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Purpose: Depatux-m is an antibody drug conjugate (ADC) that targets and inhibits growth of cancer cells overexpressing the epidermal growth factor receptor (EGFR) or the 2–7 deletion mutant (EGFRvIII) in tumor models in vitro and in vivo. Treatment of patients suffering from relapsed/refractory glioblastoma (GBM) with a combination of depatux-m and temozolomide (TMZ) tended to increase overall survival. As a first step to understand the nature of the interaction between the two drugs, we investigated whether the interaction was synergistic, additive or antagonistic. Methods: The efficacy of ADCs, antibodies, TMZ and radiation was tested in xenograft models of GBM, U-87MG and U-87MG EGFRvIII. Both models express EGFR. U-87MG EGFRvIII was transduced to express EGFRvIII. Changes in tumor volume, biomarkers of cell death and apoptosis after treatment were used to measure efficacy of the various treatments. Synergism of depatux-m and TMZ was verified in three-dimensional cultures of U-87MG and U-87MG EGFRvIII by the method of Chou and Talalay. Results: Combined with TMZ and radiotherapy (RT), depatux-m inhibited xenograft growth of U-87MG and U-87MG EGFRvIII more than either treatment with depatux-m or TMZ + RT. Durability of the response to depatux-m + TMZ + RT or depatux-m + TMZ was more pronounced in U-87MG EGFRvIII than in U-87MG. Efficacy of depatux-m + TMZ was synergistic in U-87MG EGFRvIII and additive in U-87MG. Conclusion: Adding depatux-m enhances the efficacy of standard of care therapy in preclinical models of GBM. Durability of response to depatux-m + TMZ in vivo and synergy of the drug-drug interaction correlates with the amount of antigen expressed by the tumor cells. [ABSTRACT FROM AUTHOR]

ABT-700 is a therapeutic antibody against the hepatocyte growth factor receptor (MET). At doses or regimens that lead to exposures exceeding optimum in vivo, the efficacy of ABT-700 is unexpectedly reduced. We hypothesized that this reduction in efficacy was due to a "prozone-like" effect in vivo. A prozone-like effect, which is a reduction in efficacy beyond optimum exposure, is caused due a mechanism similar to the generation of false negative flocculation tests by excessive antibody titres. In vitro, we demonstrate that at higher ABT-700 concentrations, this "prozone-like" effect is mediated by a progressive conversion from bivalent to ineffective monovalent binding of the antibody. In vivo, the efficacy of ABT-700 is dependent on an optimum range of exposure as well. Our data suggest that the "prozone-like" effect is operative and independent of target expression. ABT-700 dose, regimen, exposure, and tumor burden are interdependent variables influencing the "prozone-like" effect and mediating and in vivo efficacy. By optimization of dosage and regimen we demonstrate that the "prozone-like" effect can be alleviated and ABT-700 efficacy at varying tumor loads can be further extended in combination with cisplatin. Our results suggest that optimization of exposure taking tumor burden into account may alleviate "prozone-like" effects without compromising efficacy. [ABSTRACT FROM AUTHOR]

Background: c-Met is the receptor tyrosine kinase for hepatocyte growth factor (HGF) encoded by the MET proto-oncogene. Aberrant activation of c-Met resulting from MET amplification and c-Met overexpression is associated with poor clinical outcome in multiple malignancies underscoring the importance of c-Met signaling in cancer progression. Several c-Met inhibitors have advanced to the clinic; however, the development of inhibitory c-Met-directed therapeutic antibodies has been hampered by inherent agonistic activity.Method: We generated and tested a bivalent anti-c-Met monoclonal antibody ABT-700 in vitro for binding potency and antagonistic activity and in vivo for antitumor efficacy in human tumor xenografts. Human cancer cell lines and gastric cancer tissue microarrays were examined for MET amplification by fluorescence in situ hybridization (FISH).Results: ABT-700 exhibits a distinctive ability to block both HGF-independent constitutive c-Met signaling and HGF-dependent activation of c-Met. Cancer cells addicted to the constitutively activated c-Met signaling driven by MET amplification undergo apoptosis upon exposure to ABT-700. ABT-700 induces tumor regression and tumor growth delay in preclinical tumor models of gastric and lung cancers harboring amplified MET. ABT-700 in combination with chemotherapeutics also shows additive antitumor effect. Amplification of MET in human cancer tissues can be identified by FISH.Conclusions: The preclinical attributes of ABT-700 in blocking c-Met signaling, inducing apoptosis and suppressing tumor growth in cancers with amplified MET provide rationale for examining its potential clinical utility for the treatment of cancers harboring MET amplification. [ABSTRACT FROM AUTHOR]

