Littérature scientifique sur le sujet « TJ 7.5 UL 2003 »

Abstract PBSC mobilization for auto transplantation of NHL pts with multiple regimens of prior chemotherapy is hard to achieve and 25%–30% of patients experience mobilization failure. AMD is a small bicyclam compound which specifically binds to CXCR4 receptor and blocks signaling through SDF-1. Previous studies in normal donors suggested clear dose dependent CD34+ cell mobilization as a single agent as well as additively with G-CSF with little toxicity (ASH meeting, 2002; 2003). Similarly, previous studies with NHL and Myeloma patients resulted with a dose-dependent augmentation of CD34+ cell mobilization in pts receiving G-CSF with little toxicity. The exact mechanism of AMD-induced mobilization of CD34+ cells was not studied in patients and AMD was not used before for PBSC mobilization in hard to mobilize NHL patients. Furthermore, its effect on mobilization of DCs and lymphoma cells was not studied before. On November 2003, we initiated a phase II study of 10, hard to mobilize NHL patients, receiving 16ug/kg of G-CSF for 4 days and G-CSF followed by 240ug/kg of AMD on day 5, 9 hours before apheresis collection. G-CSF and AMD were continued for additional day or 2, as needed, in order to collect the target dose of ≥ 2x106 PBSC/kg. Ten liters of blood were exchanged in ~4hours of apheresis. Median age was 54 years (44 to 63 years). Of the 10 patients enrolled, 6 pts had diffuse large cell lymphoma and 3 had follicular histology with 8/10 received 2 regimens of chemotherapy, 2 of which received also radiation prior to mobilization. At mobilization, 5/9 pts were primary refractory, 3 pts were in 1st relapse, 1 pt in 2nd relapse and 1 pt in 2nd CR. We determined percent CD34+ cells and percent DC1 and DC2 cells as well as percent lymphoma cell mobilization (by Real time DNA-PCR) at baseline (before administration of G-CSF) and before and after AMD, in the blood and in the apheresis product. To date 7 pts were transplanted. Five pts collected in 1 day and 5 pts collected in 2 days. No adverse events were observed during mobilization. All patients collected ≥ 2x106 PBSC/kg and 7 pts have been transplanted with a dose of 2-7x106 PBSC/kg. All transplanted pts engrafted with a mean of 10 days (9 to 12 days) for ≥ 500ANC and with a mean of 13 days (12–14 days for 6/7 pts) to reach 20K of plts. One pt had a delayed plt engraftment and was engrafted on day 27. Addition of AMD to G-CSF, prior to the first or 2nd PBSC collection resulted in a mean increase of percent CD34+ cells from 0.11% to 0.17% ( p=0.017), with a similar mean increase in CD34+ cells/ul (35/ul to 81/ul; p=0.0001) followed by normalization of CD34+ cells/ul within 24 hours. Similarly, addition of AMD to G-CSF resulted in an increase in the mean of DC1 cells from 79/ul to 156/ul (p=0.009) and from a mean of 62/ul to164/ul (p=0.006) for DC2 cells. One pt had 0.08% lymphoma cells at baseline by DNA-PCR for the major breakage point of the Bcl-2 translocation sequence, with no detectable lymphoma cells in the blood or apheresis collection post AMD. All other pts were negative for lymphoma pre and post AMD by this test. Adverse events and sever adverse events related to study were minimal. We conclude that AMD is a safe drug with clinical benefit in increasing PBSC and DC mobilization with no detectable mobilization of lymphoma cells.

