Targeting the CXCR4 pathway using a novel anti-CXCR4 IgG1 antibody (PF-06747143) in chronic lymphocytic leukemia.

BackgroundThe CXCR4-CXCL12 axis plays an important role in the chronic lymphocytic leukemia (CLL)-microenvironment interaction. Overexpression of CXCR4 has been reported in different hematological malignancies including CLL. Binding of the pro-survival chemokine CXCL12 with its cognate receptor CXCR4 induces cell migration. CXCL12/CXCR4 signaling axis promotes cell survival and proliferation and may contribute to the tropism of leukemia cells towards lymphoid tissues and bone marrow. Therefore, we hypothesized that targeting CXCR4 with an IgG1 antibody, PF-06747143, may constitute an effective therapeutic approach for CLL.MethodsPatient-derived primary CLL-B cells were assessed for cytotoxicity in an in vitro model of CLL microenvironment. PF-06747143 was analyzed for cell death induction and for its potential to interfere with the chemokine CXCL12-induced mechanisms, including migration and F-actin polymerization. PF-06747143 in vivo efficacy was determined in a CLL murine xenograft tumor model.ResultsPF-06747143, a novel-humanized IgG1 CXCR4 antagonist antibody, induced cell death of patient-derived primary CLL-B cells, in presence or absence of stromal cells. Moreover, cell death induction by the antibody was independent of CLL high-risk prognostic markers. The cell death mechanism was dependent on CXCR4 expression, required antibody bivalency, involved reactive oxygen species production, and did not require caspase activation, all characteristics reminiscent of programmed cell death (PCD). PF-06747143 also induced potent B-CLL cytotoxicity via Fc-driven antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity activity (CDC). PF-06747143 had significant combinatorial effect with standard of care (SOC) agents in B-CLL treatment, including rituximab, fludarabine (F-ara-A), ibrutinib, and bendamustine. In a CLL xenograft model, PF-06747143 decreased tumor burden and improved survival as a monotherapy, and in combination with bendamustine.ConclusionsWe show evidence that PF-06747143 has biological activity in CLL primary cells, supporting a rationale for evaluation of PF-06747143 for the treatment of CLL patients

Determinación de la prevalencia de Dirofilaria immitis, mediante la Prueba Rápida de Inmunocromatografía en perros del municipio de puerto barrios, Izabal, en el año 2016

La Dirofilariasis, es una infección causada por Dirofilaria immitis que afecta el corazón del perro, y menos frecuente en el gato. Es una enfermedad que utiliza a los mosquitos de los géneros Aedes, Anopheles y Culex , y es así como se disemina la enfermedad. Además, puede llegar a infectar al humano de una forma accidental. Se realizó un estudio en el municipio de Puerto Barrios, Izabal, con el objetivo de establecer la prevalencia de perros seropositivos y contribuir con el estudio epidemiológico de D. immitis¸ en Guatemala. Para este estudio transversal descriptivo, se muestrearon 80 caninos completamente al azar. En el estudio se incluyeron caninos machos y hembras, mayores de un año de edad, sin previo tratamiento a ivermectina. Se tomó una muestra de sangre periférica de la vena cefálica o safena, de cada uno. Cada una de las muestras fue sometida a la de prueba inmunocromatografía rápida (Uranotest Dirofilaria®,) para determinar la presencia de antígenos de D. immitis. En el estudio, no se encontró la presencia de antígenos circulantes en los perros muestreados, por lo tanto la prevalencia fue de cero. Sin embargo, este hallazgo no descarta la presencia del parásito en el municipio de Puerto Barrios, Izabal. Debido al resultado obtenido fue establecer alguna relación entre sexo, edad, raza y procedencia con la seropositividad

Gemtuzumab Ozogamicin (GO) Inclusion to Induction Chemotherapy Eliminates Leukemic Initiating Cells and Significantly Improves Survival in Mouse Models of Acute Myeloid Leukemia

Gemtuzumab ozogamicin (GO) is an anti-CD33 antibody-drug conjugate for the treatment of acute myeloid leukemia (AML). Although GO shows a narrow therapeutic window in early clinical studies, recent reports detailing a modified dosing regimen of GO can be safely combined with induction chemotherapy, and the combination provides significant survival benefits in AML patients. Here we tested whether the survival benefits seen with the combination arise from the enhanced reduction of chemoresidual disease and leukemic initiating cells (LICs). Herein, we use cell line and patient-derived xenograft (PDX) AML models to evaluate the combination of GO with daunorubicin and cytarabine (DA) induction chemotherapy on AML blast growth and animal survival. DA chemotherapy and GO as separate treatments reduced AML burden but left significant chemoresidual disease in multiple AML models. The combination of GO and DA chemotherapy eliminated nearly all AML burden and extended overall survival. In two small subsets of AML models, chemoresidual disease following DA chemotherapy displayed hallmark markers of leukemic LICs (CLL1 and CD34). In vivo, the two chemoresistant subpopulations (CLL1+/CD117− and CD34+/CD38+) showed higher ability to self-renewal than their counterpart subpopulations, respectively. CD33 was coexpressed in these functional LIC subpopulations. We demonstrate that the GO and DA induction chemotherapy combination more effectively eliminates LICs in AML PDX models than either single agent alone. These data suggest that the survival benefit seen by the combination of GO and induction chemotherapy, nonclinically and clinically, may be attributed to the enhanced reduction of LICs

