Reduction In Marrow Blasts Research Articles

A Phase I Trial of a Pharmacodynamically-Conceived Decitabine and Thioguanine Combination in Patients with Advanced Myeloid Malignancies

Background: Using a chemosensitivity screening assay, we previously demonstrated that decitabine and thioguanine combinations can rescue therapeutic efficacy in primary leukemia cells isolated from patients with relapsed and refractory acute myeloid leukemia (AML). Although both decitabine and thioguanine have single-agent anti-leukemic activity, they have not previously been used concurrently. To test the safety and preliminarily assess possible additive/synergistic activity of this combination, we are performing a Phase I dose escalation trial of thioguanine given with decitabine.Patients and Methods: Patients with untreated AML over 60 years who are not suitable candidates for standard induction therapy, as well as those with relapsed/refractory AML, advanced myelodysplastic syndrome, and chronic myelomonocytic leukemia (CMML) are eligible. Three thioguanine dose levels are being evaluated: 80, 120, and 160 mg/m2/day, given in two divided doses on Days 1-12 of each induction course for up to two cycles and Days 1-7 of maintenance cycles. Decitabine 20 mg/m2 is administered IV on Days 3-12 during induction cycles and on Days 3-7 during maintenance cycles. In addition to standard safety measures and clinical outcomes, the biologic activity of the combination is assessed by patient specific pharmacodynamic measures. These measures include an in vitro chemosensitivity assay, genome-wide analysis of DNA methylation changes, and BH3 profiling in order to measure the degree to which samples are primed to undergo apoptotic cell death.Results: Six patients (median age, 69 yrs; range, 66–83 yrs) with newly diagnosed AML (n=2), relapsed/refractory AML (n=3), and newly diagnosed CMML (n=1) have been treated to date with thioguanine at the 80 mg/m2 dose. Dose-limiting toxicity was seen in one patient who developed acute renal failure (ARF) requiring hemodialysis. Infectious complications were the most common toxicity and included two episodes of grade 3 neutropenic colitis in one patient, grade 3 pseudomonal bacteremia, grade 3 staphylococcal bacteremia, and a dental infection requiring extraction. No other grade 3–4 non-hematologic toxicities were observed. Three patients remain on active treatment three to seven months from the initiation of therapy. Two patients were removed from study due to disease progression (n=1) and grade 4 ARF noted above (n=1). A patient with CMML was removed to undergo allogeneic hematopoietic stem cell transplantation after achieving a hematologic remission with red cell transfusion independence and platelet count normalization. The median number of cycles administered was 3 (range, 1-5). Bone marrow blast reductions to less than 5% were seen in all 4 evaluable patients with AML and included 1 CR and 1 CRi. The overall response rate in this high risk patient population was 67% (4 of 6 patients). Importantly, the patient who achieved a CR was 83 years old with relapsed disease following 4 previous cycles of single-agent decitabine therapy, demonstrating that this regimen can rescue previous hypomethylating agent failures. Clinical activity was well-correlated with the in vitro cytotoxicity assays. The chemosensitivity assay results for thioguanine on pre-treatment mononuclear cells directly correlated with clinical outcome in both response to therapy and clinical resistance. BH3 profiling was also performed on pre-treatment myeloblasts. Significant apoptotic priming corresponded to good initial clinical response. In addition, in the single patient who responded and subsequently relapsed, decreased apoptotic priming was observed in the relapsed sample, suggesting that the thioguanine/decitabine regimen applies selective pressure for reduction in apoptotic priming. Detailed analysis of treatment-related changes in DNA methylation will be presented and compared to prior work showing decitabine-induced hypomethylation in CD34+ leukemic cells during single agent therapy with decitabine.Conclusions: Combination decitabine and thioguanine has been well-tolerated and has shown surprising anti-leukemic activity at the lowest dose level studied. Importantly, the in vitro chemosensitivity testing and BH3 profiling accurately predicted the observed clinical responses while also confirming the etiology of the loss of therapeutic response. Accrual to this trial continues at higher dose levels to determine the maximum tolerated dose. DisclosuresLetai:AbbVie, Inc: Consultancy, Research Funding; Tetralogic: Consultancy, Research Funding.

Feasibility of BIBF1120 (nintedanib) combined with low-dose cytarabine in elderly patients with AML ineligible for intensive treatment.