The Bcl-2 family inhibitors venetoclax and navitoclax demonstrated potent antitumor activity in chronic lymphocytic leukemia patients, notably in reducing marrow load and adenopathy. Subsequent trials with venetoclax have been initiated in non-Hodgkin's lymphoma and multiple myeloma patients. Traditional preclinical models fall short either in faithfully recapitulating disease progression within such compartments or in allowing the direct longitudinal analysis of systemic disease. We show that intravenous inoculation of engineered RS4;11 (acute lymphoblastic leukemia) and Granta 519 (mantle cell lymphoma) bioluminescent reporter cell lines result in tumor engraftment of bone marrow, with additional invasion of the central nervous system in the case of Granta 519. Importantly, apoptosis induction and response of these systemically engrafted tumors to Bcl-2 family inhibitors alone or in combination with standard-of-care agents could be monitored longitudinally with optical imaging, and was more accurately reflective of the observed clinical response. [ABSTRACT FROM AUTHOR]

The article looks at a study regarding the selective BCL-2 family inhibitors venetoclax to dissect cell survival dependencies and define improved strategies for cancer therapy. Topics discussed include Navitoclax has also been shown to enhance the efficacy of docetaxel in preclinical models of solid tumors, efficacy and toxicity of the navitoclax-docetaxel combination and selective inhibitors have the potential to enhance the efficacy of docetaxel in solid tumors.

ABT-719 is a 2-pyridone antimicrobial which inhibits DNA gyrase activity. It has considerable subcutaneous (sc) and oral efficacy in the treatment of experimental pyelonephritis induced in carrageenan-treated mice by clinical isolates of Enterococcus faecalis, Enterococcus faecium, Escherichia coli, and Pseudomonas aeruginosa. Therapeutic ED50s, defined here as producing a 2 log10 reduction in kidney bacterial burden, provide a reliable end point for comparison of drug efficacy in this experimental infection. Therapeutic ED50s for ABT-719 against these infections were equal to or up to ten-fold lower than those for ciprofloxacin, used as a reference because of similarity in mode of action. Against E. faecalis, the therapeutic ED50s for ABT-719 were 4.5–13.6 mg/kg.day for sc administration and 6.8–8.9 mg/kg.day for oral administration. ABT-719 was more potent than ciprofloxacin and vancomycin against the E. faecalis strains, which showed ciprofloxacin and vancomycin resistance covering a range of MICs. Against E. faecium, the therapeutic ED50s for ABT-719 were 8.8 mg/kg.day (sc) and 9.4 mg/kg.day (oral). Against an isolate of E. faecium showing ciprofloxacin and vancomycin resistance the ED50 for ABT-719 to achieve a 1 log10 reduction in kidney bacterial burden was 17.9 mg/kg.day by sc administration. While ABT-719 had lower efficacy against this isolate than against others, ciprofloxacin and vancomycin failed to show efficacy. Against E. coli, the therapeutic ED50, for ABT-719 was 1.1 mg/kg.day (oral), and against P. aeruginosa, this value was 2.7 mg/kg.day (oral) with values against both of these pathogens similar to those for ciprofloxacin. ABT-719, which represents the new 2-pyridone compound class, has promise for the treatment of urinary tract infections, as suggested by the significant efficacy seen against experimental pyelonephritis caused by E. coli, P. aeruginosa and susceptible and resistant enterococci. [ABSTRACT FROM PUBLISHER]

