Daniel W. Drolet

Preclinical and phase 1A clinical evaluation of an anti-VEGF pegylated aptamer (EYE001) for the treatment of exudative age-related macular degeneration

Background Recent studies have suggested that vascular endothelial growth factor (VEGF) is an important stimulus for the growth of new blood vessels in the eye. Anti-VEGF therapy is thus a potential treatment for exudative macular degeneration and diabetic retinopathy. Methods Previously described animal models of vascular leakage and ocular neovascularization, including the Miles assay, the rat corneal angiogenesis model, and the mouse retinopathy of prematurity (ROP) model, were used to study this drug. After these studies, a phase IA single ascending dose study of intravitreal injections of the drug was performed in 15 patients with subfoveal choroidal neovascularization secondary to exudative age-related macular degeneration (AMD). Results The Miles assay model showed almost complete attenuation of VEGF-mediated vascular leakage following addition of EYE001, and the corneal angiogenesis model also showed a significant reduction in neovascularization with EYE001. The ROP model showed inhibition of 80% of the retinal neovascularization compared with controls (P = 0.0001). The phase IA safety study of patients with exudative AMD showed no significant safety issues related to the drug. Ophthalmic evaluation revealed that 80% of patients showed stable or improved vision 3 months after treatment and that 27% of eyes demonstrated a three-line or greater improvement in vision on the Early Treatment for Diabetic Retinopathy Study chart at this time. Conclusion Anti-VEGF therapy is a promising new avenue for the treatment of neovascular diseases of the eye, including exudative macular degeneration and diabetic retinopathy. Preclinical data from studies with EYE001 support clinical evaluation of its efficacy in such diseases. This report is the first to describe administration of anti-VEGF therapy in humans for exudative macular degeneration and shows the safety of such therapy for single injections. Further clinical studies are necessary to determine the safety of multiple intravitreal injections of EYE001 and larger studies are needed to prove the efficacy of this novel, potentially therapeutic agent for neovascular AMD.

POU-domain proteins: structure and function of developmental regulators

POU-domain proteins are a group of developmental regulators found in organisms as distant as worm and man. The sequence conservation of the POU-domain has allowed the characterization of increasing numbers of proteins containing the domain, many of which act to control the generation and maintenance of differentiated cell phenotypes in organs as diverse as skin and brain. Analysis of the means by which POU-domain proteins regulate transcription has led to a further understanding of how this group initiates specific developmental programs.

Pharmacokinetics and safety of an anti-vascular endothelial growth factor aptamer (NX1838) following injection into the vitreous humor of rhesus monkeys.

AbstractPurpose. The objective of this study was to determine the pharmacokinetics and safety for NX1838 following injection into the vitreous humor of rhesus monkeys.nMethods. Plasma and vitreous humor pharmacokinetics were determined following a single bilateral 0.25, 0.50, 1.0, 1.5, or 2.0 mg/eye dose. In addition, the pharmacokinetics and toxicological properties of NX1838 were determined following six biweekly bilateral injections of 0.25 or 0.50 mg/eye or following four biweekly bilateral injections of 0.10 mg per eye followed by two biweekly bilateral injections of 1.0 mg per eye.nResults. Plasma and vitreous humor NX1838 concentrations were linearly related to the dose administered. NX1838 was cleared intact from the vitreous humor into the plasma with a half-life of approximately 94 h, which was in agreement with the plasma terminal half-life. Vascular endothelial growth factor (VEGF)-binding assays demonstrated that the NX1838 remaining in the vitreous humor after 28 days was fully active. No toxicological effects or antibody responses were evident.nConclusions. The no observable effect level was greater than six biweekly bilateral 0.50 mg/eye doses or two biweekly bilateral 1.0 mg/eye doses. These pharmacokinetic and safety data support monthly 1 or 2 mg/eye dose regimens in human clinical trials.

Aptamer affinity chromatography:: combinatorial chemistry applied to protein purification

The systematic evolution of ligands by exponential enrichment process is a combinatorial chemistry method that allows the identification of specific oligonucleotide sequences, known as aptamers, that bind to a desired target molecule with high affinity and specificity. Here, a DNA-aptamer specific for human L-selectin was immobilized to a chromatography support to create an affinity column. This column was effectively applied as either the first or second step in the purification of a recombinant human L-selectin-Ig fusion protein from Chinese hamster ovary cell-conditioned medium. The fusion protein was efficiently bound to the column and efficiently eluted by gentle elution schemes. Application of the aptamer column as the initial purification step resulted in a 1500-fold purification with an 83% single step recovery. These results demonstrate that oligonucleotide aptamers can be effective affinity purification reagents.

