, 1-10 cycles). The overall response rate was 69%, including complete response in 6%, very good partial response in 19%, and partial response in 44%. The response rate was not influenced by previous thalidomide and/or bortezomib treatment. The median time to progression (TTP) was 9 months and the median overall survival (OS) was 22 months. A significantly longer TTP was observed in patients who previously underwent allogeneic stem cell transplantation (12.5 months vs. 8 months; P = .036). Overall survival was significantly affected by performance status (P < .0001). Lenalidomide toxicity was predominantly hematologic (37%; Common Toxicity Criteria > or = 3) and the incidence of venous thrombotic events was low (5%) using the recommended prophylaxis.

CONCLUSION

This analysis confirms that, outside clinical prospective trials, treatment with lenalidomide is highly effective and feasible in heavily pretreated patients with multiple myeloma.

Rituximab maintenance treatment of relapsed/resistant follicular non-Hodgkin's lymphoma: long-term outcome of the EORTC 20981 phase III randomized intergroup study

PURPOSE

In 2006, we published the results of the European Organisation for Research and Treatment of Cancer phase III trial EORTC 20981 on the role of rituximab in remission induction and maintenance treatment of relapsed/resistant follicular lymphoma (FL). At that time, the median follow-up for the maintenance phase was 33 months. Now, we report the long-term outcome of maintenance treatment, with a median follow-up of 6 years.

PATIENTS AND METHODS

Overall, 465 patients were randomly assigned to induction with either six cycles of cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) or rituximab plus CHOP (R-CHOP). Those in complete remission or partial remission after induction (n = 334) were randomly assigned to maintenance treatment with rituximab (375 mg/m(2) intravenously once every 3 months) or observation.

RESULTS

Rituximab maintenance significantly improved progression-free survival (PFS) compared with observation (median, 3.7 years v 1.3 years; P < .001; hazard ratio [HR], 0.55), both after CHOP induction (P < .001; HR, 0.37) and R-CHOP (P = .003; HR, 0.69). The 5-year overall survival (OS) was 74% in the rituximab maintenance arm, and it was 64% in the observation arm (P = .07). After progression, a rituximab-containing salvage therapy was given to 59% of patients treated with CHOP followed by observation, compared with 26% after R-CHOP followed by rituximab maintenance. Rituximab maintenance was associated with a significant increase in grades 3 to 4 infections: 9.7% v 2.4% (P = .01).

CONCLUSION

With long-term follow-up, we confirm the superior PFS with rituximab maintenance in relapsed/resistant FL. The improvement of OS did not reach statistical significance, possibly because of the unbalanced use of rituximab in post-protocol salvage treatment.

Pharmacokinetics and pharmacokinetic/pharmacodynamic associations of ofatumumab, a human monoclonal CD20 antibody, in patients with relapsed or refractory chronic lymphocytic leukaemia: a phase 1-2 study

The purpose of this phase 1-2 study was to investigate the association between the pharmacokinetic properties of ofatumumab, a human monoclonal CD20 antibody, and outcomes in 33 patients with relapsed/refractory chronic lymphocytic leukaemia receiving 4 weekly infusions of ofatumumab. The ofatumumab concentration profiles were fitted well by a two-compartment model with different elimination rate constant at first infusion compared to the remaining infusions in line with the observed rapid and sustained B-cell depletion. Exposure to ofatumumab was linked to clinical outcomes: high exposure was associated with higher probability of overall clinical response and longer progression-free survival. This association still remained statistically significant even when adjusting for relevant baseline covariates including tumour burden.

BCL-2/IgH polymerase chain reaction status at the end of induction treatment is not predictive for progression-free survival in relapsed/resistant follicular lymphoma: results of a prospective randomized EORTC 20981 phase III intergroup study

PURPOSE

The prognostic value of residual BCL2/immunoglobulin heavy chain (BCL2/IgH) -positive cells in peripheral blood (PB) or bone marrow (BM) after induction treatment in follicular lymphoma (FL) is still controversial. In a prospective randomized phase III intergroup trial of 465 patients with relapsed/resistant follicular lymphoma (FL), we showed that addition of rituximab to cyclophosphamide, doxorubicin, vincristine, and prednisone induction results in increased overall and complete response rates, and that rituximab maintenance strongly improves median progression-free survival (PFS) as well as overall survival. Here, we studied whether BCL2/IgH major break point levels in PB/BM correlated with response rates/quality for the induction phase and PFS for the maintenance phase.