7053 Background: Elderly unfit patients with AML have a dismal prognosis. The oral multikinase inhibitor BIBF1120 (nintedanib) was reported to exert growth inhibitory and proapoptotic effects in myeloid cells, especially when used in combination with cytarabine (AraC). Methods: This phase I study evaluated the combination of AraC (20mg subcutaneously twice daily on days 1-10 every 28 days) with BIBF1120 in 3 predefined dose levels (DL: 100, 150, and 200mg orally twice daily) in elderly patients with AML ineligible for intensive treatment or treatment with 5-Aza in a 3+3 design. Protocol-specific definitions: Therapy-related cytopenias constituted no adverse events (AE). AEs of special interest (AESI) were elevation of AST and/or ALT >3x upper level of normal (ULN) combined with an elevation of bilirubin >2x ULN, and any hollow organ perforation occurring after the first intake of study medication. DLT was defined as non-hematological SAR CTC grade ≥IV with possible or definite relationship to BIBF1120 occurring during or up to 28 days after the first cycle. Results: Between April 2012 and October 2013, 13 patients were enrolled into the phase I part of this trial (DL1: 3 patients, DL2: 4 patients, DL3: 6 patients). 1 patient in DL2 did not receive study medication and was replaced. Median age was 73 (range: 62 – 86) years. Disease status was untreated (4 patients), relapsed (5) and refractory (4) AML. Cytogenetic risk was favorable (1 patient), intermediate (5), unfavorable (6) or missing (1). 8 SAEs occurred (DL1: 1, DL2: 3, DL3: 5). All of the 3 SARs were neutropenic fever grade 3 (DL2: 1, DL3: 2). 2 SUSARs were observed, 1 fatal hypercalcemia (DL2) and 1 fatal GI tract infection (DL3). No AESI were observed. The phase II recommended dose (P2RD) was set as DL3 by the DMC. 2 patients with relapsed AML responded (1 CR, 1 CRi). Bone marrow blast reductions without fulfilling the PR criteria were observed in 3 patients. One-year survival from start of therapy was 46% after a median follow-up of 308 days. Conclusions: BIBF1120 combined with LD-AraC shows a favorable safety profile. Preliminary survival data are promising. Continuation of this trial with a P2RD of 2 x 200mg in a randomised phase II is planned. Clinical trial information: NCT01488344.

A Phase I Study Of AC220 (Quizartinib) In Combination With Cytarabine and Etoposide In Relapsed/Refractory Childhood ALL and AML: A Therapeutic Advances In Childhood Leukemia & Lymphoma (TACL) Study

BackgroundAC220 is a novel class III receptor tyrosine kinase (RTK) inhibitor that is potent and highly selective for mutant and wild type (WT) FLT3 with lower activity against other class III RTKs including KIT, CSF1R, RET and PDGFR. In childhood acute myeloid leukemia (AML), FLT3 internal tandem duplication mutations (FLT3-ITD) confer poor prognosis. In childhood acute lymphoblastic leukemia (ALL), high WT FLT3 expression is seen in the high risk MLL-rearranged subset. Study DesignTACL 2009-004 was the first clinical trial using AC220 in children, and the first study overall in combination with intensive chemotherapy. Children > 1 month and ≤ 21 years of age with relapsed/refractory AML or MLL-rearranged ALL (MLL-r ALL) were eligible. A standard 3+3 dose escalation design was utilized to identify a safe and biologically active dose. The three doses tested (25, 40 and 60 mg/m2/day) are significantly lower than those tested in adults. All patients (pts) received intravenous (IV) cytarabine(1 gm/m2/dose every 12 hours) and IV etoposide (150 mg/m2/dose daily) on days 1-5. AC220 was administered once daily as an oral solution on days 7-28. Patients were eligible to receive up to 2 courses of therapy. Plasma inhibitory assay (PIA) testing was performed at trough time points weekly to determine biologic activity of AC220. ResultsTwenty-two pts were enrolled: 18 patients were evaluable for response and 20 were evaluable for toxicity. Four pts (1 ALL, 3 AML (2 FLT3-ITD)) not evaluable for response received < 75% of AC220 and 2 pts without DLTs were not evaluable for toxicity for the same reason. Four pts had relapsed MLL-r ALL, 17 relapsed AML and 1 secondary AML. Of pts with AML, 9 were FLT3-WT, 8 FLT3-ITD+, and one had unknown FLT3 status. The median number of prior regimens was 2 (range 1-10) for ALL and 3 (range 1-5) for AML. No pts with ALL had prior hematopoietic stem cell transplant (HSCT) while 10/18 with AML had prior HSCT. Toxicities were consistent with intensive relapsed leukemia regimens. Across all dose levels, non-hematologic toxicities ≥ grade 3 attributed to AC220 included vomiting (n=1), elevated transaminases (n=1), anorexia (n=2), rash (n=1), hypophosphatemia (n=1), hypoxia (n=1), headache (n=1), and infection (n=2). One of 6 pts experienced a dose-limiting toxicity (DLT) on dose level 2 (40 mg/m2/day) of grade 3 elevated lipase, and 1 of 9 pts experienced DLT of hyperbilirubinemia on dose level 3 (60 mg/m2/day). Near total (>99%) inhibition of FLT3 phosphorylation by PIA was seen in every patient across all dose levels. Therefore, dose escalation past 60 mg/m2/day was not performed and a maximum tolerated dose (MTD) was not reached. Responses are listed in the table below. Of note, 4/6 (67%) FLT3-ITD patients achieved CR or CRi. Both FLT3-ITD pts with SD had significant reduction in marrow blasts without peripheral blood count recovery. Conclusions: AC220 plus intensive chemotherapy is well tolerated at 60 mg/m2/day with near complete inhibition of FLT3 phosphorylation in all pts tested to date. The favorable toxicity profile and encouraging response rates warrant further testing ofAC220 in pediatric pts with FLT3-ITD mutated AML. Disclosures:Off Label Use: AC220 is not approved for use in pediatric acute leukemia. Gammon:Ambit: Employment.