This study was designed to test the ability of the Bcl-2 family inhibitor ABT-263 to potentiate commonly used chemotherapeutic agents and regimens in hematologic tumor models. Models of B-cell lymphoma and multiple myeloma were tested in vitro and in vivo with ABT-263 in combination with standard chemotherapeutic regimens, including VAP, CHOP and R-CHOP, as well as single cytotoxic agents including etoposide, rituximab, bortezomib and cyclophosphamide. Alterations in Bcl-2 family member expression patterns were analyzed to define mechanisms of potentiation. ABT-263 was additive with etoposide, vincristine and VAP in vitro in the diffuse large B-cell lymphoma line (DLBCL) DoHH-2, while rituximab potentiated its activity in SuDHL-4. Bortezomib strongly synergized with ABT-263 in the mantle cell lymphoma line Granta 519. Treatment of DoHH-2 with etoposide was associated with an increase in Puma expression, while bortezomib upregulated Noxa expression in Granta 519. Combination of ABT-263 with cytotoxic agents demonstrated superior tumor growth inhibition and delay in multiple models versus cytotoxic therapy alone, along with significant improvements in tumor response rates. Inhibition of the Bcl-2 family of proteins by ABT-263 enhances the cytotoxicity of multiple chemotherapeutics in hematologic tumors and represents a promising addition to the therapeutic arsenal for treatment of these diseases. [ABSTRACT FROM AUTHOR]

Apoptosis is a highly regulated process of programmed cell death essential for normal physiology. Dysregulation of apoptosis contributes to the development and progression of various diseases, including cancer, neurodegenerative disorders, and chronic heart failure. Quantitative noninvasive imaging of apoptosis in preclinical models would allow for dynamic longitudinal screening of compounds and facilitates a more rapid determination of therapeutic efficacy. In this study, we report the in vivo characterization of Z-DEVD-aminoluciferin, a modified firefly luciferase substrate that in apoptotic cells is cleaved by caspase-3 to liberate aminoluciferin, which can be consumed by luciferase to generate a luminescent signal. In two oncology models, namely SKOV3-luc and MDA-MB-231-luc-LN, at 24, 48, and 72 h after treatment with docetaxel, animals were injected with Z-DEVD-aminoluciferin and bioluminescent images were acquired. Significantly more light was detected at 24 (P<0.05), 48 (P<0.01), and 72 h (P<0.01) in the docetaxel-treated group compared with the vehicle-treated group, with caspase-3 activation at these time points confirmed using immunohistochemistry. Importantly, whereas significant differences between groups were detected as early as 24 h after treatment by molecular imaging, caliper measurements were unable to detect a difference for 4–5 additional days. Taken together, these data show that in vivo imaging of apoptosis using Z-DEVD-aminoluciferin could provide a sensitive and rapid method for early detection of drug efficacy, which could potentially be used by numerous therapeutic programs. [ABSTRACT FROM AUTHOR]

Objectives: The goals of the study were 1) to evaluate the efficacy of clinically relevant antibacterial therapies in the ferret model of helicobacter-induced gastritis and 2) to compare these results to the efficacy achieved clinically in humans. Methods: Ferrets were inoculated with H. mustelae, and gastritis was allowed to develop. The double therapy of clarithromycin and omeprazole and the triple therapies of clarithromycin or amoxicillin with metronidazole and omeprazole were administered. Efficacy was evaluated by Helicobacter burden cultured from biopsy samples and by histopathological evaluation of Helicobacter burden and gastric inflammation with pylorus and fundus samples obtained 4 wk after the end of antibacterial therapy. Results: Clarithromycin-based double and triple therapies significantly reduced Helicobacter burden and decreased gastric inflammation. Clarithromycin-based double therapy was more effective than amoxicillin-based triple therapy. Reduction of the length of clarithromycin therapy from 14 to 7 days decreased efficacy. Antibacterial therapies in the ferret did not produce eradication rates comparable to clinical results, even though the serum concentrations of clarithromycin in ferret were in excess of concentrations used in humans. Relapse of Helicobacter infection after the end of therapy occurred in some cases. Conclusions: Although the ferret model of Helicobacter gastric infection underestimated the clinical efficacy of antibacterial treatments in humans, the model was valuable for comparing the relative efficacy of antibacterial therapies. [ABSTRACT FROM AUTHOR]