Nahor Haddish-Berhane

Discovery of (S)-6-(3-Cyclopentyl-2-(4-(trifluoromethyl)-1H-imidazol-1-yl)propanamido)nicotinic Acid as a Hepatoselective Glucokinase Activator Clinical Candidate for Treating Type 2 Diabetes Mellitus

Glucokinase is a key regulator of glucose homeostasis, and small molecule allosteric activators of this enzyme represent a promising opportunity for the treatment of type 2 diabetes. Systemically acting glucokinase activators (liver and pancreas) have been reported to be efficacious but in many cases present hypoglycaemia risk due to activation of the enzyme at low glucose levels in the pancreas, leading to inappropriately excessive insulin secretion. It was therefore postulated that a liver selective activator may offer effective glycemic control with reduced hypoglycemia risk. Herein, we report structure-activity studies on a carboxylic acid containing series of glucokinase activators with preferential activity in hepatocytes versus pancreatic β-cells. These activators were designed to have low passive permeability thereby minimizing distribution into extrahepatic tissues; concurrently, they were also optimized as substrates for active liver uptake via members of the organic anion transporting polypeptide (OATP) family. These studies lead to the identification of 19 as a potent glucokinase activator with a greater than 50-fold liver-to-pancreas ratio of tissue distribution in rodent and non-rodent species. In preclinical diabetic animals, 19 was found to robustly lower fasting and postprandial glucose with no hypoglycemia, leading to its selection as a clinical development candidate for treating type 2 diabetes.

Bench to bedside translation of antibody drug conjugates using a multiscale mechanistic PK/PD model: a case study with brentuximab-vedotin

To build a multiscale mechanism based pharmacokinetic–pharmacodynamic (PK/PD) model for antibody drug conjugates (ADCs), using brentuximab-vedotin as an example, for preclinical to clinical translation of ADC efficacy. Brentuximab-vedotin experimental data, collected from diverse publications, were employed in the following steps to build and validate the model: (1) characterization of ADC and payload PK at the cellular level, (2) characterization of payload PK in plasma and tumor tissue of xenograft mouse, (3) characterization of ADC PK in mouse plasma, (4) prediction of the tumor payload concentrations in xenograft mouse by integrating parameters obtained from steps 1–3 with the novel tumor disposition model for ADC, (5) characterization of preclinical brentuximab-vedotin tumor growth inhibition data using the novel PK/PD model, (6) characterization of ADC and payload PK in cancer patients, and (7) prediction of clinical responses of brentuximab-vedotin using the PK/PD model, by integrating PK parameters obtained from step 6, and translated mouse parameters from step 5; and comparing them with clinical trial results. The tumor disposition model was able to accurately predict xenograft tumor and plasma payload concentrations. PK/PD model predicted progression free survival rates and complete response rates for brentuximab-vedotin in patients were comparable to the observed clinical results. It is essential to understand and characterize the disposition of ADC and payload, at the cellular and physiological level, to predict the clinical outcome of ADC. A first of its kind mechanistic model has been developed for ADCs, which can integrate preclinical biomeasures and PK/PD data, to predict clinical response.

Antibody–drug conjugates: an emerging modality for the treatment of cancer

Antibody–drug conjugates (ADCs) offer promise as a therapeutic modality that can potentially reduce the toxicities and poor therapeutic indices caused by the lack of specificity of conventional anticancer therapies. ADCs combine the potency of cytotoxic agents with the target selectivity of antibodies by chemically linking a cytotoxic payload to an antibody, potentially creating a synthetic molecule that will deliver targeted antitumor therapy that is both safe and efficacious. The ADC repertoire contains a range of payload molecules, antibodies, and linkers. Two ADC molecules, Kadcyla® and Adcetris®, have been approved by the FDA, and many more are currently in clinical development.

Designing glucokinase activators with reduced hypoglycemia risk: discovery of N,N-dimethyl-5-(2-methyl-6-((5-methylpyrazin-2-yl)-carbamoyl)benzofuran-4-yloxy)pyrimidine-2-carboxamide as a clinical candidate for the treatment of type 2 diabetes mellitus

Glucokinase is a key regulator of glucose homeostasis and small molecule activators of this enzyme represent a promising opportunity for the treatment of Type 2 diabetes. Several glucokinase activators have advanced to clinical studies and demonstrated promising efficacy; however, many of these early candidates also revealed hypoglycemia as a key risk. In an effort to mitigate this hypoglycemia risk while maintaining the promising efficacy of this mechanism, we have investigated a series of substituted 2-methylbenzofurans as “partial activators” of the glucokinase enzyme leading to the identification of N,N-dimethyl-5-(2-methyl-6-((5-methylpyrazin-2-yl)-carbamoyl)benzofuran-4-yloxy)pyrimidine-2-carboxamide as an early development candidate.