PATIENTS AND METHODS

Samples were obtained before and after induction therapy and at the end of the 2 years maintenance/observation period. BCL2/IgH major break point-positive cells were quantified by genomic quantitative polymerase chain reaction in 792 samples from 238 patients.

RESULTS

Pretreatment BCL2/IgH levels had no significant prognostic value for overall response or complete remission rates after induction treatment, but pretreatment positive BM results had an adverse prognostic value for PFS from first randomization (P = .023). Importantly, BCL2/IgH levels at the end of induction treatment had no prognostic value for PFS from second randomization. The highly significant improved PFS by rituximab maintenance was observed in both BCL2/IgH PB/BM-positive and -negative groups.

CONCLUSION

Postinduction BCL2/IgH major break point status in BM/PB is not useful for decisions on subsequent therapy for patients with relapsed/resistant FL.

The practice of reporting transfusion-related acute lung injury: a national survey among clinical and preclinical disciplines

BACKGROUND

Transfusion-related acute lung injury (TRALI) is hypothesized to be a "two-hit" entity, in which an inflammatory condition (e.g., sepsis) predisposes to TRALI. TRALI is a clinical diagnosis. Disciplines involved in managing TRALI may differ in decision-making on the reporting of TRALI.

STUDY DESIGN AND METHODS

A survey was conducted among critical care physicians, hematologists, hemovigilance workers, and transfusion medicine physicians, using case vignettes and a questionnaire. The vignettes varied in patient- and blood product-related factors that may influence the decision to report a TRALI case. Multiple linear regression analysis was performed. A positive beta-coefficient is in favor of reporting.

RESULTS

Ninety-two questionnaires were returned (response rate, 68%). For all disciplines, preferences in favor of reporting TRALI were onset of symptoms within 1 hour (beta = 0.4), after transfusion of a single unit of FFP (beta = 0.5), and in the absence of acute lung injury before transfusion (beta = 1.3). An admission diagnosis of sepsis was a negative preference (beta = -0.3). Massive transfusion (6 RBC plus 4 FFP units) was a negative preference for transfusion medicine physicians (beta = -0.3), but a positive preference for the other disciplines. The questionnaire revealed that massive transfusion and the age of blood products were considered relatively more important reasons to report TRALI by critical care physicians compared to the other disciplines (p < 0.05).

CONCLUSION

A pretransfusion inflammatory condition is a reason to withhold from reporting of a suspected TRALI case. Disciplines involved in managing TRALI differ in decision-making of reporting TRALI, which may contribute to variance in incidence.

Array CGH analysis of chronic lymphocytic leukemia reveals frequent cryptic monoallelic and biallelic deletions of chromosome 22q11 that include the PRAME gene

We used BAC array-based CGH to detect genomic imbalances in 187 CLL cases. Submicroscopic deletions of chromosome 22q11 were observed in 28 cases (15%), and the frequency of these deletions was second only to loss of the 13q14 region, the most common genomic aberration in CLL. Oligonucleotide-based array CGH analysis showed that the 22q11 deletions ranged in size from 0.34 Mb up to approximately 1 Mb. The minimally deleted region included the ZNF280A, ZNF280B, GGTLC2, and PRAME genes. Quantitative real-time PCR revealed that ZNF280A, ZNF280B, and PRAME mRNA expression was significantly lower in the 22q11 deletion cases compared to non-deleted cases.

In vivo dynamics of stable chronic lymphocytic leukemia inversely correlate with somatic hypermutation levels and suggest no major leukemic turnover in bone marrow

Although accumulating evidence indicates that chronic lymphocytic leukemia (CLL) is a disease with appreciable cell dynamics, it remains uncertain whether this also applies to patients with stable disease. In this study, (2)H(2)O was administered to a clinically homogeneous cohort of nine stable, untreated CLL patients. CLL dynamics in blood and bone marrow were determined and compared with normal B-cell dynamics in blood from five healthy individuals who underwent a similar (2)H(2)O labeling protocol. Average CLL turnover rates (0.08-0.35% of the clone per day) were approximately 2-fold lower than average B-cell turnover rates from healthy individuals (0.34-0.89%), whereas the rate at which labeled CLL cells in blood disappeared (0.00-0.39% of B cells per day) was approximately 10-fold lower compared with labeled B cells from healthy individuals (1.57-4.24% per day). Leukemic cell turnover variables inversely correlated with the level of somatic hypermutation of the CLL clone (IgVH mutations). Although CLL cells in bone marrow had a higher level of label enrichment than CLL cells in blood, no difference between proliferation rates and proapoptotic and antiapoptotic profiles of CLL cells from these compartments was observed. These data suggest that, in stable disease, there is a biological relationship between the degree of somatic hypermutation of the CLL clone and its dynamics in vivo. Furthermore, in contrast to lymph nodes, the bone marrow does not seem to be a major CLL proliferation site.

