Immunogenicity, efficacy and safety of Nuwiq® (human-cl rhFVIII) in previously untreated patients with severe haemophilia A-Interim results from the NuProtect Study.

INTRODUCTION: Nuwiq® (Human-cl rhFVIII) is a fourth generation recombinant FVIII, produced in a human cell line, without chemical modification or protein fusion. No inhibitors developed in studies with Nuwiq® in 201 previously treated patients with haemophilia A (HA). The immunogenicity, efficacy and safety of Nuwiq® in previously untreated patients (PUPs) with severe HA are being assessed in the ongoing NuProtect study. METHODS: The study, conducted across 38 centres worldwide, is evaluating 110 true PUPs of all ages and ethnicities enrolled for study up to 100 exposure days (EDs) or 5 years maximum. The primary objective is to assess the immunogenicity of Nuwiq® (inhibitor activity ≥0.6 BU) using the Nijmegen-modified Bethesda assay at a central laboratory. RESULTS: Data for 66 PUPs with ≥20 EDs from a preplanned interim analysis were analysed. High-titre (HT) inhibitors developed in 8 of 66 patients after a median of 11.5 EDs (range 6-24). Five patients developed low-titre inhibitors (4 transient). The cumulative incidence (95% confidence interval) was 12.8% (4.5%, 21.2%) for HT inhibitors and 20.8% (10.7%, 31.0%) for all inhibitors. During inhibitor-free periods, median annualized bleeding rates during prophylaxis were 0 for spontaneous bleeds and 2.40 for all bleeds. Efficacy was rated as "excellent" or "good" in treating 91.8% of bleeds. Efficacy of surgical prophylaxis was "excellent" or "good" for 8 (89%) procedures and "moderate" for 1 (11%). No tolerability concerns were evident. CONCLUSION: These interim data show a cumulative incidence of 12.8% for HT inhibitors and convincing efficacy and tolerability in PUPs treated with Nuwiq® .

Safety and effectiveness of room temperature stable recombinant factor VIIa in patients with haemophilia A or B and inhibitors: Results of a multinational, prospective, observational study.

INTRODUCTION: A room temperature stable formulation of recombinant activated factor VII (NovoSeven® ), allowing convenient storage and therefore improved treatment access, has been developed. Bioequivalence to the previous NovoSeven® was demonstrated in healthy humans, leading to European approval (2008). Although no confirmed cases of neutralising antibodies to rFVIIa in patients with haemophilia A or B have been observed with the original formulation, changes in formulation or storage condition may alter immunogenicity. AIM: SMART-7™ was designed to investigate the safety of NovoSeven® in a real-world setting in patients with haemophilia A or B with inhibitors. METHODS: Study medication was not provided by the sponsor, and treatment was at the discretion of the treating physician, in accordance with the local label. Patient baseline information was collected at enrolment. Information on safety, drug exposure and bleeding episodes was collected and FVII antibody screening was encouraged at baseline and performed at the investigator's discretion. RESULTS: Fifty-one patients were enrolled and 31 completed the study. Forty-one adverse events (AEs) were reported in 23 patients; 25 AEs in 14 patients were serious. No thromboembolic events were observed. Although four cases of reduced therapeutic response were reported, FVII antibody screening was negative. Forty-eight patients experienced 618 bleeding episodes and 93.4% of 609 evaluated bleeds were stopped by treatment. Of the 538 bleeding episodes treated with NovoSeven® monotherapy, 94.2% stopped by end of treatment. CONCLUSION: Data collected during the SMART-7™ study revealed no treatment-related safety issues and no FVII-binding antibodies for patients treated with NovoSeven® under real-world conditions.

Molecular cytogenetic characterization of five F8 complex rearrangements: utility for haemophilia A genetic counselling.

