ALBERT

Description: Pathological angiogenesis associated with wound healing often occurs subsequent to an inflammatory response that includes the secretion of cytokines such as tumor necrosis factor (TNF). Controversy exists on the angiogenic actions of TNF, with it being generally proangiogenic in vivo, but antiangiogenic in vitro. We find that whereas continuous administration of TNF in vitro or in vivo inhibits angiogenic sprouting, a 2- to 3-day pulse stimulates angiogenesis by inducing an endothelial “tip cell” phenotype. TNF induces the known tip cell genes platelet-derived growth factor B (PDGFB) and vascular endothelial cell growth factor receptor-2 (VEGFR2), while at the same time blocking signaling through VEGFR2, thus delaying the VEGF-driven angiogenic response. Notch signaling regulates tip cell function, and we find that TNF also induces the notch ligand jagged-1, through an NFκB-dependent mechanism. Enrichment of jagged-1 in tip cells was confirmed by immunofluorescent staining as well as by laser capture microdissection/quantitative reverse-transcription–polymerase chain reaction (qRT-PCR) of tip cells sprouting in vitro. Thus, in angiogenesis, the temporal expression of TNF is critical: it delays angiogenesis initially by blocking signaling through VEGFR2, but in addition by inducing a tip cell phenotype through an NFκB-dependent pathway, it concomitantly primes endothelial cells (ECs) for sprouting once the initial inflammatory wave has passed.

Description: High-dose therapy plus autologous stem cell transplant (ASCT) is the standard of care for patients with multiple myeloma (MM) aged ≤65 years. Melphalan–prednisone (MP)-based therapy is the standard for non-ASCT candidates but is not typically used for transplant-eligible patients as prolonged therapy with melphalan can adversely affect stem cell collection. The phase 3 VISTA study demonstrated the superior efficacy of bortezomib plus MP (VMP) versus MP in previously untreated MM patients ineligible for ASCT. In this phase 2 study, we evaluated the efficacy of a shorter course of VMP on a different treatment schedule as induction therapy prior to ASCT or as frontline therapy in non- ASCT candidates. Patients aged ≥18 years with previously untreated MM received up to six 28-day cycles of bortezomib 1.3 mg/m2 IV, days 1, 4, 8, and 11, plus oral melphalan 6 mg/m2 and oral prednisone 60 mg/m2, days 1–7. After 2–6 cycles, ASCT-eligible patients could proceed to stem cell mobilization (G-CSF 10 mg/kg/day ± GM-CSF 250 mg/m2/ day or cyclophosphamide 4 g/m2 + GM-CSF) and conditioning with melphalan 200 mg/ m2 (140 mg/m2 if aged 〉65 years). Response was assessed every two cycles and post- ASCT by International Uniform Response Criteria. The primary end point was complete response (CR) rate to VMP. A total of 45 patients were enrolled; 27 were male. Median age was 63 years (range 33–75). MM subtype was 67% IgG, 16% IgA, and 9% each κ- and λ- light-chain; 37% of patients had ISS Stage III MM, 22% had ECOG performance status 〉1, and 70% had ≥40% plasma cells in bone marrow. In total, 20 patients proceeded to ASCT. Median duration of VMP was 4 cycles in both non-ASCT (range 1–6) and ASCT (range 2–6) patients. Response rate (best response) to VMP was 95% (42 of 44 evaluable patients), including 9% stringent CR (sCR), 9% CR (18% ≥CR [95% CI: 7%, 30%]), 27% very good partial response (VGPR), and 50% partial response (PR). Best response was achieved after cycle 2 in 10 patients, cycle 4 in 25 patients, and cycle 6 in 7 patients. All 20 ASCT patients had successful stem cell mobilization; median yield of CD34+ cells/ kg was 5.6 x 106 (range 2.3–12.2 x 106), in a median of 2 collection days. Post-transplant responses were 10% sCR, 20% CR, 55% VGPR, and 5% PR; the remaining 2 patients need further follow-up for response assessment. Response improved post-VMP to post-ASCT in 10 patients (6 PR to VGPR, 2 PR to CR, 2 VGPR to CR). After median follow-up of 14.0 months (range 7.4–47.7) and 14.6 months (range 8.2–42.9) in non-ASCT and ASCT patients, respectively, both median time to progression and progression-free survival were 19.8 months (95% CI: 14.3 months, not estimable [NE]) in non-ASCT patients and 27.9 months (95% CI: 14.6 months, NE) in ASCT patients. A total of 7 patients (5 non- ASCT, 2 ASCT) have died; 1-year survival rate was 82% (95% CI: 59%, 93%) in