Background: Patients (pts) with AML harboring FLT3 internal tandem duplications (ITD) have poor outcomes, in particular pts with a high ITD mutant to wild-type (wt) allelic ratio (AR; ≥0.5). The 2017 update of the European LeukemiaNet (ELN) recommendations addressed the importance of the ITD AR in the genetic risk stratification and defined distinct NPM1/FLT3-ITD genotypes. Aims: In this exploratory post-hoc analysis from randomized pts treated within the RATIFY trial evaluating the addition of midostaurin to standard chemotherapy, we investigated the prognostic impact of the NPM1/FLT3-ITD genotypes according to the 2017 ELN risk categories. Methods: In total, 319 of 717 pts with FLT3-ITD positive AML were included who gave informed consent for biomarker analyses and who could be categorized according to 2017 ELN genetic risk stratification. Median age was 47.9 years (range, 18–60); median follow-up time was 4.8 years. Results: Pts were categorized as follows: (i) favorable-risk (n = 85), NPM1mut/FLT3-ITDlow, irrespective of secondary chromosome abnormalities and concurrent gene mutations; (ii) intermediate-risk (n = 111), NPM1mut/FLT3-ITDhigh and NPM1wt/FLT3-ITDlow, both subgroups without adverse cytogenetics and without concurrent RUNX1, ASXL1, TP53 mutations; (iii) adverse-risk (n = 123), NPM1wt/FLT3-ITDhigh; as well as NPM1mut/FLT3-ITDhigh and NPM1wt/FLT3-ITDlow with adverse-risk cytogenetic and/or molecular markers; frequencies of RUNX1, ASXL1, and TP53 mutations in adverse-risk AML were 29.2%, 19.8%, and 1.9%, respectively. Rates of allogeneic transplantation (alloSCT) in first complete remission (CR) were not different among the groups, with 29.4%, 35.1%, and 35.0% in pts. with favorable-, intermediate-, and adverse-risk AML, respectively. Rates of CR (including responses after induction 1 and 2) were negatively associated with adverse-risk genetics (51.2% vs 69.4% and 64.0% in favorable- and intermediate-risk, respectively; p = 0.02); multivariable logistic regression analysis revealed adverse-risk as significantly different compared to favorable-risk (odds ratio [OR] 0.534, 95% confidence interval [CI] 0.287–0.979; p = 0.044), whereas no difference was seen between the two other risk groups; treatment with midostaurin had no impact (p = 0.32). Overall survival (OS) differed among the 3 ELN-risk groups; 5-year survival rates were 63%, 43%, 33% for favorable, intermediate- and adverse-risk groups, respectively. The OS curves did not show differential effects of midostaurin among the 3 risk groups (Figure 1), with a benefical effect seen for midostaurin vs placebo in all 3 groups with hazard ratios (HR) estimated as HR = 0.52, HR = 0.51, and HR = 0.55 for favorable-, intermediate-, and adverse-risk groups, respectively. A multivariable Cox model adjusted for age, WBC, sex, and bone marrow blasts was used to test the effects of treatment and risk classification. The resulting model revealed an increasing HR with increasing risk category (p < 0.001; intermediate vs. favorable, HR = 1.70, 95% CI 1.08–2.68; adverse vs. favorable risk, HR = 2.48, 95% CI 1.59–3.86), while treatment with midostaurin significantly reduced risk compared to placebo (p < 0.001; HR = 0.53, 95% CI 0.38–0.72).Summary/Conclusion: Data from this post-hoc exploratory analysis confirm the prognostic value of the 2017 ELN risk categories also among AML pts with the distinct NPM1/FLT3-ITD genotypes. A Cox model revealed a significant effect for midostaurin compared to placebo independent of the ELN risk groups. Analysis with regard to potential confounding effects of allogenic transplantation are ongoing.