Phase I Trial Of The Targeted Alpha-Particle Nano-Generator Actinium-225 (225Ac)-Lintuzumab (Anti-CD33) In Combination With Low-Dose Cytarabine (LDAC) For Older Patients With Untreated Acute Myeloid Leukemia (AML)

Abstract 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 isotope generator 225Ac (t½=10 days), which yields 4 α-particles, was conjugated to lintuzumab. A phase I trial demonstrated that 225Ac-lintuzumab is safe at doses ≤ 3 μCi/kg and has anti-leukemic activity across all dose levels studied (Jurcic et al. ASH, 2011). We are conducting a multicenter, phase I dose escalation trial to determine the maximum tolerated dose (MTD), toxicity, and biological activity of fractionated-dose 225Ac-lintuzumab in combination with LDAC. Patients and Methods Patients ≥ 60 yrs who had untreated AML with poor-prognostic factors, such as an antecedent hematologic disorder (AHD), unfavorable cytogenetic or molecular abnormalities, and significant comorbidities, were eligible. Patients received LDAC 20 mg bid for 10 days every 4-6 weeks. During cycle 1, beginning 4-7 days after LDAC, two doses of 225Ac-lintuzumab were given approximately one week apart. Results Seven patients (median age, 76 yrs; range, 72-80 yrs) were treated, all of whom had AHDs. Five (71%) had intermediate-risk cytogenetics, and two (29%) had unfavorable cytogenetics. The median CD33 expression was 76% (range, 69-95%). Prior therapy for myelodysplastic syndrome included hypomethylating agents (n=4) and allogeneic hematopoietic cell transplantation (n=1). Patients received 225Ac-lintuzumab at doses of 0.5 (n=3) or 1 (n=4) μCi/kg/fraction, two fractions per patient (total administered activity, 68-199 μCi). Dose-limiting toxicity was seen in one patient receiving 1 μCi/kg/fraction who had grade 4 thrombocytopenia in the setting of an aplastic bone marrow that persisted &gt; 6 wks after completing the second fraction of 225Ac-lintuzumab. Other toxicities included grade 3 febrile neutropenia (n=5), bacteremia (n=1), pneumonia (n=1), cellulitis (n=1), transient increase in creatinine (n=1), and generalized weakness (n=1). Bone marrow blast reductions were seen in 4 of 6 evaluable patients (67%) after cycle 1 (mean blast reduction, 58%; range, 34-100%). No CRs, however, were observed. The median number of cycles administered was 2 (range, 1-4), and the median time to progression was 2.5 months (range, 2-7+ months). Conclusions Fractionated-dose 225Ac-linutuzmab in combination with LDAC is feasible, safe, and has anti-leukemic activity. Accrual continues to define the MTD, with planned dose levels up to 2 μCi/kg/fraction. Additional patients will be treated at the MTD in the phase II portion of this trial to determine response rate, progression-free survival, and overall survival. Disclosures: Jurcic: Actinium Pharmaceuticals, Inc.: Membership on an entity’s Board of Directors or advisory committees. Ravandi:Actinium Pharmaceuticals, Inc.: Research Funding. Pagel:Actinium Pharmaceuticals, Inc.: Equity Ownership, Membership on an entity’s Board of Directors or advisory committees, Research Funding. Park:Actinium Pharmaceuticals, Inc.: Research Funding. Douer:Actinium Pharmaceuticals, Inc.: Research Funding. Estey:Actinium Pharmaceuticals, Inc.: Membership on an entity’s Board of Directors or advisory committees. Cicic:Actinium Pharmaceuticals, Inc.: Employment, Equity Ownership. Scheinberg:Actinium Pharmaceuticals, Inc.: Ac-225-Lintuzumab, Ac-225-Lintuzumab Patents &amp; Royalties, Equity Ownership, Membership on an entity’s Board of Directors or advisory committees.

A Phase I Trial of Lenalidomide in Combination with Intermediate Dose Cytarabine (IDC) in Relapsed or Refractory Acute Myeloid Leukemia (AML) Patients

