Reduction In Bone Marrow Blasts Research Articles

Haploidentical cellular therapy in elderly patients with acute myeloid leukemia: Description of its use in high risk patients

Guo et al. reported an innovative approach for the treatment of acute myeloid leukemia (AML) in a 2011 issue of Blood 1. The report showed for the first time that the infusion after chemotherapy of peripheral blood stem cells (PBSC) from haploidentical donors significantly improved the outcome in elderly AML patients, without major toxicities. After an initial engraftment, haploidentical donor cells are rejected by the host immune response. Indeed, the precise mechanism of action of this cell-therapy procedure is not fully understood and several mechanisms have been hypothesized to explain its beneficial effects: (i) donor allogeneic Natural killer (NK)- or T-cells might exert a direct cytotoxicity on leukemic cells; (ii) a proinflammatory effect of the allogeneic host–donor interaction might trigger an autologous antitumor immunity; and (iii) cell-therapy might induce modifications in leukemic cells or in stromal/vascular cells that ultimately elicit an autologous immune responses. So far, the data obtained, Guo et al. have not been confirmed by other groups worldwide. We recently treated with this protocol three elderly patients with high-risk AML. Compared to the Chinese experience, the patients were all affected by high-risk AML. As summarized in Table 1, Patient #1 had treatment-related AML following prolonged chemotherapy (six total lines) for ovarian cancer and her blasts had a mixed phenotype with complex karyotype. Patients #2 and #3 had AML with myelodysplasia-related changes, one of them (Patient #2) had received four azacitidine courses, with poor response and worsening of both hematological and clinical conditions. Institutional ethics approval was obtained for the use of this treatment protocol. All three patients received an induction regimen (a “3+7” regimen with mitoxantrone and ara-C) followed by the infusion of Granulocyte colony-stimulating Factor (G-CSF)-mobilized PBSC from haploidentical familial donors, according to the original protocol 1. The potential reactivity of patient T-cells against their haploidentical counterparts was proved in vitro by mixed lymphocyte reaction. This in vitro reactivity resulted in vivo in graft-rejection, with detectable microchimerism in only one patients and absence of acute or chronic Graft versus Host Disease (GVHD) in all patients. As detailed in Table 1, Patient #1 had a partial response, with Bone Marrow (BM) blast reduction from 90 to 45%. She then received an intensified salvage regimen (high-dose ara-C and idarubicin plus cyclosporine to overcome Minimal Residual Disease (MRD) resistance) 2, followed by a second infusion of haploidentical PBSC. After this cycle, she had a complete hematological recovery, and the BM aspirate showed complete remission of disease at flow cytometry. Six weeks later, AML relapsed; the patient was not further treated and died shortly thereafter. Patient #2 and #3 received 1 infusion of haploidentical PBSC after induction chemotherapy. Patient #2 was refractory, he refused further treatment and died few weeks later. Patient #3 achieved Complete Remission (CR); however, she was unable to receive consolidation therapy due to the development of fungal endophthalmitis and chronic sinusitis by Fusarium. She completely recovered within 3 months, with a mild residual chronic renal insufficiency. Despite lack of consolidation therapy, she is still in CR at 11 months of follow up. Our observation in high-risk elderly AML patients confirms that infusion of haploidentical-mobilized PBSC following induction chemotherapy is feasible and safe. Compared to Guo et al. 1, 3, we applied the strategy in AML patients with very unfavorable prognosis, two of them previously treated either with multiple chemotherapy lines or with repeated azacitidine courses. In spite of previous treatments, the haploidentical infusion did not induce acute GVHD. Considering the presenting features, the achievement of CR in two of three patients was encouraging and somehow unexpected, especially for the long-surviving patient who achieved CR after a single course of chemotherapy followed by haploidentical PBSC infusion. Finally, the two patients achieving CR had a leukothrombocytopenia duration shorter than one might have expected, suggesting a possible role of the infused cells in favoring hematopoietic recovery. We conclude that the “nonengraftment haploidentical cell-therapy” is feasible also in high-risk and previously treated AML patients, although the real efficacy in this setting needs to be further investigated 4. Indeed, based on our preliminary experience, a prospective trial will be launched soon to evaluate the procedure in elderly AML patients, including AML secondary to myelodysplasia, either untreated or after azacytidine, therapy-related AML as well as de novo AML A. Cignetti,1,2* M. Ruella,1,2 A. R. Elia,2 V. Tassi,3 V. Redoglia,4 D. Gottardi,1C. Tarella1,2 1University Division of Hematology and Cell Therapy, Mauriziano Hospital and University of Torino, Torino, Italy 2Molecular Biotechnology Center (M.B.C.), University of Torino, Torino, Italy 3Blood Bank, Molinette Hospital and University of Torino, Torino, Italy 4Division of Hematology, Molinette Hospital and University of Torino Torino, Italy

Azacitidine in patients with WHO-defined AML – Results of 155 patients from the Austrian Azacitidine Registry of the AGMT-Study Group

ObjectiveThe Austrian Azacitidine Registry is a multi-center database (ClinicalTrials.gov: NCT01595295). The nature and intent of the registry was to gain a comprehensive view of the use, safety and efficacy of the drug in a broad range of AML-patients treated in real-life scenarios.Patients and methodsThe sole inclusion criteria were the diagnosis of WHO-AML and treatment with at least one dose of azacitidine. No formal exclusion criteria existed. A total of 155 AML-patients who were mostly unfit/ineligible for intensive chemotherapy, or had progressed despite conventional treatment, were included. True ITT-analyses and exploratory analyses regarding the potential prognostic value of baseline-variables/performance-/comorbidity-/risk-scores on overall survival (OS), were performed.ResultsIn this cohort of 155 pretreated (60%), and/or comorbid (87%), elderly (45% ≥75 years) AML-patients, azacitidine was well tolerated and efficacious, with an overall response rate (CR, mCR, PR, HI) of 45% in the total cohort (ITT) and 65% in patients evaluable according to IWG-criteria, respectively. Pre-treatment with conventional chemotherapy (P = .113), age ≤/>80 years (P = .853), number of comorbidities (P = .476), and bone marrow (BM) blast count (P = .663) did not influence OS. In multivariate analysis hematologic improvement alone (without the requirement of concomitant bone marrow blast reduction), although currently not regarded as a standard form of response assessment in AML, was sufficient to confer OS benefit (18.9 vs. 6.0 months; P = .0015). Further deepening of response after first response was associated with improved OS (24.7 vs. 13.7 months; P < .001).ConclusionsIn this large cohort of AML-patients treated with azacitidine, age >80 years, number of comorbidities and/or BM-blasts >30% did not adversely impact OS.

Phase II Study of Bortezomib as a Single Agent in Patients with Previously Untreated or Relapsed/Refractory Acute Myeloid Leukemia Ineligible for Intensive Therapy

We explored the safety and efficacy of bortezomib given as single agent in patients with untreated or relapsed/refractory acute myeloid leukemia (AML), unfit for conventional chemotherapy. Fourteen patients were treated with bortezomib 1.5 mg/m2 administered twice weekly for two weeks, every 3 weeks. Median age was 70 years (range 60–81) and the median number of cycles delivered was 2 (range 1–4). Of 13 evaluable patients, in 8 (61%), the administration of bortezomib resulted in an antileukemic effect as demonstrated by peripheral blood and/or bone marrow blast reduction. In 4 (50%) of these 8, a decrease by 37% of transfusion requirement was also observed (P = 0.009). Overall median survival was 4 months (range 0.25–10). Neurotoxicity was the most frequent adverse event with 7 of 13 (54%) patients experiencing grades 3-4 peripheral neuropathy. Neurotoxicity led to treatment discontinuation in 4 (57%) of 7. In conclusion, the observed anti-leukemic activity of bortezomib indicates that there is room for designing additional studies in which combination with other chemotherapeutic agents should be considered. Clinical registration no.: EUDRACT 2006-006923-38.