BACKGROUNDPatients with acute myeloid leukemia (AML) and a FLT3 mutation have poor outcomes. We conducted a phase 3 trial to determine whether the addition of midostaurin - an oral multitargeted kinase inhibitor that is active in patients with a FLT3 mutation - to standard chemotherapy would prolong overall survival in this population.METHODSWe screened 3277 patients, 18 to 59 years of age, who had newly diagnosed AML for FLT3 mutations. Patients were randomly assigned to receive standard chemotherapy (induction therapy with daunorubicin and cytarabine and consolidation therapy with high-dose cytarabine) plus either midostaurin or placebo; those who were in remission after consolidation therapy entered a maintenance phase in which they received either midostaurin or placebo. Randomization was stratified according to subtype of FLT3 mutation: point mutation in the tyrosine kinase domain (TKD) or internal tandem duplication (ITD) mutation with either a high ratio (> 0.7) or a low ratio (0.05 to 0.7) of mutant to wild-type alleles (ITD [high] and ITD [low], respectively). Allogeneic transplantation was allowed. The primary end point was overall survival.RESULTSA total of 717 patients underwent randomization; 360 were assigned to the midostaurin group, and 357 to the placebo group. The FLT3 subtype was ITD (high) in 214 patients, ITD (low) in 341 patients, and TKD in 162 patients. The treatment groups were well balanced with respect to age, race, FLT3 subtype, cytogenetic risk, and blood counts but not with respect to sex (51.7% in the midostaurin group vs. 59.4% in the placebo group were women, P = 0.04). Overall survival was significantly longer in the midostaurin group than in the placebo group (hazard ratio for death, 0.78; one-sided P = 0.009), as was event-free survival (hazard ratio for event or death, 0.78; one-sided P = 0.002). In both the primary analysis and an analysis in which data for patients who underwent transplantation were censored, the benefit of midostaurin was consistent across all FLT3 subtypes. The rate of severe adverse events was similar in the two groups.CONCLUSIONSThe addition of the multitargeted kinase inhibitor midostaurin to standard chemotherapy significantly prolonged overall and event-free survival among patients with AML and a FLT3 mutation. (Funded by the National Cancer Institute and Novartis; ClinicalTrials.gov number, NCT00651261.)

Graft-versus-host disease-associated angiomatosis (GVHD-AA) is an uncommon manifestation of chronic GVHD consisting of friable vascular proliferations. Using fluorescence in situ hybridization, we demonstrate the presence of donor-derived endothelial cells within areas of GVHD-AA. This is the first documented occurrence of a benign neoplastic growth in relationship to a form of chronic GVHD.

Histone deacetylase (HDAC) inhibitors either alone or in combination with hypomethylating agents have limited clinical effect in acute myeloid leukemia (AML). Previously, we demonstrated that AML patients with higher miR (microRNA) -29b expression had better response to the hypomethylating agent decitabine. Therefore, an increase in miR-29b expression preceding decitabine treatment may provide a therapeutic advantage. We previously showed that miR-29b expression is suppressed by a repressor complex that includes HDACs. Thus, HDAC inhibition may increase miR-29b expression. We hypothesized that priming AML cells with the novel HDAC inhibitor (HDACI) AR-42 would result in increased response to decitabine treatment via upregulation of miR-29b . Here, we show that AR-42 is a potent HDACI in AML, increasing miR-29b levels and leading to downregulation of known miR-29b targets (that is, SP1, DNMT1, DNMT3A and DNMT3B). We then demonstrated that the sequential administration of AR-42 followed by decitabine resulted in a stronger anti-leukemic activity in vitro and in vivo than decitabine followed by AR-42 or either drug alone. These preclinical results with AR-42 priming before decitabine administration represent a promising, novel treatment approach and a paradigm shift with regard to the combination of epigenetic-targeting compounds in AML, where decitabine has been traditionally given before HDACIs.

DNMT3A mutations and response to the hypomethylating agent decitabine in acute myeloid leukemia