S380 Context: Lintuzumab, a humanized anti-CD33 antibody, has modest activity against AML. To increase the antibody's potency yet avoid nonspecific cytotoxicity seen with b-emitting isotopes, Ac (t1/2 1⁄410 days), which yields 4 a-emitting isotopes, was conjugated to lintuzumab. Objectives: We sought to determine the MTD, toxicity, pharmacokinetics, and antileukemic activity of Ac-lintuzumab. Design: We conducted a first-in-man, phase I, 3+3, dose-escalation trial from 2006-2012. Setting: This was a single-institution study performed at a tertiary cancer center. Patients: Eighteen patients (median age, 64 yrs; range, 45-80 yrs) with relapsed (n1⁄411) or refractory (n1⁄47) AML were treated. Intervention: Patients received a single infusion of Ac-lintuzumabat doses of 0.5 (n1⁄43), 1 (n1⁄44), 2 (n1⁄43), 3 (n1⁄46) or 4 (n1⁄42) mCi/kg. Main Outcome Measure: MTD was defined as the highest dose for which the incidence of DLT was 35 days in 1 patient receiving 4 mCi/kg and death from sepsis in 2 patients receiving 3 and 4 mCi/kg. The MTD was 3 mCi/kg. Myelosuppression was the most common toxicity. Median time to resolution of grade 4 leukopenia was 27 days (range, 0-71 days). Significant extramedullary toxicities were limited to transient grade 3 liver function abnormalities in 3 patients. We analyzed plasma pharmacokinetics by gamma counting at energy windows for 2 daughters of Ac, francium-221 and bismuth-213. Two-phase elimination kinetics were seen with mean plasma t1/2 -a and t1/2 -b of 1.9 and 38 hours, respectively, similar to other lintuzumab constructs containing long-lived radionuclides. Peripheral blasts were eliminated in 10 of 16 evaluable patients (63%), but only at doses of 1 mCi/kg. Marrow blast reductions were seen in 10 of 15 evaluable patients (67%) at 4 weeks, including 8 patients (53%) who had blast reductions of 50%. Three patients receiving 1, 3, and 4 mCi/kg achieved marrow blasts of 5%. Conclusions: This is the first study to show that therapy with a targeted a-particle generator is feasible in humans. Ac-lintuzumab had antileukemic activity across all dose levels and is now being investigated in a multicenter phase I/II trial in combination with low-dose cytarabine for older AML patients.

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.

A Phase I Study of AC220 in Combination with Cytarabine and Etoposide in Relapsed/Refractory Childhood ALL and AML: A Therapeutic Advances in Childhood Leukemia & Lymphoma (TACL) Study

AbstractAbstract 3605 Background:AC220 is a novel class III receptor tyrosine kinase (RTK) inhibitor that is potent and highly selective for mutant and wild type (WT) FLT3 and other class III RTK’s including KIT, CSF1R, RET and PDGFR. In childhood acute myeloid leukemia (AML), ∼18% of children have FLT3 internal tandem duplication mutations (FLT3-ITD), and ∼10% high WT FLT3 expression. FLT3-ITD is associated with poor prognosis. In childhood acute lymphoblastic leukemia (ALL), the highest levels of FLT3 mRNA expression occur in cases of infants (80%) and childhood ALL with MLL rearrangements (MLL-r) (5%), both conferring poor prognosis.1,2 Study Design:TACL 2009–004is a first-in-children study using AC220 in combination with cytarabine and etoposide. Children > 1 month and < 21 years of age with relapsed/refractory AML or MLL-rearranged ALL are eligible. A standard 3+3 dose escalation design is utilized. The three doses tested (25, 40 and 60 mg/m2/day) are significantly lower than those tested in adults. Dose escalation past 60 mg/m2 occurs only if adequate biologic activity as determined by a plasma inhibitory assay (PIA) is not achieved. Intravenous (IV) cytarabine (1 gm/m2/dose every 12 hours) and IV etoposide (150 mg/m2/dose daily) are given over 5 days. AC220 is administered once daily as an oral solution on days 7–28. Patients can receive up to 2 courses of therapy. PIA testing is performed at trough time points weekly during exposure to AC220 to determine biologic activity. Results:To date, 13 patients (pts) were enrolled and 12 are evaluable for toxicity and response. One pt died from infectious complications (not drug-related) after a single dose of AC220 and was replaced. Median age at study entry was 10.2 years (range 11 mo – 20 yrs), average number of prior regimens was 2.8 (range 1–5), and 5 pts had prior stem cell transplant. Nine pts had relapsed AML, 2 had relapsed MLL-r ALL, and 1 had secondary AML. Of patients with AML, 4 had FLT3-ITD mutations and one had a D835 mutation. Toxicities were consistent with intensive relapsed leukemia regimens. Across all dose levels, non-hematologic toxicities ≥ grade 3 attributed to AC220 included vomiting (n=1), elevated transaminases (n=1), anorexia (n=2), and infection (n=3). One pt experienced a dose-limiting toxicity (DLT) on dose level 2 (40 mg/m2/day) of recurrent grade 3 elevated lipase. Dose level 2 was expanded to 6 pts without additional DLTs. Of 3 pts treated at 60 mg/m2/day, there have been no DLTs. Near total (>99%) inhibition of FLT3 phosphorylation by PIA is seen in every patient across all dose levels. Of 12 pts evaluable for response to date, 1 patient achieved a complete response (CR), 3 achieved complete response with incomplete neutrophil and platelet recovery (CRi), 5 had stable disease (SD), and 3 had progressive disease (PD). Responses in the 4 FLT3-ITD pts include 1 CR, 2 CRi and 1 SD. The FLT3-ITD patient with SD had reduction in marrow blasts without peripheral blood count recovery. An additional 6 pts will be enrolled at 60 mg/m2/day to complete safety evaluation and confirm biologic activity. Conclusions:AC220 plus intensive chemotherapy is well tolerated at doses up to 60 mg/m2/day with near complete inhibition of FLT3 phosphorylation in all pts tested to date. Response rates to date in pre-treated children with relapsed FLT3-ITD AML are encouraging. Disclosures:Off Label Use: AC220 in relapsed/refractory pediatric acute leukemia. Gammon:Ambit Biosciences: Employment.

