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Anthracyclines used in the treatment of acute myelogenous leukemia (AML) inhibit the activity of the mammalian topoisomerase II (topo II) isoforms, topo II α and topo IIβ. In 230 patients with non-M3 AML who received frontline ara-C/daunorubicin we determined expression of topo IIα and topo IIβ by RT-PCR and its relationship to immunophenotype (IP) and outcomes. Treatment outcomes were analyzed by logistic or Cox regression. In 211 patients, available for analysis, topo IIα expression was significantly lower than topo IIβ (P < 0.0001). In contrast to topo IIα, topo IIβ was significantly associated with blast percentage in marrow or blood (P = 0.0001), CD7 (P = 0.01), CD14 (P < 0.0001) and CD54 (P < 0.0001). Event free survival was worse for CD56-negative compared to CD56-high (HR = 1.9, 95% CI [1.0–3.5], p = 0.04), and overall survival was worse for CD-15 low as compared to CD15-high (HR = 2.2, 95% CI [1.1–4.2], p = 0.02). Ingenuity pathway analysis indicated topo IIβ and immunophenotype markers in a network associated with cell-to-cell signaling, hematological system development/function and inflammatory response. Topo IIβ expression reflects disease biology of highly proliferative disease and distinct IP but does not appear to be an independent variable influencing outcome in adult AML patients treated with anthracycline-based therapy. [ABSTRACT FROM AUTHOR]

Inhibition of cholesterol synthesis and uptake sensitizes acute myeloid leukemia (AML) blasts to chemotherapy. A Phase 2 study of high dose pravastatin given in combination with idarubicin and cytarabine demonstrated an impressive response rate [75% complete remission (CR), CR with incomplete count recovery (CRi)]. However, this population was a favorable risk group as eligible patients had to have a CR/CRi lasting ≥3 months following their most recent chemotherapy. Therefore, the study was amended to treat patients with poor risk disease including those with CR/CRi <6 months following their last induction regimen or with refractory disease. Here, we present results in this poor risk group. This trial included a significant number of patients with poor risk cytogenetics (43%) and poor risk molecular mutations. The response rate was 30% and approximately one-fourth of patients were able to proceed to allogeneic hematopoietic stem cell transplant (HSCT). The median overall survival for patients proceeding to allogeneic HSCT is 27.1 months. Although this trial did not meet criteria for a positive study based on the response rate (p = .062), these results are encouraging given the poor risk population and suggest that targeting the cholesterol pathway may have therapeutic benefit in AML. [ABSTRACT FROM AUTHOR]

Background Constitutive activation of STAT5 (by phosphorylation) has been identified in a number of malignancies, including acute myeloid leukemia ( AML). Objectives We investigated whether the level of phosphorylated STAT5 ( pSTAT5) expression correlates with clinical outcome in AML. Methods Adult patients with newly diagnosed AML receiving induction chemotherapy and with an available diagnostic bone marrow were evaluated. Results Forty-two percent of patients had pSTAT5 expression >0 on immunohistochemical analysis of fixed bone marrow core biopsies. In multivariable analyses, controlling for age, history of antecedent hematologic disorder, cytogenetic risk, and WBC at diagnosis, pSTAT5 expression was significantly associated with an increased risk of death ( HR 1.96, 95% CI 1.19-3.23, P = 0.008) and of relapse after achieving complete remission ( HR 2.31, 95% CI 1.16-4.63, P = 0.018). Conclusions Validation of pSTAT5's prognostic value requires additional study in a larger group of uniformly treated patients. However, our data suggests that targeting this signaling pathway in AML may improve the outcome of patients. [ABSTRACT FROM AUTHOR]

Abstract: The c-kit receptor is expressed in 95% of relapsed acute myeloid leukemias (AMLs) and mediates leukemic proliferation. We conducted a Phase 1 study of the c-kit inhibitor, imatinib mesylate (IM), in combination with cytarabine and daunorubicin (7+3) in c-kit+ relapsed AML. IM was dose escalated using a 3 by 3 design. Phosphorylated STAT5 was absent to minimally present in residual blasts on day 14 bone marrows. The maximum tolerated dose of IM was 300mg. The dose-limiting toxicity was Grade 3–4 hepatic toxicity. The CR/CRp rate was 57%. Cytotoxic therapy that includes IM for relapsed AML is well-tolerated and effective. [Copyright &y& Elsevier]