Abstract Backgrounds/Aims: Hepatic veno-occlusive disease (VOD) is a life-threatening complication associated with allogenic stem cell transplantation (SCT). Although some risk factors including the intensified conditioning regimen, the second SCT, and liver dysfunction have been implicated on the pathogenesis of VOD, its etiology remains undetermined. Plasma von Willebrand factor (VWF) is produced in vascular endothelial cells (ECs) as unusually-large VWF multimers (UL-VWFMs) and released into circulation, where UL-VWFMs are cleaved into the small multimers with a specific metalloprotease ADAMTS13. Thus, the elevated level of plasma VWF, together with UL-VWFMs, has been thought in part to be a reflection of vascular EC injuries. Previously, we reported that plasma ADAMTS13 activity significantly decreased in patients with VOD during the first 4 weeks after SCT, compared with those without VOD (BMT2002, 29:789). Since ADAMTS13 down-sizes UL-VWFM by its proteolytic cleavage and reduces its thrombogenicity, we have here performed multicentric, prospective randomized study as to whether the infusion of fresh frozen plasma (FFP), a source of ADAMTS13, can prevent the occurrence of VOD in high-risk group patients with SCT. Methods: The study was conducted at 10 hospitals between April 2001 and March 2003. Patients for allogenic SCT were enrolled to participate in the study, if they were high-risk for VOD abovementioned. Forty-three patients enrolled in this study were randomly divided into two groups: 23 patients with FFP infusion and 20 patients without. FFP was infused twice a week during conditioning regimen and until day 28 after SCT. The amount of FFP infused depends on body weight as follows; 1 unit (=80 ml) for patients under 10 kg, 2 units for 10–20 kg, 3 units for 20–30 kg, 4 units for 30–40 kg, and 5 units for over 40 kg. Plasma ADAMTS13 activity was measured by a novel monoclonal antibody-based highly sensitive ELISA (Transfusion2006, 46:1444). Results: Three patients with hepatic VOD occurred within 20 patients who did not receive the FFP infusion, but none were observed in 23 patients who received the FFP infusion. We analyzed both the groups with special references to plasma levels of VWF and ADAMTS13. A significant difference was found in plasma levels of VWF:Ag, where the patients received FFP infusion had the lower values at day 0, day 7, and day 28, than those without receiving FFP infusion. However, no clear difference of plasma levels of ADAMTS13 activity was observed in both the groups. Most interestingly, however, a heightened degradation of VWFM (a total lack of the high ~ intermediate molecular size multimers) was found in patients with VOD who did not receive FFP infusion, but this finding was not seen in those without VOD who received FFP infusion. Conclusions: FFP infusion apparently reduces plasma levels of VWF:Ag, together with the disappearance of UL-VWFMs, and thereby prevents the occurrence of VOD. On the other hand, in the patients with hepatic VOD, prior to the disease progression the high~intermediate multimers including UL-VWFMs were already consumed, by which platelet aggregation/thrombi might occur, as evidenced by VWFM analysis.

Abstract Introduction: Traditional prognostic factors for adult acute lymphocytic leukemia (ALL) include age, white blood count at diagnosis, and cytogenetic (CG) risk. We sought to identify a more detailed prognostic risk score for newly diagnosed adult patients (pts) based on these and other pre-treatment characteristics. Methods: 82 newly diagnosed ALL pts given induction chemotherapy (IC) at our institution between the years 2003-2011 were included, and data were obtained by chart review. Institutional review board approval was obtained. Variables examined included: gender, age, immunophenotype, CG risk, pre-IC body mass index (BMI), pre-IC and day 28 serum albumin, absolute lymphocyte (ALC) and neutrophil (ANC) counts, positive culture (blood or other) during IC, positive imaging suggestive of infection (during IC), and allogeneic hematopoietic cell transplant (AHCT). CG risk was ascribed by CALGB criteria (Blood 1999; 93: 3983). BMI was defined by: underweight (≤ 18.5), normal (> 18.5-25.0), overweight (> 25.0-30.0), moderately obese (> 30.0-35.0), severely obese (> 35.0-40.0), and very severely obese (> 40.0). The primary endpoint was overall survival (OS) which was measured from IC to death or last follow-up. Proportional hazards models were used for univariable and multivariable analyses. In the multivariable analysis stepwise variable selection was used to identify independent predictors. Results were internally validated using a bootstrap algorithm. For convenience measured factors were discretized using a recursive partitioning algorithm. Prognostic groups were formed by assigning “points” to each factor that were based on the magnitude of the estimated regression coefficients of the final model, and then summing the total number of points present. Results: Median age at diagnosis was 43 yrs (range 18-78); 58% male. 71% of pts (58/82) had a B-cell immunophenotype. CG risk included: normal: 15 pts (18%), high: 41 pts (50%), miscellaneous: 9 pts (11%), and unknown: 17 pts (21%). Twenty-four pts (29%) were Ph+. The majority of pts (70%: 57/82) received the CALGB 19802 regimen (Cancer 2013; 119: 90) for IC +/- a tyrosine kinase inhibitor (if they were Ph+). 