Phase III trial of consolidation therapy with yttrium-90-ibritumomab tiuxetan compared with no additional therapy after first remission in advanced follicular lymphoma

PURPOSE

We conducted an international, randomized, phase III trial to evaluate the efficacy and safety of consolidation with yttrium-90 ((90)Y)-ibritumomab tiuxetan in patients with advanced-stage follicular lymphoma in first remission.

PATIENTS AND METHODS

Patients with CD20(+) stage III or IV follicular lymphoma, who achieved a complete response (CR)/unconfirmed CR (CRu) or partial response (PR) after first-line induction treatment, were randomly assigned to receive (90)Y-ibritumomab tiuxetan (rituximab 250 mg/m(2) on day -7 and day 0 followed on day 0 by (90)Y-ibritumomab tiuxetan 14.8 MBq/kg; maximum of 1,184 MBq) or no further treatment (control). The primary end point was progression-free survival (PFS), which was calculated from the time of random assignment.

RESULTS

A total of 414 patients (consolidation, n = 208; control, n = 206) were enrolled at 77 centers. (90)Y-ibritumomab tiuxetan consolidation significantly prolonged median PFS (after a median observation time of 3.5 years) in all patients (36.5 v 13.3 months in control arm; hazard ratio [HR] = 0.465; P < .0001) and regardless of whether patients achieved PR (29.3 v 6.2 months in control arm; HR = 0.304; P < .0001) or CR/CRu (53.9 v 29.5 months in control arm; HR = 0.613; P = .0154) after induction treatment. Median PFS with consolidation was prolonged in all Follicular Lymphoma International Prognostic Index risk subgroups. After (90)Y-ibritumomab tiuxetan consolidation, 77% of patients in PR after induction converted to CR/CRu, resulting in a final CR rate of 87%. The most common toxicity with (90)Y-ibritumomab tiuxetan was hematologic, and grade 3 or 4 infections occurred in 8% of patients.

CONCLUSION

Consolidation of first remission with (90)Y-ibritumomab tiuxetan in advanced-stage follicular lymphoma is highly effective with no unexpected toxicities, prolonging PFS by 2 years and resulting in high PR-to-CR conversion rates regardless of type of first-line induction treatment.

Whole-genome scanning by array comparative genomic hybridization as a clinical tool for risk assessment in chronic lymphocytic leukemia

Array-based comparative genomic hybridization (array CGH) provides a powerful method for simultaneous genome-wide scanning and prognostic marker assessment in chronic lymphocytic leukemia (CLL). In the current study, commercially available bacterial artificial chromosome and oligonucleotide array CGH platforms were used to identify chromosomal alterations of prognostic significance in 174 CLL cases. Tumor genomes were initially analyzed by bacterial artificial chromosome array CGH followed by confirmation and breakpoint mapping using oligonucleotide arrays. Genomic changes involving loci currently interrogated by fluorescence in situ hybridization (FISH) panels were detected in 155 cases (89%) at expected frequencies: 13q14 loss (47%), trisomy 12 (13%), 11q loss (11%), 6q loss (7.5%), and 17p loss (4.6%). Genomic instability was the second most commonly identified alteration of prognostic significance with three or more alterations involving loci not interrogated by FISH panels identified in 37 CLL cases (21%). A subset of 48 CLL cases analyzed by six-probe FISH panels (288 total hybridizations) was concordant with array CGH results for 275 hybridizations (95.5%); 13 hybridizations (4.5%) were discordant because of clonal populations that comprised less than 30% of the sample. Array CGH is a powerful, cost-effective tool for genome-wide risk assessment in the clinical evaluation of CLL.