Abstract 1750 This icon denotes a clinically relevant abstract

6535 Background: The Myeloproliferative Disorder-Research Consortium (MPD-RC) designed the first U.S. prospective phase II study of allogeneic PBSC transplantation in patients with primary myelofibrosis (PMF) or MF secondary to essential thrombocythemia (ET-MF) or polycythemia vera (PV-MF). Methods: Between April 2007 and December 2009, 42 patients were transplanted with HLA matched PBSC from related (MRD) (n = 23) or unrelated (MUD) (n = 19) donors. A regimen with fludarabine/melphalan (FluMel) ± ATG was used. Patients with PMF (n = 25), ET-MF (n = 13) or PV-MF (n = 4) were all at intermediate/high risk according to the Lille score system and the majority had grade 3 marrow fibrosis. Median age was 54 years (range: 36-64). Splenomegaly was present in 79% of the patients while 17% had prior splenectomy. Results: Neutrophil and platelet engraftment occurred on d26 (range: 9-57) and d27 (range: 9-365), respectively. Graft failure/rejection occurred in 5 MUD patients. At a median follow-up of 185 days (range: 15-742), 78% of MRD patients are alive; 9 of 19 MUD cases (47%) died and 3 were taken off study. Causes of death in 5 cases in the MRD group were: GVHD (n = 2), hemorrhage, secondary cancer and relapse; and in 9 cases in the MUD group were: GVHD (n = 2), hemorrhage (n = 2), renal failure (n = 2), pulmonary toxicity, venous occlusive disease and infection. Acute GVHD ≥ grade 2 in MRD and MUD was 45% (15% grade 3-4) and 47% (10% grade 3-4), respectively. Overall clinical response according to the International Working Group criteria in patients with > 6 months follow-up in the MRD group was 79%, with CR/PR 47% and clinical improvement 32%.Transplant-related mortality (TRM) was 13%. Analysis of response rate in MUD cases has been limited by the high TRM (47%). Overall and event-free survival were superior in MRD vs MUD transplants (p = 0.005). Conclusions: Our initial findings confirm that FluMel regimen is effective and causes low toxicity in MRD transplant in MF patients. The higher TRM observed in MUD transplants may suggest a need for a more reduced intensity chemotherapy in this setting. No significant financial relationships to disclose.

7075 Background: L is active in myelodysplastic syndromes and myeloma and may also have activity in AL or CLL. Methods: A phase I dose escalation study of L in separate cohorts of relapsed AL or relapsed CLL, respectively, is ongoing. L was given initially at 25mg/day orally on days 1–21 of repeated 28 day cycles in both cohorts. Results: In AL, 12 patients (pts) have enrolled to date (11-AML) with a median age of 62 years (range, 22–79). 4 pts were treated at dose level 1 (25mg/day) and 8 at level 2 (35mg/day). One DLT was seen at level 2: an AML pt, age 79, died suddenly of uncertain cause (no pulmonary embolism), and the level was expanded. 3 pts had early progression and were replaced (pts were not evaluable for toxicity). Complete remission (CR) occurred in two pts. At level 1, a 74 year old with AML and normal karyotype in 2nd relapse, with widespread leukemia cutis but no blood/marrow involvement, had remarkable resolution of disease after 2 cycles and is in CR after 4 cycles. At level 2, a 69 year old with AML and trisomy 13 had CR (by IWG criteria, including cytogenetic CR) after 2 months. In the CLL cohort, 4 pts (ages 43–60 with 2–9 prior therapies) have enrolled. 3 pts were given the initial starting dose of 25mg/day. Each had early or late DLT including serious tumor flare in 2 cases, one with airway obstruction due to massive tonsillar adenopathy requiring emergent tonsillectomy. The tonsil had increased expression of Ki67, CD3, CD4, CD8, and granzyme B positive cells after L, relative to a pretreatment node. Due to excess toxicity with the 25mg initial dose, a 2.5mg/day dosing schedule with gradual intra-patient escalation was initiated. 1 pt has enrolled at this dose to date. Pharmacodynamic (PD) studies in CLL demonstrate L-induced B-cell activation (upregulation of CD40 and CD86) that may correlate with development of tumor flare. Conclusions: L induced CR in 2 cases of relapsed non-del 5q AML. Dose escalation continues in AL. In CLL, higher doses had unacceptable toxicity; low dose followed by gradual intra-patient dose escalation is being pursued. PD studies suggest B-cell activation may contribute to development of tumor flare in CLL. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Celgene

