ALBERT

Description: Abstract 3453 Poster Board III-341 Introduction Increasing insight into the biology of CLL suggests a relevant interplay between tumor cells and the microenvironment. Preclinical data point to the potency of Lenalidomide to favourably modulate such interactions and remarkable clinical activity has been demonstrated in monotherapy trials in pretreated and also in previously untreated CLL patients. However, tumor flare and tumor lysis have been observed as problems and the optimal dose and schedule is still under investigation. In addition, the potential for interaction with effective standard treatment for CLL is unknown. We used a combination of Fludarabine and Rituximab as a backbone to establish a tolerable Lenalidomide dose in a dose escalation design. Study design The study treatment follows two phases: In the induction phase the maximal tolerated dose (MTD) of Lenalidomide in combination with FR should be determined. The protocol combines 6 cycles of Fludarabine (40mg/m2 po d1-3) and Rituximab (375mg/m2 iv day 4 on cycle 1 and 500mg/m2 iv day 1 on cycles 2-6), both in a 28 day cycle. Lenalidomide is given at a starting dose of 2,5 mg daily (day 7-21 of cycle 1) and with dose escalation steps to 5, 10, 15, 20 and 25mg of Lenalidomide from day 1-21 of the following cycles, if toxicity of the combination permits. In a second phase, Rituximab (375mg/m2 iv) at 2, 4 and 6 months after the last cycle is combined with Lenalidomide (day 1-28 of 28 day cycles) at the last tolerated dose for 6 months of maintenance. 40 patients are planned for this study. We herewith present the planned interim analysis for dose finding and safety endpoints for the induction phase of the first 10 patients recruited into the study. Results Mean age of patients was 70 years (range 59-76). Six of 10 patients had stage Rai III/IV and mean WBC count was 159 G/L. Seven of 10 patients had at least one high risk feature from CD38 and FISH analysis or by mutation status. Of the 60 planned cycles 46 (77%) are currently evaluable for this analysis. No systematic toxicity determining MTD was found. 50% of patients proceeded through dose escalation steps as planned. Two patients have already tolerated 25mg of Lenalidomide with their FR cycles. Regarding toxicities, grade 3 and 4 neutropenia was expected in this combination and observed in 7/10 patients. However it was not used as a dose limiting toxicity per se. Still, one 75 year old patient was dose reduced because of febrile neutropenia in the previous cycle. Overall three infectious episodes were observed on treatment. Two patients experienced thrombotic events one of which was then taken off study because of Richter transformation, which might in hindsight have been present from study onset. Surprisingly, 5/10 patients experienced significant skin toxicity, mostly in the form of skin rashes, which was deemed dose limiting in two patients. It was, however, clearly associated with Pneumocystis prophylaxis in one patient, who then went on to receive the full Lenalidomide dose without further rashes. No tumor lysis or flare reaction was observed in the 10 patients reported. Preliminary efficacy data show that all patients achieved at least a PR after 3 cycles of therapy (except for the patient with the Richter transformation). Of the 3 patients currently evaluable after 6 cycles of treatment one CR and two very good PRs were observed before starting the maintenance phase of the study. Conclusions The combination of Lenalidomide with Fludarabine and Rituximab seems clinically feasible and no tumor lysis or flare reaction have been observed, possibly due to the Lenalidomide step up design, as well as the initial tumor load reduction by the chemo-immunotherapy backbone. No clear dose dependent toxicity has emerged as dose limiting for Lenalidomide escalation in this combination. However, 50% of patients had to be dose-limited due to not clearly dose-dependent skin and vascular toxicities. A regime of thromboprophylaxis as well as a delayed start of prophylaxis against pneumocystis have since been amended to improve the management of the patients. In addition, and remarkably, the regimen shows clinical efficacy despite controversial in vitro reports, suggesting a potential negative interaction between Lenalidomide and Rituximab. This might be due to the Lenalidomide pause before each Rituximab cycle or may reflect a difference between in vitro and in vivo. Disclosures Egle: Roche: Research Funding, Speakers Bureau. Off Label Use: Lenalidomide treatment in CLL, Rituximab maintenance in CLL. Greil:Roche: Honoraria, Research Funding; Celgene: Research Funding.