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.

A Phase II Open-Label, Ac220 Monotherapy Efficacy Study In Patients with Refractory/Relapsed Flt3-Itd Positive Acute Myeloid Leukemia: Updated Interim Results

Abstract 2576FLT3-ITD mutations in Acute Myeloid Leukemia (AML) are associated with early relapse after standard chemotherapy and poor survival. AC220 is a potent, selective, oral FLT3 tyrosine kinase inhibitor that showed promising activity in FLT3-ITD+ patients (pts) in a Phase I study.This Phase II monotherapy trial was conducted to examine the safety and efficacy of AC220 monotherapy in pts with relapsed/refractory FLT3-ITD+ AML. Patients were enrolled into two cohorts: Cohort 1 enrolled pts ≥60 yrs and relapsed/refractory to 1st-line chemotherapy and Cohort 2 pts ≥18 yrs and relapsed/refractory to 2nd-line chemotherapy or hematopoietic stem cell transplantation (HSCT).A planned analysis was performed in February 2011 on the first 62 pts which comprised the exploratory group with the subsequent ∼240 pts being the confirmatory group for which the data will remain sequestered until study completion. The exploratory group was enrolled between 19 November 2009 and 25 August 2010. 53/62 (85%) pts were evaluable for efficacy (FLT3-ITD+ by central laboratory, received at least 1 dose of AC220, 1 post-tx response assessment and no major efficacy-related protocol deviations). The composite CR (CRc=CR+CRp+CRi) rate was 45% (24/53: 2 CRp, 22 CRi) and PR rate was 24% (13/53). Importantly, of the pts refractory to any prior therapy, 62% (16/26) had CRc and 19% (5/26) had PR in response to AC220. Median duration of CRc has not yet been reached in Cohort 1 and was 10.6 wks in Cohort 2. Overall, 8% (2/25) of pts in Cohort 1 and 30% (11/37) of pts in Cohort 2 underwent HSCT and were censored for duration of CRc. Median overall survival was 24.7 weeks for efficacy evaluable pts, 24.1 wks for Cohort 1 and not yet reached in Cohort 2 (pts were not censored at HSCT). At the time of the analysis 51/62 patients were off study (most commonly due to disease progression (19), HSCT (13) or adverse event (7). 55% of pts were still alive.The most common (>19%) drug-related AEs were nausea, QTc prolongation, vomiting, fatigue, dysgeusia, anorexia, febrile neutropenia, diarrhea, and dyspepsia. QTc prolongation occurred in 21 (34%) pts (Grade 3 in 11 pts, 18%). The incidence of QTc prolongation was decreased by reducing AC220 starting dose from 200 (35%) to 135 mg/day (8.3%) (males) and 90 mg/day (5.9%) (females). 15 pts (24%) experienced fatal treatment-emergent AEs; none were considered drug-related. An additional analysis will be conducted when all pts have > 1 yr follow up which will be available at the time of the meeting.These preliminary data suggest that AC220 achieves clinically meaningful reductions in marrow blasts in a substantial proportion of pts with both refractory and relapsed FLT3-ITD+ AML, and many of these pts were successfully bridged to HSCT. These encouraging efficacy results and an acceptable safety profile in this high risk population support continued clinical evaluation in mono- and combination therapy. Disclosures:Cortes:Ambit: Research Funding; Novartis: Research Funding.

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.

Persistent ERK Activation in Bone Marrow Blasts May Account for the Difference in Bone Marrow Versus Peripheral Blood Response to FLT3 Inhibition in FLT3/ITD AML