Targeted Alpha-Particle Immunotherapy with Bismuth-213 and Actinium-225 for Acute Myeloid Leukemia

ABSTRACT Lintuzumab, a humanized anti-CD33 antibody, targets myeloid leukemia cells and has modest activity against acute myeloid leukemia (AML). To increase the antibody's potency yet avoid nonspecific cytotoxicity seen with β-emitting isotopes, lintuzumab was conjugated to the α-emitters bismuth-213 (213Bi) and actinium-225 (225Ac). The 46-minute half-life of 213Bi limits its widespread use. Therefore, 225Ac was also conjugated to various antibodies using DOTA-SCN. We conducted a phase I trial of 213Bi-lintuzumab and subsequently administered cytarabine with 213Bi-lintuzumab in a phase I/II study. The toxicity and biological activity of 225Ac-linutuzumab in patients with relapsed/refractory AML in a phase I dose-escalation trial was determined. An initial phase I trial demonstrated the feasibility, safety and antileukemic activity of 213Bi-lintuzumab. 213Bi-lintuzumab produced responses in 24% of AML patients receiving doses ≥ 37 MBq/kg after partial cytoreduction with cytarabine. 225Ac-labeled immunoconjugates killed in vitro at doses at least 1,000 times lower than 213Bi analogs. Eighteen patients with relapsed/refractory AML received 18.5 to 148 kBq/kg of 225Ac-lintuzumab in a phase I study. Dose-limiting toxicities were myelosuppression lasting &gt;35 days in one patient and death due to sepsis in two patients. The maximum tolerated dose (MTD) was 111 KBg/kg. Bone marrow blast reductions were seen across all dose levels. Targeted α- particle immunotherapy with 213Bi- and 225Ac-lintuzumab is safe, has significant antileukemic effects, and can produce remissions after partial cytoreduction. How to cite this article Jurcic JG. Targeted Alpha-Particle Immunotherapy with Bismuth-213 and Actinium-225 for Acute Myeloid Leukemia. J Postgrad Med Edu Res 2013;47(1): 14-17.

BCL-2 Inhibition with ABT-737 Prolongs Survival in an NRAS/BCL2-Mediated MOUSE MODEL of Myelodyspastic Syndrome (MDS) Progressing to ACUTE Myelogenous Leukemia (AML) by Targeting Leukemia Initiating CELLS

AbstractAbstract 678 Background and aims:BCL-2 activation plays a role in the progression of MDS to AML and BCL 2 inhibition may represent a therapeutic target in such patients. Using our double transgenic mouse model MRP8[NRASD12/BCL2], in which the transgenes induce MDS progressing to AML with dysplasia (Omidvar Cancer Res, 2007), we assessed the effect of ABT-737, a small molecule and mimetic inhibitor binding the BH3 domain of the BCL-2 family of proteins, on survival and leukemia initiating cells (LIC) in this mouse model. Methods:In this MRP8[NRASD12/hBCL2] double transgenic mouse model 2-week old mice have MDS with a mean of 6% bone marrow (BM) blasts (compared with 3% in the normal wild type littermates), while adult mice have AML, with a mean of 60% marrow blasts. In the present study, double transgenic mice were treated just after weaning and genotyping at 3 weeks of age with 75 mg/kg dose of ABT-737 (MDA & Abbott) 3 times weekly for 30 days. A cohort of mice (60 untreated and 35 treated) was followed for survival. Mice were sacrificed and BM harvested after treatment and Giemsa stained for BM analysis by microscopy (n=6 in each group), for LICs characterized as part of the lineage negative (Lin-)/Sca1+/cKit+ (LSK) population by flow cytometry (in 8 treated and 12 untreated mice), and for progenitor assays (n=4 in each group). Hematoxylin and eosin stained liver sections were examined and apoptosis assessed by the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL) assays of liver sections (n=4 per group). RNA was extracted from Sca+ enriched spleen cells from untreated and treated mice (n=3 from each group) and assayed for gene expression profiling using exon specific arrays (Affymetrix). Results:Survival from birth of 35 treated mice was significantly longer than for 60 untreated mice (p<0.0001) underscoring drug efficacy and tolerance (Fig. 1). This correlated with a reduction of bone marrow blasts (19%±7% in treated versus 60%±6% in untreated mice, p<0.0001). After ABT-737 treatment, the proportion of BM LSK cell population decreased to nearly normal levels (normal wild type littermates mean of 3%, n=4) (12.9±1.4 in untreated versus 6.4±1.1 in treated, p<0.005)) with a complete restoration of colony growth to normal range (40±10 in wild type normal mice, 79.6±7.0 in untreated versus 48.6±13.5 in treated, p<0.01). Decreased invasion of the liver and spleen was observed due to increased apoptosis (3±2 in untreated to 50±12% in treated, p<0.001). Exon specific gene expression arrays with Sca1+ enriched splenocytes showed that 997 genes were differentially expressed between the treated and the untreated mice; 764 and 233 genes were upregulated and downregulated respectively amongst which were upregulated genes important for stem cell development, maintenance and differentiation such as TCF712 (or TCF4), PIWII2, BRMPR1a and Spp1. This may reflect the partial restoration of normal stem cell function, which is consistent with the reduced LSK and progenitor numbers. Downregulation of anti-apoptotic genes such as BCL-2a1b or upregulation of pro-apoptotic genes such as PARP4, CALPAIN2, TNFR, and CARD was observed, consistent with the TUNEL data. Restoration of normal hematopoiesis was confirmed by the upregulation of myeloid differentiation genes (CD14, CSF1, RARalpha) and down regulation of genes implicated in cell cycle (Hsp60, MYC and E2F1). Conclusions:ABT-737 extends lifespan in NRASD12/BCL2 transgenic mice, a preclinical model of high risk MDS/AML. ABT-737 targets the leukemia initiating cell, and regulates, amongst several, cell cycle (proliferation), differentiation and apoptosis pathways. These data suggest that clinical trials in high risk MDS and AML patients are warranted. [Display omitted] Disclosures:Grange:Genosplice Technology: Employment.

Phase 2 Trial of the Farnesyltransferase Inhibitor Tipifarnib in Previously Untreated Older Adults with AML and Baseline Presence of a Specific 2-Gene Expression Signature Ratio

AbstractAbstract 1508 Background:Tipifarnib is an orally bioavailable farnesyltransferase inhibitor with well-established antileukemic activity in a minority of unselected patients with AML. Seeking to identify patients most likely to have tipifarnib-responsive AML, we applied a PCR-based quantitative 2 gene expression signature ratio (RASGRP1:APTX), which had been tested and validated retrospectively as a predictor of response and survival in previous large studies of tipifarnib, as a molecular screening tool for selection of patients to this pilot trial. Objectives:1) primary: to determine the complete response (CR +CRi) rate in AML patients prospectively selected for tipifarnib treatment on the basis of a 2-gene signature (RASGRP1:APTX ratio) in bone marrow aspirates. 2) secondary: to assess safety, overall survival, and immunophenotypic expression of RASGRP1 on baseline bone marrow blasts for correlation with PCR-based detection. Methods:This was a multicenter, open-label, phase 2 study. Key eligibility criteria included 1) patients with previously untreated AML, age ≥65 years and deemed unsuitable for or refusing traditional induction chemotherapy, and 2) RASGRP1: APTX ratio of ≥5.0 (measured in bone marrow aspirate) based upon qRT-PCR. Other inclusion criteria included: ECOG PS 0–2, adequate end-organ function, and WBC < 30,000/microliter. Treatment consisted of Tipifarnib 300 mg BID × 21 days, with 7 days off. Dose escalation to 600 mg BID following cycle 1 was permitted for patients who had stable disease (SD) after cycle 1. Patients who achieved CR/CRi or PR after 2 cycles were eligible to continue treatment for up to 6 cycles maximum. Results:A total of 62 patients were consented to the trial. Of these, 21 (34%) were eligible based upon the required 2-gene ratio. Assay results were reported within 72 hours for all patients. Median age was 75 years. Fourteen (67%) patients had adverse karyotype and 14 (67%) had secondary AML (including 7 patients who received prior therapy for MDS). Three patients were replaced during cycle 1, due to withdrawal of consent or early unrelated death, such that 18 patients were considered evaluable for response. Median RASGRP1:APTX was 14.8. Two patients (11%) achieved CR and 6 (33%) additional patients had both SD and achievement of ≥50% reduction in bone marrow blasts by completion of cycle 2. Two of these 6 patients also had ≥50% increase in peripheral blood neutrophils or platelets. All 8 patients with CR or SD received at least 2 cycles of therapy. There was no correlation between baseline RASGRP1:APTX ratio and response. Overall, tipifarnib was well tolerated. Early death (≤ 30 days) was observed in only 1 patient (5%). The most common therapy-related non-hematologic toxicities (mainly grade 1–2) included: anorexia (33%), nausea (33%), fatigue (28%), febrile neutropenia (23%) and diarrhea (23%). Due to the trial not meeting its primary endpoint of at least 3 CR/CRi after 2 cycles, accrual to the trial was suspended. Conclusion:Monotherapy with tipifarnib in preselected elderly patients with AML and a RASGRP1:APTX ratio of ≥5 was associated with significant antileukemic activity and good tolerance. Although the primary endpoints during the first stage of the trial were not met, this study demonstrated the ability to rapidly and efficiently execute a biomarker-driven trial in an aggressive malignancy. Given the observed antileukemic activity in this selected population, along with a favorable toxicity and bioavailability profile for chronic dosing, further study of tipifarnib with less rigid endpoints than CR/CRi is warranted. Updated survival and RASGRP1 protein expression data will also be presented. Disclosures:Off Label Use: Tipifarnib in AML. Knoblauch:Johnson & Johnson: Employment. Karkera:Johnson & Johnson: Employment.