Loss of luminal Ca2+ activation in the cardiac ryanodine receptor is associated with ventricular fibrillation and sudden death

Different forms of ventricular arrhythmias have been linked to mutations in the cardiac ryanodine receptor (RyR)2, but the molecular basis for this phenotypic heterogeneity is unknown. We have recently demonstrated that an enhanced sensitivity to luminal Ca2+ and an increased propensity for spontaneous Ca2+ release or store-overload-induced Ca2+ release (SOICR) are common defects of RyR2 mutations associated with catecholaminergic polymorphic or bidirectional ventricular tachycardia. Here, we investigated the properties of a unique RyR2 mutation associated with catecholaminergic idiopathic ventricular fibrillation, A4860G. Single-channel analyses revealed that, unlike all other disease-linked RyR2 mutations characterized previously, the A4860G mutation diminished the response of RyR2 to activation by luminal Ca2+, but had little effect on the sensitivity of the channel to activation by cytosolic Ca2+. This specific impact of the A4860G mutation indicates that the luminal Ca2+ activation of RyR2 is distinct from its cytosolic Ca2+ activation. Stable, inducible HEK293 cells expressing the A4860G mutant showed caffeine-induced Ca2+ release but exhibited no SOICR. Importantly, HL-1 cardiac cells transfected with the A4860G mutant displayed attenuated SOICR activity compared with cells transfected with RyR2 WT. These observations provide the first evidence that a loss of luminal Ca2+ activation and SOICR activity can cause ventricular fibrillation and sudden death. These findings also indicate that although suppressing enhanced SOICR is a promising antiarrhythmic strategy, its oversuppression can also lead to arrhythmias

Discovery of CX-5461, the First Direct and Selective Inhibitor of RNA Polymerase I, for Cancer Therapeutics

Accelerated proliferation of solid tumor and hematologic cancer cells is linked to accelerated transcription of rDNA by the RNA polymerase I (Pol I) enzyme to produce elevated levels of rRNA (rRNA). Indeed, upregulation of Pol I, frequently caused by mutational alterations among tumor suppressors and oncogenes, is required for maintenance of the cancer phenotype and forms the basis for seeking selective inhibitors of Pol I as anticancer therapeutics. 2-(4-Methyl-[1,4]­diazepan-1-yl)-5-oxo-5<i>H</i>-7-thia-1,11<i>b</i>-diaza-benzo­[<i>c</i>]­fluorene-6-carboxylic acid (5-methyl-pyrazin-2-ylmethyl)-amide (CX-5461, <b>7c</b>) has been identified as the first potent, selective, and orally bioavailable inhibitor of RNA Pol I transcription with in vivo activity in tumor growth efficacy models. The preclinical data support the development of CX-5461 as an anticancer drug with potential for activity in several types of cancer

Additional file 3: Figure S3. of Targeting the CXCR4 pathway using a novel anti-CXCR4 IgG1 antibody (PF-06747143) in chronic lymphocytic leukemia

The PF-06747143 parent IgG1 antibody (m15 IgG1) induces cell death and this activity is similar in HR and LR CLL patients. Primary CLL-B cells derived from CLL patients were incubated either alone (n = 10) or co-cultured with stroma-NK-tert cells (n = 10) and treated with vehicle, IgG1 control Ab, or m15-IgG1 antibody for 48 h. Cell death was measured using CD19/CD5/Annexin V staining followed by flow cytometry analysis. The data is derived from five high-risk (HR) and five low-risk (LR) CLL patients. The HR patients are presented with solid symbols (•) and LR patients denoted with hollow symbols (○). The individual data points for each group are shown. The horizontal lines represent the mean for each group Statistical comparisons were performed using Bonferroni’s correction test. (PDF 744 kb

Additional file 4: Figure S4. of Targeting the CXCR4 pathway using a novel anti-CXCR4 IgG1 antibody (PF-06747143) in chronic lymphocytic leukemia

m15-IgG1 and m15-IgG4 have similar cell death activity in HR and LR CLL patients, in presence or absence of stromal cells. The primary CLL-B cells derived from CLL patients were incubated either alone (n = 4) or co-cultured with stroma-NK-tert cells (n = 4) and treated with vehicle, m15-IgG1, m15-IgG4, IgG1 control antibody, or IgG4 control antibody for 48 h. Cell death was measured using CD19/CD5/Annexin V staining followed by flow cytometry analysis. The data is presented as % specific induced cell death (% SICD). The data shown is derived from two high-risk (HR) and two low-risk (LR) CLL patients. The HR patients are presented with solid symbols (•) and LR patients denoted with hollow symbols (○). The individual data points for each group are shown. The horizontal lines represent the mean for each group. Statistical comparisons were performed using Bonferroni’s correction test. (PDF 1032 kb

Additional file 6: Figure S6. of Targeting the CXCR4 pathway using a novel anti-CXCR4 IgG1 antibody (PF-06747143) in chronic lymphocytic leukemia

m15-IgG1-induced LR or HR CLL-B cell death is independent of caspase activation. CLL-B cells were treated for 6 h with m15-IgG1 (1, 10, or 100 nM) or IgG1 control antibody. Caspases 3, 8, and 9 were measured using a colometric detection method. The data shown is derived from four high-risk (HR) and four low-risk (LR) CLL patients. The HR patients are denoted by triangles and LR patients denoted by circles. The individual data points for each group are shown. The horizontal lines represent the mean for each group. Statistical comparisons were performed using Bonferroni’s correction test. (PDF 915 kb