6515 Background: Decitabine, an inhibitor of DNA methyltransferase (DNMT) enzymes, has activity in myeloid malignancies at doses >1 log below the MTD of 2250mg/m2/course which may be optimal for DNA demethylation and minimize cytotoxicity. Methods: We designed a two step trial for AML patients (pts) to determine: Step 1, the lowest dose of decitabine to induce 100% increase in or re-expression of epigenetically silenced genes in 5/6 pts treated at a dose level; and Step 2, the MTD of the histone deacetylase (HDAC) inhibitor VA given with this dose of decitabine, and whether this MTD or a lower dose leads to 90% decrease in HDAC activity. Results: Decitabine was administered to 17 pts at two dose levels. Pts had relapsed/refractory AML (N=10) or age>60 and ineligible/refused standard therapy (N=7) and ranged in age from 36–83 years. Pts received decitabine at 15–20mg/m2/IV over 1 hr daily for 10 days (d) (3 pts also had VA 15mg/kg on days 5–21), every 28 d. Mean plasma decitabine Cmax (by a validated LC-MS/MS method) was 93 ng/ml (N=7). 10/13 pts had at least 100% increase in expression of p15 or estrogen receptor (ER, including 5/6 given 20mg/m2/d decitabine alone), and all 10 had clinical response. Of the 3 pts who did not have increased gene expression none responded. Western blotting showed depletion of DNMT protein in 4/6 pts. Bisulfite sequencing of the promoter region of ER confirmed that decitabine induced >50% decrease in methylation in the only pt yet examined (p<0.001). 9/14 pts had decrease in global DNA methylation as measured by LC-MS/MS. 10/15 pts had clinical benefit: 6 pts had clinical response, 2 with CR (1 with t-AML) and 4 with CRi (1 with a 20yr history of P. vera); 4 pts had clinical improvement-1 met all CR criteria except for BM disease by flow, 1 had platelet >100K, 2 had stabilization of disease for 4–6 months. Conclusions: We demonstrated clinical activity of low dose decitabine associated with decreased levels of the DNMT1 target and increased or re-expression of epigenetically silenced genes. Combination of decitabine at 20mg/m2/d with VA (Step 2) has begun; complete clinical results, gene re-expression/ demethylation, and histone deacetylation data will be presented. (NCI U01 CA 76576–05) [Table: see text]

6561 Background: RNR converts ribonucleotides to deoxyribonucleotides for DNA synthesis. AraC is converted into AraC triphosphate (AraCTP) and competes with deoxycytidine for DNA incorporation. We hypothesized that RNR downregulation by G leads to lower deoxycytidine levels, preferential AraCTP incorporation into DNA and increased cytotoxicity. A CTEP-sponsored Phase I dose escalation study of G +HiDAC in relapsed/refractory AML tested this hypothesis. Methods: Cohort I (18–59 yrs) received G (dose level (DL) 1: 3.5 mg/m2/d) by continuous IV infusion (CIVI) on d 1–6 + AraC IV q12 hrs on d 2, 4, 6 (DL1: 2500 mg/m2/dose). Cohort II (≥60 yrs) received G CIVI on d 1–6 +AraC IV on d 2 −6 (DL1: 1500 mg/m2/d). An ELISA-based assay measured plasma and intracellular concentration (IC) of G. Results: To date, cohort I included 9 pts with relapsed and 9 with refractory AML; 9 had intermediate and 9 adverse risk cytogenetics (CyG); 8 received prior HiDAC. Cohort II included 10 pts with relapsed and 6 with refractory AML; 8 pts had intermediate and 8 high risk CyG; 5 pts received prior HiDAC. Toxicities were comparable to HiDAC alone. The younger pts had higher AUC and longer t1/2. Of 16 pts evaluable in cohort I (median time to 1st relapse 6 mos), 6 had complete remission (CR) and 1 incomplete CR (no disease and incomplete blood count recovery). In cohort II, no responses were observed. At 120 hrs of antisense infusion, median G IC in marrow cells was higher (i.e., 175 vs75 nM) in younger than in older pts. A median 50% decrease in RNR protein was noted in 5/9 and 5/10 pts in cohort I and II, respectively. In cohort I, a median 50% decrease and 200% increase in RNR was noted in CR (n=4) and non-responder (NR; n=9) pts, respectively. In cohort II R2 downregulation did not predict response. In cohort I 62% of the ICs was in nucleus and 21.2% in cytoplasm in CR pts (n=3) vs. 20.3% and 53.5% in NR pts(n=5). Conclusions: G/HiDAC is feasible. Robust plasma and IC levels of G and target downregulation are achievable in vivo. Responses (41%) were observed only in the younger cohort, where CR pts had higher G nuclear IC and target downregulation than NR pts. Dose escalation continues in the younger cohort to establish a dose for Phase II trials. No significant financial relationships to disclose.