Evaluation of Rigosertib in Patients with a Myelodysplastic Syndrome (MDS) or Acute Myeloid Leukemia (AML) Relapsed or Refractory to Hypomethylating Agents: A Phase I/II Study

Abstract 3794 Background:Rigosertib is a small molecule anti-cancer agent with a multi-targeted mechanism of action. It is a multi-kinase/PI3 kinase inhibitor that promotes G2/M arrest and selectively induces apoptosis in cancer cells. Leukemic cells exhibit significantly higher levels of sensitivity to rigosertib compared to normal marrow progenitors and increasing cytotoxicity upon prolonged and repetitive exposure (Chen Proc AACR 2008). Azacitidine is first-line therapy for patients (pts) with higher-risk MDS and produces a response rate of 50%. Pts relapsed or refractory to hypomethylating agents have a short life expectancy of approximately 4 to 6 months (Jabbour 2010, Prebet 2011). There are no approved second line therapies for this patient population. Methods:A phase I/II study of Rigosertib is being conducted in pts with MDS and AML. Pts with higher-risk disease had to have failed a hypomethylating agent. In the phase I component, pts were entered in cohorts of escalating doses in a classic 3+3 design ranging from 650 up to 1700 mg/m2/d continuous IV infusion (CIV) for durations from 72 hours to 144 hours every 2 weeks (1 cycle) for 4 cycles of treatment during the induction phase. Subsequent treatments were administered every 3 to 4 weeks. A maximum tolerated dose of 1375 mg/m2 was identified for the phase II component, and subsequent pts were treated with this dose as a CIV for 72 hours. A CBC was performed weekly and a bone marrow (BM) was performed at baseline and week 4, 8, and then q3 months afterwards. Results:Twenty-one patients with MDS or AML refractory/relapsed to a hypomethylating agent have been treated with rigosertib. The study cohort comprised pts with a diagnosis of intermediate-2 MDS (2 pts), high risk MDS (5 pts), chronic myelomonocytic leukemia (1 pt), and AML (13 pts) (all AML had an antecedent MDS). The median age was 79 years. 86% of pts were male. Patients received between 1–19 cycles of treatment. Their cytogenetic profiles were diverse with the most recurrent abnormalities including a complex karyotype (5 pts), normal (5 pts), monosomy 7 (4 pts), and trisomy 8 (2 pts). Responses according to IWG 2006 criteria were observed in the BM and peripheral blood: marrow CR (4), hematologic improvement (HI) (2); erythroid (1) platelet (1). Time to response was 2–4 cycles. An additional 2 pts had a >50% BM blast decrease from baseline but not to < 5%. Three pts had stable disease after treatment but their courses were complicated by infections requiring hospitalization and removal from the study. Three pts were deemed to be inevaluable because they received less than 2 cycles of treatment or did not have a follow-up bone marrow evaluation. Thus, 9/18 evaluable pts (50%) demonstrated either a bone marrow/peripheral blood response (6) or stable disease (3). The median overall survival of those with marrow CR+PR was 10.1 months versus 2 months for those without a bone marrow response (p=0.0011, log-rank test). Of those pts who did not respond or were inevaluable, the majority (83%) had AML, many with a proliferative course. The most frequent grade 1–2 side-effects included dysuria, hematuria, fatigue, anorexia, nausea, and diarrhea. Possibly related grade 3 side-effects included fatigue, hematuria, and dyspnea, each in one pt. Six of 21 pts developed cystitis manifested by dysuria and/or hematuria. Among responding or stable patients, 5 of 9 had cystitis compared with 1 of 12 non-responders. Patients who developed symptomatic cystitis were treated with sodium bicarbonate with improvement. The relationship between dysuria and/or cystitis and response is being investigated. Conclusions:Rigosertib appears to be safe and well tolerated in patients with refractory or relapsed MDS and AML. It has biologic activity with reduction in BM blasts and improvement in the peripheral blood counts in a subset of treated pts, and these effects are associated with increased survival. Dysuria/cystitis may be a response related biomarker and requires further analysis. Data regarding pharmacokinetics and pharmacodynamics will be presented and correlated to response. Given promising initial results, a phase III multicenter randomized trial is underway to compare rigosertib to best supportive care with a primary endpoint of overall survival in patients with higher risk MDS who have failed, progressed, or relapsed after treatment with hypomethylating agents. Disclosures:Reddy:Onconova: Research Funding. Holland:Onconova: Research Funding. Wilhelm:Onconova: Employment, Equity Ownership. Silverman:Onconova: Research Funding.

Targeting Hypoxia and AKR1C3 with PR104 in Patients with Acute Leukemia

Abstract 3615We have recently demonstrated vast expansion of hypoxic areas in the leukemic microenvironment (Benito et al, PLoS One,2011; 6: e23108). These findings provided rationale for utilization of hypoxia activated pro-drugs (HAP). The pre-prodrug PR104 is rapidly converted systemically to its alcohol metabolite PR104A, which then undergoes metabolic activation to DNA-crosslinking nitrogen mustards catalyzed by hypoxia-dependent reductases, and by aldo-keto reductase 1C3 (AKR1C3), independently of hypoxia. Impressive activity in murine leukemia models, high AKR1C3 expression in AML blast cells (Birtwistle et al., Mutat Res 2009; 662: 67) and the observation of dose-limiting myelosuppression in solid tumor phase 1 studies (Jameson et al., Cancer Chem Pharmacol 2010;65:791) served as rationale for a Phase I/II Study of PR104 in patients (pts) with relapsed/refractory acute leukemia. To evaluate the extent of bone marrow (BM) and peripheral blood (PB) hypoxia at different time points, the hypoxia marker Pimonidazole (PIM) was administered intravenously in consenting patients. Further, AKR1C3 activity was monitored in acute leukemia blasts. Methods:Pts with relapsed/refractory AML or ALL ≥1 prior treatment received PR104 with response and toxicity assessed by day 42. Hypoxia tracer PIM was infused over 20 min at 0.5 g/m2 prior to a BM biopsy and collection of PB at baseline, day 14 (D14) or D28 relative to PR104 administration. Degree of hypoxia was determined by FACS 16 (+/− 6) hrs after PIM administration. The activity of AKR1C3 was measured with a coumberone fluorogenic assay, using SN34037 as a selective AKR1C3 inhibitor, in BM biopsies or PB prior to PR104 administration and was compared to BM or PB samples from normal donors. Results:The clinical outcomes of the entire study will be reported separately. At MD Anderson Cancer Center, 39 pts have received PR104 at doses of 1.1 (3pts), 1.6 (1pt), 2.2 (1pt), 3 (17pts) or 4 gm/m2 (17pts) as 1-hr intravenous infusion q 2 wks for up to 3 cycles. Nineteen (49%) had ≥2 prior treatments and 34 (87%) had a first CR duration of <52 wks. Five pts (13%) had reduction of BM blasts by > 50 percent from baseline on D14. Additionally, 9 pts (23%) had BM aspirates on D14 that yielded insufficient samples and therefore the % of blasts could not be assessed. Four of 34 patients (12%, 95% CI) at 3 or 4g/m2 had responses and proceeded with stem cell transplant. No responses were seen in the 5 patients given PR104 at doses < 3gm/m2.The extent of hypoxia was evaluated by PIM in BM on Day 14 after PR104 in 12 pts using FACS : in 3 pts with clearance of BM blasts, the % PIM+ cells ranged from 0.2% to 9.7%, while in 9 pts with persistent disease, hypoxic cells represented 7.3%-99% of the BM cells. In 3 pts, all with persistent disease, PIM was also administered prior to PR104, and PIM baseline positivity was compared to PIM on D14 or D28 post PR104. In 2 cases the % of PIM+ cells went up from 10% to 20% (% BM blasts: baseline=15; D14=hypocellular) or from 0.6% to 4% (% BM blasts: baseline=75;D18=28) respectively while in the other there was no significant change between the two time points and the %PIM+ cells remained at 7% (% BM blasts: baseline=48%; C1D14=72%). Low level hypoxia in these 3 pts was associated with lack of response to PR104. When possible, PIM staining was compared in BM vs PB samples (N=13). Hypoxic cells were readily detectable in PB consistent with preclinical data by Azab et al. (Blood, 2012, 119:5782), although the % of PIM+ cells was lower than in BM (Average %PIM+ cells: BM 14.4+/−4.5; PB 9+/−3.7), suggesting that these circulating “hypoxic” cells have been labeled by PIM in the BM and subsequently egressed into PB. The activity of AKR1C3 reductase was higher in AML (N=4) or ALL samples (N=6) than in normal PB or BM (N=4) (average AML=2.08+/−0.52; ALL=1.22+/−0.46; NBM=0.77+/−0.007; NPB=0.27+/−0.008). There was no correlation between pre-treatment AKR1C3 activity and achievement of CR. Conclusions:This is the first study measuring hypoxia in patients with leukemia using PIM hypoxia tracer. PIM expression after PR104 administration indicates that hypoxia is a prevalent feature of the leukemic microenvironment and associates with disease burden. AKR1C3 appears to be upregulated in acute leukemias and its potential as a biomarker and/or as a target should be explored. Targeting hypoxia and AKR1C3 with PR104 is feasible and warrants further evaluation in acute leukemias. Disclosures:Wilson:Proacta, Inc.: Employment, Stock Other. Melink:Proacta, Inc.: Employment, Stock Other. Estey:Proacta, Inc.: Research Funding. Gutheil:Proacta, Inc.: Employment, Stock Other. Konopleva:Proacta, Inc.: Research Funding.