Tight regulation of the Epstein-Barr virus setpoint: interindividual differences in Epstein-Barr virus DNA load are conserved after HIV infection

Healthy individuals carry a constant number of Epstein-Barr virus-infected B cells in the peripheral blood over time. Here, we show that interindividual differences in Epstein-Barr virus DNA levels are maintained after HIV infection, providing evidence for the existence of an individual Epstein-Barr virus setpoint. Immune activation may contribute to the increase in this setpoint after human immunodeficiency virus seroconversion.

Rituximab maintenance in indolent lymphoma: indications and controversies

Over the past few years it has been shown in previously untreated and relapsed/refractory follicular lymphoma that rituximab maintenance has a clear clinical benefit after induction with rituximab plus chemotherapy, chemotherapy alone, or rituximab monotherapy. However, the optimal dose, schedule, and duration of rituximab maintenance therapy still need to be established. The important issue of maintenance treatment versus retreatment upon relapse is the topic of the ongoing large randomized phase III Rituximab Extended Schedule or Retreatment Trial (RESORT). Current data indicate that rituximab maintenance can be safely administered for up to 2 years, although assessment of long-term safety requires longer follow-up.

Cellular immune therapy for chronic lymphocytic leukemia

Although chemotherapy can induce complete responses in patients with chronic lymphocytic leukemia (CLL), it is not considered curative. Treated patients generally develop recurrent disease requiring additional therapy, which can cause worsening immune dysfunction, myelosuppression, and selection for chemotherapy-resistant leukemia-cell subclones. Cellular immune therapy promises to mitigate these complications and potentially provide for curative treatment. Most experience with this is in the use of allogeneic hematopoietic stem-cell transplantation (allo-HSCT), in which graft-versus-leukemia (GVL) effects can be observed and shown responsible for long-term disease-free survival. However, use of allo-HSCT for CLL is limited because of the lack of suitable donors and the treatment-related morbidity/mortality for elderly patients, who constitute the majority at risk for developing this disease. The GVL effect, however, suggests there are specific CLL-associated antigens that could be targeted in autologous cellular immune therapy. Effective strategies for this will have to overcome the disease-related acquired immune deficiency and the capacity of the leukemia-cell to induce T-cell tolerance, thereby compromising the activity of even conventional vaccines in patients with this disease. We will discuss the different strategies being developed to overcome these limitations that might provide for effective cellular immune therapy of CLL.

Intermediate-dose melphalan compared with myeloablative treatment in multiple myeloma: long-term follow-up of the Dutch Cooperative Group HOVON 24 trial

BACKGROUND AND OBJECTIVES

The Dutch-Belgian HOVON group performed a randomized phase 3 trial to compare single non-myeloablative intensive treatment with double, intensive treatment in previously untreated patients with multiple myeloma (MM).

DESIGN AND METHODS

Three hundred and three patients with stage II/III MM were randomized after VAD induction chemotherapy to receive two cycles of non-myeloablative intermediate-dose melphalan (70 mg/m2) (single treatment) or the same regimen followed by cyclophosphamide 120 mg/kg iv plus total body irradiation (TBI) 9 Gy and autologous stem cell transplantation (double, intensive treatment). In both treatment arms interferon .IIa was given as maintenance until relapse/progression.

RESULTS

A significantly higher proportion of patients achieved a complete remission (CR) on protocol treatment with double, intensive therapy (32 % vs 13 %, p<0.001). Double treatment produced better outcome in terms of event-free survival (median 22 vs 21 months, 28% vs 14% at 4 years and 15% vs 7% at 6 years after randomization; logrank p=0.013; univariate HR 0.74, 95% CI, 0.58-0.94), progression-free survival (median 27 vs 24 months, 33% vs 16% at 4 years, and 17% vs 9% at 6 years after randomization; logrank p=0.006; HR=0.71, 95% CI 0.56-0.91), but not overall survival (median 50 vs 55 months, 52% vs 56% at 4 years and 39% vs 36% at 6 years after randomization; logrank p=0.51; HR=1.10, 95% CI 0.83-1.46). The achievement of a CR had a favorable prognostic impact on event-free survival (HR=0.60 , 95% CI=0.44 -0.82 , p=0.001) and progression-free survival (HR=0.62 , 95% CI=0.45 -0.84, p=0.002).

INTERPRETATION AND CONCLUSIONS

Double, intensive treatment resulted in a better CR rate, event-free survival and progression-free survival but not overall survival compared to single non-myeloablative treatment in previously untreated patients with multiple myeloma.