27% of pts (22/ 82) received AHCT in CR1. Estimated median OS is 41.5 months (95% CI: 15.5-N/A). In univariable analysis age, pre-induction BMI, Day 28 ALC, pre- and Day 28 albumin, Day 28 ANC, Day 28 platelet count, evidence of infection, and CG risk were all seen to impact outcome. In multivariable analysis pre-IC BMI and albumin, age, and Day 28 ALC were identified as independent predictors. Assigning 1 “points” each for age >50, albumin prior to IC ≤ 3.2 g/dL, or Day 28 ALC ≤ 50 /uL and 2 points for BMI ≥ 35, 3 prognostic groups were defined: favorable (0 points) 32% of pts (26/80): estimated 5-yr OS of 68% +/-11%; intermediate (1 points) (29% of pts, 23/80): estimated 5 yr OS of 39% +/-11%, and unfavorable (≥ 2 points) (39% of pts, 31/80) with estimated 5 yr OS of 17% +/- 7% (Figure 1). Conclusion: We have constructed a simple prognostic model for newly diagnosed adults with ALL. This model will need to be validated in a larger group of uniformly treated patients. Table 1 Prognostic Factors for OS in Univariable and Multivariable Analysis Factor Univariable (HR (95% C.I.)) Multivariable (HR (95% C.I.)) Age at dx (≤50 vs. >50) 3.29 (1.80-5.99), p=.0001 2.83 (1.45-5.53), p=.002 Pre-IC BMI (<35 vs. >35) 2.95 (1.57-5.52), p=0.0008 3.88 (1.84-8.17), p=.0004 Pre-IC albumin (≥ 3.2 vs. < 3.2 g/dl) 2.61 (1.43-4.77), p=0.002 2.66 (1.33-5.30), p=.0006 Day 28 ALC (> 50/uL vs. ≤50/uL) 3.57 (1.61-7.91), p=0.002 3.11 (1.33-7.28), p=.009 CG risk 2.03 (0.98-4.22); p=0.06 ------ Day 28 albumin (>2.3 vs. ≤2.3 g/dl) 3.37 (1.66-6.83), p=0.0008 ------ Day 28 ANC (>200/uL vs. ≤200/uL) 4.51 (1.94-10.51), p=.0005 ------ Day 28 platelets (>75K/uL vs. ≤75K/uL) 2.44 (1.26-4.72), p=.008 ------ Any positive culture (no vs. yes) 2.19 (1.19-4.04), p=0.01 ------ Blood culture positive for bacteria (no vs. yes) 2.34 (1.28-4.30), p=0.006 ------ Positive imaging suggestive of infection (no vs. yes) 2.44 (1.34-4.46), p=0.004 ------ Positive blood culture and image (no vs. yes) 1.96 (1.07-3.57), p=0.03 ------ Figure 1 Prognostic Groups Figure 1. Prognostic Groups Disclosures No relevant conflicts of interest to declare.

8018 Background: WM is an indolent B-cell lymphoma. NA are widely used in the treatment of WM, and are considered as appropriate first line agents for the treatment of WM (Gertz et al, Semin Oncol 2003; Treon et al, Blood 2006). Increased incidences of disease transformation and development of MDS/AML have been observed among patients with indolent B-cell malignancies receiving NA. We therefore sought to delineate the incidence for these events in a large population of WM patients treated at our institution. Methods: 326 previously treated patients with the consensus panel definition of WM, who received treatment with (n=173) or without (n=153) a NA were included in this analysis. Baseline characteristics between NA and non-NA treated patients were not significantly different and were as follows: median age 59 years; male/female ratio 1.4; median B2M 2.9 mg/L; serum IgM 3,000 mg/dL; BM involvement 40%; Hct 34%; WBC 5,100/ul, and PLT count 243,000/ul. For patients receiving NA, treatment consisted of either fludarabine (n=117; 68%), cladribine (n=48; 27%) or both (n=8; 5%). For non-NA treated patients, therapy included chlorambucil, rituximab, CVP, CHOP, thalidomide, and cyclophosphamide alone or in combination with rituximab, and alemtuzumab. Median follow-up of patients was 64 (range 10–270) months. Results: Among NA treated patients, 10 (5.7%) patients had transformation to an aggressive NHL (to DLBCL) (n=7; 4%) or developed MDS/AML (n=3; 1.7%). Disease transformation and development of MDS/AML occurred at a median time of 48 (range 7–114), and 48 (range 38–52) months following NA treatment, respectively. In contrast, among non-NA treated patients, only 1 patient demonstrated disease transformation (to DLBCL) at 10 months and no patients developed AML/MDS (p=0.025). Conclusions: These data demonstrate an increased incidence of disease transformation and development of MDS/AML among WM patients treated with NA. No significant financial relationships to disclose.