Detection and plasma pharmacokinetics of an anti-vascular endothelial growth factor oligonucleotide-aptamer (NX1838) in rhesus monkeys

Aptamers are oligonucleotide ligands selected, in vitro, to bind a specified target protein. The first aptamer to reach human clinical testing is NX1838, a polyethylene glycol conjugated aptamer that inhibits vascular endothelial growth factor. This paper describes the validation of a high-performance liquid chromatographic anion-exchange method for the determination of NX1838 in plasma. Measurements of intact NX1838 had a coefficient of variation of less than 8% and an accuracy between 107% and 115%. The assay was utilized to determine NX1838 plasma pharmacokinetics in rhesus monkeys following a single 1 mg/kg intravenous or subcutaneous dose. Following intravenous administration, the maximum achieved plasma concentration was 25.5 microg/ml with a terminal half-life of 9.3 h and clearance rate of 6.2 ml/h. After subcutaneous administration, the fraction of the dose absorbed into the plasma compartment was 0.78 with a time to peak concentration (4.9 microg/ml) of 8 to 12 h.

Expression patterns of the hepatic leukemia factor gene in the nervous system of developing and adult mice

Hepatic leukemia factor (HLF) is a bZIP transcription factor related to the CES-2 protein, which controls apoptosis of the NSM serotoninergic neurons in Caenorhabditis elegans. Ectopic expression of HLF as an E2A-HLF fusion protein in t(17;19)-positive human pro-B cell acute lymphoblastic leukemias is believed to promote malignancy by interfering with apoptosis. While HLF has been linked to malignancies of the lymphoid system, it is not normally expressed in these cells. Rather, HLF transcripts are detected in the liver, kidney, lung and adult nervous system by Northern blotting. Despite the links to cell death, little is known of the distribution or function of HLF in the adult and developing mammalian nervous system. Therefore, we cloned mouse Hlf and studied its expression by in situ hybridization. During embryonic brain development, Hlf expression was restricted to the anterior pituitary and meninges. By early postnatal life, Hlf was highly expressed in somatosensory cortex, thalamic nuclei, and structures arising from ectodermal placodes. Subsequently, Hlf expression increased in the central nervous system and was found throughout the brain by adulthood. In the developing pituitary gland, Hlf was highly expressed in the rostral tip of the anterior lobe. This pattern is similar to that of Tef, an Hlf-related bZIP protein. However, while Tef is expressed in the anterior pituitary of the adult mouse, Hlf was detected in both the anterior and posterior pituitary. Hlf expression was not associated with cells undergoing programmed cell death in the nervous system. Hlf expression increased markedly with synaptogenesis and was coincident with barrel formation revealed by cytochrome oxidase staining. Together, these data suggest that Hlf plays a role in the function of differentiated neurons in the adult nervous system rather than programmed cell death.

The effect of rifampicin, a prototypical CYP3A4 inducer, on erlotinib pharmacokinetics in healthy subjects

PurposeErlotinib, N-(3-ethynylphenyl)-6,7-bis(2-methoxyethoxy) quinazolin-4-amine is approved for the treatment for non-small cell lung cancer and pancreatic cancer. Because erlotinib is metabolized predominately by CYP3A4, co-administration of compounds that increase CYP3A4 activity may alter the efficacy and safety of erlotinib therapy. Two phase I studies were conducted in healthy male subjects to evaluate the effect of pre- or co-administered rifampicin, a CYP3A4 inducer, on the pharmacokinetics of erlotinib.MethodsStudy 1 included Groups A (erlotinib 150xa0mg days 1 and 15, rifampicin 600xa0mg days 8–14) and B (erlotinib 150xa0mg days 1 and 15) in a parallel group study design. Study 2 subjects received erlotinib 150xa0mg day 1, erlotinib 450xa0mg day 15, and rifampicin 600xa0mg days 8–18. The primary endpoint in each study was the ratio of exposure (AUC0–∞ and Cmax) between days 1 and 15. Urinary cortisol metabolic induction ratios were determined in Study 1 for Group A subjects only.ResultsIn Study 1, the geometric mean ratios of AUC0–∞ and Cmax were 33 and 71xa0%, respectively, and the mean cortisol metabolic index increased from 7.4 to 27.0, suggesting cytochrome P450 (CYP) enzyme induction. In Study 2, the geometric mean ratios for AUC0–∞ and Cmax were 19 and 34xa0% (when dose adjusted from 450 to 150xa0mg erlotinib), respectively, a greater relative decrease than observed in Study 1.ConclusionsErlotinib exposure (AUC0–∞ and Cmax) was reduced after pre- or concomitant dosing with rifampicin. Doses of ≥450xa0mg erlotinib may be necessary to compensate for concomitant medications with strong CYP3A4 enzyme induction effect.