6568 Background: Flavopiridol is a cyclin dependent kinase inhibitor with in vitro activity in many cancer cell lines. However, phase I/II studies of either 24 or 72-hour continuous infusion schedules demonstrated no significant clinical activity. Discordant binding of flavopiridol to human plasma proteins as compared to fetal calf serum prompted us to perform pharmacokinetic modeling studies which suggested that optimal dosing would be a 30 min IV bolus followed by 4 hr IV infusion. With this schedule, our group has observed impressive clinical activity in refractory CLL. Methods: We intensified this schedule for relapsed or refractory adult AML and ALL patients (pts) to administer an IV bolus over 30 min followed by an infusion over 4 hrs on 3 consecutive days in a phase I trial. Results: To date, 10 pts have been treated at 2 dose levels. Pts had relapsed/refractory AML (N=6) or ALL (N=4) and were 25–77 yrs old. 4 pts received flavopiridol at 20 mg/m2 IV bolus and 30 mg/m2 infusion; 6 received 30 mg/m2 bolus followed by 35 mg/m2 infusion. The most significant toxicity was tumor lysis; treatment was well tolerated, and toxicities were similar to those previously reported by our group with the single day dosing schedule used in CLL. Plasma levels were 1–2 μM during the infusion (N=7) and declined with a terminal half life comparable to that previously reported with a 72 hr infusion. Significant anti-leukemic activity was seen in 5/7 evaluable pts at both dose levels. Tumor lysis was seen in both ALL and AML (see table ). Downregulation of Mcl-1 protein by immunoblotting was seen in 2/3 pts tested to date. Conclusions: Single agent flavopiridol given with this novel, pharmacologically modeled schedule has clinical activity in pts with relapsed/refractory ALL and AML. Further study in acute leukemia using this schedule is warranted; dose escalation to the current trial is ongoing. (NCI U01 CA 76576–05) [Table: see text] No significant financial relationships to disclose.

Preclinical studies with the histone deacetylase (HDAC) inhibitor depsipeptide (FK228) in chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML) have demonstrated that it effectively induces apoptosis at concentrations at which HDAC inhibition occurs. We initiated a minimum effective pharmacologic dose study of depsipeptide, targeting an in vivo dose at which acetylation of histone proteins H3 and H4 increased by 100% or more in vitro. Ten patients with CLL and 10 patients with AML were treated with 13 mg/m2 depsipeptide intravenously days 1, 8, and 15 of therapy. Neither life-threatening toxicities nor cardiac toxicities were noted, although the majority of patients experienced progressive fatigue, nausea, and other constitutional symptoms that prevented repeated dosing. Several patients had evidence of antitumor activity following treatment, but no partial or complete responses were noted by National Cancer Institute criteria. HDAC inhibition and histone acetylation increases of at least 100% were noted, as well as increases in p21 promoter H4 acetylation, p21 protein, and 1D10 antigen expression. We conclude that depsipeptide effectively inhibits HDAC in vivo in patients with CLL and AML, but its use in the current schedule of administration is limited by progressive constitutional symptoms. Future studies with depsipeptide should examine alternative administration schedules.

PURPOSES:Pharmacologic downregulation of Bcl-2, an antiapoptotic protein overexpressed in cancer, might increase chemosensitivity in acute myeloid leukemia (AML). Herein, we investigated the feasibility of this approach in untreated elderly AML patients by administering oblimersen sodium (G3139), an 18-mer phosphorothioate antisense to Bcl-2, during induction and consolidation treatments.PATIENTS AND METHODS:Untreated patients with primary or secondary AML (stratified to cohort 1 or 2, respectively) who were > or = 60 years received induction with G3139, cytarabine, and daunorubicin at one of two different dose levels (45 and 60 mg/m2) and, on achievement of complete remission (CR), consolidation with G3139 and high-dose cytarabine. An enzyme-linked immunosorbent assay (ELISA)-based assay was used to measure plasma and intracellular concentrations (IC) of G3139. Bcl-2 mRNA and protein levels were quantified by real-time reverse transcriptase polymerase chain reaction and ELISA, respectively, in bone marrow samples collected before induction treatment and after 72 hours of G3139 infusion, prior to initiation of chemotherapy.RESULTS:Of the 29 treated patients, 14 achieved CR. With a median follow-up of 12.6 months, seven patients had relapsed. Side effects of this combination were similar to those expected with chemotherapy alone and were not dose limiting at both dose levels. After 72-hour G3139 infusion, Bcl-2/ABL mRNA copies were decreased compared with baseline (P = .03) in CR patients and increased in nonresponders (NRs; P = .05). Changes in Bcl-2 protein showed a similar trend. Although plasma pharmacokinetics did not correlate with disease response, the median IC of the antisense was higher in the CR patients compared with NRs (17.0 v 4.4 pmol/mg protein, respectively; P = .05).CONCLUSION:G3139 can be administered safely in combination with intensive chemotherapy, and the degree of Bcl-2 downmodulation may correlate with response to therapy.