A Priori Prediction of Tumor Payload Concentrations: Preclinical Case Study with an Auristatin-Based Anti-5T4 Antibody-Drug Conjugate

The objectives of this investigation were as follows: (a) to validate a mechanism-based pharmacokinetic (PK) model of ADC for its ability to a priori predict tumor concentrations of ADC and released payload, using anti-5T4 ADC A1mcMMAF, and (b) to analyze the PK model to find out main pathways and parameters model outputs are most sensitive to. Experiential data containing biomeasures, and plasma and tumor concentrations of ADC and payload, following A1mcMMAF administration in two different xenografts, were used to build and validate the model. The model performed reasonably well in terms of a priori predicting tumor exposure of total antibody, ADC, and released payload, and the exposure of released payload in plasma. Model predictions were within two fold of the observed exposures. Pathway analysis and local sensitivity analysis were conducted to investigate main pathways and set of parameters the model outputs are most sensitive to. It was discovered that payload dissociation from ADC and tumor size were important determinants of plasma and tumor payload exposure. It was also found that the sensitivity of the model output to certain parameters is dose-dependent, suggesting caution before generalizing the results from the sensitivity analysis. Model analysis also revealed the importance of understanding and quantifying the processes responsible for ADC and payload disposition within tumor cell, as tumor concentrations were sensitive to these parameters. Proposed ADC PK model provides a useful tool for a priori predicting tumor payload concentrations of novel ADCs preclinically, and possibly translating them to the clinic.

Pharmacodynamic Model of Sodium–Glucose Transporter 2 (SGLT2) Inhibition: Implications for Quantitative Translational Pharmacology

ABSTRACTSodium–glucose co-transporter-2 (SGLT2) inhibitors are an emerging class of agents for use in the treatment of type 2 diabetes mellitus (T2DM). Inhibition of SGLT2 leads to improved glycemic control through increased urinary glucose excretion (UGE). In this study, a biologically based pharmacokinetic/pharmacodynamic (PK/PD) model of SGLT2 inhibitor-mediated UGE was developed. The derived model was used to characterize the acute PK/PD relationship of the SGLT2 inhibitor, dapagliflozin, in rats. The quantitative translational pharmacology of dapagliflozin was examined through both prospective simulation and direct modeling of mean literature data obtained for dapagliflozin in healthy subjects. Prospective simulations provided time courses of UGE that were of consistent shape to clinical observations, but were modestly biased toward under prediction. Direct modeling provided an improved characterization of the data and precise parameter estimates which were reasonably consistent with those predicted from preclinical data. Overall, these results indicate that the acute clinical pharmacology of SGLT2 inhibitors in healthy subjects can be reasonably well predicted from preclinical data through rational accounting of species differences in pharmacokinetics, physiology, and SGLT2 pharmacology. Because these data can be generated at the earliest stages of drug discovery, the proposed model is useful in the design and development of novel SGLT2 inhibitors. In addition, this model is expected to serve as a useful foundation for future efforts to understand and predict the effects of SGLT2 inhibition under chronic administration and in other patient populations.

A CD3-bispecific molecule targeting P-cadherin demonstrates T cell-mediated regression of established solid tumors in mice

Strong evidence exists supporting the important role T cells play in the immune response against tumors. Still, the ability to initiate tumor-specific immune responses remains a challenge. Recent clinical trials suggest that bispecific antibody-mediated retargeted T cells are a promising therapeutic approach to eliminate hematopoietic tumors. However, this approach has not been validated in solid tumors. PF-06671008 is a dual-affinity retargeting (DART®)-bispecific protein engineered with enhanced pharmacokinetic properties to extend in vivo half-life, and designed to engage and activate endogenous polyclonal T cell populations via the CD3 complex in the presence of solid tumors expressing P-cadherin. This bispecific molecule elicited potent P-cadherin expression-dependent cytotoxic T cell activity across a range of tumor indications in vitro, and in vivo in tumor-bearing mice. Regression of established tumors in vivo was observed in both cell line and patient-derived xenograft models engrafted with circulating human T lymphocytes. Measurement of in vivo pharmacodynamic markers demonstrates PF-06671008-mediated T cell activation, infiltration and killing as the mechanism of tumor inhibition.

Abstract 2476: Bispecific redirected T-cell immunotherapy targeting P-cadherin expressing tumors