BACKGROUND: Genomic inversions are usually balanced, but unusual patterns have been described in haemophilia A (HA) patients for intron 22 (Inv22) and intron 1 (Inv1) inversions leading to the hypothesis of more complex rearrangements involving deletions or duplications. AIM: To characterize five abnormal patterns either in Southern blot and long-range PCR for Inv22 or in PCR for Inv1. MATERIALS AND METHODS: All patients were studied using cytogenetic microarray analysis (CMA). RESULTS: In all cases, CMA analysis found that each inversion was associated with complex Xq28 rearrangement. In three patients, CMA analysis showed large duplication ranging from 230 to 1302 kb and encompassing a various number of contiguous genes among which RAB39B. RAB39B duplication is a strong candidate gene for X-linked intellectual disability (XLID). Surprisingly, none of the severe HA patients with RAB39B duplication reported in this study or in the literature exhibited XLID. We hypothesise that F8 complex rearrangement down regulated RAB39B expression. In the two remaining patients, CMA analysis found Xq28 large deletion (from 285 to 522 kb). Moyamoya syndrome was strongly suspected in one of them who carried BRCC3 deletion. CONCLUSION: Because several F8 neighbouring genes are associated with other pathologies such as XLID and cardiovascular disease, all HA patients where complex Xq28 rearrangement was suspected should be referred to a geneticist for possible utility of a pangenomic study. Such investigation should be carefully considered in genetic counselling in female carriers to assess the risk of transmitting severe HA with a "contiguous gene syndrome".

Cancer detection and management in patients with haemophilia: a retrospective European multicentre study.

Lymphomas or hepatocarcinomas related to blood-borne transmitted diseases are well-known malignancies in persons with haemophilia (PWH). However, rising life expectancy has increased the number of PWH suffering from other malignancies. This study aimed to collect cancer occurrence data in PWH followed in five European haemophilia treatment centres (Brussels, Geneva, Marseille, Montpellier and Paris-Bicêtre) over the last 10 years and to analyse some particular features of cancer occurring in PWH. In total, 45 malignancies were diagnosed in 1067 PWH. The most common malignancies were hepatocellular carcinoma (12/45) and urogenital tract tumours (9/45). Bleeding at presentation or changes in bleeding pattern was indicative of cancer in four patients. Three patients with mild haemophilia developed anti-factor VIII inhibitors after intensive substitution therapy prior to surgery or invasive procedures. There was no bleeding associated with chemotherapy or radiotherapy. A few bleeding complications occurred following invasive (3/39) or surgical procedures (2/27) as a result of insufficient hemostatic coverage or in spite of adequate substitution. No bleeding was noted after liver or prostate biopsies. Following cancer diagnosis, five patients were switched from on-demand to prolonged prophylaxis substitution. In the majority of cases, the standard cancer treatment protocol was not modified on account of concomitant haemophilia. Thus, oncological treatments are not contraindicated and should not be withheld in PWH assuming that adequate haemostasis correction is undertaken. As shown by our study results, a change in bleeding pattern in adult PWH should raise suspicion of a malignancy. Intensive substitution must be considered a risk factor for inhibitor development.

Real-world outcomes with recombinant factor VIIa treatment of acute bleeds in haemophilia patients with inhibitors: results from the international ONE registry.

The ONE Registry (OR) was an international prospective observational study of on-demand recombinant factor VIIa (rFVIIa) treatment for mild to moderate bleeds in haemophilia A/B patients with inhibitors. To describe real-world use of single and multi dose rFVIIa and to compare outcomes, including effectiveness, safety, quality of life and treatment satisfaction associated with treatment. Baseline data included demographics, treatment, medical and bleed history and patient/caregiver-reported outcomes regarding bleeds. rFVIIa was prescribed according to routine practice; regimens varied and initial dose was categorized as low (LD, ≤ 120 µg kg(-1) ), intermediate (ID, >120 and <250 µg kg(-1) ) or high (HD, ≥ 250 µg kg(-1) ). OR included 102 patients and 85 (83%) reported 494 bleeds overall. Mean age was 23 years (SD 16.4), with 52% ≥ 18 years. Majority of bleeds (n = 350, 71%) involved ≥ 1 joints; 46% involved a target joint. Median initial dose was 90 µg kg(-1) in LD (range 87-120, n = 156), 174 µg kg(-1) in ID, (range 121-249, n = 127) and 270 µg kg(-1) in HD, (range 250-375, n = 211). For spontaneous bleeds, effective haemostasis rate at 9 h was 63% LD, 60% ID and 56% HD. Rates of combined partially effective/effective haemostasis was 85% LD, 96% ID and 86% HD. Median number of doses in HD was one (range 1-7), compared with two in LD (range 1-17) and ID (range 1-23). No thromboembolic events were reported in 1145 doses given. These observational data in real life are consistent with previous studies which have shown similar overall effectiveness of rFVIIa and similar effectiveness and safety across different patterns of standard initial dosing.

Assessing risk factors: prevention of inhibitors in haemophilia.