A Phase I Trial of Escalating Dose of the Rapamycin Analog Everolimus in Combination with the Kinase Inhibitor Midostaurin in Patients (pts) with Relapsed, Refractory or Poor Prognosis Acute Myeloid Leukemia (AML)

Abstract 3627 Background:In pts with mutant FLT3 AML single agent studies with inhibitors of FLT3, such as midostaurin, yielded a high rate of peripheral blast reduction but complete and partial remissions were uncommon. One approach to overcome resistance is to combine a FLT3 inhibitor with an agent that down-regulates another leukemogenic pathway including those downstream to activated FLT3. Preclinical work has suggested that mTOR inhibitors, such as rapamycin or its analogs including everolimus, and the FLT3 inhibitor midostaurin synergistically kill mutant FLT3 dependent cell lines. Aims:To identify the maximum tolerated dose (MTD) of everolimus that can be given in combination with 50 mg orally twice daily midostaurin (established as well tolerated and capable of decreasing peripheral blast count [Fischer JCO 2010]), to determine toxicities, to observe anti-leukemic effects, to measure pharmacokinetics of each agent when administered in combination, and to observe pharmacodynamic effects including decrease in the phospho-FLT3 to total FLT3 ratio in blasts as evidence of enzyme inhibition. Methods:In this phase I study pts were treated with a combination of midostaurin at 50 mg po BID continuously beginning on day 2 and everolimus po administered on day 1 and continuously from day 8 onward. Dose escalation of everolimus was conducted according to standard 3 + 3 schema; the doses of everolimus explored were 5 mg QOD (dose level 1) and 5 mg QD (dose level 2). An additional 15 pts were enrolled at the MTD. Results:A total of 29 pts were enrolled (24 with relapsed and/or refractory AML, 4 with newly diagnosed AML considered inappropriate candidates for standard therapy, and 1 with relapsed CMML; 11 FLTwt, 14 FLT3-ITD positive, 3 FLT3 D835Y positive, 1 FLT3 D835H positive). The mean age was 66 (range 40–85) and ECOG performance statuses were 0 in 6 pts, 1 in 16 pts, and 2 in 7 pts. After 1 of 3 pts treated at the everolimus starting dose of 5 mg QOD experienced a DLT (grade 5 infection) the cohort was expanded to 6 pts; of the latter 3 pts enrolled 1 experienced a DLT of grade 3 hypoxia. The eligibility criteria were subsequently amended so as to be more stringent, including a DLCO requirement of 50% predicted. After an additional 3 evaluable pts tolerated the 5 mg QOD dose, we escalated to 5 mg QD; 3 of 4 pts treated at this dose level experienced DLT (grade 3 hypoxia, grade 3 mucositis, grade 5 soft-tissue infection), and subsequent pts were treated at the MTD, everolimus 5 mg QOD (25 pts in total received this dose). The most common drug-related toxicities at the MTD (any grade) were fatigue (40%), nausea (32%), hypertriglyceridemia (24%), vomiting (24%), hyperglycemia (20%), and elevated AST (20%). In addition to the pt who died in the first everolimus cohort, 5/25 pts discontinued due to drug-related grade 3 toxicity, including pneumonia (1), hypoxia (2), allergic reaction (1), and nausea (1). Grade 3 events that did not result in treatment discontinuation included thrombocytopenia (1), dyspnea (2), hyponatremia (1), hypokalemia (1), gum pain (1), abdominal pain (1), pneumonitis (1), and febrile neutropenia (2).One mutant FLT3 D835Y pt achieved CR and went on to allogeneic SCT. 3 pts (2 FLT3-ITD positive, 1 FLTwt) experienced a blast response (a ≥50% peripheral or bone marrow blast reduction) with 2 of these pts ultimately progressing and 1 discontinuing due to toxicity. Overall blast response or better was achieved in 4/29 pts (14%), 8 pts had stable disease, and 17 pts had progressive disease and/or received less than 15 days of therapy (6). In the 6 pts who received less than 15 days of therapy reasons for treatment termination included grade 3 (1) and grade 5 toxicity (2), progressive disease (2), and physician decision (1). The incidence of blast response or better in FLT3mut pts (4/18, 22%) was not clearly higher than that observed in other studies involving midostaurin administered at 50 mg po BID as a single agent. Pharmacokinetic and pharmacodynamic data are being analyzed, though at least one patient’s blasts revealed a treatment-related decrease in the phospho FLT3/FLT3 ratio, suggesting enzyme inhibition. Conclusion:The combination of midostaurin (50 mg BID) and everolimus (5 mg QOD) is tolerable and has efficacy in AML, but it is unclear whether the addition of the rapamycin analog results in superior outcomes compared with midostaurin alone. Disclosures:Stone:Novartis: Consultancy, Research Funding. Off Label Use: evorlimus in AML. Griffin:Novartis: Consultancy, Research Funding. DeAngelo:Novartis: Consultancy.

Phase 1 study of an anti-CD33 immunotoxin, humanized monoclonal antibody M195 conjugated to recombinant gelonin (HUM-195/rGEL), in patients with advanced myeloid malignancies

We conducted a phase 1 study of an anti-CD33 immunotoxin, humanized monoclonal antibody M195 conjugated to recombinant gelonin (HUM-195/rGEL), in patients with relapsed, refractory myeloid leukemias. Twenty-eight patients received the construct intravenously at four dose levels (12, 18, 28 and 40 mg/m(2) per course) in a "3+3" study design. The dose-limiting toxicity was infusion-related allergic reaction including hypoxia and hypotension. The 28 mg/m(2) total dose was considered the maximally tolerated dose. Four patients developed a reduction in peripheral blood blasts of at least 50%. Three patients treated with the 10, 12 and 28 mg/m(2) doses showed a 38-50% reduction in bone marrow blasts. There was normalization of platelets in one patient treated with 40 mg/m(2). Pharmacokinetic analysis demonstrated that the highest blood levels achieved were 200-300 ng/mL which cleared with a half-life of ∼20 hours. Antigenicity was low with one patient at the 12 mg/m(2) dose and one patient at the 18 mg/m(2) dose (2/23, <10%) developing antibodies to the recombinant gelonin component after 28 days. We concluded that HUM-195/rGel can be safely administered in a multi-dose cycle to patients with advanced myeloid malignancies and warrants further investigation.