non- ASCT patients and 95% (95% CI: 69%, 99%) in ASCT patients. Most common grade 3/4 adverse events in all 45 patients during VMP therapy included peripheral neuropathy (24%), thrombocytopenia (20%), neutropenia (18%), and infection (9%). Only 1 patient had deep-vein thrombosis. In conclusion, VMP represents a highly effective therapy for previously untreated MM, with 45% of patients achieving VGPR or better, including 18% sCR/CR. Toxicities were predictable and generally manageable. Short-course VMP therapy did not negatively impact stem cell mobilization, supporting its use as induction therapy prior to ASCT. Very high post-transplant response rates were seen, with 85% of patients achieving ≥VGPR, including 30% sCR/CR. Since achievement of CR/VGPR is associated with improved long-term outcomes in MM, the preliminary outcome data presented here appear promising; however, longer follow-up is required.

Description: Background: Under conditions of iron overload, ascorbic acid is oxidised at an increased rate leading to a risk of vitamin C deficiency. With deferoxamine (DFO) standard therapy, vitamin C is usually given at a dose of 2–3mg/kg on the days of DFO infusion as this increases iron excretion by up to 30%. With deferarisox (DFX) chelation treatment, although supplementation is permitted, there is currently no information about the effects of vitamin C supplementation on iron excretion and it is often left to patients or their clinician’s discretion as to whether supplementation is given. With long-term treatment, in the absence of supplementation there is a potential risk that vitamin C deficiency will develop and this could influence response to treatment. Patients and Methods: We have measured fasting plasma vitamin C in 41 patients who have been on long term deferasirox treatment for transfusional iron overload for between 1.5 and 5 years. 32 of these patients had received no supplementation and 9 patients had received 2–3 mg/kg/ day of supplementation. We have examined whether trends in serum ferritin, myocardial T2* and liver iron, during the final year of observation, relate to plasma levels of vitamin C. Results: Fasting plasma Vitamin C was significantly lower in the 41 patients (mean=30.3μmol/l, SD=20.8) than healthy control patients (mean=60.29μmol/l SD=12.6) (P

Description: BACKGROUND: With new chelation regimes such as deferasirox, there has been interest in their effects on serum creatinine, as about one third of patients show a small non-progressive increase within a few weeks of starting treatment. A question arises as to whether creatinine increases occur with other modalities of chelation therapy. The effects of deferoxamine (DFO) on serum creatinine have not been widely studied, particularly when intensive chelation regimes are used with 24 hour (h) exposure. Intensified 24h DFO for patients with high risk iron overload has been in use for selected patients for over 20 years. However, whilst factors leading to retinal and ototoxicity are well described, effects on serum creatinine are largely confined to case reports. We postulated that small increments in serum creatinine might be an inevitable effect of treatment intensification. We therefore undertook retrospectively to examine the effects on serum creatinine in patients in whom standard DFO therapy (40mg/kg as 8–10h infusions 5 days/ week) was switched to an intensive DFO monotherapy regime with 24h/day therapy. PATIENTS AND METHODS: We examined the records of 10 patients with transfusion dependent thalassaemia attending the haematology department at University College London Hospitals, between 1989 and 2008, who required an intensification of their DFO regime as a result of failure to control their iron burden with their existing regime. Nine out of the 10 patients required portacath insertion for their DFO to be delivered intravenously, the tenth patient was switched to subcutaneous DFO administered 24h/ day. The patient characteristics were as follows: 8 male and 2 female. Two had thalassaemia intermedia and the rest had thalassaemia major. Those with a portacath were commenced on warfarin as thromboprophylaxis for the portacath. Co-morbidities for the patients included splenectomy (2); diabetes (2); cardiac failure (3); arrhythmias (2). The mean dose of deferoxamine administered was 52mg/kg/24h (9 of the patients had doses between 