The formation of antibodies against factor VIII or factor IX that inhibit replacement therapy is currently the most serious treatment-related complication faced by patients with haemophilia. This review highlights non-modifiable and modifiable risk factors that determine the development of these antibodies. The non-modifiable risk factors include patient genotype for haemophilia, immunogenotype, ethnicity and positive family history. Age, intensity of treatment and the type of clotting factor administered are identified as modifiable risk factors. These risk factors are likely to be identified more accurately in forthcoming prospective randomized controlled trials and current patient registries. Through a more complete picture of a patient's overall risk profile, individually tailored treatment schedules might be developed that could minimize the incidence of inhibitor formation and thus maximize therapeutic benefit.

Devising a best practice approach to prophylaxis in boys with severe haemophilia: evaluation of current treatment strategies.

Data from prospective studies clearly demonstrate the efficacy of prophylactic treatment of haemophilia in reducing joint- or life-threatening bleeding and the associated consequences for quality of life. Debate remains, however, regarding the optimal implementation of prophylaxis. Our aim in this review was to identify a best practice approach to factor replacement prophylaxis in boys with haemophilia. We evaluate prophylactic treatment regimens currently used in Swedish, Canadian and French centres and highlight key issues, including the optimal age for starting prophylaxis, the optimal treatment dosage/schedule and patient compliance.

Replacement therapy for invasive procedures in patients with haemophilia: literature review, European survey and recommendations.

Although most surgical and invasive procedures can be performed safely in patients with haemophilia, the optimal level and duration of replacement therapy required to prevent bleeding complications have not been established conclusively. For providing more insight into optimal therapy during invasive procedures, a literature review of surgical procedures in patients with haemophilia was conducted. Concomitantly, current practice was surveyed in 26 European Haemophilia Comprehensive Care Centres, representing 15 different countries. The review identified 110 original papers published between 1965 and 2007. Of these, only two studies were randomized controlled trials. Target levels and the duration of replacement therapy in the published studies were as follows. For major orthopaedic surgery: preoperative targets were 80-90%; postoperative targets showed a high degree of variation, with trough levels ranging from 20% to 80%, duration 10-14 days; for liver biopsy, 70-100%, 1-7 days; tonsillectomy: 90-100%, 5-11 days; indwelling venous access device insertion: 100%, 3-10 days; circumcision: 50-60%, 2-4 days; dental surgery: 30-50%, single treatment. With the exception of dental surgery, current practice in Europe, as assessed by the survey, was largely in agreement with published data. In conclusion, this study provides both a comprehensive review and a large survey of replacement therapy in patients with haemophilia undergoing invasive procedures; these data have informed the consensus practical treatment recommendations made in this paper. This study highlights the need for better-designed studies in order to better define minimal haemostatic levels of replacement therapy and optimal treatment duration.

Haemophilia in the first years of life.

Surgery in infants and young children with haemophilia, when preceded by accurate diagnosis and accompanied by safe and effective factor prophylaxis, is not associated with a significant risk of haemorrhage. Haemophilic newborns undergoing circumcision or major surgery prior to diagnosis and in the absence of appropriate haemostatic prophylaxis remain as a concern. Inhibitor development has replaced haemorrhage as the major surgical complication in the developed world, largely because of the intensity of treatment used to secure haemostasis. For that reason only, essential surgery should be performed. Intracranial haemorrhage (ICH) during the neonatal period affects 3.5-4.0% of all haemophilia boys in countries with a good standard of health care, which is considerably (40-80 times) higher than expected in the normal population. Because of the high frequency of sporadic cases, ICH in the neonatal period can only be partially prevented by improved carrier diagnosis and counselling. Infections and thrombosis are the major serious complications of central venous lines. Large differences are seen in the frequency of these complications, the most plausible explanations are probably related to the protocol used for device care, the quality of education and the compliance of the users, an issue addressed in an on-going study.

[Management of autoimmune thrombocytopenic purpura: a prospective study of 147 children from the regional network RHémaP]. / Purpura thrombocytopénique auto-immun: à propos d'une cohorte prospective de 147 enfants pris en charge dans le réseau d'hématologie pédiatrique des régions PACA et Corse (RHémaP).

