ALBERT

Description: Key Points This study strengthens the previous observation of elevated mitochondrial DNA copy number and future risk of chronic lymphocytic leukemia.

Description: Background: Chronic Lymphocytic Leukemia (CLL) has been related to an increased susceptibility to infections particularly in advanced stages. Evidence is accumulating of an immune impaired response at early stages that could affect prognosis. We evaluated the pattern of seroresponse to common infections in CLL Rai0 cases and in general population controls. Methods: A case-control study within the multicase-control study (MCC Spain) and the International Cancer Genome Consortium (ICGC) was designed. 204 CLL cases, 69.6% newly diagnosed and 30.4% prevalent, and 370 population controls matched by sex, age and recruitment area were analyzed. All subjects provided a blood sample and answered a personal interview. In addition to socio-demographic, behavioral and medical characteristics for cases and controls, data on CD38, ZAP70 and common CLL deletions were available for analysis. Seroreactivities against the antigens from JC polyomavirus (JCPyV; VP1), Merkel cell poliomavirus (MCPyV; VP1), herpes simplex 1 (HSV1; gB), Epstein-Barr virus (EBV;zebra, EBNA, EA-D and VCAp18) and cytomegalovirus (CMV;­ pp150, CM2, pp52, pp28 and pp65) were measured using bead-based multiplex serology technology. Multivariate logistic regression models were used to examine seroprevalence to different viral infections and seroreactivity intensity (in tertiles) in cases and controls. Generalised additive models were used to explore seroreactivity patterns. Results: Seropositivity was very high in both cases and controls and was significantly higher for all infections tested among controls: HSV1 92.0% cases vs. 94.4% controls; CMV 84,4% vs. 88,3%; EBV 97,5% vs. 98,9%; JCPyV 56.6% vs. 68.9% and MCV 81.4% vs. 83.4%. Among seropositive subjects, a statistically significant decrease in antibody response was observed among CLL cases compared to controls (HSV-1 p

Description: Introduction: Ibrutinib is a covalent inhibitor of Bruton Tyrosine Kinase (BTK), approved for the treatment of Mantle Cell Lymphoma (MCL), Chronic Lymphocytic Leukemia (CLL) and Waldenstrom's Macroglobulinemia (WM). BTK is expressed in platelets and is believed to have a central role in platelet activation through GPIb and GPIV pathway. However, the clinical significance of inhibition of BTK is unclear in terms of bleeding and it is known that patients with congenitally deficient BTK do not exhibit increased risk of bleeding. Objectives: The main objectives were: (1) identify possible alterations in hemostasis induced by Ibrutinib in patients who start taking the drug, and (2) to monitor the development of hemorrhagic adverse effects in patients who start taking Ibrutinib. Methods: From August 31, 2015 and January 31, 2016 we conducted a prospective study including all consecutive patients with the diagnosis of MCL, CLL or WM treated in 2nd line or more, with Ibrutinib as single-drug therapy. The following parameters were analyzed on day 0 (baseline), 10 and 28 after starting treatment with Ibrutinib: APTT, PT, platelet count, PFA-100 Collagen/Epinephrine and Collagen/ADP, aggregometry impedance in whole blood by multiplate assay with AA, ADP, Ristocetin and TRAP as agonists. Von Willebrand factor antigen (vWF:Ag), Ristocetin cofactor (vWF:RCo) and coagulant factor VIII were also analyzed. We collected prospectively bleeding adverse events. Results: In the period of study, we enrolled 11 patients, 7 were males and 4 females, with a median age of 63 years old (range, 53-88). Five patients had the diagnosis of CLL, 5 patients had MCL and 1 patient had WM. After a median follow-up of 6 months, 3 out of 11 (27.3%) developed grade 1 bleeding adverse events. Of these, 1 patient was under anticoagulant treatment with intermediate dose of enoxaparin, and another patient had low levels of vWF:Ag and vWF:RCo, suggesting a possible acquired von Willebrand disease. Five out of 11 (45.5%) of patients had a prolonged shutter speed Collagen/Epinephrine at baseline, with a median of 175 sec (range, 94-270). After Ibrutinib exposure, median shutter speed Collagen/epinephrine at 10 days was 231 sec (range, 108-287), p=0.02; and at 30 days was 142 sec (range, 79-300), p=n.s. Four out of 11 patients (36.4%) had a prolonged shutter speed Collagen/ADP at base line, with a