Good Laboratory Practice Preclinical Safety Studies for GSK2696273 (MLV Vector-Based Ex Vivo Gene Therapy for Adenosine Deaminase Deficiency Severe Combined Immunodeficiency) in NSG Mice.

GSK2696273 (autologous CD34+ cells transduced with retroviral vector that encodes for the human adenosine deaminase [ADA] enzyme) is a gamma-retroviral ex vivo gene therapy of bone marrow-derived CD34+ cells for the treatment of adenosine deaminase deficiency severe combined immunodeficiency (ADA-SCID). ADA-SCID is a severe monogenic disease characterized by immunologic and nonimmunologic symptoms. Bone-marrow transplant from a matched related donor is the treatment of choice, but it is available for only a small proportion of patients. Ex vivo gene therapy of patient bone-marrow CD34+ cells is an alternative treatment. In order to prepare for a marketing authorization application in the European Union, preclinical safety studies in mice were requested by the European Medicines Agency (EMA). A pilot study and a main biodistribution study were performed according to Good Laboratory Practice (GLP) at the San Raffaele Telethon Institute for Gene Therapy test facility. In the main study, human umbilical cord blood (UCB)-derived CD34+ cells were transduced with gamma-retroviral vector used in the production of GSK2696273. Groups of 10 male and 10 female NOD-SCID gamma (NSG) mice were injected intravenously with a single dose of transduced- or mock-transduced UCB CD34+ cells, and they were observed for 4 months. Engraftment and multilineage differentiation of blood cells was observed in the majority of animals in both groups. There was no significant difference in the level of chimerism between the two groups. In the gene therapy group, vector was detectable in lymphohemopoietic and nonlymphohemopoietic tissues, consistent with the presence of gene-modified human hematopoietic donor cells. Given the absence of relevant safety concerns in the data, the nonclinical studies and the clinical experience with GSK2696273 supported a successful application for market authorization in the European Union for the treatment of ADA-SCID patients, for whom no suitable human leukocyte antigen-matched related donor is available.

Cassette dosing for pharmacokinetic screening in drug discovery: comparison of clearance, volume of distribution, half-life, mean residence time, and oral bioavailability obtained by cassette and discrete dosing in rats.

The purpose of this investigation was to compare selected pharmacokinetic (PK) parameters obtained by cassette and discrete dosing of compounds in rats. The concordance of PK properties obtained by the two dosing strategies was evaluated for 116 compounds representing various therapeutic programs and diverse chemical structures. The correspondence between cassette- and discrete-dosing-derived PK properties was examined semiquantitatively and qualitatively. For semiquantitative comparison, compounds with cassette-to-discrete PK parameter ratios between 0.5 and 2 (inclusive) were considered to be in agreement. For qualitative comparison, compounds were divided into three categories (low, moderate, and high) based on the value of the PK parameter; compounds that fell into the same category following cassette and discrete dosing were considered to be in agreement. Of the 116 compounds evaluated, 89%, 91%, 80%, and 91% of the compounds were semiquantitatively equivalent for the intravenous PK parameters of clearance (CL), volume of distribution (Vdss), terminal elimination plasma half-life (HL), and mean residence time (MRT), respectively, whereas 79%, 80%, 79%, and 72% were qualitatively similar for CL, Vdss, MRT, and terminal elimination plasma HL, respectively. Following oral administration, bioavailability concordance was 72% when assessed qualitatively and 78% when determined semiquantitatively. Results from these analyses indicate that a cassette dosing strategy is a viable approach to screen compounds for PK properties within a drug discovery setting.

Design and synthesis of orally bioavailable serum and glucocorticoid-regulated kinase 1 (SGK1) inhibitors.

The lead serum and glucocorticoid-related kinase 1 (SGK1) inhibitors 4-(5-phenyl-1H-pyrrolo[2,3-b]pyridin-3-yl)benzoic acid (1) and {4-[5-(2-naphthalenyl)-1H-pyrrolo[2,3-b]pyridin-3-yl]phenyl}acetic acid (2) suffer from low DNAUC values in rat, due in part to formation and excretion of glucuronic acid conjugates. These PK/glucuronidation issues were addressed either by incorporating a substituent on the 3-phenyl ring ortho to the key carboxylate functionality of 1 or by substituting on the group in between the carboxylate and phenyl ring of 2. Three of these analogs have been identified as having good SGK1 inhibition potency and have DNAUC values suitable for in vivo testing.

Discovery of novel aminothiadiazole amides as selective EP(3) receptor antagonists.

This Letter discloses a series of 2-aminothiadiazole amides as selective EP(3) receptor antagonists. SAR optimization resulted in compounds with excellent functional activity in vitro. In addition, efforts to optimize DMPK properties in the rat are discussed. These efforts have resulted in the identification of potent, selective EP(3) receptor antagonists with excellent DMPK properties suitable for in vivo studies.

Synthesis and SAR of amino acid-derived heterocyclic progesterone receptor full and partial agonists.

Two classes of amino acid-derived heterocyclic progesterone receptor ligands were developed to address the metabolic issues posed by the dimethyl amide functionality of the lead compound (1). The tetrazole-derived ligands behaved as potent partial agonists, while the 1,2,4-triazole ligands behaved as potent full agonists.

Synthesis and SAR of potent LXR agonists containing an indole pharmacophore.

A novel series of 1H-indol-1-yl tertiary amine LXR agonists has been designed. Compounds from this series were potent agonists with good rat pharmacokinetic parameters. In addition, the crystal structure of an LXR agonist bound to LXRalpha will be disclosed.

Discovery of potent and orally bioavailable N,N'-diarylurea antagonists for the CXCR2 chemokine receptor.

A series of 3-substituted N,N'-diarylureas was prepared and the structure-activity relationship relative to CXCR2 receptor affinity as well as their pharmacokinetic properties were examined. In vitro microsomal metabolism studies indicated that the lower clearance rates of the 3-sulfonamido-substituted compounds were most likely due to the suppression of glucuronidation.