MLL (ALL-1) chimeric fusions and MLL partial tandem duplications (PTD) may have mechanistically distinct contributions to leukemogenesis. Acute myeloid leukemia (AML) blasts with the t(9;11)(p22; q23) express MLL-AF9 and MLL wild-type (WT) transcripts, while normal karyotype AML blasts with the MLLPTD/WT genotype express MLL PTD but not the MLL WT. Silencing of MLL WT in MLLPTD/WT blasts was reversed by DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors, and MLL WT induction was associated with selective sensitivity to cell death. Reduction of MLL PTD expression induced MLL WT and reduced blast colony-forming units, supporting opposing functions for MLL PTD and MLL WT whereby the MLL PTD contributes to the leukemic phenotype via a recessive gain-of-function. The coincident suppression of the MLL WT allele with the expression of the MLL PTD allele, along with the functional data presented here, supports the hypothesis that loss of WT MLL function via monoallelic repression contributes to the leukemic phenotype by the remaining mutant allele. These data from primary AML and the pharmacologic reversal of MLL WT silencing associated with a favorable alteration in the threshold for apoptosis suggest that these patients with poor prognosis may benefit from demethylating or histone deacetylase inhibitor therapy, or both.

GTI-2040 is a 20-mer antisense to the R2 component of RNR mRNA. RNR is required for the conversion of ribonucleotides to deoxyribonucleotides, a crucial step during DNA synthesis and repair. Cytarabine (AraC) is a cytotoxic agent that is converted into AraC triphosphate (Ara-CTP) and is the backbone of several regimens in AML. Ara-CTP competes with deoxycytidine for DNA incorporation. We hypothesize that RNR downregulation by GTI-2040 results in decrease of levels of deoxycytidine thereby leading to a preferential DNA incorporation of ARA-CTP and increase in its cytotoxic activity. To test this hypothesis we undertook a CTEP-sponsored Phase I dose-escalation study of GTI-2040 plus HiDAC in patients (pts) with relapsed or refractory AML. Pts were stratified in 2 cohorts according to age. Cohort I (18–59 yrs) received escalating doses of GTI-2040 (dose level 1: 3.5 mg/m2/d) by continuous IV infusion (CIVI) on d 1–6 combined with escalating doses of cytarabine IV over 2 hrs q12 hrs on d 2, 4, and 6 (dose level 1: 2500 mg/m2/dose). Cohort II (≥60 yrs) received GTI CIVI on d 1–6 and cytarabine IV over 4 hrs on d 2 to 6 (dose level 1: 1500 mg/m2/d). To date, 30 pts were enrolled. Pts received median of 1 prior regimen (range 1–3). Cohort I included 8 pts with relapsed and 6 with refractory disease; 7 had intermediate risk cytogenetics (CyG) and 7 adverse CyG; 6 received prior HiDAC. Cohort II included 10 pts with relapsed and 6 with refractory disease; 8 pts had intermediate risk CyG and 8 high risk CyG; 5 pts received prior HiDAC. Toxicities were comparable to HiDAC therapy alone. Grade 3/4 non-hematologic toxicities included fatigue, fevers, anorexia, pneumonitis, and catheter related infections; a grade 3 reversible cerebellar toxicity (n=1) was observed at level 1/cohort I. An ELISA-based assay with a limit of quantification of 50 pMol was used to determine GTI2040 plasma and intracellular (IC) concentrations. Dose-dependent increase in plasma steady state concentration (Css) and area under the curve (AUC) of GTI2040 was observed in both cohorts, although higher AUC and longer t1/2 were demonstrated in the younger pts compared to the older ones. In cohort I, disease responses were seen at all dose levels Five of 14 pts achieved complete remission (CR) and one achieve incomplete CR (CRi; i.e., no marrow disease and incomplete blood count recovery). In cohort II, no disease response was observed. Median IC GTI2040 concentration in BM mononuclear cells at 120 hours following start of antisense infusion was higher in younger (i.e., 175 nM) than in older (i.e., 75 nM) pts. A median decrease in R2 protein levels of 50% (range 50–90%) detected by immunoblotting was noted in 5/9 and 5/10 pts in cohort I and II, respectively. In cohort I CR pts (n=4) had a median 50% decrease and non-responders (n=9) had a median 200% increase in R2 levels. In cohort II changes in R2 levels did not predict disease response. In summary, combination of GTI-2040/HiDAC is feasible. PK/PD studies demonstrate achievable plasma and IC levels of the antisense and target downregulation. Disease response was observed only with the dose/schedule administered to younger pts. Dose escalation in this group continues to establish a recommended dose for Phase II trials. [NCI U01 CA 76576-05].