Description: Retrospective studies could not proof a correlation of elevated platelet counts at diagnosis with thrombotic events. However, randomized and prospective clinical studies on platelet lowering therapies justify recommendations for the normalization of platelet counts as an appropriate endpoint for treatment in high-risk essential thrombocythemia (ET). Furthermore, there is increasing evidence that leukocytosis is an important risk factor for arterial thrombosis, especially in WHO classified ET. Leukocytosis is even more pronounced in prefibrotic primary myelofibrosis (PMF) compared to WHO classified ET. Patient cohorts that were diagnosed prior to the WHO classification likely consist of a mixture of ET and prefibrotic PMF. Some authors suppose interplay between white blood cells (WBC) and platelets in patients with myeloproliferative diseases. The current study considers the Austrian cohort of a European registry, which was established to document the efficacy of the platelet-lowering therapeutic anagrelide in myeloproliferative neoplasms. Out of 845 patients, only those with a confirmed diagnosis of ET according to the PVSG classification until 2001 or according to the WHO classification thereafter were included in the analysis. Median follow up of the 620 included patients is 3.1 years (range 1.21-5.73 years), corresponding to 2428 patient years. 418 patients (67%) were females and the median age at study entry was 62 years (range 51-72 years). Thirty four patients (5.5%) experienced at least one major arterial or venous event until data analysis corresponding to 1.40 events per 100 patient years. The influence of platelet and WBC counts on thrombotic risk was assessed by correlating the first major thrombotic event with the median of all blood counts recorded during the course of the disease until an event or until end of observation. The median platelet counts until the first event occurred and until end of observation (in patients without an event) were 595.8 G/l (range 495.0-743.0 G/l) and 500.0 G/l (range 410.5-619.5 G/l), respectively, and thus were substantially different (p= 0.008). The median WBC counts until the first event occurred and until end of observation (in patients without an event) were statistically not different but might indicate a trend with 9.60 G/l (range 8.70-10.95 G/l) and 8.42 G/l (range 7.05-10.70 G/l), respectively (p=0.084). By using the calculated (Youden index) cut offs of 574.5 G/L for platelets and 8.48 G/L for WBC counts, respectively, the Cox regression analysis revealed a clear influence of platelets (p= 0.008) as well as WBC counts (p= 0.011) above the cut offs until the time to a major event. Interestingly, in this analysis, the influence of higher platelet counts on major thrombotic events was more pronounced than that of higher WBC counts. The frequency of major events per 100 patient years was highest when both platelet and WBC counts ranged above the calculated cut offs and was substantially different from the frequency when both, platelet and WBC counts ranged below the cut offs (3.05 vs. 1.4, p

Description: Abstract 2839 Patients affected by low-risk essenthial thrombocythosis (ET) may develope thrombotic/haemorragic events at a lower rate compared to high-risk ET patients. So far, it has not be possible to identify useful markers to predict which of these patients are more likely to have an event. Previous authors [Carobbio A et al, Blood 2007] have shown that leukocytosis at diagnosis is associated with a high hazard risk (HR) of developing a thrombotic event, while high platelets count is not. Subsequently other authors [Gangant N et al, Cancer 2009] have contradicted this findings and instead shown that in low-risk ET, the increase in leukocyte count over time correlates with thrombotic events [Passamonti F et al ISTH 2009]. For these reasons we decided to evaluate risk parameters in a dynamic manner with the aim of identifying those patients who are more likely to have an event and might benefit from preventive treatment. We performed a large multicentre retrospective study that included several North Italian Haemathology centres and a large Austrian university hospital. Patient data was analysed using random effect linear regression model and a dedicated Cox model with dynamic proportional risk. We studied 136 patients with low risk ET. Out of those, 45 had a thrombotic/haemorragic event and 91 never had an event (events included: stroke, TIA, IMA, PE, PAD, epystaxis and gastrointestinal bleeding). Overall, the median age was 42 years (IQR 20; range 18–60), the median Hb was 14.0 g/dL (IQR 2.3; range 4.4–18), the median WBC was 8.1 ×103/Â μL (IQR 3.3; range 3.3–23.8), the median PLT was 701 ×103/ÂL (IQR 404; range 206–1806). Gender was M 33% (n=45), F 67% (n=91); smokers were 24% (n=18/N=74); hypercholesterolemia was 18% (n=17/N=92). The FBCs of both groups were recorded from the date of diagnosis (entry time) and up to 3 years of follow up or to the development of a thrombotic/haemorragic event (exit time). A total number of 1294 FBCs were provided by the group with event and compared to a total of 4487 FBCs from the group without event. The follow-up Hb values showed a decreasing linear pattern linear from baseline values. The PLT-count showed a trend similar to Hb over the period of follow-up in both the group without events and in the group with events. The WBC showed a decrease during follow-up in the group with events and an increase in the group without events. Surprisingly, the risk of developing an adverse event after 60 months of follow-up was reduced by 20% for each increase of 1 g/dL Hb (p =0.007), was increased by 8% for each WBC increase of 1 103/uL (p =0.026) and was decreased by 6% for each PLT increase of 100 × 103 /uL (p =0.434). No differences were seen between venous or arterious thrombotic events (Log rank test, p=0.842). In conclusion, this study confirms that baseline FBCs values are not predictive of events within the ET low risk group. The emerging new finding is that the risk of developing an event is higher when Hb is reduced. This strongly suggests a protective role of Hb in the low-risk ET group. Previous studies have shown that red cells might store and generate nitric oxide (NO), a key endothelial modulator [Kim-Shapiro DB et al 2006]. The presence of NO would keep PLT in resting state, would reduce endothelial cell adhesion and in turn reduce thrombosis rate. However this needs to be confirmed. Disclosures: Steurer: Amgen: Consultancy, Honoraria. Pizzolo:Hoffmann-La Roche: Consultancy, Honoraria.