AIM: Assessment of the impact of guidelines from a regional pediatric network to standardize the management of childhood immune thrombocytopenic purpura (ITP). MATERIALS AND METHODS: Consensus guidelines were drawn up in centers of the pediatric network for hematological diseases, RHémaP, and a cohort of children referred for ITP in these centers was set up. A 1-year follow-up was recorded for each patient over a 43-month period. RESULTS: We report data from a cohort of 147 children. At diagnosis, we recorded severe thrombocytopenia (median=8G/l) and 141 children had hemorrhagic symptoms (96%). Only 23 children had a bone marrow aspiration (BMA) at diagnosis (16.3%), which meant a high level of implementation of the RHémaP recommendations (96%) since indications of BMA were limited to rare indications. For 135 children (91.8%), treatment fulfilled the RHémaP guidelines that were mainly based on the platelet count: 121 received intraveinous immunoglobulin (IVIG) and 14 were not treated. Among those who received IVIG, 110 were good responders (91%) at the 96-h evaluation (platelet count greater than 20G/l), nine (7.4%) were poor responders, and 1 died of intracranial hemorrhage. At 6 months, chronic ITP was observed in 40 children (32.8%). Chronic ITP was associated with a higher platelet count at diagnosis and an older age (p<10(-3) and p=10(-3), respectively). CONCLUSION: The practices recorded over a 43-month period in our cohort fulfilled the RhémaP guidelines and we conclude that we managed to standardize regional practices for children with ITP. We observed conventional epidemiological characteristics in this cohort. Older children and higher platelet count at diagnosis were significantly associated with higher frequency of chronic ITP.

Health status and quality of life in long-term survivors of childhood leukaemia: the impact of haematopoietic stem cell transplantation.

We compared late side effects and quality of life (QoL) in 430 survivors of childhood acute leukaemia based on whether they had undergone haematopoietic cell transplantation (n=142) or not (n=288). Mean age was 18.2 years and mean follow-up duration was 11.9 years. Multivariate logistic regression analyses were performed to compare the risk of each type of late effect in the two groups. Based on age, VSP-A or SF36 questionnaires were used to assess QoL. For each QoL dimension, multiple linear regression was done to construct models of association with the treatment group. Transplanted patients experienced more side effects, including height growth failure, gonadal dysfunction, hypothyroidism and cataract. Children and adolescents in the two treatment groups reported similar QoL levels for almost all dimensions except a better perception of school work by young transplanted children and more difficulties in relating to the medical staff for transplanted adolescents. In adults, two differences in physical domain of QoL were detected but the calculated effect sizes were less than 0.2 in each case, suggesting an uncertain clinical significance. In spite of a higher risk of physical adverse events in the transplanted group, very few clinically significant differences in QoL are detectable.

CD34(+) progenitors are reproducibly recovered in thawed umbilical grafts, and positively influence haematopoietic reconstitution after transplantation.

Cord blood (CB) units are increasingly used for allogeneic transplantation. Cell dose, a major factor for CB selection, is evaluated before freezing by each CB bank, using various techniques. This may introduce variability and affect the prediction of cell recovery after thawing, or haematopoietic reconstitution. Forty-two children were transplanted at the same institution with unrelated CB units. All units were thawed and evaluated at the same cell therapy facility, using standard procedures. We investigated: (i) factors that affect cell loss after thawing, and (ii) the importance of CD34(+) cell doses. Prefreeze and post-thaw CD34(+) cell doses were statistically correlated, thus suggesting that variability in numeration techniques used by different CB banks does not compromise the biological and clinical value of these figures. CD34(+) cell recovery appeared to be correlated with the absolute number of CD34(+) cells per frozen bag. Infused CD34(+) is the cell dose that better correlates with platelet reconstitution delay; in addition, when using a quartile comparison, haematopoietic recovery appeared to be related with prefreeze and post-thaw CD34(+) cell doses. We conclude that enumeration of CD34(+) cells in CB units is of biological significance, and may help select CB units and identify patients at risk of delayed recovery.

Prevalence and risk factors of iron overload after hematopoietic stem cell transplantation for childhood acute leukemia: a LEA study.