35–60 mg/kg/24h and only 1 patient had a dose of 100 mg/kg/24h). RESULTS: The results of the study revealed a mean ferritin of 6113.2μg/L ± 1681.3 and 3910.5μg/L ± 1438.4 pre and post intensification of DFO respectively. Of the 10 patients, 6 of them displayed an increase in creatinine of over 25% of their original level on standard DFO, the other 4 also had an increase albeit a more modest one. The increase in creatinine did not correlate with the dose of DFO given. The creatinine pre-intensification showed a mean of 62.3μmol/L ± 10.19 and post intensification showed 92.3μmol/L ± 11.17. This was a statistically significant difference with a p value of 0.0016 using a paired student t test. No patient went on to develop progressive renal dysfunction and creatinine returned to baseline in all patients when the regime returned to standard therapy. CONCLUSIONS: We conclude that intensification of DFO using 24h chelation results in small increments in serum creatinine, even when doses are as low as 40–70mg/kg. The findings suggest that increments in creatinine with chelation therapy are more frequent than hitherto recognised and may be a general effect of continuous chelation therapy. These changes were reversible on returning to original intermittent DFO. While none of these patients developed permanent changes, we propose that patients who are commenced on DFO, especially at continuous intensified doses, should have their creatinine measured on a regular basis, and caution should be employed with those patients who have borderline high creatinine.

Description: Chronic iron overload associated with hereditary hemochromatosis or repeated red cell transfusions is known to cause cardiac failure. Cardiac arrhythmias have been incidentally noted in patients with iron overload, but often times dismissed as being caused by other co-morbid conditions. Studies with iron-loaded gerbils suggest a role for iron in the development of cardiac arrhythmias, however these studies utilized short duration recordings of anesthetized gerbils. Furthermore, we were unable to reproduce these loading protocols without significant morbidity and mortality. Our goal was to characterize iron-induced arrhythmias in the chronically instrumented, untethered, telemetered gerbil. Monitored gerbils were divided into 2 groups: iron-loaded (n=23) and control (n=8). Iron loaded gerbils received iron dextran intraperitoneally at a dose of 1.7 (n=4), 3.0 (n=5) or 6.2 (n=14) g/kg; control gerbils received dextran. Gerbils were weighed and given a physical exam weekly. Electrocardiograms were recorded for 10 seconds every 30 minutes for approximately 6 months (DSI Ponehma) and reviewed daily. Quantitative analysis was completed on 6 iron loaded (6.2g/kg) and 3 control gerbils. Heart rate and intervals were calculated and arrhythmias were characterized and counted. Cardiac and hepatic histology and tissue iron concentration were assessed. All gerbils showed evidence of frequent sinus arrhythmia (more than one episode per hour). However, except for two control gerbils that showed frequent unifocal PVCs, no significant arrhythmias were noted in daily review. There was no difference in heart rate, P duration, PR interval, QRS duration or QT interval between groups. Neither total number of arrhythmias nor arrhythmias per minute were different between groups. One iron-loaded gerbil had a single episode (11 beats) of supraventricular tachycardia. Two iron-loaded gerbils had PVCs, one had only a single beat and the other had 9 unifocal PVCs over the duration of the study. Iron-loaded gerbils rarely showed other arrhythmias One control gerbil had 260 unifocal PVCs over the duration of the study. Other arrhythmias were noted rarely. Body weight and heart weight was not different between groups, while liver weight increased with increasing iron dose. Cardiac and hepatic iron were significantly increased in iron loaded gerbils when compared to control. Liver weight increased as iron dose increased. Seven of 14 gerbils loaded to 6.2 g/kg developed ascites as assessed both by physical examination and necropsy. We conclude that an iron load sufficient to cause clinical liver disease does not, in the absence of co-morbid conditions, cause cardiac arrhythmias in the gerbil model of iron overload. This suggests that iron alone is insufficient to cause cardiac arrhythmias.