AML patients with IDH1 or IDH2 mutations treated with hypomethylating agents: A case series.

6576 Background: Isocitrate dehydrogenase 1 (IDH1) and IDH2 mutations play a significant role in acute myeloid leukemia (AML), yet optimal treatment for AML patients with IDH mutations remains unclear. IDH mutations have been associated with a globally hypermethylated genomic state, as the result of increased levels of 2-HG, a regulator of histone methylation. We sought to retrospectively determine responses of patients with IDH-mutated AML to treatment with hypomethylating agents. Methods: We reviewed clinical data for AML patients treated at The University of Texas M. D. Anderson Cancer Center from June 2001 to December 2011 whose stored leukemia samples from bone marrow aspirateshad been tested retrospectively for IDH1 and IDH2 mutations. We searched three databases that contained records for 407 AML patients. We selected patients who had been treated with the hypomethylating agents 5-azacitidine or decitabine, alone or in conjunction with other therapeutics. We retrospectively reviewed the patients’ medical records to obtain demographic, laboratory, treatment, and clinical data. We evaluated response measured by remission status, reduction in bone marrow blasts and peripheral blood blasts, and time to relapse. Results: We identified 104 patients (25.6%) who had either an IDH1 or IDH2 mutation, and of these, 8 patients had also been treated with hypomethylating agents. A ninth AML patient, who is IDH2-mutant, is currently undergoing treatment with decitabine alone. Of these 9 patients, three had a durable complete remission without recovery of blood counts (CRp), three had a partial response (PR), with or without blood count recovery, and three had no response. All 9 patients did have an initial decrease in the percentage of bone marrow blasts, peripheral blood blasts, or both. Conclusions: This series of patients demonstrates the possibility that AML patients with IDH1 or IDH2 mutations benefit from the use of hypomethylating agents, and suggests it is worthwhile to prospectively investigate treatment of patients with IDH-mutated AML using hypomethylating agents.

Phase I Trial of the Targeted Alpha-Particle Nano-Generator Actinium-225 (225Ac)-Lintuzumab (Anti-CD33; HuM195) in Acute Myeloid Leukemia (AML)

Abstract 768 Background:Lintuzumab, a humanized anti-CD33 antibody, targets myeloid leukemia cells and has modest activity against AML. To increase the antibody’s potency yet avoid nonspecific cytotoxicity seen with β-emitting isotopes, the α-emitter bismuth-213 (213Bi) was conjugated to lintuzumab. Substantial clinical activity was seen in phase I and II trials, but the use of 213Bi is limited by its 46-min half-life. The isotope generator, 225Ac (t½=10 days), yields 4 α-emitting isotopes and can be conjugated to a variety of antibodies using DOTA-SCN. 225Ac-labeled immunoconjugates kill in vitro at radioactivity doses at least 1,000 times lower than 213Bi analogs and prolong survival in mouse xenograft models of several cancers (McDevitt et al. Science 2001). Methods: We are conducting a first-in-man phase I dose escalation trial to determine the safety, pharmacology, and biological activity of 225Ac-lintuzumab in AML. Results: Fifteen patients (median age, 62 yrs; range, 45–80 yrs) with relapsed (n=10) or refractory (n=5) AML were treated to date. Patients received a single infusion of 225Ac-lintuzumab at doses of 0.5 (n=3), 1 (n=4), 2 (n=3), 3 (n=3), or 4 (n=2) μCi/kg (total administered activity, 23–402 μCi). No acute toxicities were seen. Myelosuppression was the most common toxicity; the median time to resolution of grade 4 leukopenia was 26 days (range, 0–71 days). DLT was seen in 3 patients, including myelosuppression lasting >35 days in 1 patient receiving 4 μCi/kg and death due to sepsis in 2 patients treated at the 3 and 4 μCi/kg dose levels. Febrile neutropenia was seen in 4 patients, and 4 patients had grade 3/4 bacteremia. Extramedullary toxicities were limited to transient grade 2/3 liver function abnormalities in 4 patients. With a median follow-up of 2 mos (range, 1–24 mos), no evidence of radiation nephritis was seen. We analyzed plasma pharmacokinetics by gamma counting at energy windows for 2 daughters of 225Ac, francium-221 (221Fr) and 213Bi. Two-phase elimination kinetics were seen with mean plasma t½-α and t½-β of 1.9 and 35 hours, respectively. These results are similar to other lintuzumab constructs labeled with long-lived radioisotopes. Peripheral blood blasts were eliminated in 9 of 14 evaluable patients (64%), but only at doses of ≥1 μCi/kg. Bone marrow blast reductions were seen in 8 of 12 evaluable patients (67%) at 4 weeks, including 6 patients (50%) who had a blast reduction of ≥50%. Three patients treated with 1, 3, and 4 μCi/kg achieved bone marrow blast reductions to ≤5%. Conclusions: This is the first study to show that therapy with a targeted α-particle generator is feasible in humans. 225Ac-lintuzumab has antileukemic activity across all dose levels. Accrual to this trial continues to define the MTD. Disclosures:Jurcic:Actinium Pharmaceuticals, Inc.: Membership on an entity’s Board of Directors or advisory committees, Research Funding. McDevitt:Actinium Pharmaceuticals, Inc.: Consultancy, Research Funding. Cicic:Actinium Pharmaceuticals, Inc.: Employment, Equity Ownership, Patents & Royalties. Scheinberg:Actinium Pharmaceuticals, Inc.: Membership on an entity’s Board of Directors or advisory committees, Patents & Royalties, Research Funding.

A Phase II Study of CLAG Regimen in Combination with Imatinib Mesylate in relapsed or Refractory Acute Myeloid Leukemia

Abstract 2604 BACKGOUNDThere is no standard salvage chemotherapy regimen for relapsed or refractory (RR) AML. Receptor activated tyrosine kinases such as c-kit, c-fms and PDGFR are known targets of inhibition by imatinib mesylate (IM) and are frequently expressed on AML blasts and marrow stromal cells and are therefore capable of activating survival pathways in these leukemic cells. Preclinical data suggested synergy in vitro between cytarabine and IM on AML cell growth inhibition. A phase I study demonstrated that the combination of IM with CLAG regimen was safe and feasible (Walker, et al, Leukemia Research 2008, 32(12)). We now report the results of a phase 2 clinical study of CLAG in combination with imatinib mesylate in patients with RR-AML. METHODSThis was a single-institution two-stage phase 2 study. The study was approved by scientific review committee and IRB. Eligibility criteria included RR-AML, or CML blast crisis. Key exclusion criteria were: ECOG performance status > 2, inadequate kidney or liver function tests, history of chronic liver disease, hepatitis, or HIV infection, prior therapy with CLAG regimen, or active systemic infection. Relapse was defined as evidence of disease following documented CR (complete response) or CRi (incomplete count recovery) to the most recent prior regimen (divided into early ≤ 12 months and late >12 months). Refractory disease was defined as failure to achieve CR after 2 cycles of induction chemotherapy, persistent disease (less than 50% reduction) in bone marrow blasts after one cycle, or persistent disease following the most recent salvage regimen. The CLAG regimen consisted of: Cladribine, 5mg/m2 administered via 2 hour IV daily for 5 consecutive days starting on day 2; Cytarabine, 2gm/m2 administered through a 4 hour IV starting 2 hours after Cladribine for 5 days starting on day 2; G-CSF: 300mcg SC for 6 days starting 12–24 hours (Day 1) before the first dose of Cladribine. IM 400mg orally twice daily was administered on day 2 to day 15. Re-induction was allowed if patient had partial response (PR). The primary endpoint was remission rate measured by standard AML response criteria; secondary endpoints included overall survival (OS) and progression free survival (PFS). Correlative studies included examinination for exon 8 and 17 c-kit mutations, phosphorylation status of c-kit receptor after IM exposure, and ex-vivo cell viability assays. RESULTSBetween August 2009 and April 2011, 40 patients were consented at Moffitt Cancer Center and 38 patients were treated and evaluable. The median age was 62 years (range 26–79), 22 (58%) were male, and the majority 33 (87%) were Caucasian. Seven patients (18%) had refractory AML, 19 (50%) had early relapse, and 12 (32%) had late relapse. Eight patients (21%) had prior MDS. At original diagnosis, only 2 patients had favorable risk, 18 had intermediate risk, 16 had poor risk and 2 had missing karyotype. The median duration of follow up was 9.4 months. The overall response rate (CR + CRi) for all 38 evaluable patients was 37% (CR=26%,11% CRi). Early death (within 30 days) occurred in only 2 of 38 (5.3%) patients. The CR/CRi rate in early relapse/refractory AML was 8/26 (30.8%) (95%CI 14.3–51.8) and 6/12 (50%) (95%CI 21.1–78.9%) in late relapse.The median OS was 11.1 month (95%CI 4.8–13.4), the median PFS was 4.9 month (95% CI 1.6–11.7). Among responders, 8/14 patients proceeded to allogeneic hematopoietic cell transplant.The regimen was generally well tolerated. Commonly observed non-hematologic toxicities included: edema (81%), nausea (71%), diarrhea (66%), febrile neutropenia (58%), vomiting (50%), pneumonia (40%), anorexia (32%), sepsis (29%) and rash (29%). The most common grade 3 or higher adverse events (>5% of patients) included febrile neutropenia (58%), pneumonia (34%), sepsis (29%), hypokalemia (24%)., diarrhea (11%), and rash (5%). The two early deaths were attributed to hemorrhage and hepatic failure. CONCLUSIONCLAG plus IM was well tolerated, with encouraging signs of activity in patients with poor-risk AML. Future directions for the development of this class of tyrosine kinase inhibitors (TKI) in AML include incorporation of next-generation TKIs, utilization of these agents as maintenance strategy, and identification of molecular signatures which may predict response. Updated survival and molecular correlative data will be presented. Disclosures:Komrokji:Novartis: Research Funding, Speakers Bureau. Off Label Use: Imatinib use in AML. Pinilla-Ibarz:Novartis: Research Funding, Speakers Bureau.