Data on post-transplant iron overload (IO) are scarce in pediatrics. We conducted a prospective multicenter cohort study (Leucémie de l'Enfant et de l'Adolescent cohort) to determine the prevalence and risk factors of IO in 384 acute leukemia survivors transplanted during childhood. Prevalence of IO (ferritin level ⩾350 ng/mL) was 42.2% (95%CI 37.2-47.2%). Factors significantly associated with IO were: 1) in univariate analysis: older age at transplant (P<0.001), allogeneic versus autologous transplantation (P<0.001), radiation-based preparative regimen (P=0.035) and recent period of transplantation (P<0.001); 2) in multivariate analysis: older age at transplant in quartiles (Odds Ratio (OR)=7.64, 95% CI: 3.73-15.64 for age >12.7 years and OR=5.36, 95% CI: 2.63-10.95 for age from 8.2 to 12.7 years compared to age < 4.7 years), acute myeloid leukemia (OR=3.23, 95% CI: 1.47-7.13), allogeneic graft (OR=4.34, 95% CI: 2.07-9.12 for alternative donors and OR=2.53, 95% CI: 1.2-5.33 for siblings, compared to autologous graft) and radiation-based conditioning regimen (OR=2.45, 95% CI: 1.09-5.53). Graft-versus-host disease was an additional risk factor for allogeneic graft recipients. In conclusion, IO is a frequent complication in pediatric long-term survivors after transplantation for acute leukemia, more frequently observed in older children, those transplanted from alternative donors or with graft-versus-host disease.

Impact of choice of treatment for bleeding episodes on inhibitor outcome in patients with mild/moderate hemophilia a and inhibitors.

Patients with mild/moderate hemophilia A (MHA) may develop inhibitors to factor VIII (FVIII). In this condition, FVIII clotting activity (FVIII:C) baseline levels may remain stable for some patients, but may be reduced to less than 0.01 U/mL for others. Several risk factors for the development of inhibitors in MHA have been proposed. Genetic factors, such as mutations in the FVIII gene, may play a central role; however, other influences, such as intensive treatment with FVIII products, may also be important. Optimal treatment regimens have yet to be determined, not only for the eradication of inhibitors, but also for the management or surgical prophylaxis of hemorrhages associated with this condition. Several treatment options for the control of bleeding in patients with MHA and inhibitors (MHAI) are currently available, and the choice of therapeutic strategy should be given careful consideration; some treatments may produce an anamnestic response, thus delaying the return to FVIII:C baseline levels and adversely affecting the duration of the severe bleeding phenotype. To increase our knowledge of MHAI, a retrospective collection of data is currently being performed among hemophilia centers in France and Belgium. Based on five examples of patients with MHAI collated from preliminary study data, we illustrate the impact on inhibitor outcome of the therapeutic choices used to treat bleeding episodes in these patients.

[Relevance of early paediatric care for boys with severe haemophilia]. / Enjeux d'une prise en charge pédiatrique précoce de l'hémophilie sévère.

Major molecular and genetic findings over the last decades and subsequent applications for diagnosis and therapeutic concerns have dramatically improved the evolution of severe haemophilia in countries with high economic resources. Another major factor of progress consisted in the setting of comprehensive care centres coordinating the care at a regional level. The early involvement of paediatricians for this rare and potentially serious chronic disease, which may be symptomatic from birth, is relevant in this context. Indeed, the early diagnosis of severe haemophilia and the involvement of expert caregivers in a multidisciplinary approach, are essential to make the acceptance of the disease easier. The diagnosis announcement should go together with a therapeutic project, which is nowadays based on long-term prophylaxis. Awaiting for likely curative treatments in the future, such as gene therapy, early implementation of prophylaxis and observance of this gold standard treatment during all the period of growth are critical to prevent the haemophilic arthropathy, to favour the future social and work-related integration and overall to improve the quality of life. The occurrence of an inhibitor represents the major residual complication of replacement therapy, especially for young children with severe haemophilia A. Even though new therapeutic resources brought substantial improvements for inhibitor patients, a better understanding of risk factors is a key issue since more accurate replacement regimen might induce tolerance during the first exposures and subsequently might prevent this complication. Prophylaxis and inhibitors that represent major concerns in paediatric care of severe haemophilia are included as main research objectives for the national registry " FranceCoag Network".

α1 -antitrypsin Pittsburgh and plasmin-mediated proteolysis.