Description: Dendritic cells (DCs) are key regulators of the immune system; they capture antigens and then can either stimulate an immune response or induce tolerance. Our aim was to activate individual DC signaling pathways to regulate the immune response. We therefore expressed constitutive activators of mitogen-activated protein kinase (MAPK) pathways or the interferon pathway, together with tumor antigens, using lentivectors. Triggering of p38 activated DCs substantially enhanced the antitumor immune response and prolonged survival of tumor-bearing mice. Activation of extracellular signal–regulated kinase (ERK) increased TGF-β expression while expression of a constitutively activated interferon regulatory factor-3 (IRF3) stimulated IL-10 secretion by DCs. ERK and IRF3 suppressed the immune response and stimulated expansion of regulatory T cells. These results provide a toolkit to regulate immune responses to viral vector or DC immunization; vaccine responses to foreign or tumor antigens can be enhanced and harmful responses to self-antigens or introduced transgenes can be reduced.

Description: CD123 (IL-3Rα) is a phenotypic marker of putative leukemic stem cells (LSC) in AML (Jordan, Leukemia2000;14:1777). We and others have found that CD34+38− cells from AML patients (pts) express high levels of CD123, in contrast to absence of expression on CD34+38− cells in normal individuals. Binding of CD123 by monoclonal antibody (mAb) 7G3 inhibits IL-3-dependent signalling and proliferation in vitro. In a NOD-SCID xenograft model 7G3 inhibits human AML engraftment, but not normal human hematopoiesis (Lock ASH2007; Abs161). CSL360, a recombinant chimeric IgG1 mAb derived from 7G3, binds the same epitope. CSL360 concentrations ≥ 0.1μg/mL in vitro inhibited 90% AML cell growth in the presence of supraphysiological IL-3 levels. Preclinical toxicology studies with doses up to 100 mg/kg weekly × 4 in cynomolgus monkeys showed no CSL360-related effects in clinical signs, hematology, chemistry, urinalysis, gross pathology or histopathology. A Phase 1 study of safety, pharmacokinetics (PK) and bioactivity of CSL360 in relapsed, refractory or high risk AML began in March 2007. Pts receive 12 weekly iv infusions if not withdrawn early due to treatment-related toxicity or disease progression. Additional treatments may be given to pts who achieve a response. Bone marrow aspirates/trephine samples are obtained at screening, after dose 3 and before doses 5 and 11. More than 180 infusions have been administered to 26 AML pts (21 M, 5 F; 17 de novo, 8 MDS-related, 1 treatment-related AML) in 5 dose level cohorts: 0.1, 0.3, 1.0, 3.0 and 10 mg/kg. There is no intra-patient dose escalation. PK parameters over the dose range, estimated in 19 pts over 7 days after doses 1 and 4, were linear with dose-proportional increases in the AUC and Cmax; dose 1 Cmax ranged from 0.62 – 287.33 μg/mL and dose 4 Cmax from 1.02 – 178.22 μg/mL. CSL360 mean plasma half-life (dose 1, 83 ± 33 h; dose 4, 117 ± 59 h) appears to be independent of dose and treatment number. Dose 1 systemic clearance (0.21 ± 0.16 L/h) and volume of distribution (0.39 ± 0.22 L/kg) were relatively low, consistent with this size IgG. In all pre-treatment samples anti-CSL360 antibody titers were negative, determined by enzyme immunoassay. Anti-CSL360 antibodies were detected post-treatment in 8/12 pts; these antibodies have not been fully quantified or characterised. CSL360 has been well tolerated; a MTD has not been defined. Seven pts received all 12 doses, 13 pts were withdrawn due to progressive disease or investigator’s decision, 3 pts were withdrawn in association with infections, 2 pts withdrew consent, and 1 pt is ongoing. Three serious adverse events have been considered possibly related or related to CSL360: 1 invasive fungal infection (Gr 5), and 2 infusion reactions (Gr 2; hospitalised). Other adverse events are consistent with expectations for the disease population. Of 8 pts in the 3 mg/kg and 10 mg/kg cohorts who are evaluable for response after ≥ 4 doses, 1 complete response (CR) has been observed. A 22 yr old male, de novo FAB M1 cytogenetically normal AML, who had