Rituximab maintenance therapy: a step forward in follicular lymphoma

Whilst recent advances in the treatment of follicular lymphoma (FL) have improved the outlook for many patients, relapses still occur and the search continues for strategies to extend the duration of remission without significantly increasing toxicity. One such strategy is the use of rituximab maintenance therapy for patients responding to initial induction. There is now a large body of evidence demonstrating clear benefits of rituximab maintenance versus observation following induction with either rituximab plus chemotherapy (R chemo), chemotherapy alone, or rituximab monotherapy, in both first-line and relapsed/refractory settings. A very important finding is that rituximab maintenance can significantly improve overall survival in FL patients responding to induction with either R-chemo or chemotherapy alone. Also, compared with rituximab retreatment at disease progression, the maintenance approach produces much better complete remission rates and significantly longer continuous remissions and progression-free survival. Various maintenance schedules have been explored, all of which demonstrate clear benefits. However, the optimal dose, schedule, and duration of maintenance therapy still need to be established. Current data indicate that rituximab maintenance can be safely administered for up to 2 years, although assessment of long-term safety requires longer follow-up. From the patient's perspective, rituximab maintenance also prolongs the period in which patients are symptom-free and able to lead a relatively normal daily life. Also, rituximab maintenance may help patients feel they can control their disease, rather than passively waiting for relapse.

CD27-CD70 interactions sensitise naive CD4+ T cells for IL-12-induced Th1 cell development

Stimulation of CD27, a member of the tumour necrosis factor receptor family, by its ligand CD70 induces expansion of IFNgamma secreting CD4+ and CD8+ T cells in vivo. We here analysed the mechanisms through which CD27 mediates this effect. CD27 co-stimulation induced cell division but did not directly instruct naive CD4+ T cells to differentiate into IFNgamma-producing Th1 cells. Rather, in concert with signals delivered through the TCR-CD3 complex, CD27 co-stimulation enhanced the Th1-specific transcription factor T-bet and caused up-regulation of the IL-12Rbeta2 chain. Consequently, CD27-costimulated T cells yielded vast numbers of IFNgamma-secreting cells in response to IL-12. Additionally, CD27 ligation induced a strong up-regulation of Bcl-xL, but not of related anti-apoptotic molecules. Thus, CD27-CD70 interactions may promote Th1 formation by permitting naive T cells to respond to differentiation signals and by promoting survival of activated effector T cells.

Differential Noxa/Mcl-1 balance in peripheral versus lymph node chronic lymphocytic leukemia cells correlates with survival capacity

The gradual accumulation of chronic lymphocytic leukemia (B-CLL) cells is presumed to derive from proliferation centers in lymph nodes and bone marrow. To what extent these cells possess the purported antiapoptotic phenotype of peripheral B-CLL cells is unknown. Recently, we have described that, in B-CLL samples from peripheral blood, aberrant apoptosis gene expression was not limited to protective changes but also included increased levels of proapoptotic BH3-only member Noxa. Here, we compare apoptosis gene profiles from peripheral blood B-CLL (n = 15) with lymph node B-CLL (> 90% CD5+/CD19+/CD23+ lymphocytes with Ki67+ centers; n = 9). Apart from expected differences in Survivin and Bcl-xL, a prominent distinction with peripheral B-CLL cells was the decreased averaged level of Noxa in lymph nodes. Mcl-1 protein expression showed a reverse trend. Noxa expression could be reduced also in vitro by CD40 stimulation of peripheral blood B-CLL. Direct manipulation of Noxa protein levels was achieved by proteasome inhibition in B-CLL and via RNAi in model cell lines. In each instance, cell viability was directly linked with Noxa levels. These data indicate that suppression of Noxa in the lymph node environment contributes to the persistence of B-CLL at these sites and suggest that therapeutic targeting of Noxa might be beneficial.