Description: Abstract 292 Introduction: CLL cells derive essential cues from their microenvironment, that may be targets for therapy. To this end the immunomodulatory drug Lenalidomide has shown remarkable clinical activity in monotherapy trials in CLL. However, tumor lysis and tumor flare have been major obstacles in development and marked and unexplained differences in the individual tolerance of the substance remains an unsolved problem. Furthermore, the potential for interaction with standard treatment for CLL is unknown. We employed the combination of Fludarabine and Rituximab for early reduction of tumorload and used it as a backbone to establish a tolerable Lenalidomide dose in combination. Study design: In the induction phase a maximal tolerated dose (MTD) of Lenalidomide in combination with FR was to be determined during 6 cycles of Fludarabine (40mg/m2 po d1-3 q28d) and Rituximab (375mg/m2 iv d4 cycle 1; 500mg/m2 iv d1 cycles 2–6, q28d). In cycle 1 Lenalidomide was added day 7–21 at 2,5 mg. Toxicity permitting, Lenalidomide dose was escalated to 5, 10, 15, 20 and 25mg d1-21 over cycles 2–6. Data from this phase are presented in this planned analysis. Data from a 6 month Lenalidomide/Rituximab maintenance phase will be presented later. Results: The median age of the 45 recruited patients was 66 years (range 43–79). Half of the patients were in stages Rai III/IV and the median β2-MG was 4.4 mg/l. At least one high risk feature from CD38, FISH analysis and mutation status was present in 64% of patients. Five patients stopped treatment during induction (Two due to rashes, two as patient's choice and one due to early Richter's transformation). No systematic toxicity determining an MTD, the primary study endpoint, was found. In striking contrast to a small previous report, 34% of our patients proceeded through dose escalation steps as planned to receive a dose of 25mg of Lenalidomide with their last cycle of FR. The individual MTD was equal or higher than 10mg in 73% of ITT patients and 71% in this group were dose-limited due to individual differences in myelotoxicity. In ITT analysis 27% of patients had an MTD of less than 10mg. Grade 3 and 4 neutropenia was expected in this combination and observed in 88% of patients in any cycle. While it was not used as a dose limiting toxicity per se, 42% of patients were dose-limited due to myelotoxicity at some level. Infectious episodes of grade 3 severity were observed in 5 patients (11%), resulting in a relatively mild rate given the observed myelotoxicity and the phase I/II design. Surprisingly, 1/3 of the patients experienced greater than G2 skin toxicity and this was deemed dose-limiting in nine patients. No tumor lysis or greater than G2 flare reactions were observed. Full response assessment for induction treatment is available for 39 patients. Complete responses were observed in 49% and partial responses in 38% of the ITT population. In 35 patients flow MRD is available and 10 patients have reached MRD negativity. Response quality was not associated with risk factors, age or with lenalidomide dose in those receiving 6 cycles of treatment. Remarkably, one of three patients with deletion 17 achieved an MRD negative CR. Since we could not define a clinical predictor for the patients' tolerance of lenalidomide, we performed extensive immunophenotyping of T cells in pretreatment samples, using markers for functional T cells subsets, their Th polarity and for suppressive or exhausted T cell subsets. Employing a combined endpoint including non-hematological dose-limiting events or MTD 〈 10mg as a comparator, we identified a fraction of non-exhausted memory CD4 cells as highly significant predictor of dose-limiting non-hematologic events (p