Abstract Autologous stem cell transplantation is curative for many patients with hematologic malignancies. Approximately 20% of patients do not have an adequate stem cell mobilization. Recently, work from our laboratories has shown that parathyroid hormone (PTH) increases osteoblast number and expansion of the stem cell compartment in mice. In murine models, the addition of PTH caused an increase in the absolute number of stem cells. Daily PTH injection caused an increase in the absolute number of murine stem cells and improved survival in transplant recipients of limiting numbers of stem cells. (Nature425: 841, 2003). This observation suggested that PTH might be able to increase stem cell numbers in humans. PTH is an FDA approved drug used for treatment of osteoporosis. In this Phase I study, patients who have collected less than 2 million CD34+ cells/kg after 1 or 2 stem cell mobilization attempts received 14 days of sc PTH, in escalating dose cohorts of 40 mcg, 60 mcg, 80 mcg, and 100 mcg per day, with G-CSF 10mcg/kg/day for the last four days. Patients with >5 CD34+/uL on Day +14 proceeded to stem cell apheresis and autologous stem cell transplant. 14 patients have enrolled on this study, now enrolling at the highest dose cohort, and 12 patients have completed treatment for this analysis with 3 patients per dose cohort. The median age was 57 years (range 24–71 years), and 9 (75%) patients are female. In 10 patients (83%) one attempt at stem cell mobilization failed with either growth factor alone or growth factor plus chemotherapy; in the other 2 patients (17%) two attempts at mobilization failed to attain adequate cells. The diagnoses were as follows: non Hodgkin’s lymphoma (7 patients, 58%), Hodgkin’s disease (5 patients, 42%). There were no dose limiting toxicities defined as calcium > 11.5, ionized calcium > 1.5, phosphate <1.0, or systolic blood pressure less than 80mm Hg. 3 patients had a self-limited fever, one patient had an unexplained eosinophilia, and 1 patient required an admission with fever, rigors, and headache. 6 of 12 patients (50%) achieved the target peripheral CD34 level of 5/uL, of whom 4 underwent stem cell apheresis. The median CD34 cells/uL on Day +14 was 4.3 (range 0–18.8). 2 patients who achieved the target peripheral CD34 level of 5/uL did not complete collections, 1 due to access problems, and 1 due to physician preference. The 4 patients who continued with the study collected a median CD34+ dose/kg of 2.2 x 106 (range 0.9–2.7) from stem cell apheresis with a median of 2 collections (range 1–4). These 4 patients proceeded to autologous stem cell transplant, with median days to neutrophil and platelet engraftments of 11 (range 10–12) and 14 (range 12–19), respectively. In conclusion, 1) PTH is well tolerated in this population, even at a dose of 100 mcg; 2) PTH plus G-CSF may be effective in patients that fail primary or secondary stem cell mobilization attempts; 3) PTH plus G-CSF should be tested in a larger Phase II study to improve donor stem cell yield. Future directions may also include the use of parathyroid hormone to improve engraftment efficiency in settings of low stem cell dose such as adult cord blood transplantation.