CD27 contributes to the early systemic immune response to Mycobacterium tuberculosis infection but does not affect outcome

The development of a strong Th1-mediated adaptive immune response is considered of main importance for host defense against the intracellular pathogen Mycobacterium tuberculosis. The induction of a cellular immune response is not only dependent on the engagement of the TCR but also requires co-stimulation. In order to study the role of the co-stimulatory molecule of the tumor necrosis factor receptor family member CD27 during murine M. tuberculosis infection, we intranasally infected wild-type (WT) and CD27 knockout (KO) mice with 10(5) colony-forming units M. tuberculosis. Whereas there were no differences in bacterial growth, inflammation and IFNgamma production by CD4+ and CD8+ lymphocytes in the lungs early after infection, the number of splenic CD8+ T cells producing the key Th1 cytokine IFNgamma was lower in CD27 KO mice than in WT mice. After 6 weeks, CD27 KO mice had 3.6-fold higher mycobacterial counts in their lungs and displayed more pulmonary inflammation and increased numbers of infiltrated leukocytes. Despite these differences early in infection, an equal number of WT and CD27 KO mice died during a 43-week observation period and lung bacterial loads and inflammation were comparable in the surviving animals. Our data suggest that CD27 does not contribute to the local IFNgamma-mediated response and long-term protection against M. tuberculosis.

Rituximab maintenance improves clinical outcome of relapsed/resistant follicular non-Hodgkin lymphoma in patients both with and without rituximab during induction: results of a prospective randomized phase 3 intergroup trial

We evaluated the role of rituximab (R) both in remission induction and maintenance treatment of relapsed/resistant follicular lymphoma (FL). A total of 465 patients were randomized to induction with 6 cycles of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) (every 3 weeks) or R-CHOP (R: 375 mg/m(2) intravenously, day 1). Those in complete remission (CR) or partial remission (PR) were randomized to maintenance with R (375 mg/m(2) intravenously once every 3 months for a maximum of 2 years) or observation. R-CHOP induction yielded an increased overall response rate (CHOP, 72.3%; R-CHOP, 85.1%; P < .001) and CR rate (CHOP, 15.6%; R-CHOP, 29.5%; P < .001). Median progression-free survival (PFS) from first randomization was 20.2 months after CHOP versus 33.1 months after R-CHOP (hazard ratio [HR], 0.65; P < .001). Rituximab maintenance yielded a median PFS from second randomization of 51.5 months versus 14.9 months with observation (HR, 0.40; P < .001). Improved PFS was found both after induction with CHOP (HR, 0.30; P < .001) and R-CHOP (HR, 0.54; P = .004). R maintenance also improved overall survival from second randomization: 85% at 3 years versus 77% with observation (HR, 0.52; P = .011). This is the first trial showing that in relapsed/resistant FL rituximab maintenance considerably improves PFS not only after CHOP but also after R-CHOP induction.

Detailed kinetics of EBV-specific CD4+ and CD8+ T cells during primary EBV infection in a kidney transplant patient

The etiology of infectious mononucleosis is poorly understood and usually detected many weeks after infection. Here, we present a unique case of primary symptomatic EBV infection after kidney transplantation, in whom we analyzed both EBV-specific CD4+ and CD8+ T cells in detail from the moment of infection up to latency. We show that EBV-specific T-cell responses in peripheral blood during primary EBV infection after kidney transplantation peaked early after the appearance of viral load, but well before onset of IM symptoms, suggesting that IM in this case is not caused by high numbers of CD8+ T cells per se but may be caused by lack of homing to lymph nodes or tonsils.

Reconstitution of EBV Latent but Not Lytic Antigen-Specific CD4+and CD8+T Cells after HIV Treatment with Highly Active Antiretroviral Therapy

The incidence of (EBV-related) malignancies in HIV-infected subjects has declined since the introduction of highly active antiretroviral therapy (HAART). To investigate the effect of HAART on EBV infection, we performed a longitudinal analysis of the T cell response to both a latent and a lytic Ag and EBV viral load in 10 subjects from early in HIV infection up to 5 years after HAART. All individuals responded to HAART by a decline in HIV viral load, a restoration of total CD4+ T cell numbers, and a decline in T cell immune activation. Despite this, EBV load remained unaltered, even after 5 years of therapy, although a decline in both CD4+ and CD8+ T cells specific for the lytic EBV protein BZLF1 suggested a decreased EBV reactivation rate. In contrast, latent EBV Ag EBNA1-specific CD4+ and CD8+ T cell responses were restored after 5 years of treatment to levels comparable to healthy individuals. In two individuals who were treated by HAART late during HIV progression, a lymphoma developed shortly after initiation of HAART, despite restoration of EBV-specific CD4+ and CD8+ T cells. In conclusion, long-term HAART does not alter the EBV DNA load, but does lead to a restoration of EBNA1-specific T cell responses, which might allow better control of EBV-infected cells when applied early enough during HIV infection.