Abstract 736Given the poor prognosis of AML patients with FLT3/ITD mutations, a number of small molecule FLT3 inhibitors are being investigated in clinical trials for these patients. When administered as monotherapy, these agents induce clearance of peripheral blood blasts, but usually have only minimal effects on bone marrow blasts. For example, treatment with sorafenib, while effective in clearing the peripheral blood of blasts, has resulted in only modest marrow blast reductions (Borthakur et al, Haematologica 2010). In contrast, AC220 (quizartinib), a more recently developed FLT3 inhibitor, has induced a much higher rate of marrow responses in an ongoing clinical trial (Cortes et al, 2011 EHA, abstract #1019). We wished to investigate the difference in response to FLT3 inhibition between peripheral blood and bone marrow blasts, and to better understand the basis for the difference in apparent efficacy between sorafenib and AC220. In our approach, we used a FLT3/ITD cell line (Molm14) and primary blasts from FLT3/ITD AML patients treated with sorafenib and AC220 either in suspension or in co-culture with human bone marrow stromal cells. We found that both sorafenib and AC220 could successfully inhibit FLT3, STAT5, AKT, and ERK signaling in Molm14 cells in suspension at concentrations below 100nM, with apoptosis induced in a dose-dependent fashion. The IC50 for inducing apoptosis was 0.4 nM for AC220 and 3.3 nM for sorafenib. The co-culture of Molm14 with bone marrow stroma did not affect the ability of AC220 and sorafenib to inhibit FLT3 and STAT5. However, downstream signaling of AKT and ERK was augmented by co-culture with stroma, and, in comparison with suspension cultures, 3-fold higher concentrations of sorafenib and AC220 were required to inhibit them. The addition of exogenous FL (2.5 ng/mL) to Molm14 cells co-cultured with stroma further enhanced the phosphorylation of FLT3, Akt and ERK, but not of STAT5. Cell survival (as determined by an apoptosis assay) correlated tightly with Akt and ERK phosphorylation. By comparison, treatment with another cytokine, IL-3, had no effect on the response to FLT3 inhibitors on or off stroma. Thus, in the Molm14 model, the resistance to FLT3 inhibitors conferred by both FL and bone marrow stroma could be overcome by increasing the dosage of drugs. In Molm14 cells co-cultured with stroma and with FL, the IC50 for inhibition of ERK was 20nM and 100nM for AC220 and sorafenib, respectively. In primary FLT3/ITD AML blasts, STAT5 activation did not appear to be affected by FLT3 inhibition, either on or off stroma. Strikingly, ERK was strongly activated in these blasts when they were co-cultured with stroma, and this activation was unaffected by FL or by FLT3 inhibition. As reported previously, FLT3/ITD AML blasts cultured in suspension underwent apoptosis in response to FLT3 inhibition. However, when cultured for several days on stroma, FLT3 inhibition did not induce apoptosis. We conclude that bone marrow stroma provides survival signals to FLT3/ITD AML blasts that allow them to survive in the presence of even very potent FLT3 inhibition. We have previously presented data that FLT3 inhibition by AC220 induces terminal differentiation of bone marrow blasts (rather than apoptosis) in vivo (Levis et al, 2010 ASH, abstract #660). Our data suggests that FLT3 inhibition needs to be extremely potent in order to induce a meaningful affect on leukemia cells in the bone marrow, explaining the difference in responses between sorafenib and the more potent inhibitor AC220. The persistent activation of ERK in blasts on stroma irrespective of the activation of the FLT3 signaling pathway suggests that this represents an important survival signal conferred by the bone marrow stroma that may account for the difference in response to FLT3 inhibition observed between peripheral blood and bone marrow blasts. Disclosures:Levis:Ambit Biosciences, Inc: Consultancy.

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.

Phase II Study of the Cyclin-Dependent Kinase (CDK) Inhibitor Dinaciclib (SCH 727965) In Patients with Advanced Acute Leukemias