Abstract Abstract 3063 Background: Dying mammalian cells release danger signals that stimulate antigen presenting cells (APCs) to promote an immune response. It has been demonstrated that uric acid released from injured cells alerts the immune system to cell death, acts as a danger signal to stimulate cytotoxic T cell responses and that elimination of uric acid in mouse models reduces this immune response (Ref: Nature 2003; 425:516–521). Rasburicase is a recombinant urate-oxidase enzyme that catalyzes oxidation of uric acid into an inactive soluble metabolite and is currently used to prevent tumor lysis syndrome. We hypothesized that rasburicase administered during myeloablative conditioning prior to allogeneic HCT will reduce the serum levels of uric acid and thereby may decrease the incidence of acute GVHD via inhibition of danger signal-mediated activation of host APCs. Methods: In this pilot trial at the Massachusetts General Hospital, between 2007 and 2010, 23 patients (median age: 41 years, range: 19–59) with hematologic malignancies in complete remission (AML, n=13; ALL, n=8; MDS, n=1; MPD, n=1;) received myeloablative preparative regimens (Bu/Cy, n=14; Cy/TBI, n=7; Bu/Flu, n=2) followed by GCSF-mobilized HLA-matched (MRD, n=18; MUD, n=5) peripheral blood HCT. GVHD prophylaxis consisted of cyclosporine or tacrolimus and methotrexate for MRD transplants and tacrolimus/MTX and anti-thymocyte globulin (Thymoglobulin) for MUD transplants. Rasburicase was administered beginning on the first day of conditioning therapy, at a dose of 0.20 mg/kg intravenously daily for 5 consecutive days. Outcomes were compared to 44 controls at this institution from the same time period identified using retrospective chart review. Patients in the control group received allopurinol during the conditioning as a part of the institutional guidelines. Associations between categorical variables were evaluated using Fisher's exact test. Overall and disease-free survival (OS and DFS) were estimated using the method of Kaplan and Meier. Results: The mean serum uric acid concentration was 0.2 mg/dl (range, 0–1.7) on 6 consecutive days, beginning the day after the first dose of rasburicase. Engraftment was achieved in all patients, and the median times to neutrophil (at least 0.5 × 109/ul) and platelet engraftment (at least 20 × 109/ul) were 18 days (range, 7–26 × 109/ul) and 16 days (range, 8–57 × 109/ul), respectively. The only serious toxicity caused by rasburicase was intravascular hemolysis in one patient who was found to have G6PD deficiency; this patient received only 2 doses of rasburicase. Greater than or equal to grade II-IV acute GVHD occurred in 5 out of 23 patients (22%), 4/18 in MRD and 1/5 in MUD recipients: grade II, n=1; grade III, n=2; and grade IV, n=2. When compared with 44 patients (AML 28, ALL 5, MDS 4, NHL 5, MPD 1, CML 1), comparable to rasburicase-treated patients with respect to age, gender, disease status, donor sources, conditioning and GVHD prophylaxis, who received myeloablative HCT (MRD, n=32; MUD, n=12) at the MGH during the same time period as the patients in the rasburicase-treated group, there was significantly less grade II or higher aGVHD in the rasburicase group (rasburicase: 22% vs. institutional control: 48% [total 21/44, 13/32 in MRD and 8/12 MUD recipients], Fisher's exact test, p=0.033). There was no significant difference in the incidence and severity of chronic GVHD between the two groups (rasburicase, 61%, control 48%; Fisher's exact test, p=0.721). At 3 years, there was no significant difference in disease-free survival (DFS) or overall survival (OS) between the rasburicase-treated and control groups (DFS: rasburicase vs. control 51.2% vs. 40.4%, p=0.97; OS: rasburicase vs. control 55.3% vs. 44.9%, p=0.88). Conclusion: Rasburicase can be safely administered during myeloablative conditioning, results in a profound lowering of serum uric acid levels and has the potential to reduce the incidence of acute GVHD. Based on these data a prospective randomized phase II trial is planned in order to verify whether rasburicase inhibits acute GVHD after myeloablative HCT and to study the possible mechanisms of protection from GVHD. Disclosures: Off Label Use: Rasburicase for GVHD prevention in allo-HSCT.