Essentials Patients with α-1-antitrypsin (α1-AT) Pittsburgh exhibit a mild bleeding tendency. A new case of α1-AT Pittsburgh with suspected high antifibrinolytic potential was studied. We showed that α1-AT Pittsburgh inhibits tissue plasminogen activator and plasmin. The antifibrinolytic potential of the variant contributes to explaining the mild bleeding phenotype. SUMMARY: α1 -Antitrypsin (α1 -AT) Pittsburgh has a Met358 to Arg substitution at the reactive Met-Ser site of α1 -AT, which enables the protein to act as a potent thrombin inhibitor. Four patients with α1 -AT Pittsburgh have been described to date. An additional young girl was recently diagnosed with α1 -AT Pittsburgh in our center after presenting with a large hematoma in the forearm. Interestingly, all of these patients showed a potent thrombin inhibitor in the plasma and a mild bleeding phenotype. This observation suggests that the in vivo consequences of the mutation may contribute to the maintenance of normal hemostatic balance. We assessed inhibition of the fibrinolytic system by the variant protein by evaluating the fibrinolysis inhibitory potential of the patient's plasma, purified wild-type α1 -AT and purified Pittsburgh α1 -AT with an electrophoretic zymography system, western blotting, and clot fibrinolysis. Our results indicate that the patient's plasma and purified α1 -AT Pittsburgh have strong potential to inhibit tissue-type plasminogen activator and plasmin.

MAGE-A genes are not expressed in human leukemias.

Immunotherapy is promising to improve the prognosis of human leukemias, at least as adjuvant treatment. Tumor-associated antigens such as antigens encoded by MAGE-A1, -A2, -A3, -A4, -A6 and -A12 genes might provide tools in this field. We demonstrated recently that the presentation peptides encoded by MAGE-A genes might make leukemic blasts suitable targets to cytolytic T lymphocytes. We reported previously negative data of MAGE-A1 gene expression in hematological malignancies, but in further studies positive results of MAGE-A gene expression were published in some subtypes of hematological malignancies such as T leukemia, myeloma and Hodgkin's disease. This led us to enlarge the screening of MAGE-A gene expression in human leukemias. In the RT-PCR screening of a large panel including 154 patients, only weak signal were detected in a few samples. We conclude that MAGE-A genes are not expressed in human leukemias.

Fine characterization of childhood and adult acute lymphoblastic leukemia (ALL) by a proB and preB surrogate light chain-specific mAb and a proposal for a new B cell ALL classification.

The expression of the surrogate light chain (psiL) - made of the lambda-like (or lambda5) and the VpreB proteins - is a B cell-specific maturation marker. Using an anti-human VpreB mAb (4G7), we recently identified in human normal bone marrows, proB and preB cells that express the psiH-psiL proB (proBCR) and the mu-psiL preB (preBCR) receptors, respectively. In the present study, FACS and biochemical analysis confirm the broad proB and preB reactivity of the 4G7 mAb that contrasts with the narrow specificity of other available anti-psiL reagents for preB cells. This mAb was used to explore intracytoplasmic and cell surface expression of the VpreB protein on a series of 92 precursor B cell ALLs (from 40 child and 52 adult patients), in combination with 24 other mAbs. The major result concerns the identification within proB (or BI) and common (or BII) ALLs, of proBCR and proBCR+ ALLs that express the VpreB in the cytoplasm or at the cell surface, respectively. The percentage of ALLs within these two VpreB sub-groups differ considerably between the ALL origin. In the pediatric series, ALLs present in the majority a proBCR+ phenotype whereas we observed a proBCR+ phenotype for adult ALLs. Based on VpreB expression, and in combination with other published data, we propose a refined classification for precursor B cell ALLs.

Acute myeloid leukaemia triggering via CD40 induces leukocyte chemoattraction and cytotoxicity against allogenic or autologous leukemic targets.

The CD40 antigen is a member of the tumor necrosis factor receptor superfamily which interacts with its ligand and regulates the immune response via a dialogue between T-lymphocytes and antigen-presenting or tumor cells. Tumor triggering via CD40 exerts direct effects on cancer cells, which have mainly been investigated in terminally differentiated hematological malignancies such as low-grade lymphoma. We focused our attention on minimally differentiated acute myeloid leukemia (AML-M0), an aggressive hematological malignancy in which severe prognosis suggests the requirement for innovative therapeutic strategies. Here we demonstrate, for the first time to our knowledge, a CD40-triggered IL-8, RANTES and IL-12 secretion by leukemic cells. Supernatants from CD40-stimulated leukemia cells had chemoattractant effects on T-lymphocytes, natural killer cells and monocytes. Moreover, these supernatants, when complemented with low-dose IL-2, induced significant lymphokine-activated and natural killer cytotoxicity, leading to leukemia lysis both in allogenic HLA-matched and autologous settings. Stimulation of leukemia cells via CD40 could participate significantly to the anti-leukemia immune response by contributing to the development of an inflammatory response and to in situ cytotoxicity. Leukemia(2000) 14, 123-128.