median of 105 sec (range, 63-190). After Ibrutinib exposure, median shutter speed Collagen/ADP at 10 days was 107 sec (range, 66-192), p=n.s; and at 30 days was 78 sec (range, 75-149), p=n.s. Regarding platelet aggregometry impedance, 2 patients had abnormal platelet aggregation baseline at TRAP assay, 6 at ADP assay, 3 at AA assay and 4 at Ristocetin assay. After Ibrutinib exposure, there was a worsening of platelet aggregation in ADP analysis at 10 days of treatment but became normal after 30 days of treatment. There was an improvement with TRAP at both 10 and 30 days of treatment. Of notice, all 3 patients with minor bleeding had abnormal hemostasis studies baseline before starting with Ibrutinib. Conclusions: Almost half of patients showed an altered haemostasis baseline studies before starting with Ibrutinib. The biology of the disease appears to cause in subjects primary hemostasis changes that result in a basal bleeding risk regardless of the treatment used. Only minor bleeding complications were observed under Ibrutinib treatment, all with baseline altered platelet function; 2 of the three patients who developed bleeding complications had other bleeding risk factors associated. PFA-100 Collagen/Epinephrine is prolonged in almost 50% of patients after Ibrutinib is started compared with baseline study. Aggregometry impedance only worsened with ADP at 10 days, but went into normal level at 30 days. There is an interindividual variability in alterations of haemostasis and hemorrhagic clinical signs. Disclosures Cordoba: Janssen: Research Funding, Speakers Bureau.

Description: Introduction Acute myeloid leukemia (AML) is a clonal disease characterized by multiple genetic anomalies. The internal tandem duplications (FLT3-ITD mutations) in the juxtamembrane domain of the receptor occur in approximately 15-35% of de novo AML . This mutation is one of the most frequent genetic alterations, and confers an increased risk of treatment failure and a reduced disease-free survival (DFS). There are scarce data regarding the possible implication of the length of the FLT3-ITD fragment in the clinical outcome . We sought to shed light on the possible prognostic relevance of the length of the FLT3-ITD fragment in AML patients. Methods Twenty five patients (n=25) diagnosed with de novo AML in Hospital Universitario 12 de Octubre between 2005-2017 were included in the study. The median follow-up was 10 months from diagnosis (range 0.5-138 months). The median age was 65 years (range 1-85 years) with 72% of female patients. Bone marrow or blood samples were analyzed by fragment length analysis in an ABI3100 sequencer in order to detect the FLT3-ITD mutation. A ROC curve was plotted to predict death for any reason. Overall survival (OS) was estimated by Kaplan-Meier curves and groups were compared by a stratified log-rank test based on allelic burden of FLT3 (≥ 0.5 vs

Description: Cell-based therapies are emerging as potent agents against cancer and other diseases, but are uniquely uncontrolled "living drugs". For example, chimeric antigen receptor (CAR) T cells can effectively target hematologic malignancies yet pose a risk for toxic hyperactivation. Future cell-based therapies, including CAR T cells, could be improved by incorporating specific and reversible control systems. However, clinically suitable ON- and OFF-switches engineered from non-immunogenic human polypeptide sequences and regulated by non-immunosuppressive FDA-approved drugs are needed. Here we report the engineering of a robust lenalidomide-responsive degron tag, which we then used to construct a degradable CAR affording reversible OFF-switch functional control at clinically relevant lenalidomide doses. Thalidomide, lenalidomide, and pomalidomide are effective and clinically approved therapies for multiple myeloma, subtypes of non-Hodgkin lymphoma, and myelodysplastic syndrome with chromosome 5q deletion. These drugs exert therapeutic properties by acting as molecular glue, bridging interactions between the CRL4CRBN ubiquitin ligase and disease-relevant proteins that are subsequently ubiquitinated and degraded by the proteasome. A set of Cys2-His2 (C2H2) zinc fingers have emerged as degron motifs mediating drug-dependent interactions with the CRL4CRBN ubiquitin ligase. We hypothesized that these small, modular, human polypeptide domains could be further engineered and repurposed as tags to induce drug-dependent depletion