A phase Ib study of vosaroxin, an anticancer quinolone derivative, in patients with relapsed or refractory acute leukemia

This study of vosaroxin evaluated dose-limiting toxicity (DLT), maximum-tolerated dose (MTD), pharmacokinetics (PK), clinical activity and pharmacodynamics in relapsed/refractory leukemia. Dosing was weekly (days 1, 8 and 15) or twice weekly (days 1, 4, 8 and 11). Seventy-three treated patients had a median age of 65 years, 85% had acute myeloid leukemia and 78% had refractory disease. Weekly schedule: 42 patients received 18–90 mg/m2; MTD was 72 mg/m2. Twice-weekly schedule: 31 patients received 9–50 mg/m2; MTD was 40 mg/m2. DLT was stomatitis; primary non-hematologic toxicity was reversible gastrointestinal symptoms and febrile neutropenia. Thirty-day all-cause mortality was 11%. Five patients had complete or incomplete remissions; median duration was 3.1 months. A morphologic leukemia-free state (bone marrow blast reduction to <5%) occurred in 11 additional patients. Antileukemic activity was associated with total dose or weekly time above 1 μmol/l plasma vosaroxin concentration (P<0.05). Vosaroxin exposure was dose proportional over 9–90 mg/m2. The average terminal half-life was ~25 h and clearance was non-renal. No induction or inhibition of vosaroxin metabolism was evident. Vosaroxin-induced DNA damage was detected as increased intracellular γH2AX. Vosaroxin had an acceptable safety profile, linear PK and encouraging clinical activity in relapsed/refractory leukemia.

Clinical Activity of Azacitidine In Combination with the Oral mTOR Inhibitor Everolimus (RAD001) In Relapsed and Refractory AML: Interim Analysis of a Phase Ib/II Study

AbstractAbstract 3301 BackgroundAlthough the demethylating agent azacitidine has an established role in myelodysplastic syndromes and encouraging activity in oligoblastic acute myeloid leukemia (AML), information regarding its role in relapsed and refractory AML is still emerging. The French ATU reported an overall response rate (ORR; CR/CRi+PR) in relapsed and refractory AML of 11% (Itzykson et al. ASH 2009 #1054). In a similar population, azacitidine salvage therapy produced a CR/CRi rate of 19% (Ayari S, et al. ASH 2009 #2044). Rapamycin, an inhibitor of the AKT downstream target mammalian Target Of Rapamycin (mTOR), is reported to specifically target leukemic stem cells and orally bioavailable rapamycin derivatives, such as everolimus (RAD001), are in active clinical development. Clinical responses with single agent everolimus in relapsed, refractory AML, however, have been modest (Yee et al, Clin Cancer Research 2006 and Boehm et al, European Journal of Internal Medicine 2009). AimBuilding on our experience combining everolimus with low dose cytarabine (submitted to ASH, 2010), we have sought to investigate the feasibility and preliminary efficacy of combining everolimus with azacitidine in relapsed and refractory AML. MethodsPhase Ib/II open label dose escalation study. Patients were treated with azacitidine 75 mg/m2 s.c. daily on days 1–5 and 8–9 of each 28-day cycle with either 2.5, 5 or 10 mg everolimus orally on days 5–21 for a maximum of 12 cycles. ResultsThis preliminary analysis includes 20 patients (M 14, F 6), median age 64 years (range 17–76) receiving 2.5 mg (n=6), 5 mg (n=12) or 10 mg (n=2) everolimus. 9 (45%) had chemotherapy refractory and 11 (55%) relapsed AML after 1 (n=8), 2 (n=10) or 3 (n=2) previous lines of therapy. 7/17 (41%) had poor risk and 10/17 (59%) intermediate risk cytogenetics. 6/19 (32%) had secondary AML. The overall response rate (ORR) in 14 evaluable patients was 36% (2 CR, 3 PR). Stable disease (SD) was observed in 7 (50%) patients and 2 (14%) had progressive disease. Absolute bone marrow blast reductions from baseline in the 5 responders ranged from 9 to 88% (Figure 1). Grade 3/4 non-hematologic toxicities are summarized as follows: 2.5 mg everolimus cohort- septicemia (n=1) and mucositis (n=1, dose limiting toxicity; DLT), 5 mg everolimus cohort- septic arthritis (n=1, DLT). Febrile neutropenia during the first cycle of therapy was reported in 5/20 (25%). Safety analysis in the 10 mg everolimus cohort is ongoing. With a median follow up of 82 days, 30 day mortality was 0%. Enrolment continues to a planned 40 patients. Of interest, 2 out of 3 patients with FLT3-ITD+ AML refractory to high-dose cytarabine and antracyclines, had a striking reduction in bone marrow blasts after commencing azacitidine + everolimus (2.5 mg) therapy, with the absolute blast count falling from 95% to 16% and 92% to 5%, respectively, and lasting for at least 5 months in both. One of these patients has so far proceeded to allogeneic stem cell transplant (allo-SCT). Another patient with 3rd relapse of AML after failing allo-SCT, achieved CR after 3 cycles of treatment with azacitidine + everolimus (2.5 mg) and remains in CR after 157 days. [Display omitted] ConclusionIn relapsed and refractory AML, azacitidine in combination with the mTOR inhibitor everolimus was well tolerated and demonstrates substantial clinical activity in this advanced AML population. Further evaluation of this promising combination is ongoing. Disclosures:Wei:Novartis: Advisory board, Research Funding; Celgene: Research Funding. Off Label Use: AML therapy. Catalano:Celgene: Research Funding; Roche: Honoraria, Research Funding, Travel Grants.