Abstract Decitabine, an inhibitor of DNA methyltransferase (DNMT) enzymes, has clinical activity in myeloid malignancies, even at low doses (>1 log below the MTD) which may be optimal for demethylation rather than only cytotoxicity. We designed a two step trial for AML patients (pts) to determine: Step 1) the minimal effective pharmacologic dose (MEPD) of decitabine as a single agent (defined as lowest dose to induce reexpression of genes commonly methylated in AML in 5/6 pts treated at a single dose level) and Step 2) the MTD of the histone deacetylase inhibitor valproic acid given in combination with decitabine at this MEPD. To date, Step 1 is ongoing; decitabine alone has been administered to 14 pts at two dose levels. Pts had relapsed/refractory AML (N=8) or age>60 and ineligible/refused standard induction therapy (N=6). Pts ranged in age from 57–83 years and had received ≥ 2 prior inductions (N=6), 1 prior induction (2), or were untreated (4). 8 pts received decitabine at 15mg/m2/IV over 1 hr daily (d) for 10 consecutive d, and 6 received 20mg/m2/d on the same schedule, every 28 d. Plasma decitabine levels were analyzed by a validated LC-MS/MS method with a sensitivity of 2 ng/ml developed in our laboratory. Plasma drug concentration-time courses on d 1 and 10 achieved a mean Cmax of 93 ng/ml (N=7) and followed a two compartment infusion model. The mean short and long half-lives were 2.7 and 36.9 min, respectively, with a trend of decreasing the longer half-life on d 10. According to published bone marrow (BM) response criteria (Cheson, JCO 2003), 4/10 pts who completed two cycles of therapy responded (2 at each dose level). 3 had complete response with incomplete recovery of counts (CRi), and one achieved CR. Hematologic improvement (HI) or clinical benefit was seen in 3 additional pts: one achieved neutrophils of 2,200/uL, platelets (plts)>100,000/uL, disappearance of circulating blasts, and disappearance of BM blasts except by flow cytometry; one pt achieved plt transfusion independence (plts>100,000/uL); one pt had stabilization of disease for 6 months. Two more pts who remain on study are not yet evaluable for BM response but have already had significant HI with plts of 259,000 and 74,000/uL, respectively, after one cycle of therapy. Two pts were not evaluable for response due to death from sepsis or death related to decitabine-induced differentiation syndrome (first reported by Blum, ASH 2004), respectively. Decitabine was well tolerated, given typically as an outpatient. There were no severe non-hematologic drug related toxicities. Pts with HI or BM response required plt transfusion support when subsequent cycles were administered. At 15mg/m2/d x 10 d: 4/6 pts experienced at least 100% increase in reexpression genes commonly methylated in AML such as p15 or estrogen receptor; immunoblotting demonstrated DNMT1 protein depletion in 4/6 pts lasting 4–42 d. Clinical trial design based on achieving the MEPD is feasible in AML; we demonstrate clinical activity of low dose decitabine associated with changes in levels of the DNMT1 target and reexpression of epigenetically silenced genes. Complete PK and PD studies including gene reexpression by quantitative RT-PCR, DNMT1 protein levels by immunoblotting, and decitabine-induced promoter demethylation by COBRA/bisulfite sequencing will be presented. (NCI U01 CA 76576-05)

Abstract Early response to therapy as determined by Day 8 prednisolone response (PR) and minimal residual disease (MRD) are highly predictive of risk of relapse in childhood ALL. They are currently employed in risk-stratification in modern chemotherapeutic regimens. Leukemia biological factors like hyperdiploidy, oncogene fusions like TEL-AML1, MLL rearrangements and BCR-ABL are widely used for risk stratification but patient’s pharmacogenetic profile has thus far not been utilised for tailoring therapy because of conflicting or equivocal results. We investigated potential candidate genes involved in drug transport and metabolism of steroids, vincristine, L-asparaginase and anthracyclines used in the BFM induction backbone to exploit the plausible pathways of early chemoresistance. We studied 282 children with ALL enrolled in the Malaysia-Singapore 2003 ALL trial. Poor prednisolone response (PPR) is defined as absolute blast count ≥1,000/uL after 7 days of prednisolone and 1 IT MTX. MRD quantification at day 33 induction using IgH and TCR markers based on European MRD Study Group standards. Four potential candidate genes MDR1 3435C>T, GSTT1, GSTM1, NQO1 609C>T were studied using Polymerase Chain Reaction and Restriction Fragment Length Polymorphism. Statistical analysis was carried out using multinomial regression model. We had 241 good prednisolone responders (GPR), and 34 poor prednisolone responders (PPR). There were 112 patients with negative MRD (<10−4) while 129 had positive MRD ≥10−4 (35 had high MRD > 5 × 10−3). Only MDR1 3435TT genotype was strongly associated with poor PR (p=0.011; OR=2.8; 95%CI=1.3–6.4), MRD positive disease ≥10−4 (p=0.011, OR=2.8, 95%CI= 1.3–5.9) and high levels of MRD >5×10−3 as compared to MRD <10−4 (p<0.0001; OR=5.9; 95%CI=2.3–15.1). Interestingly, MDR1 3435CT heterozygosity is significantly associated good early response: with low levels of <MRD10−4 as compared to high MRD levels >5×10−3 (p=0.022; OR=0.4; 95%CI=0.2–0.9). Oral prednisolone and dexamethasone are the most powerful drugs in the treatment of childhood ALL. MDR1 3435C>T although a synonymous SNP, is associated with lower P-glycoprotein because of reduced MDR1 3435T mRNA stability. MDR1 3435 TT homozygote has 4 fold reduced levels of P-glycoprotein in the duodenum and is associated with reduced drug absorption like digoxin. We postulate that TT homozygote; there is reduced absorption of oral steroids in the gut, resulting in low oral bioavailability and poor early response as determined by poor prednisolone response and high MRD. On the other hand, in the CT heterozygote, drug oral bioavailability is not the drug-limiting step. The predominant effect of reduced P-glycoprotein expression in the cells are associated with reduced efflux of drugs, hence higher levels of intracellular drug resulting in good treatment response. MDR1 C3435T polymorphism is highly correlated with early response to therapy in childhood ALL as determined by prednisolone response and MRD levels at the end of induction.