Description: Antiangiogenic effects of the proteasome inhibitor bortezomib were analyzed on tumor xenografts in vivo. Bortezomib strongly inhibited angiogenesis and vascularization in the chicken chorioallantoic membrane. Bortezomib's inhibitory effects on chorioallantoic membrane vascularization were abrogated in the presence of distinct tumor xenografts, thanks to a soluble factor secreted by tumor cells. Through size-exclusion and ion-exchange chromatography as well as mass spectroscopy, we identified GRP-78, a chaperone protein of the unfolded protein response, as being responsible for bortezomib resistance. Indeed, a variety of bortezomib-resistant solid tumor cell lines (PC-3, HRT-18), but not myeloma cell lines (U266, OPM-2), were able to secrete high amounts of GRP-78. Recombinant GRP-78 conferred bortezomib resistance to endothelial cells and OPM-2 myeloma cells. Knockdown of GRP78 gene expression in tumor cells and immunodepletion of GRP-78 protein from tumor cell supernatants restored bortezomib sensitivity. GRP-78 did not bind or complex bortezomib but induced prosurvival signals by phosphorylation of extracellular signal–related kinase and inhibited p53-mediated expression of proapoptotic Bok and Noxa proteins in endothelial cells. From our data, we conclude that distinct solid tumor cells are able to secrete GRP-78 into the tumor microenvironment, thus demonstrating a hitherto unknown mechanism of resistance to bortezomib.

Description: Abstract 5064 Background: In 2001 Thromboreductin® was registered in Austria as the first EU country for the treatment of Essential Thrombocythemia (ET). Due to the low incidence of ET authorities demanded to establish a patient registry to evaluate safety and efficacy of anagrelide in the long-term treatment of ET. Following market authorization in several EU countries the patient registry is now being maintained in 10 Central European countries. Whereas most clinical trials have only a relatively short follow-up, a patient registry is able to provide long-term data. Patients and Methods: This multinational, multi-center post-marketing observational registry is conducted to assess long-term efficacy and safety of anagrelide in patients with ET under “real-life” conditions. The clinical information is entered into the registry by the treating physicians. Besides relevant clinical data such as risk factors, past thrombotic as well as bleeding events, disease symptoms classified as “major” and “minor” events and previous ET therapies including anticoagulation, laboratory values including renal and liver function parameters as well as blood counts are monitored regularly. Results: This evaluation of the Thromboreductin® Patient Registry database includes 1572 ET patients (median age: 59 years), 1059 (67%) were women and 513 (33%) were male patients; 62% of patients were pretreated with cytoreductive agents, 38% were treatment naïve. The median observation period was 1.9 years (range: 7 days – 10 years), with 168 patients (11%) being followed for at least 5 years. Treatment with anagrelide lowered the platelet count from a median of 742 × 109 /l (95%CI 717/757) to a median of 415 × 109 /l (95%CI, 397/435). Eighty-four percent of patients achieved platelet counts 〈 450 × 109 /l, no differences between pretreated (85%) and treatment-naïve /82%) patients were observed. During the 3464 patient years (PY) included in this evaluation a total of 338 ET-related events (including both thrombotic and bleeding events) were reported of which 102 (2,9% per PY) were considered as “major”. Of the 220 patients with a history of ET-related events, 178 patients (81%) have so far remained event-free under anagrelide therapy. Adverse effects were lower than those previously reported in clinical trials with headache, palpitations and diarrhea being the most frequent side effects (all 〈 3%) leading to treatment discontinuation in 43 patients (2,7%). No new toxicities have been observed. Conclusion: We consider anagrelide to be safe and effective in terms of lowering platelet counts and reducing disease-related events in unselected ET patients treated outside clinical trials under “real-life” conditions. Based on our favourable long-term data we suggest that anagrelide may be considered a first-line agent in the management of ET. Disclosures: Steurer: AOP Orphan Drugs: Honoraria. Petrides:AOP Orphan Drugs: Consultancy.