Loss of EBNA1-specific memory CD4+ and CD8+ T cells in HIV-infected patients progressing to AIDS-related non-Hodgkin lymphoma

We previously observed a loss of Epstein-Barr virus (EBV)-specific CD8+ T cells in subjects progressing to EBV-related non-Hodgkin lymphoma (NHL), correlating with loss of CD4+ T cells. The aim of the present study was to determine the role of EBV-specific CD4+ T cells in the development of NHL during chronic HIV infection. To this end, CD4+ and CD8+ memory T cells, capable of both proliferation and subsequent interferon gamma (IFNgamma) production, directed against a latent (Epstein-Barr virus nuclear antigen 1 [EBNA1]) and a lytic (BamH fragment Z left frame 1 [BZLF1]) EBV antigen were studied longitudinally in 9 progressors to NHL, 4 progressors to non-EBV-related AIDS, and 4 slow progressors to AIDS. In all 3 groups we observed a decline of EBV-specific memory CD4+ and CD8+ T-cell responses during HIV infection. However, whereas latent antigen EBNA1-specific CD4+ T cells were lost well before diagnosis in all subjects who developed an AIDS-related NHL (and EBNA1-specific CD8+ T cells were significantly lower compared with the other groups), these cells were better preserved in progressors to non-EBV-related disease and slow progressors. Loss of EBNA1-specific T-cell immunity thus might be important for progression to NHL. Interestingly, BZLF1-specific T cells were not lost in all progressors to NHL, suggesting a different function of these cells in the surveillance of EBV-infected B cells.

Cutting Edge: CD95 Maintains Effector T Cell Homeostasis in Chronic Immune Activation

The elimination of activated T cells is important to maintain homeostasis and avoid immunopathology. CD95 (Fas/APO-1) has been identified as a death mediator for activated T cells in vitro but the function of CD95 in death of mature T cells in vivo is still controversial. Here we show that triggering of the costimulatory TNF receptor family member CD27 sensitized T cells for CD95-induced apoptosis. CD95-deficient (lpr/lpr) T cells massively expanded and differentiated into IFN-gamma-secreting effector cells in transgenic mice that constitutively express the CD27 ligand, CD70. Concomitantly, CD95-deficient CD70 transgenic mice became moribund by 4 wk of age with severe liver pathology and bone marrow failure. These findings establish that CD95 is a critical regulator of effector T cell homeostasis in chronic immune activation.

Immune activation modulates hematopoiesis through interactions between CD27 and CD70

The differentiation of hematopoietic stem cells into mature blood cell lineages is tightly regulated. Here we report that CD27, which is expressed on stem and early progenitor cells in bone marrow, can be important in this process. Deletion of CD27 increased the myeloid colony-forming potential of stem and early progenitor cells and enhanced B lymphoid reconstitutive capacity in competitive transplantation experiments. Conversely, stimulation of CD27(+) progenitor cells with CD70, the unique ligand for CD27, inhibited colony-forming potential in vitro and lymphocyte outgrowth in vivo. As CD70 is expressed only on activated immune cells, we suggest that CD27 triggering on early progenitor cells provides a negative feedback signal to leukocyte differentiation during immune activation.

CD40 stimulation of B-cell chronic lymphocytic leukaemia cells enhances the anti-apoptotic profile, but also Bid expression and cells remain susceptible to autologous cytotoxic T-lymphocyte attack

To enhance the poor antigen-presenting capacity of B-cell chronic lymphocytic leukaemia (B-CLL), CD40 triggering has been considered as an active immunotherapy. However, CD40 stimulation also has an anti-apoptotic effect and may further impair the dysregulated response of B-CLL to apoptotic stimuli. Therefore, we measured the expression of virtually all regulators of apoptosis before and after CD40 stimulation. These findings were correlated with sensitivity for chemotherapy- and death-receptor-induced apoptosis and T-cell-mediated killing. CD40 stimulation enhanced the constitutive anti-apoptotic profile of B-CLL cells by upregulation of Bcl-xL and Bfl-1 and downregulation of the BH3-only protein Harakiri. Unexpectedly, the BH3-only protein Bid was strongly induced. Functionally, CD40-stimulated B-CLL cells became resistant to drug-induced apoptosis and, despite upregulation of CD95 and Bid, were not sensitive to CD95L. In contrast, autologous T cell killing, triggered by loading CLL cells with viral (CMV) peptides, was very efficient both before and after CD40 stimulation. Upon CTL interaction, CLL targets underwent mitochondrial depolarization and caspase-3 activation. Thus, despite an increased anti-apoptotic profile, CD40 triggered B-CLL cells remain excellent targets for resident cytotoxic T cells. These data support therapeutic exploitation of CD40 stimulation in B-CLL, provided that a strong CTL component is induced.