Introduction: Strong evidence exists supporting the important role T-cells play in the immune response against tumors. Still, the ability to initiate tumor specific immune responses remains a challenge. We have developed a Dual-Affinity Re-Targeting (DART®) protein engineered with enhanced pharmacokinetic properties to extend in vivo half-life, and designed to engage and activate endogenous polyclonal T cell populations via the CD3 complex in the presence of P-cadherin expressing tumors. We designate this bispecific redirecting T-cell molecule as P-cadherin LP-DART. P-cadherin up-regulation has been reported in various tumors, including breast, gastric, endometrial, colorectal and pancreatic cancers, and is correlated with poor survival of patients. Methods: The P-cadherin LP-DART was stably expressed by CHO cells and purified to homogeneity via standard antibody-purification methods. Functional in vitro studies were performed with a panel of human cancer cell lines and human T cells isolated from healthy donors. In vivo tumor growth inhibition studies were performed in immunodeficient athymic nude or NOD-scid IL2Rgamma null (NSG) mice bearing human tumor cell line- or patient derived-xenografts and human T-cells, and treated with P-cadherin LP-DART. Results: P-cadherin LP-DART exhibited binding to a broad panel of cancer cell lines expressing various levels of endogenous cell surface P-cadherin, and comparable binding to a number of human donor derived T-cells expressing CD3. In the presence of T-cells, this bispecific molecule elicited P-cadherin expression level dependent cytotoxic T-lymphocyte (CTL) responses against the different tumor cell lines, and induced antigen dependent T-cell activation and cytokine release. P-cadherin LP-DART also demonstrated potent in vivo anti-tumor activity against implanted tumor xenografts. Significant tumor growth inhibition was observed across a range of potential indications that express P-cadherin. Measurement of in vivo pharmacodynamic markers support P-cadherin LP-DART mediated CTL infiltration and killing as the mechanism of tumor inhibition. Conclusions: P-cadherin LP-DART displays potent in vitro and in vivo redirected T-cell activity against a broad panel of cancer cell lines expressing a range of cell surface P-cadherin levels. These data support further investigation of P-cadherin LP-DART as a potential novel therapeutic treatment for cancers expressing P-cadherin. Citation Format: Timothy S. Fisher, Adam Root, Bryan Peano, Allison Rohner, Justin Lucas, Mark Elliott, Konstantinos Tsaparikos, Hui Wang, Jonathan Golas, Maria Gavriil, Susan Benard, Tao He, Tracey Clark, Nahor Haddish-Berhane, Ralph Alderson, Yinhua Yang, Syd Johnson, Paul Moore, Lioudmila Tchistiakova, Hans-Peter Gerber, Chad May. Bispecific redirected T-cell immunotherapy targeting P-cadherin expressing tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2476. doi:10.1158/1538-7445.AM2015-2476

Abstract 5111: Bio-distribution and tumor targeting of a P-cadherin x CD3 bi-specific redirected T-cell molecule using fluorescence molecular tomography imaging

Introduction: Previously we have shown the utility of Fluorescent Molecular Tomography (FMT) imaging in evaluating bio-distribution of biologics. P-cadherin LP-DART is a bi-specific Dual Affinity Re-Targeting (DART®) molecule targeting CD3 expressed on T-cells and P-cadherin expressed on tumors. In this study we evaluated the bio-distribution and tumor targeting of P-cadherin LP-DART using FMT imaging in a colorectal xenograft model. Methods: NSG or athymic nude mice with subcutaneous HCT-116 xenografts were used. Studies that included engraftment of T-cells received either PBMNCs or T-cells isolated from healthy human volunteers. Bio-distribution studies were initiated when the tumors reached 300-500 mm 3 . P-cadherin LP-DART or a negative control-DART (non-targeted domain x CD3 binding domain) was conjugated with a near-infrared fluorophore VivoTag680XL (VT680), and the labeling efficiency was determined by spectrophotometer. T-cells used in trafficking studies were labeled with CellVue815. Cell surface P-cadherin expression and P-cadherin LP-DART binding was determined by flow cytometry. T-cell activity was measured with cytotoxic T-lymphocyte (CTL) assays. FMT imaging was performed longitudinally post injection of labeled bi-specifics. Data was analyzed using TrueQuant software. Plasma and tissues were collected for PK analysis by ELISA or histology. Results: VT680 conjugation to P-cadherin LP-DART did not significantly affect the binding to P-cadherin, whereas CD3 binding was decreased. In vivo FMT imaging revealed high levels of P-cadherin LP-DART accumulation in the tumors. The in vivo kinetics revealed that the peak accumulation in tumors was 96hrs post-injection. At 240hrs post-injection, there was still measurable P-cadherin LP-DART detected in tumors. Ex vivo imaging showed 20-25 fold increase in accumulation of P-cadherin LP-DART compared to negative control DART. Comparison of P-cadherin LP-DART accumulation between PBMNC engrafted and non-engrafted model showed no significant difference in quantity or kinetics. There was no significant difference in the kinetics of elimination in the whole-body, heart or liver between P-cadherin LP-DART or negative control. Ex vivo comparison of accumulation in various organs showed no difference between P-cadherin LP-DART or negative control. Cell trafficking studies with CellVue labeled T-cells showed the co-localization of T-cells and P-cadherin LP-DART in tumors. Conclusion: FMT imaging showed that P-cadherin LP-DART specifically targeted HCT-116 tumors. Cell trafficking studies showed that engrafted T-cells accumulated in tumors. This study shows the utility of FMT in bio-distribution studies of biologics and in vivo cell trafficking. Citation Format: Anand Giddabasappa, Vijay Gupta, Timothy S. Fisher, John David, Norberg Rand, Allison Rohner, Justin Cohen, Tracey Clark, Nahor Haddish-Berhane, Adam Root, Chad May. Bio-distribution and tumor targeting of a P-cadherin x CD3 bi-specific redirected T-cell molecule using fluorescence molecular tomography imaging. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5111. doi:10.1158/1538-7445.AM2015-5111