Efficacy of Low Dose Clofarabine Plus Intermediate Dose Cytarabine In An Unselected AML Refractory/Relapsed Adult Population

AbstractAbstract 4349Advanced AML in adult patients is a difficult challenge for hematologists with several unsuccessful approaches attempted during the last years. We tested the combination of the new nucleoside analogue Clofarabine in association with Cytarabine in a consecutive series of adult patients with advanced acute myeloid leukemia. From April 2007 to April 2010, 29 unselected advanced disease (not M3) acute myeloid leukemia (AML) patients were included in this multicenter study. There were 14 female and 15 male. Median age was 44 years (range 22–65). Twenty patients were in second or more advanced relapse and 9 had refractory disease to one or more chemotherapy regimens. Patients were treated with one cycle of five days clofarabine 22,5 mg/m2/day together with five days cytarabine 1 g/m2/day. The low dose (22,5 mg/m2) clofarabine was selected because of the burden of therapy that our patients had already received. In 19 patients gemtuzumab ozogamicin 6 mg/m2 was added by Centre physician decision. Toxicity and remission status were defined according with WHO criteria. Partial remission was considered as improvement of peripheral blood count and reduction of bone marrow blasts > 50%). Toxicity: Grade IV haematology toxicity was recorded in all patients. Extra haematological toxicity was as follows: four patients presented ≥ grade III cutaneous toxicity, ten hepatic toxicity; three patients mucositis. Eight patients experienced a life threatening infection while in aplasia (six systemic septicemia and two pneumonia) which were ultimately fatal in four. Disease response: overall, 16 over 29 patients (55%) entered in complete remission (CR) and 4 in partial remission. Overall response rate was 69%. Outcome: over the sixteen patients who entered complete remission: 1 was lost at follow up, 1 relapsed, 1 was treated with azacitidine and 2 with another cycle of clofarabine. These three patients who received a not transplant intensification therapy are, so far, alive in complete remission. In eleven patients an allogeneic transplantation (with an unrelated or sibling donor) was performed as intensification therapy: to date, 8 of these 11 patients are alive in continuous complete remission after a median follow up of 6,5 months (2-36) while three died (two while in CR). Overall 11 (68%) of the 16 patients who entered into complete remission are alive and well. The new nucleoside analogue Clofarabine showed efficacy and synergism with cytarabine in treating AML. Even if 29/29 patients experienced grade IV haematological toxicity, infection rate was low and suitable considering the status of the disease. Extra haematological toxicity was acceptable and easily manageable. Considering the dismal outcome of these patients, we believe that intensification should be performed to allow a continuous complete remission. Indeed we were able to transplant 11/16 patients, eight of which maintained the complete remission after transplantation. Notably, 3 patients remained alive in complete remission out of a transplantation approach. It is not possible to draw any conclusion about the role, if any, of gemtuzumab ozogamicin. In summary, we showed that low dose clofarabine plus cytarabine because of efficacy and low extra-hematology toxicity could be a real bridge to allogeneic transplantation in these very poor risk pre-treated acute leukaemia patients. A longer follow up is awaited. Disclosures:Off Label Use: Clofarabine in refractpry/relapsed AML.

Evaluation of ON01910.Na In Patients with a Myelodysplastic Syndrome (MDS) or Acute Myeloid Leukemia (AML) Relapsed or Refractory to Hypomethylating Agents: A Phase I Study

AbstractAbstract 2944 Background:ON 01910.Na a novel benzyl styryl sulfone derivative is under clinical development in hematologic malignancies. It is a multi-kinase/PI3 kinase inhibitor that promotes G2/M arrest and selectively induces apoptosis in cancer cells. Leukemic cells exhibit significantly higher levels of sensitivity to ON 01910.Na compared to normal marrow progenitors and increasing cytotoxicity upon prolonged and repetitive exposure (Skidan Proc AACR 2006; Chen Proc AACR 2008). Azacitidine (AzaC), is first line therapy for patients (pts) with higher-risk MDS and produces a response rate of 50%. Pts relapsed or refractory to hypomethylating based therapies have a poor prognosis and there are no accepted effective second line treatments, thus a need for new agents. Methods:A phase I/II study of ON 01910.Na is being conducted in pts with hematological malignancies. In the phase I component pts are entered in cohorts of escalating doses in a classic 3+3 design in doses ranging from 650 up to 1700 mg/m2/d continuous IV infusion (CIV) for durations from 72 hours up to 144 hours every 2 weeks (1 cycle) for 4 cycles of treatment during the induction phase. Subsequent treatments are administered every 3 to 4 weeks. A CBC is performed weekly and a bone marrow (BM) is performed at baseline and week 4, 8, and then q3 months thereafter. Pts with higher-risk disease had to have failed a hypomethylating agent. Results:Ten pts with MDS or AML relapsed/refractory to a hypomethylating agent have been treated with ON 01910.Na thus far (table 1). The study cohort comprised pts with a diagnosis (Dx) RAEB-2 (4 pts), RAEB-T (1 pt), and AML (5 pts) (median age of 75 years). Their cytogenetic profile included 1 pt with normal, 2 with intermediate (+8), and 7 pts with poor risk cytogenetics (monosomy 7 and/or complex). Patients were treated between 5 and 70 weeks. Responses according to IWG 2006 criteria were observed in the BM and peripheral blood: Marrow CR (3), hematologic improvement (HI-P) (2); erythroid (1) platelet (1). An additional 2 pts had a >50% BM blast decrease from baseline but not to <5%. Thus, 5/10 (50%) demonstrate a bone marrow response. Survival of these pts was 7.3, 15.7, and 16.4 months; one patient remains on study 5+ months. Four of the five responders had MDS at the initiation of treatment: RAEB-2 (3), CMMoL (1), AML (1). Responders had monosomy 7 (2), trisomy 8 (1) and complex cytogenetics (2). One pt had an elimination of the MDS clone and the others had persistence of the abnormal karyotype throughout their treatment course. Five pts had SD without HI at 4 weeks, 2 pts progressed to AML. All 5 non-responders had AML; 4 with a proliferative course. These latter received only 2 (2) or 3 (3) cycles before succumbing to disease related infectious complications. Survival for these patients ranged from 1.3 – 2 months with a median duration on study of 42 days. The most frequent side effects grade2 2 for all pts included fatigue, anorexia, nausea, and dysuria in patients receiving extended duration infusions. One pt had a grade 3 urinary frequency. No hematologic toxicities occurred and no bone marrow toxicity or hypoplasia was noted. Pharmacokinetic studies are ongoing, data to date demonstrate no evidence of drug accumulation in patients who are treated repeatedly. Conclusion:ON 01910.Na appears to be safe and well tolerated in patients with refractory or relapsed MDS and AML. ON 01910.Na has biologic activity with reduction in BM blasts, eradication of the MDS clone and improvement in the peripheral blood counts in some pts. These effects are associated with increased survival albeit in limited numbers of pts treated thus far. Further study of ON 01910.Na is warranted to better define biologic activity, appropriate target populations and to define mechanism of action.Table 1Pt IDInitial Dx/OnStudy DxPrior TherapyOn Study % BM BlastsMax BM Response (IWG 2006 criteria)Dosing Cohorts (mg/m2/d) CIV# of cyclesDuration On Study (mo)OS (mo)001High/AMLAzaC80PR6501077.3002Int-1 MF/highAzaC11CR10501415.715.7003AML/AMLAzaC + saha45NR105021.62004High/highAzaC17CR10501916.416.4005Int-2/AMLAzaC91NR137521.21.5006CMMoL/CMMoLDecitabine22PR137541.64.7007Int-2/AMLAzaC66NR137531.41.7008Int-1/AMLAzaC44NR170031.41.7009MDS-MF-AML/AMLDecitabine51NR170031.21.3010Int-2/highAzaC & decitabine15CR137575+5+ Disclosures:Silverman:Onconova Therapeutics Inc: Research Funding, Research support of Clinical Trial. Wilhelm:Onconova Therapeutics Inc: Employment, Equity Ownership.

A Phase I/II Trial of the Potent Hsp90 Inhibitor STA-9090 Administered Once Weekly In Patients with Advanced Hematologic Malignancies