of engineered proteins. By systematically shuffling the subdomains of all known zinc finger degrons and functionally screening this hybrid zinc finger library, we engineered "super-degron" tags that are more efficiently degraded at lower drug concentrations than any C2H2 zinc finger in the human proteome. We then incorporated one of these super-degrons (SD01) into a second-generation CAR targeting CD19 (FMC63-4-1BB-CD3z), thereby constructing a degradable CAR (Figure 1A). In a Jurkat T cell model, addition of lenalidomide induced rapid and near-complete depletion of the degradable CAR (Figure 1B/C). When co-cultured with target cells expressing CD19, therapeutically relevant lenalidomide concentrations robustly inhibited T cell activation (Figure 1D). Indeed, the IC50 for inhibition of IL2 secretion and CD69 expression were 2 and 22 nM lenalidomide, respectively, whereas in myeloma patients the plasma concentration of lenalidomide following one 25 mg oral dose decays from ~1000 to 10 nM over the course of 24 hours (Connarn et al, CPDD, 2017). In primary T cells, 100 nM lenalidomide suppressed degradable CAR effector functions including tumor cell killing and cytokine release (Figure 1E). Using pomalidomide, which has a longer in vivo half-life, we demonstrated robust and reversible depletion of the degradable CAR in T cells engrafted in NSG mice. Together, these findings demonstrate reversible OFF-switch control of degradable CARs at clinically relevant lenalidomide concentrations. Experiments are underway to determine whether, in the context of tumor clearance in NSG mice, degradable CAR T cell effector functions can be paused and subsequently released with short-term administration of lenalidomide. Whereas the current management of CAR T cell hyperactivation syndromes consists of supportive care, tocilizumab, and/or high-dose corticosteroids, we propose that cytokine release and CAR-related encephalopathy syndromes may be more easily diagnosed and managed with degradable CARs. The super-degron tags presented here are generalizable and clinically suitable tools to achieve chemical genetic control of diverse genetically engineered cell therapies. Disclosures Jan: Broad Institute: Other: Contributor to a patent filing on this technology that is held by the Broad Institute.. Sievers:Broad Institute: Other: Contributor to a patent filing on this technology that is held by the Broad Institute.. Maus:Broad Institute: Other: Contributor to a patent filing on this technology that is held by the Broad Institute.. Ebert:Broad Institute: Other: Contributor to a patent filing on this technology that is held by the Broad Institute.; Deerfield: Research Funding; Celgene: Research Funding.

Description: Chimeric Antigen Receptor (CAR) T-cells have shown great promise in achieving stable remission of B cell acute lymphoblastic leukemia and are being utilized to treat a variety of other hematologic and non-hematologic malignancies. However, this therapy is associated with significant adverse effects (e.g., cytokine release syndrome and neurotoxicity), largely related to the high cell doses requisite for achieving therapeutic response(s). E-selectin, an endothelial molecule expressed on microvessels of bone marrow and tumors, is critical for extravasation of blood-borne cells. E-selectin binds to sialyl Lewis X (sLeX), a sialofucosylated tetrasaccharide motif decorating specialized glycoproteins and glycolipids on circulating cells. Given that better site-specific delivery of administered CAR T-cells would yield more efficacious immunotherapy while limiting off-target effects, we sought to determine whether these cells express E-selectin ligands. CAR T-cells targeting glioblastoma were created by lentiviral transduction of human T-cells with anti-EGFR-BBz-mCherry CAR construct. Transduced cells (T) and untransduced cells (UT) were subjected to stimulation with anti-CD3/CD28 microbeads followed by culture expansion in presence of interleukin-2 (IL2) for 10 days ("10"). In some cases, cells were expanded for 7 additional days by co-culturing with irradiated U87 glioblastoma cell line ("17"). These cells were compared to resting T-cells (non-expanded; NE). Expression of sLeX on each T-cell population (NE, T10, T17, UT10 or UT17) was measured by flow cytometry. We observed that NE T-cells display moderate expression of sLeX as previously reported in literature (Silva, Fung et al., J. Immunol., 