A nonclinical safety and pharmacokinetic evaluation of N6022: a first-in-class S-nitrosoglutathione reductase inhibitor for the treatment of asthma.

S-nitrosoglutathione reductase is the primary enzyme responsible for the metabolism of S-nitrosoglutathione (GSNO), the bodys main source of bioavailable nitric oxide. Through its catabolic activity, GSNO reductase (GSNOR) plays a central role in regulating endogenous S-nitrosothiol levels and protein S-nitrosation-based signaling. By inhibiting GSNOR, we aim to increase pulmonary GSNO and induce bronchodilation while reducing inflammation in lung diseases such as asthma. To support the clinical development of N6022, a first-in-class GSNOR inhibitor, a 14-day toxicology study was conducted. Sprague-Dawley rats were given 2, 10 or 50 mg/kg/day N6022 via IV administration. N6022 was well tolerated at all doses and no biologically significant adverse findings were noted in the study up to 10 mg/kg/day. N6022-related study findings were limited to the high dose group. One male rat had mild hepatocellular necrosis with accompanying increases in ALT and AST and several male animals had histological lung assessments with a slight increase in foreign body granulomas. Systemic exposure was greater in males than females and saturation of plasma clearance was observed in both sexes in the high dose group. Liver was identified as the major organ of elimination. Mechanistic studies showed dose-dependent effects on the integrity of a rat hepatoma cell line.

Purification of a highly modified RNA-aptamer: Effect of complete denaturation during chromatography on product recovery and specific activity

To evaluate RNA-aptamers as potential drug candidates, efficient and scaleable purification protocols are needed. Because aptamers are highly structured and rigid molecules, denaturation during the purification process is a critical aspect to obtain a pure and active product. A two-step chromatographic procedure was developed to purify a synthetic anti-VEGF aptamer at the preparative scale. A reversed-phase chromatographic step was optimized with a highly hydrophobic ion pairing reagent, followed by ion-exchange chromatography in which heat and a chaotropic salt were used. Because of the presence of 2-modified ribose, denaturation conditions had to be optimized in both chromatographic steps to achieve a fully active molecule.

Phase I, Pharmacokinetic and Biological Correlative Study of OSI-7904L, a Novel Liposomal Thymidylate Synthase Inhibitor, and Cisplatin in Patients with Solid Tumors

Purpose: To evaluate the safety and describe the pharmacokinetic profile of OSI-7904L, a novel liposomal thymidylate synthase inhibitor, in combination with cisplatin (CDDP) in adults with advanced solid tumors. Experimental Design: CDDP was administered as a 2-h intravenous infusion followed by OSI-7904L intravenously over 30 min, both given every 3 weeks. Doses of each drug were escalated in separate cohorts of patients. Five dose levels of CDDP/OSI-7904L were explored: 60/6, 60/9, 60/12, 60/7.5, and 75/7.5 mg/m2. Pharmacokinetic samples, baseline plasma homocysteine, and genotype polymorphisms were evaluated. Results: Twenty-seven patients were treated with 101 total courses of CDDP/OSI-7904L. Dose-limiting toxicity was observed in 2 patients in the CDDP/OSI-7904L 60/12 mg/m2 cohort. One patient experienced rash, stomatitis, dehydration, renal failure, hyperbilirubinemia, and fatal neutropenic sepsis, whereas the other patient experienced grade 3 nausea, vomiting, and ileus. Therefore, the CDDP/OSI-7904L 60/9 mg/m2 cohort was expanded, with 2 of 6 patients reporting significant fatigue. Other toxicities were mild or moderate. Intermediate dose levels of 60/7.5 and 75/7.5 mg/m2 were evaluated, and the latter was identified as the recommended dose for phase II studies. No major pharmacokinetic interactions between CDDP and OSI-7904L were observed. Three patients had partial responses (gastric adenocarcinoma and heavily pretreated breast cancer). There was no significant relationship between baseline homocysteine and toxicity. Conclusions: The recommended doses for CDDP and OSI-7904L administered once every 3 weeks are 75 and 7.5 mg/m2, respectively. Pharmacokinetic interaction between the agents was not apparent. Preliminary clinical activity was observed in breast and gastric cancer.