Description: Patients with essential thrombocythemia (ET) are at increased risk towards atherothrombotic complications. The JAK2 V617F mutation is found in at least half of the patients with ET and screening for JAK2 V617F mutational status has been included in the World Health Organization diagnostic criteria for ET. Further somatic driver mutations including mutations in exon 12 of the JAK2 gene, MPL mutations W515L/W515K, as well as mutations in exon 9 of the calreticulin (CALR) gene have been suggested as diagnostic markers for ET. Due to the close relation of ET to thrombotic events, early diagnosis of ET is of high clinical relevance, especially in patients with increased cardiovascular risk, like coronary patients. However, elevated blood cell counts are often ascribed to a reactive genesis within an acute coronary event. For this reason mostly no further clarification concerning myeloproliferative neoplasms is done. In the present study, therefore, we determined the prevalence of JAK2 V617F, JAK2 exon 12, MPL W515L, MPL W515K, and CALR exon 9 mutations in a cohort of patients undergoing coronary angiography for the evaluation of suspected or established stable coronary artery disease and suspected diagnosis of ET. We aimed at identifying those with occult ET proposing need for additional treatment. From a total of 1,589 coronary patients, 12 patients had increased platelets (〉450 x10 9/L) predisposing them to ET. Mutation analysis among these patients showed three individuals with the JAK2 V617F mutation and one with an ins/del mutation in exon 9 of the CALR gene confirming suspected diagnosis of ET. Consequently, frequency of ET was 0.25% among our coronary patients. For comparison, in the United States between 38 and 57 ET cases per 100,000 age-adjusted inhabitants have been reported. This corresponds to an up to 7-fold accumulation of ET cases in coronary patients compared to the general population. We conclude that the prevalence of ET is increased in coronary patients compared to the general population. For this reason comprehensive mutation analysis should be considered in all cardiovascular risk patients with persistent elevation of thrombocytes, not only to identify patient subgroups at high risk but also to individualize therapeutic strategies. Disclosures No relevant conflicts of interest to declare.

Description: There is compelling evidence that white blood cell (WBC) counts impact the risk of thrombosis in patients with myeloproliferative neoplasms (MPN) (Barbui Blood 2013). Moreover, recent publications disclosed significant differences regarding certain disease characteristics and the course of disease in WHO 2008 (Tefferi Blood 2007) classified essential thrombocythemia (ET) and prefibrotic primary myelofibrosis (PMF) (Kvasnicka Am J Hematol 2008; Barbui JCO 2011; Buxhofer-Ausch Am J Hematol 2012). Hence, patients cohorts classified prior to WHO 2008 may likely consist of a mix of patients with ET and prefibrotic PMF. We aimed to reproduce the influence of WBC counts on the thrombotic risk in patients under real-life conditions. Therefore we assessed data of 825 Austrian patients from a patient registry for anagrelide in ET that was initiated 2001 in Austria due to an official authorities demand and is now being maintained in several Central European countries. Efficacy of treatment was assessed by investigating the course of platelet counts and event free survival relating to the first minor or major thrombotic event. WBC counts from the first available time points were correlated with the first thrombotic event. The cut off for the WBC subgroup analysis was set at 8,5 G/l. Statistical analysis was performed using the open-source R statistical software package, version 3.0.2. Non-parametric two-sided 95% confidence intervals for medians were calculated. Survival probabilities were assessed by applying the Kaplan-Meier method. For the comparison of time to event between the leukocyte- specific subgroups the log-rank test was used. Median Follow up of the study cohort is 3,07 years. Platelet count at start of anagrelide was median 777 G/l (95% CI 757-803). After 12, 24 and 36 months patients presented with median platelet counts of 473, 457 and 438 G/l, respectively. Median WBC count at start of therapy was 9 G/l (95% CI 8,7-9,3) and after 12, 24 and 36 months 8,5 G/l, 9,2 G/l and 8,7G/l, respectively. Incidence of thrombotic events per 100 patient- years was 5,14 for all events and 1,65 for major events only. 102 patients experienced at least one minor or major thrombotic event (major events n=36). Median time to the first minor or major thrombotic event was 1,27 years. Probability of event free survival at 1 year is 94,4% and at 3 years 87,6%. Patients with a baseline WBC count of higher than 8,5 G/l exhibit a significantly shorter probability of event free survival than patients below the cut off (p= 0,007 for all thrombotic events; p= 0,026 for major events only). This data proof the efficacy of anagrelide in lowering platelet counts and reducing significantly the risk of thrombotic events in patients with ET. The significantly shorter event free survival of patients with a WBC count above 8,5 G/l confirms earlier studies for the first time in a real-life setting. This result emphasizes the separation of true ET from prefibrotic PMF by using the WHO 2008 classification. Moreover, further investigations are needed to assess, whether a correlation of certain platelet and leukocyte counts modifies the risk of thrombotic events in MPN. Disclosures Schloegl: AOP Orphan Pharmaceuticals AG: Research Funding.