2017). T10 CAR T-cells display significantly lower sLeX compared to NE T-cells, while T17 CAR T-cells completely lack sLeX. Similar pattern of sLeX expression was observed on UT10 and UT17 populations, indicating that culture expansion progressively depletes sLeX expression on T-cells, regardless of transduction with a CAR construct. To analyze the capacity of CAR T-cells to bind E-selectin under hemodynamic shear conditions, we utilized a microfluidic flow chamber wherein T-cells are perfused over human umbilical vein endothelial cell (HUVEC) monolayers treated with TNFα to induce E-selectin expression. Consistent with the observed cell surface sLeX levels, NE T-cells display robust rolling interactions on TNFα-stimulated HUVECs, whereas T10 and T17 CAR T-cells exhibit essentially no endothelial interactions. To overcome this shortfall, we assessed whether sLeX expression can be enforced on the CAR T-cell surface via glycoengineering using glycosyltransferase programmed stereosubstitution (GPS), i.e., fucosyltransferase-mediated α(1,3)-fucose installation that converts terminal sialylated type 2 lactosamines to sLeX. GPS engenders markedly increased CAR T-cell sLeX expression, yielding full (100%) sLeX -expression of the CAR T-cell populations, while increasing sLeX expression from a baseline of 20-30% to maximally 60-70% of the NE T-cell populations. The glycoengineered CAR T-cells display markedly enhanced (〉20 fold) adhesive interactions on TNFα-stimulated endothelial cells compared to that of unfucosylated CAR T-cells. Collectively, our data indicate that culture expansion induces down-regulation of endogenous α(1,3)-fucosylation, and, importantly, the missing fucose can be restored via GPS. Finally, to assess whether the enforced E-selectin binding has a meaningful biologic effect, we examined homing of GPS-modified cells to an E-selectin bearing bed (marrow) within 24 hours of intravenous administration. We consistently observed 〉3-fold increase in marrow infiltrates of culture-expanded GPS-modified T-cells compared to their unmodified counterparts. Overall, these results draw attention to an inherent inability of CAR T-cells to migrate to sites where they are needed. Our data reveal that culture expanded T-cells lack E-selectin binding capacity, however, sLeX display can be enforced by cell surface glycoengineering. Improved E-selectin binding yields superior tissue colonization. As such, glycoengineering CAR T-cells may translate into lowering of cell dosing, thereby improving both the efficacy and safety, and reducing both cell expansion and clinical care costs, of this promising therapeutic approach. Disclosures Maus: kite therapeutics: Consultancy, Research Funding; windmil therapeutics: Consultancy; crispr therapeutics: Consultancy, Research Funding; agentus: Consultancy, Research Funding; novartis: Consultancy; adaptimmune: Consultancy. Sackstein:Warrior Therapeutics LLC: Equity Ownership, Patents & Royalties.

Description: Abstract 3660 Poster Board III-596 Introduction Despite the major advances in the treatment of classical Hodgkin Lymphoma (cHL) patients, around 30% to 40% of cases in advanced stages may relapse or die as result of the disease. Current predictive systems, based on clinical and analytical parameters, fail to identify accurately this significant fraction of patients with short failure-free survival (FFS). Transcriptional analysis has identified genes and pathways associated with clinical failure, but the biological relevance and clinical applicability of these data await further development. Robust molecular techniques for the identification of biological processes associated with treatment response are necessary for developing new predictive tools. Patients and Methods We used a multistep approach to design a quantitative RT-PCR-based assay to be applied to routine formalin-fixed, paraffin-embedded samples (FFPEs), integrating genes known to be expressed either by the tumor cells and their reactive microenvironment, and related with clinical response to adriamycin-based chemotherapy. First, analysis of 29 patient samples allowed the identification of gene expression signatures related to treatment response and outcome and the design of an initial RT-PCR assay tested in 52 patient samples. This initial model included 60 genes from pathways related to cHL outcome that had been previously identified using Gene Set Enrichment Analysis (GSEA). Second, we selected the best candidate genes from the initial assay based on amplification efficiency, biological significance and treatment response correlation to set up a novel assay of 30 genes that was applied to a large series of 282 samples that were randomly split and assigned to either estimation (194) or validation series (88). The results of this assay were used to design an algorithm, based on the expression levels of the best predictive genes grouped in pathways, and a molecular risk score was calculated for each tumor sample. Results Adequate RT-PCR profiles were obtained in 264 of 282 (93,6%) cases. Normalized expression levels (DCt) of individual genes vary considerably among samples. The strongest predictor genes were selected and included in a multivariate 10-gene model integrating four gene expression pathway signatures, termed CellCycle, Apoptosis, NF-KB and Monocyte, which are able to predict treatment response with an overall accuracy of 68.5% and 73.4% in the estimation and validation sets, respectively. Patients were stratified by their molecular risk score and predicted probabilities identified two distinct risk groups associated with clinical outcome in the estimation (5-year FFS probabilities 75.6% vs. 45.9%, log rank statistic p≈0.000) and validation sets (5-year FFS probabilities 71.4% vs. 43.5%, log rank statistic p

Description: In this study, we analysed the FCGR3A 158 V/F and FCGR2A 131 H/R polymorphisms as possible predictors of response to rituximab therapy in patients with Immune Thrombocytopenic Purpura (ITP) or Autoimmune Hemolytic Anemia (AHA). We analysed 45 ITP patients receiving Rituximab; 18 patients (40%) achieved a maintained response (〉100×109 platelets/L, 〉3 months after the last rituximab dose). The median duration of the response was 19 months (4–76). We also analysed 16 AHA patients treated with rituximab, 12 of whom (75%) achieved a maintained response (Hb increase 〉1,5 g/dL or Hb 〉10 g/dL, 〉3 months after last rituximab dose, with no transfusion). The median duration of response was 8 months (3–48). To analyse the codons 158 of FCGR3A and 131 of FCGR2A we used an original method of PCR with confronting two-pair primers (CTPP). Eight of 45 ITP patients (18%) were homozygous for FCGR3A 158V and 21 (47%) for 158F, while 16 (35%) were heterozygous. The maintained response rates of the three groups were 37%, 33% and 50% respectively, and did not differ significantly. We did not find any significant difference either when comparing FCGR3A 158V homozygotes vs 158F carriers or when comparing 158F homozygotes patients vs 158V carriers. When we analysed FCGR2A, 11 patients (25%) were 131H, 10 (22%) 131R and 24 (53%) were heterozygous. The analysis of the maintained response rate in these three groups (55%, 10% and 46%) showed a tendency to a better response in FCGR2A 131H homo- and heterozygous patients (p = 0.08). When we compared FCGR2A 131H homozygotes vs 131R carriers we found no significant difference. In contrast, the response rate was significantly worse in FCGR2A 131R homozygotes than in 131H carriers (p = 0.028). We did similar analyses in 15 AHA patients, of whom 4 (27%) and 7 (46%) were homozygous for FCGR3A 158V and FCGR3A 158F, respectively, while the remaining 4 were heterozygous (27%). We saw no significant difference in the maintained response rate between the three groups (75%, 86% and 50%). We found no difference either when we compared FCGR3A 158V homozygotes vs. 158F carriers or FCGR3A 158F homozygotes vs. 158V carriers. We determined the FCGR2A 131 H/R state in 16 AHA patients, of whom 3 (19%) and 5 (31%) were homozygous for 131H and 131R, respectively, 8 (50%) being heterozygous. The maintained response rate of the groups (67%, 80% and 75%) did not differ significantly. We found no differences either when comparing FCGR2A 131H homozygotes with 131R carriers or FCGR2A 131R homozygotes with 131H carriers. Our results show no significant influence of the polymorphisms of the gene FCGR3A 158 V/F on the response to rituximab either ITP and AHA patients, unlike previous reports in lymphoma. Polymorphism of FCGR2A 131 H/R could have influence in the response to rituximab therapy in ITP. Absence of 131H allotype is associated with worse response. In AHA patients the studied polymorphisms seem don’t have influence in rituximab response but it necessary to perform larger studies to assess this possible influence.

