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Katja Wosikowski, Kathy Hasenbach, Linda Allais, Pierluigi Fant, Nathalie Truchot, Monika Krampert, Ingo Roehl, Frank Jaschinski, Hanna Korhonen, Michel Janicot; Preclinical profile of ISTH0036, a potent and selective antisense oligonucleotide targeting transforming growth factor beta 2 (TGF-β2) for the treatment of ophthalmic diseases. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5714.
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© ARVO (1962-2015); The Authors (2016-present)
In ophthalmology, several diseases have been linked to the modulation of TGF-β expression. Specifically for TGF-β2, a critical role in the pathophysiology of glaucoma has been demonstrated, making this isoform a relevant therapeutic target for a disease which is the leading cause for irreversible blindness in the world. We developed a wide range of antisense oligonucleotides (ASO) based on the sequence of the human TGF-β2 mRNA. ISTH0036, a 14-mer phosphorothioate Locked Nucleic Acid-modified ASO gapmer, was selected for further testing.
In vitro, cells were treated with increasing concentrations of ISTH0036 or scrambled control ASO by gymnotic delivery. Cells were lysed and TGF-β2 mRNA levels were quantified by bDNA assay. TGF-β2 protein levels in cell supernatants were determined by ELISA. In vivo, ISTH0036 was administered via intravitreal (IVT) injection to eyes of several preclinical species. Ocular tissues were analyzed for tissue drug concentrations and target mRNA downregulation. The toxicity of ISTH0036 was tested in the rabbit following three IVT administrations at 2-week intervals.
ISTH0036 shows potent and selective downregulation of target mRNA and protein in various cell-based assays. In vivo, fast distribution of ISTH0036 to the posterior tissues (choroid & retina, ciliary body & iris, optic nerve and sclera) was observed. The highest mean concentration (114 µg/g) of ISTH0036 was measured in the ciliary body & iris of the rabbit after 24 h of injection, followed by retina & choroid, optic nerve and sclera (30-40 µg/g). High drug concentrations in posterior eye tissues were observed up to 56 days after a single IVT injection. ISTH0036 induced in vivo TGF-β2 mRNA downregulation in choroid & retina, optic nerve and lens. Preclinical safety assessment of ISTH0036 in rabbits demonstrated good tolerability with only dose-related transient local inflammation and delayed lens opacification.
ISTH0036 demonstrated potent target TGF-β2 mRNA downregulation in cell-based assays and in relevant tissues of the eye in various preclinical species. Long-lasting posterior eye tissue distribution was consistent with the observed target engagement. This, combined with the limited toxicity findings in preclinical testing, supports a rapid advancement of ISTH0036 into clinical development.
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