AbstractAbstract 3287 Background:Dinaciclib is a potent and selective inhibitor of the CDKs 1, 2, 5, and 9 that has demonstrated anti-tumor activity against both myeloid and lymphoid leukemia cell lines in vitro and human tumor xenografts in vivo. Methods:A randomized, multicenter, open-label phase 2 study of dinaciclib 50 mg/m2 administered by 2-hour i.v. infusion once every 21 days was initiated with the goal of assessing its efficacy and safety in patients (pts) with advanced acute myeloid (AML, ≥60 years old) or lymphoid (ALL, ≥18 years old) leukemia. AML pts were randomized between dinaciclib and gemtuzumab ozogamicin (GO) with cross-over to dinaciclib if no response to GO, while ALL pts only received dinaciclib. Intra-patient dose escalation of dinaciclib to 70 mg/m2 in cycle 2 was allowed. Twenty-six pts were treated on study (20 AML, 6 ALL). Data on 14 AML (2 cross-over from GO) and 6 ALL pts treated with dinaciclib are presented. Their median age was 70 (range 38–76) years and 70% were male. Sixteen pts were refractory and 4 pts had relapsed after a median of one (range 1–4) chemotherapy regimens. Four AML pts had complex karyotypes (≥3 abnormalities), 2 monosomy 7, 2 trisomy 8, 1 der (1:7)(q10;p10), 1 trisomy 21, 1 deletion 9q, and 3 had normal karyotype. Two ALL pts had t(9;22).Response: Anti-leukemia activity was observed in 60% of pts. Ten of 13 pts with circulating blasts (7/7 AML and 3/6 ALL) had >50% and 6 pts (4 AML, 2 ALL) >80% decrease in the absolute blast count (ABC) within 24 hours of the first dinaciclib dose. An additional pt had a 29% decrease in ABC. The median pre-treatment ABC was 1085 (range 220–9975) and the median ABC nadir was 169 (range 0–1350). The median duration of blast nadir was 6 days (range 2–23). A representative graph from an AML patient (below) shows a rapid decrease of circulating blasts and WBC after treatment, followed by a gradual recovery. Two patients had >50% reduction of marrow blasts (35% on d1 to 17% on d 42 in an AML pt; 81% on d1 to 27% on d 21 in an ALL pt). However, no objective responses by International Working Group criteria were observed. The median number of treatment cycles was 1 (range 1–5), with 10 pts receiving more than one cycle of treatment. Eight pts were treated with dinaciclib 70 mg/m2 starting in cycle 2.Toxicity: Treatment related AE's occurring in >30% of pts included diarrhea, nausea, vomiting, anemia, elevated AST, fatigue, leukopenia, hypocalcemia, and hypotension. The most common CTCAE v3 treatment-related grade 3 and 4 toxicities, occurring in 3 or more pts, were anemia, leukopenia, febrile neutropenia, thrombocytopenia, fatigue, increased AST, and tumor lysis syndrome (TLS). Laboratory evidence of tumor lysis in cycle 1, using the Cairo-Bishop criteria, was seen in 6 pts in addition to 3 pts with clinical TLS (JCO 2008;26:2767). Hyperacute TLS requiring hemodialysis occurred in one pt with AML, who died of acute renal failure. Subsequently, all pts were aggressively managed to prevent and treat TLS (hospitalization, hydration, allopurinol, rasburicase, oral phosphate binder administration, and early management of hyperkalemia). An additional 9 pts died on study, 8 pts from leukemia progression and 1 pt from intracranial bleed due to disease-related thrombocytopenia.Pharmacodynamics: Pre-treatment, 4 and 24 hrs post end-of-infusion samples of circulating leukemic blasts were obtained from 1 AML and 3 ALL pts. By Western blot, post-treatment decrease in Mcl-1 and increase in PARP cleavage were seen in all 4 pts at 4 hrs post-treatment, confirming that in vivo inhibition of CDKs was achieved, but recovery of Mcl-1 at 24 hrs was observed in all 4 pts, suggesting that inhibition was lost at 24 hrs. Decline in p-Rb was observed in 1 pt, while 2 pts had almost undetectable p-Rb levels at baseline. Conclusion:Dinaciclib showed anti-leukemia activity in this heavily pre-treated patient population. TLS was a notable toxicity, but was manageable in most pts with aggressive prophylaxis, monitoring and treatment. Early blast recovery and short duration of nadir observed on this study, combined with PK data showing a short t1/2 (1.5-3.3 hours) for dinaciclib and PD data demonstrating rapid reexpression of Mcl-1, support either use of longer infusion schedules (currently explored in solid tumors) or more frequent drug administration. Further exploration of dinaciclib dose and schedules in AML and ALL is planned. [Display omitted] Disclosures:Gojo:Merck & Co.: Research Funding. Off Label Use: SCH 727965 (dinaciclib) is an investigational drug. Padmanabhan:Schering-Plough: Consultancy; Merck & Co.: Research Funding. Small:Merck & Co.: Employment, Equity Ownership. Zhang:Merck & Co.: Employment. Sadowska:Merck & Co.: Research Funding. Bannerji:Merck & Co.: Employment, Equity Ownership.

Cyclic Administration of Combination of Sorafenib and Vorinostat In Poor-Risk AML: A Pharmacodynamically-Oriented Extended Phase I Trial