Description: Abstract 1772 Background: Hodgkin Lymphoma (HL) is the most curable type of Lymphoma with an overall survival at 5 years of 80%. ABVD can be considered as gold standard for first line treatment for all stages of HL. Dividing patients (pts.) in different prognostic groups has aimed to reduce chemo and radio toxicity in those patients with good prognosis. A negative PET-CT, either early during treatment of ABVD or after completion of it, has shown to be a powerful prognostic tool (Hutchings: Blood 2006; Gallamini: Haematologica 2006). Our cooperative group has an experience with 584 patients with HL in early or advanced stage treated with 3 or 6 cycles of ABVD plus involved field radiotherapy with a complete remission (CR) of 91% and an event free survival (EFS) and overall survival (OS) at 60 months of 79% and 95%.(S Pavlovsky, Clin Lymp My & Leuk, 2010). Aims: Test the efficacy of treatment to all stages of HL adjusted to PET-CT results after 3 cycles of ABVD. Evaluate the outcome of pts. who have a negative PET-CT after 3 cycles of ABVD and receive no further treatment. Intensify therapy only in pts. who have persistent hyper metabolic lesions in PET-CT after 3 cycles of ABVD. Method: Since October 2005, 198 newly diagnosed pts. with HL have been included in a prospective multicenter trial. Initially all patients received 3 cycles of ABVD. After the third cycle, pts. were evaluated with a PET-CT. Those pts. who achieved CR with a negative PET-CT, received no further treatment. Those with more than 50% of anatomic reduction of initial masses but persistent hyper metabolic lesions by PET-TC after 3 ABVD were considered in partial remission (PR) and completed 6 cycles of ABVD and radiotherapy (RT) on PET-CT positive areas. Those patients with less than PR after 3 cycles of ABVD received ESHAP and if CR, high doses of chemotherapy and an autologous stem cell transplant (ASCT). All patients were re-evaluated at the end of treatment. The median follow up is of 30 months (3-62). Results: One hundred and seventy three patients completed three cycles of ABVD followed by a PET-CT. The median age at diagnosis was 29 years. One hundred and thirty-six (79%) had localized stage (I-II) at diagnosis and 37 (21%) presented with advanced stage (III-IV). Of 155 pts. 77 (50%) pts had IPS 0–1, 66 (43%) had IPS 2–3 and 12 (8%) had IPS 4–5. Twenty six (17%) pts. had bulky disease at diagnosis. One hundred and thirty-seven (79%) pts. achieved CR with negative PET-CT after 3 cycles of ABVD. Thirty-six (21%) were PET-CT positive, of them 32 pts achieved PR and completed a total of 6 cycles of ABVD plus RT in hyper metabolic lesions. Twenty five achieved CR (72%), 5 persisted with PR and 2 died of progressive disease. Four pts showed progressive disease (PD) after 3 ABVD and received ESHAP and ASCT, 2 achieved and remained in CR, 1 is in PR and 1 died of progressive disease. Of 173 pts who completed treatment with ABVD × 3 cycles, ABVD × 6 cycles plus RT on PET-TC positive areas or ESHAP plus ASCT, 164 pts (95%) achieved CR. Of these 164 pts., 14 pts (8%) relapsed. The EFS and OS at 36 months is 83% and 97% respectively. Patients with early negative PET-TC have an event-free survival of 87% compared to 62% (P=0,001) for pts with early positive PET CT. The OS at 36 months was 100% versus 86% respectively (

Description: We analyzed the effect of aspirin, salicylate, and other nonsteroidal antiinflammatory drugs (NSAIDs) on the viability of B-chronic lymphocytic leukemia (B-CLL) cells. Aspirin induced a decrease in cell viability in a dose- and time-dependent manner. The mean IC50 for cells from 5 patients was 5.9 ± 1.13 mmol/L (range, 4.4 to 7.3 mmol/L). In some cases, 2.5 mmol/L aspirin produced an important cytotoxic effect after 4 days of incubation. No effect was observed with other NSAIDs, at concentrations that inhibit cyclooxygenase, such as ketorolac (10 μmol/mL), NS-398 (100 μmol/mL), or indomethacin (20 μmol/mL), thus suggesting the involvement of cyclooxygenase-independent mechanisms in aspirin-induced cytotoxicity. Salicylate also produced dose-dependent cytotoxic effects on B-CLL cells and the mean IC50 for cells from 5 patients was 6.96 ± 1.13 mmol/L (range, 5 to 7.8 mmol/L). Both aspirin and salicylate induced DNA fragmentation and the proteolytic cleavage of poly(ADP(adenosine 5′-diphosphate)-ribose) polymerase (PARP), demonstrating that both compounds induce apoptosis of B-CLL cells. Finally, inhibition of caspases by Z-VAD.fmk blocked proteolytic cleavage of PARP, DNA fragmentation, and cytotoxicity induced by aspirin. Mononuclear cells from normal donors showed a lower sensitivity than cells from B-CLL patients to aspirin as determined by analysis of cell viability. B and T lymphocytes from normal donors and T lymphocytes from CLL patients are more resistant to aspirin-induced apoptosis, as determined by analysis of phosphatidylserine exposure. These results indicate that aspirin and salicylate induce apoptosis of B-CLL cells by activation of caspases and that this activation involves cyclooxygenase-independent mechanisms. © 1998 by The American Society of Hematology.