Abstract BACKGROUND. c-kit is a receptor tyrosine kinase for the ligand stem cell factor and a member of the PDGF receptor family. c-kit positivity, as defined by the presence of CD117 by flow cytometry (FC) in > 20% blasts, is detected in up to 90% of patients with AML, and is a potential target for imatinib, a selective tyrosine kinase inhibitor of c-kit as well as of BCR-ABL, PDGFR, and ARG. Previous reports of treatment with single-agent imatinib at 400 mg/day showed no response in AML (Cortes et al, Cancer 2003), while up to 24% of patients treated with 600 mg/day responded (Kindler et al, Blood 2003, Abstract 3242). Little information is available on the response in AML to imatinib as a single agent at 800 mg/day. CASE AND DISCUSSION. A 42-year old Caucasian male with relapsed c-kit expressing AML with del(9q), concurrent secondary high-grade (HG) glioma and few remaining therapeutic options presented to our service. He was initially diagnosed with primary oligodendrioglioma in January 2001 and underwent subtotal tumor resection, followed by whole brain radiation therapy, followed by 6 cycles of procarbazine, CCNU, and vincristine (PCV) chemotherapy, and entered complete remission (CR). In December 2002, he was diagnosed with AML M2 with del(9q) and was treated with cytosine arabinoside (Ara-C) and daunorubicin (7+3), followed by 3 cycles of consolidation with HD Ara-C, and entered CR. In March 2004, he had recurrent abnormal magnetic resonance imaging of the brain and HG malignant glioma was diagnosed by stereotactic biopsy. He was started on temozolamide but was unable to tolerate treatment due to pancytopenia, and a bone marrow (BM) at another institution disclosed relapsed AML with 75% blasts. Upon presentation to our institution, a BM examination showed > 90% blasts, 53% of which expressed CD117 positivity by FC. Imatinib therapy was initiated at a dose of 400 mg/day and escalated to 800 mg/day (HD) after lack of response. (Table 1.) The peripheral blood (PB) white blood cell count (WBC) peaked on Day 9 of treatment with imatinib and declined thereafter. On Day 21, blasts were undetectable in the PB and there was a proportional increase of PB neutrophils (PMN). By Day 25, the BM blasts decreased to 50% and only 12% blasts showed positivity for CD117. The patient experienced severe muscle/bone pains at the start of imatinib therapy, which resolved within five days. Response to HD imatinib was also accompanied by dramatic decline in serum LDH. The patient’s platelet (PLT) count improved to a peak of 70k on Day 14, declined thereafter, and the patient required PLT transfusion support by Day 31. The patient also received dexamethasone 4 mg q6h for his HG glioma, which remained stable during this time of observation. CONCLUSION. Our case demonstrates that HD imatinib 800 mg/day has significant preferential activity against the CD117+ AML blasts, is active in a shorter time span than previously reported at lower doses, and should be studied further in combination with other agents in AML. The patient’s HG glioma may have been partially stabilized by imatinib as PDGFR overexpression has been reported in secondary glioblastomas. Table 1. Imatinib Dose, mg/day Day WBC x 10-3/uL PMN, % PB Blast, % BM Blast,% BM Blasts CD117 +, % PLT x 10-3/uL - −7 1.8 4 15 > 90 53 34 400 1 17.5 3 21 - - 28 600 7 59.6 5 40 - - 50 800 8 71.0 9 21 - - 41 800 9 100.0 9 30 - - 31 800 14 11.0 22 25 - - 70 800 21 6.3 61 0 - - 31 800 25 4.0 49 0–3 50 12 13