AbstractAbstract 3294 Background:STA-9090 is a potent, second-generation, small-molecule Hsp90 inhibitor, with a chemical structure unrelated to the first-generation, ansamycin family of Hsp90 inhibitors (e.g., 17-AAG or IPI-504). STA-9090 induces the loss of Hsp90 client proteins that are important in hematologic cancers, including BCR-ABL, c-KIT, FLT3, WT1, and JAK2. In preclinical studies, STA-9090 has shown potency up to 100 times greater than the first-generation Hsp90 inhibitors as well as activity against a wider range of kinases. In in vitro and in vivo models, STA-9090 has shown potent activity against a broad range of leukemias, lymphomas, and multiple myeloma. Methods:A safety and efficacy study of STA-9090 was undertaken for patients with acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), blast-phase chronic myelogenous leukemia (CML), high-grade myelodysplastic syndrome (MDS), and myeloproliferative neoplasms (MPN). STA-9090 was given as a weekly 1 hour infusion for 4 consecutive weeks per cycle. In the phase 1 portion of the study, an evaluation of 3 dose levels was planned: 120, 150, and 200 mg/m2; the first 2 dose cohorts are completed and dosing at 200 mg/m2 is ongoing. Plasma samples for PK analyses were collected immediately prior to infusion end (∼Cmax) on Days 1, 8, 15, and 22 in cycle 1. Additional plasma samples were collected for HSP70 protein analysis, and bone marrow aspirate and blood samples were collected for biomarker and client protein analyses. Safety assessments included the number and grade of adverse events (AEs), changes from baseline in laboratory parameters, and evaluation of electrocardiogram changes. Results:To date, 18 patients (12 males, 6 females; median age 65 years, range 21–81; Eastern Cooperative Oncology Group [ECOG] status range [0-2]) received STA-9090. Patients with the following disease types were treated: AML (n=13), ALL (n=1), biphenotypic acute leukemia (n=2), and CML without blast crisis (n=2). The median time from initial diagnosis to first treatment was 10 months; patients had received a median of 3 (range, 1–7) prior treatments and 39% were refractory to their most recent therapy. Nine patients received a median of 2.6 (range, 1–8) cycles of STA-9090 at 120mg/m2, and 9 patients received a median of 2.2 (range, 1–4) cycles of STA-9090 at 150mg/m2. AEs reported in ≥25% of patients were diarrhea, fatigue, decreased appetite, febrile neutropenia, nausea, and anemia; the majority of these AEs were mild to moderate in severity. One patient had a DLT of grade 3 elevated bilirubin at the 120mg/m2 dose. PK analyses found that STA-9090 concentrations were comparable across study days, indicative of a lack of drug accumulation. Quantitative flow cytometric analyses measuring effect of STA-9090 on Hsp90 client protein levels within leukemic marrow blasts (pre-treatment and day 9) are currently being performed. Although no formal responses in this refractory group of patients have been observed to date, one patient (a 25 year old female patient with refractory AML following 3 prior regimens, including ablative allogeneic transplantation) treated at the 120mg/m2 cohort had stable disease and bone marrow blast reduction lasting 10 weeks. Conclusions:In patients with advanced hematologic malignancies, STA-9090 has been well tolerated up to dose levels of 150 mg/m2. The recommended Phase 2 dose has not yet been determined. Accrual to the study is ongoing and updated clinical and pharmacodynamic data will be presented. Disclosures:Bradley:Synta Pharmaceuticals Corp.: Employment. Teofilovici:Synta Pharmaceuticals Corp.: Employment.

Overall Survival In Myelodysplastic Syndrome or Acute Myeloid Leukemia Patients Treated with On 01910.Na Correlates with Bone Marrow Blast Response

AbstractAbstract 3998We analyzed bone marrow (BM) response and overall survival (OS) in 48 patients (pts) with a myelodysplastic syndrome (MDS) and WHO/FAB subtypes of refractory anemia with excess blasts (RAEB) -1,- 2 or -t and acute myeloid leukemia (AML), enrolled in 4 independent ongoing clinical trials of the novel small molecule ON 01910.Na. Pts received ON 01910.Na administered as a continuous intravenous infusion (CIV) from 2 to 6 days weekly or every other week with BM response initially assessed per protocol by week 4 or 8. A BM complete response (CR) (>50% decrease from baseline BM blast and decrease below 5% for at least 4 weeks, per MDS IWG 2006 criteria) or an initial 50% decrease of BM blasts by week 4 to 8 was documented in 19/48 (40%) treated pts and was associated with a significant increase in overall survival (OS) (p = 0.0001) by the method of Kaplan-Meier (Figure 1 and Table 1). This relationship was still significant when excluding AML patients (p = 0.008). Six pts (3 RAEB-1, 3 RAEB-2) had complete BM response. Five of these six pts previously failed to respond or relapsed after azacitidine/decitabine and five out of six are alive (17 to 113 weeks follow-up; one death at 68 weeks). Eleven pts (5 AML, 3 RAEB-t, 2 RAEB-2 and 1 RAEB-1) could not be assessed at 4–8 weeks with follow-up BM evaluation; their median OS was 7.5 weeks; 9 of these 11 pts previously failed to respond or relapsed after azacitidine/decitabine. Among 10 pts with trisomy 8 cytogenetics (4 had an initial BM response), median survival was 25 weeks. FAB/WHO classification of all 48 pts was also significantly correlated with survival (Table 2, p=0.003). Overall, ON 01910.Na infusions were well tolerated. Eight pts had hematological improvements at various time points after starting therapy. Median OS was 33 weeks in the subset of 29 RAEB-1,-2,-t pts refractory or relapsing after azacitidine/decitabine, and a significant association (p = 0.056) between BM response and OS was also found in these pts (Table 1). The median survival of MDS pts who had failed to respond to prior treatment with decitabine has been reported to be approximately 17 weeks (Jabbour et al, Cancer 2010, in press). These results suggest a strong correlation between BM blast response and OS and the predictive value of BM response to ON 01910.Na for estimating overall survival of higher risk MDS or AML pts. [Display omitted] Table 1Overall Survival of Pts Treated with ON 01910.Na by BM CR and Initial (4-8 Weeks) Blast Response4–8 Week BM Blast Reduction (%)BM CR> 50% Initial Response< 50% Initial ResponseNot AssessedP value Logrank testFigure LegendRedBlueBlackGreenRAEB-1, RAEB-2, RAEB-t, & AML pts, N = 486131811Median Survival (weeks)Not reached36287.5P = 0.0001RAEB-1, RAEB-2, RAEB-t pts relapsed/refractory to azacitidine/decitabine, N = 2956126Median Survival (weeks)68Not reached333.5P = 0.056Table 2Overall Survival by FAB/WHO Classification of 48 RAEB and AML Pts Treated with ON 01910.NaFAB/WHO ClassificationRAEB-1RAEB-2RAEB-tAML (>30% BM blasts)P value Logrank testN pts1118109Median Survival (weeks)Not reached282011P = 0.003 Disclosures:Silverman:Onconova Therapeutics Inc: Research Funding, Research support of Clinical Trial. Raza:Onconova Therapeutics Inc: Research Funding, Research support for clinical trial. Greenberg:Onconova funding of clinical trial: Research Funding, Research support from Onconova for performance of this trial. Wilhelm:Onconova Therapeutics Inc.: Employment, Equity Ownership.

Treatment of FLT3-ITD Positive AML Relapsing After Allogeneic Hematopoietic Stem Cell Transplant (HSCT) with Sorafenib.

AbstractAbstract 3471AML with the internal tandem duplication of the Fms-Like Tyrosine kinase-3 gene (FLT3-ITD) has a poor prognosis, with high relapse rates. Sorafenib is an oral multikinase inhibitor of tyrosine kinases including Flt-3 with activity in AML. We used this drug to treat patients relapsing after allogeneic HSCT and herein present the results. Patients and Methods.We retrospectively evaluated 16 patients with FLT3-ITD AML that received sorafenib for at least a 7-day course either alone (n=8; 50%) or in combination (n=8; 50%) to treat AML relapsing at a median of 3 months (range, 1–7) after HSCT. Median age was 34 years (range, 20–603). Cytogenetics was diploid in 69%, high-risk in 19% and unknown in 12%. Treatment history prior to HSCT included sorafenib in 38% of the cases, and 30% were status post a 2nd HSCT. Donors were related (50%) or unrelated (50%). Seven patients (44%) received and failed other salvage chemotherapy prior to starting sorafenib (median=2 treatments; range, 1–5). At start of sorafenib salvage treatment, median WBC was 22.5 K/mm3 (range, 0.6–119), and median bone marrow blast was 58% (range, 12–88%), while 75% of the patients had circulating blasts. Sorafenib doses were as follows: 400 mg (n=3) or 800 mg daily (n=4) in combination to idarubicin/Ara-C, or 800 mg daily with 5-azacitidine (n=1); single agent: 800 mg (n=6) or 1200 mg (n=2) daily. Median duration of sorafenib single agent therapy was 39.5 days (range, 10–100), and in combination it was 7 days (range, 7–32). Complete remission (CR) rate was zero; 2 patients achieved a PR. Median reduction in bone marrow (n=9) and peripheral blood (n=12) blasts was 0% (range, 0–46), and 50% (range, 0–88), respectively. Two patients were ‘bridged’ to a 2nd HSCT, which led to CR durations of 53 and 106 days. Median survival after sorafenib initiation was 81 days and it was similar with single agent versus combination therapy (Figure 1 and 2). All patients have died. Conclusions.Treatment of overt AML relapse with sorafenib was unsuccessful as described here. It is possible that ‘pre-emptive’ treatment in the presence of minimal residual disease will be more effective, but this remains to be proven. [Display omitted] [Display omitted] Disclosures:No relevant conflicts of interest to declare.