OCT-2 and its co-activator, BOB.1, are B-cell associated transcription factors expressed in a subset of patients with acute myeloid leukemia (AML). We evaluated OCT-2 and BOB.1 expression by immunohistochemistry in patients with newly diagnosed AML. The median overall survival (OS) for patients with varying levels of OCT-2 expression was statistically different ( p = 0.03) (OCT-2 <10%: 21.7 months; OCT-2 10–50%: 18.4 months; OCT-2 >50%: 11.6 months). On multivariate analysis, co-expression of OCT-2/BOB.1 remained predictive for achievement of complete remission (HR 0.44, p = 0.010) and increased risk of relapse (HR 2.30, p = 0.047). OCT-2 (per 10% increase) was associated with a decreased progression-free survival (HR 1.10, p = 0.036) and a trend toward a worse OS (HR 1.10, p = 0.063). OCT-2 may act as a cell survival factor in AML by mediating expression of downstream targets, such as BCL-2. These results will need to be validated prospectively. [ABSTRACT FROM AUTHOR]

Treatment of acute myeloid leukemia (AML) among the elderly is challenging because of intolerance of intensive therapy and therapy-resistant biology. Hypomethylating agents (HMAs) are commonly used, with suboptimal outcomes. Vadastuximab talirine is a CD33- directed antibody conjugated to pyrrolobenzodiazepine (PBD) dimers. Preclinically, HMAs followed by vadastuximab talirine produced upregulated CD33 expression, increased DNA incorporation by PBD, and enhanced cytotoxicity. A combination cohort in a phase 1 study (NCT01902329) assessed safety, tolerability, and activity of vadastuximab talirine with HMAs. Those eligible had Eastern Cooperative Oncology Group status 0 to 1 and previously untreated CD33-positive AML, and declined intensive therapy. Vadastuximab talirine was administered intravenously at 10 mg/kg on last day of HMA (azacitidine or decitabine) infusion in 4-week cycles. Among 53 patients treated, the median age was 75 years. Patients had adverse (38%) or intermediate (62%) cytogenetic risk. Median treatment duration was 19.3 weeks. No dose-limiting toxicities were reported. The majority of adverse events were a result of myelosuppression, with some causing therapy delays. Thirty- and 60-day mortality rates were 2% and 8%, respectively. The composite remission rate (complete remission [CR] and CR with incomplete blood count recovery) was 70%. Fifty-one percent of remissions were minimal residual disease-negative by flow cytometry. Similarly high remission rates were observed in patients with secondary AML, aged at least 75 years, and with adverse cytogenetic risk. Median relapse-free survival and overall survival were 7.7 and 11.3 months, respectively. Compared with historical data for HMA monotherapy, the combination of vadastuximab talirine with HMAs produced a high remission rate, but was accompanied by increased hematologic toxicity. [ABSTRACT FROM AUTHOR]

EphA3 is an Ephrin receptor tyrosine kinase that is overexpressed in most hematologic malignancies. We performed a first-in-human multicenter phase I study of the anti-EphA3 monoclonal antibody KB004 in refractory hematologic malignancies in order to determine safety and tolerability, along with the secondary objectives of pharmacokinetics (PK) and pharmacodynamics (PD) assessments, as well as preliminary assessment of efficacy. Patients were enrolled on a dose escalation phase (DEP) initially, followed by a cohort expansion phase (CEP). KB004 was administered by intravenous infusion on days 1, 8, and 15 of each 21-day cycle in escalating doses. A total of 50 patients (AML 39, MDS/MPN 3, MDS 4, DLBCL 1, MF 3) received KB004 in the DEP; an additional 14 patients were treated on the CEP (AML 8, MDS 6). The most common toxicities were transient grade 1 and grade 2 infusion reactions (IRs) in 79% of patients. IRs were dose limiting above 250 mg. Sustained exposure exceeding the predicted effective concentration (1ug/mL) and covering the 7-day interval between doses was achieved above 190 mg. Responses were observed in patients with AML, MF, MDS/MPN and MDS. In this study, KB004 was well tolerated and clinically active when given as a weekly infusion. [ABSTRACT FROM AUTHOR]