AbstractAbstract 3272Epigenetic repression of tumor suppressor genes, including DAPK1, p16INK4a, and RUNX3, cooperates with survival signaling to confer adverse prognosis in high-risk AML, including normal karyotype (NK) Flt3ITD. Cyclic administration of the multikinase inhibitor sorafenib, whose targets include Flt3 and raf/MAPK, along with vorinostat, a pan-HDAC inhibitor, was undertaken in a group of patients with relapsed/refractory AML or older than 70. Pharmacodynamic monitoring was performed for molecular determinants of response, operating from a functional platform for communication by tyrosine kinase survival pathways and downstream epigenetic targets: Flt3-to-p52NFkB/histone deacetylases are implicated in DAPK1 repression; Flt3ITD-to-p52NFkB/stat5-to-pim1 suppresses endoplasmic reticulum (ER) stress via DAPK1 repression/4-EBP1 inhibition; Flt3-wild-type or/ITD-induced Id1 is linked to p16INK4a repression. Using a cyclic 21-day schedule consisting of 14 days of treatment followed by 7-days rest, sorafenib was given orally at 400 mg bid, and oral vorinostat administered with escalating doses in a 3×3 cohort design: dose levels of 200 mg, 300 mg, and 400 mg daily in two divided doses. Response was assessed by standard clinical parameters, including bone marrow examination at day 15. No DLTs were observed in the first two cohorts. One/six patient in the third cohort developed grade 4 diarrhea prompted by neutropenic sepsis. Three additional patients were treated at this dose, with no DLTs. The optimal dose was established as sorafenib 400 mg bid and vorinostat 200 mg bid for 14 days followed by 7 days rest. Among a total of 15 treated patients, 13 were evaluable for response. Six/thirteen (46%) patients demonstrated PR with the first cycle of treatment, and 1/13 (8%) achieved a CR with one cycle. Two/six (33%) very good partial responders and one unevaluable patient had NK Flt3ITD; all demonstrated complete clearance of peripheral blood blasts within 1 week, starting as high as 52–84,000/uL; one had reduction of marrow blasts to 10% (from initial 90%) after 2 cycles. Surprisingly, molecular phenotypes of the 3 Flt3ITD+ patients differed: pre-treatment blasts in one patient strongly expressed nuclear phospho-c-jun, p52NFkB, phospho-stat5, and Id1, with transcript levels of meis1, hoxA9, and pim2 at greater than 3-log10 by RQ-PCR. At day 3, 2–3 log reduction of hoxA9, meis1, and pim's1/2 were recorded prior to morphologic change. No epigenetic upregulation of p16INK4a or DAPK1 was observed, but an upregulation of (inactive) surface Flt3 and IRE1a, and cleavage of pro-caspase 4 indicated an evolving ER stress apoptosis. Another Flt3ITD+ patient's pre-treatment blasts had evidence of an epigenetic signature with repression of RUNX3, DAPK1, and p16INK4a transcripts, while nuclear p52NFkB/relB and stat5 were abundant by immunoblot, but transcript levels for pim1/2 were not elevated. At day 4 of therapy, again there was evidence for evolution of an ER stress apoptosis pathway, but in association with upregulation of DAPK1 and RUNX3 transcripts by 5 and 7 fold, respectively. However, hoxA9 and meis1 transcripts were not reduced and pim1/2 levels rose. With protocol-defined failure to improve at day 42, pim1/2 levels continued to rise. This patient only had mutant Flt3 alleles and most Flt3 protein was nonglycosylated/ER-internalized, which supports an evasion mechanism dependent on ER-localized Flt3ITD stat5 signaling. The patient who achieved CR, carried complex cytogenetics. Blasts had high pre-treatment Id1 expression with repression of tumor suppressors p16INK4a and RUNX3, and 2-log upregulation of p16INK4a/RUNX3 occurred at day 4. By contrast, in another patient of complex cytogenetics without CR, p16INK4a upregulation did not occur. Patients with response demonstrated depletion of p52NFkB at day 3/4. Lack of p52NFkB abrogation signaled treatment failure. Of particular interest, in vitro exposure of pre-treatment blasts of almost all patients to combination of sorafenib and SBHA (a vorinostat analogue) largely predicted clinical efficacy. In summary, the combination was safe and had clinical activity, and pharmacodynamic monitoring revealed unexpected heterogeneity within classically-defined molecular phenotypes. In addition, findings support the possibility of significantly improving responses by addition of a direct inducer of ER stress, bortezomib, to the combination. Disclosures:Sayar:Onyx/Bayer: Research Funding. Off Label Use: A trial of sorafenib and vorinostat in AML based on previously demonstated independent single-agent activity in the disease.

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.

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.

Phase I Study of Bendamustine in Refractory Leukemia.

Abstract 4156 BackgroundAlkylating agents are active in leukemia. Examples are cyclophosphamide, chlorambucil, melphalan, busulfan, and others. Bendamustine, a rationally designed drug that incorporates alkylating agent properties plus an adenosine-like ring structure, may be active in leukemia. Fractionated doses of alkylators may improve efficacy (e.g. fractioned cyclophosphamide in ALL). MethodsWe initiated a phase I-II study of bendamustine in patients with refractory leukemia, chronic myelomonocytic leukemia, or myelodysplastic syndromes. Starting dose was 50mg/m2 IV BID over 1-2 hours for 4 days every 4 weeks (3 pts.) with escalation to 75mg (3 pts.), and 100mg (6 pts). Three additional patients were treated at 50mg/m2 once that dose was declared safe as allowed by study design. Diagnoses were AML 12, ALL 2, MDS 1. Median age was 48 (range 22 to 88). All patients were refractory or had relapsed after multiple courses of chemotherapy. The median number of prior therapies was 3 (range 1 to 9). Five patients had chromosome 5, 7, or 8 abnormalities, 6 patients had miscellaneous abnormalities, 4 patients were diploid. ResultsToxicity – Grade 1-2 expected toxicities of nausea, vomiting, diarrhea, and transient transaminase elevations were seen at all dose levels. At the 75 mg/m2 dose level grade 3 transaminase elevation was seen in 1 pt. which occurred with rash and diarrhea, was thought to be related to GVHD and all subsided with dose increase of tacrolimus. One patient who began therapy with a creatinine of 1.8 had creatinine increase to 3.3 mg/DL. At the 100mg/m2 dose level 2/3 patients developed creatinine increase to 3.2 and 2.6 mg/DL. The creatinine increase occurred on day 7 and subsided by day 11 in both pts. An additional 3 pts. were treated at this dose level with no increase in creatinine to >2 mg/DL. ResultsResponse – Antileukemic activity was encouraging: 8/15 patients with peripheral blasts had >90% reduction of the leukemic cells; 2 patients had >50% reduction of marrow blasts % (90 to 10, 86 to 40).Bendamustine has shown activity in this heavily pretreated refractory leukemia group. While the creatinine elevations were not severe (grade 3-4 NCI CTC) they were consistent to consider a bendamustine dose schedule of 50-75 mg/m2 IV BID x 4 days as a reasonable phase II schedule to explore in better prognosis patients, particularly in adult ALL in phase II studies. Disclosures:Ravandi:Cephalon: Consultancy, Honoraria. Kantarjian:Cephalon: Research Funding.