relapsed post-2 allogeneic SCT, achieved a morphologic leukemia free state after 3 doses (3.0 mg/kg) and CR after 12 doses, sustained for 〉 9 weeks. The pt received 17 doses before withdrawal to treat co-morbidities. Flow cytometry studies with anti-CD123 antibodies demonstrated dose-dependent CSL360 coating of both AML blasts and LSC. Saturation of target antigen on marrow and blood cells was observed 1 day after dosing at 0.3mg/kg, associated with decreased expression of CD123 detected by an antibody to a different epitope. At higher dose levels saturation of CD123 was maintained 7 days post dosing, associated with ongoing reduction in surface CD123 expression. In a representative sample, plasma from a pt treated at 10 mg/kg specifically inhibited IL-3-induced proliferation of AML blasts ex vivo, indicating sufficient circulating concentration of CSL360 to inhibit IL-3 mediated effects in vivo. Effects of CSL360 on proliferation and apoptosis of AML cells in treated patients are being investigated. These preliminary results show anti-CD123 mAb therapy with CSL360 is safe and tolerable; biological effects have been demonstrated; a sustained CR was achieved in 1 advanced, refractory AML pt. The study is continuing, with 20 evaluable patients to be accrued and treated at 10 mg/kg weekly; at this dose level the PK and correlative assays predict that complete blockade of IL-3 signalling through CD123 can be achieved in vivo.

Description: CD38 and ZAP-70 are both useful prognostic markers for B-cell chronic lymphocytic leukemia (CLL), but are variably discordant with IGHV mutation status. A total of 5 human Fc receptor–like molecules (FCRL1-5) have tyrosine-based immunoregulatory potential and are expressed by B-lineage subpopulations. To determine their prognostic potential in CLL, FCRL expression was compared with IGHV mutation status, CD38 and ZAP-70 expression, and clinical features from 107 patients. FCRL1, FCRL2, FCRL3, and FCRL5 were found at markedly higher levels on CLL cells bearing mutated IGHV genes than on unmutated CLL cells or CD19+ polyclonal B lymphocytes. Univariate comparisons found that similar to CD38 and ZAP-70, FCRL expression was strongly associated with IGHV mutation status; however, only FCRL2 maintained independent predictive value by multivariate logistic analysis. Strikingly, FCRL2 demonstrated 94.4% concordance with IGHV mutation compared with 76.6% for CD38 and 80.4% for ZAP-70. Compared with other indicators, FCRL2 was also superior at predicting the time to first therapy; the median treatment-free interval was 15.5 years for patients with high FCRL2 expression compared with 3.75 years for FCRL2-low patients. Our studies indicate that FCRL2 has robust predictive value for determining IGHV gene mutation status and clinical progression and thus may further improve prognostic definition in CLL.

Description: Background: The prognosis for patients with CLL refractory to fludarabine and alemtuzumab (double-refractory, DR) or refractory to fludarabine with bulky (〉5cm) lymphadenopathy (bulky fludarabine-refractory, BFR) is poor. The overall response rate (ORR) to salvage therapy for such patients is approximately 20% with a median survival of 9 mo (Tam et al, Leuk Lym, 2007). New effective treatments are needed for these patients. Ofatumumab (HuMax-CD20) is a human monoclonal antibody that targets a unique small-loop epitope on CD20 and elicits potent in vitro complement-dependent cytotoxicity, even in malignant B cells with low CD20 expression levels. We report on a planned interim analysis of an international, multicenter, pivotal study of ofatumumab in patients with DR and BFR CLL. Methods: Patients with DR or BFR CLL received 8 weekly infusions of ofatumumab followed by 4 monthly infusions (Dose 1, 300 mg; Doses 2–12, 2000 mg). Patients were premedicated with paracetamol, antihistamine and glucocorticoid. The primary end point was ORR (1996 NCI-WG response criteria) assessed by an Independent end points Review Committee (IRC) over a 24 wk period. Overall survival (OS) and safety were also evaluated. Results: This interim analysis included all 138 treated patients (DR, n=59; BFR, n=79: Table); 54% received all 12 infusions and 90% received □8 infusions. The ORR (99% CI) based upon IRC assessment was 51% (34, 68%) for the DR group and 44% (30, 59%) for the BFR group; 1 patient had CR. Additionally, a considerable number of patients had stable disease (Table). Median time to next CLL therapy was 9 mo for the DR group and 8 mo for the BFR group (Table); clinical progression was typically due to worsening lymphadenopathy. The median OS was about 14 mo for the DR group and 15 mo for the BFR group (Table); based upon a landmark analysis at wk 12, response was significantly correlated with longer survival for both groups. Updated efficacy results will be presented at the meeting. Ofatumumab was associated with infusion-related adverse events on the first infusion day in 46% of patients in the DR group and 38% in the BFR group, which were grade 3 (no grade 4) in 7% and 3%, respectively (only 1 grade 3 event was considered a serious adverse event). These events generally subsided with subsequent infusions. The most common grade 3 or 4 toxicities were infections (25% in DR; 27% in BFR group) and hematologic events including neutropenia (12% in DR; 10% in BFR group) and anemia (8% in DR; 4% in BFR group). Early death (within 8 wks from start of treatment) occurred in 2 patients (3%) in the DR group (sepsis, n=1; fungal pneumonia, n=1) and 3 patients (4%) in the BFR group (PD, n=1; sepsis, n=1; myocardial infarction, n=1). No patient tested developed antibodies to ofatumumab. Conclusions: These results demonstrate the effectiveness of ofatumumab in patients with double-refractory CLL or bulky fludarabine-refractory disease. Ofatumumab was well tolerated with no unexpected toxicities. This monoclonal antibody potentially represents an active treatment option with clinical benefit for patients with very poor prognosis who have exhausted standard treatment options. The encouraging single-agent activity in patients with refractory CLL warrants further investigation of ofatumumab in earlier disease settings, in combination with other agents, as maintenance, and in other B-cell malignancies. Table DR (n=59) BFR (n=79) CI=confidence interval; NR=not reached Characteristic Median(range) Age, yrs 64 (41–86) 62 (43–84) No. of prior treatments 5 (1–14) 4 (1–16) % of patients Rai Stage III/IV 54 70 Binet Stage C 51 65 ECOG performance status 0 44 30 1–2 53 67 Lymph node or CT lesion 〉5cm 93 100 Prior rituximab-containing regimen 59 54 ORR (%) (99% CI) 51 (34, 68) 44 (30, 59) Complete response 0 1 Partial response 51 43 Stable disease 39 43 Progressive disease 3 10 Median (95% CI) Time to next CLL therapy, mo 9.0 (7.3, 10.7) 7.9 (7.1, 9.3) Overall survival, mo 13.7 (9.4, NR) 15.4 (10.2, 20.2)

Description: Children with Down syndrome (DS) display macrocytosis, thrombocytosis, and a 500-fold increased risk of developing megakaryocytic leukemia; however, the specific effects of trisomy 21 on hematopoiesis remain poorly defined. To study this question, we analyzed blood cell development in the Ts65Dn mouse model of DS. Ts65Dn mice are trisomic for 104 orthologs of Hsa21 genes and are the most widely used mouse model for DS. We discovered that Ts65Dn mice display persistent macrocytosis and develop a myeloproliferative disease (MPD) characterized by profound thrombocytosis, megakaryocyte hyperplasia, dysplastic megakaryocyte morphology, and myelofibrosis. In addition, these animals bear distorted hematopoietic stem and myeloid progenitor cell compartments compared with euploid control littermates. Of the 104 trisomic genes in Ts65Dn mice, Aml1/Runx1 attracts considerable attention as a candidate oncogene in DS–acute megakaryoblastic leukemia (DS-AMKL). To determine whether trisomy for Aml1/Runx1 is essential for MPD, we restored disomy at the Aml1/Runx1 locus in the Ts65Dn strain. Surprisingly, trisomy for Aml1/Runx1 is not required for megakaryocyte hyperplasia and myelofibrosis, suggesting that trisomy for one or more of the remaining genes can promote this disease. Our studies demonstrate the potential of DS mouse models to improve our understanding of chromosome 21 gene dosage effects in human hematologic malignancies.