Signaling through CD70 regulates B cell activation and IgG production

CD70, the cellular ligand of the TNF receptor family member CD27, is expressed transiently on activated T and B cells and constitutively on a subset of B cell chronic lymphocytic leukemia and large B cell lymphomas. In the present study, we used B cells constitutively expressing CD70 to study the functional consequences of signaling through CD70. In vitro, CD70 ligation with anti-CD70 mAbs strongly supported proliferation and cell cycle entry of B cells submitogenically stimulated with either anti-CD40 mAb, LPS, or IL-4. In this process, the cell surface receptors CD25, CD44, CD69, CD95, and GL7 were up-regulated, whereas the expression of CD21, CD62L, surface IgM (sIgM), and sIgD was decreased. Addition of CD70 mAb to low dose LPS-stimulated CD70-positive B cells strongly diminished IgG secretion and enhanced production of IgM. Signaling through CD70 on B cells was dependent on the initiation of both PI3K and MEK pathways. In vivo exposure to either CD70 mAb or the CD70 counterreceptor CD27 down-regulated CD62L and sIgM on CD70-positive B cells. CD70 signaling during T cell-dependent immune responses also decreased IgG-specific Ab titers. Together, the in vitro and in vivo data demonstrate that CD70 has potent reverse signaling properties in B cells, initiating a signaling cascade that regulates expansion and differentiation.

Tumor rejection induced by CD70-mediated quantitative and qualitative effects on effector CD8+ T cell formation

In vivo priming of antigen-specific CD8+ T cells results in their expansion and differentiation into effector T cells followed by contraction into a memory T cell population that can be maintained for life. Recent evidence suggests that after initial antigenic stimulation, the magnitude and kinetics of the CD8+ T cell response are programmed. However, it is unclear to what extent CD8+ T cell instruction in vivo is modulated by costimulatory signals. Here, we demonstrate that constitutive ligation of the tumor necrosis factor receptor family member CD27 by its ligand CD70 quantitatively augments CD8+ T cell responses to influenza virus infection and EL-4 tumor challenge in vivo by incrementing initial expansion and maintaining higher numbers of antigen-specific T cells in the memory phase. Concomitantly, the quality of antigen-specific T cells improved as evidenced by increased interferon (IFN)-gamma production and a greater cytotoxic potential on a per cell basis. As an apparent consequence, the superior effector T cell formation induced by CD70 protected against a lethal dose of poorly immunogenic EL4 tumor cells in a CD8+ T cell- and IFN-gamma-dependent manner. Thus, CD70 costimulation enhances both the expansion and per cell activity of antigen-specific CD8+ T cells.

Apoptosis via the B cell antigen receptor requires Bax translocation and involves mitochondrial depolarization, cytochrome C release, and caspase-9 activation

Various routes to apoptosis can be active during B cell development. In a model system of mature B cells, differences in caspase-3 processing have suggested that antigen receptor (BCR)-mediated apoptosis may involve a zVAD-insensitive initiator protease(s). In search of the events leading to caspase-3 activation, we now establish that both CD95- and BCR-mediated apoptosis depend on Bax activation and cytochrome C (cytC) release. Nevertheless, the timing and caspase-dependence of mitochondrial membrane depolarization differed considerably after CD95- or BCR-triggering. To delineate events subsequent to cytC release, we compared apoptosis induced via BCR triggering and via direct mitochondrial depolarization by CCCP. In both cases, partial processing of caspase-3 was observed in the presence of zVAD. By expression in 293 cells we addressed the potential of candidate initiator caspases to function in the presence of zVAD, and found that caspase-9 efficiently processed caspase-3, while caspase-2 or -8 were inactive. Finally, retroviral expression of dominant-negative caspase-9 inhibited both CD95- and BCR-mediated apoptosis. In conclusion, we obtained no evidence for involvement of a BCR-specific protease. Instead, our data show for the first time that the BCR-signal causes Bax translocation, followed by mitochondrial depolarization, and cytC release. Subsequent caspase-9 activation can solely account for events further downstream.