Abstract Abstract 2065 Poster Board II-42 Background: Hypomethylating agents have significant clinical activity in myelodysplastic syndromes (MDS) and AML. In AML, we recently demonstrated a novel epigenetic mechanism of action for the proteasome inhibitor bortezomib (Liu, Blood 2008). Bortezomib induced hypomethylation of leukemic cells in vitro and in vivo via depletion of the Sp1/NF-kB transcriptional activation complex on the DNA methyltransferase 1 (DNMT1) gene promoter, which results in down-regulation of DNMT1 mRNA and enzyme, DNA hypomethylation and re-expression of otherwise hypermethylated target genes. Based on this preclinical work, we designed a phase I dose escalation study of 5-azacytidine (AZA) in combination with bortezomib in AML. Methods: Adults with relapsed or refractory AML by WHO criteria and preserved organ function with ECOG ≤2 were eligible. Previous decitabine or AZA was permitted. Patients received AZA at 75mg/m2 IV daily for days (d) 1-7. Bortezomib was gradually dose escalated–dose level 1 (DL 1): 0.7mg/m2 by IV push given immediately after AZA on d 2 and 5; DL 2: 0.7mg/m2 on d 2, 5, 9, and 12; DL 3: 1.0mg/m2 on d 2, 5, 9, and 12; and DL 4: 1.3mg/m2 on d 2, 5, 9, and 12. Cycles were repeated every 28 d, regardless of count recovery or response at least until 3 cycles were administered. Responses were graded by International Working Group criteria for AML (Cheson, JCO 2003). Bortezomib was discontinued after 3 cycles if no objective response of complete remission (CR), CR with incomplete count recovery (CRi), or partial remission (PR) was achieved, but AZA could be continued beyond this timepoint in the absence of disease progression. For responding patients, 12 or more cycles of therapy were permitted. Dose limiting toxicities (DLT) were assigned for cycle 1 of therapy. Given the high likelihood of infection in this population regardless of therapy, infection was not considered a DLT. Six additional patients were treated at the recommended phase 2 dose (RP2D). Results: 23 patients were enrolled with a median age of 65 years (range, 42-81) and had received a median of 2 prior inductions (range, 1-5). Median presenting WBC was 3,700/uL (500-59,100/uL); median BM blast was 26% (2-93%). 14 patients were refractory to last therapy received, including 4 with primary refractory AML. 9 patients had relapsed disease; all but 2 of these had prior CR duration <1 year. Patients received a median of 2 cycles of study therapy (range, 1-12+ cycles). Dose escalation was halted once the target bortezomib dose was reached; the RP2D was AZA at 75mg/m2 d 1-7 plus bortezomib 1.3mg/m2 d, 2, 5, 9, 12. Though no toxicities were considered to be DLT in this study, infection and/or febrile neutropenia were universal. Death within 8 weeks occurred in 5 patients (22%) due to pneumonia (1), sepsis (1), or progressive disease (3). Two patients had discontinuation of bortezomib after 2 cycles due to Grade 3 neuropathy; only 1 patient received bortezomib beyond 3 cycles. In 3 patients without objective response (and with no progression), AZA alone was continued after 3 cycles of combination therapy; each reported a subjective improvement in fatigue without bortezomib. Overall, the objective response rate was 26% (6/23). Responses were as follows: 3- CR, 2- CRi, and 1-PR. One CRi patient (in cytogenetic remission also) who discontinued study treatment after 2 cycles due to unrelated trauma subsequently had complete count recovery, but a repeat marrow examination was not performed. Three patients went on to allogeneic transplantation due to response achieved. Response followed the typical pattern of azanucleoside activity, requiring more than one cycle of therapy; the median number of cycles to initial response was 2 (range, 1-5). 5/6 responders had response to combination therapy; one patient responded following 5 cycles of treatment, the last 2 cycles with AZA as a single agent. Conclusions: The combination of 5-azacytidine and bortezomib is well tolerated and active in this cohort of relapsed or refractory AML patients. Additional studies to further elucidate the role of proteasome inhibition as a mediator of hypomethylating activity in AML are warranted. Correlatives studies are ongoing. Disclosures: Blum: Celgene: Research Funding.