title: Preclinical Development of a Subcutaneous ALAS1 RNAi Therapeutic for Treatment of Hepatic Porphyrias Using Circulating RNA Quantification.
abstract: The acute hepatic porphyrias are caused by inherited enzymatic deficiencies in the heme biosynthesis pathway. Induction of the first enzyme 5-aminolevulinic acid synthase 1 (ALAS1) by triggers such as fasting or drug exposure can lead to accumulation of neurotoxic heme intermediates that cause disease symptoms. We have demonstrated that hepatic ALAS1 silencing using siRNA in a lipid nanoparticle effectively prevents and treats induced attacks in a mouse model of acute intermittent porphyria. Herein, we report the development of ALN-AS1, an investigational GalNAc-conjugated RNAi therapeutic targeting ALAS1. One challenge in advancing ALN-AS1 to patients is the inability to detect liver ALAS1 mRNA in the absence of liver biopsies. We here describe a less invasive circulating extracellular RNA detection assay to monitor RNAi drug activity in serum and urine. A striking correlation in ALAS1 mRNA was observed across liver, serum, and urine in both rodents and nonhuman primates (NHPs) following treatment with ALN-AS1. Moreover, in donor-matched human urine and serum, we demonstrate a notable correspondence in ALAS1 levels, minimal interday assay variability, low interpatient variability from serial sample collections, and the ability to distinguish between healthy volunteers and porphyria patients with induced ALAS1 levels. The collective data highlight the potential utility of this assay in the clinical development of ALN-AS1, and in broadening our understanding of acute hepatic porphyrias disease pathophysiology.
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Chan
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: Abigail
authors.initials: A
authors.lastname: Liebow
authors.affiliation: Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
authors.forename: Makiko
authors.initials: M
authors.lastname: Yasuda
authors.affiliation: Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Gan
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: Tim
authors.initials: T
authors.lastname: Racie
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Maier
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: Satya
authors.initials: S
authors.lastname: Kuchimanchi
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: Don
authors.initials: D
authors.lastname: Foster
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: Stuart
authors.initials: S
authors.lastname: Milstein
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: Klaus
authors.initials: K
authors.lastname: Charisse
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: Alfica
authors.initials: A
authors.lastname: Sehgal
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: Muthiah
authors.initials: M
authors.lastname: Manoharan
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: Meyers
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Fitzgerald
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Simon
authors.affiliation: Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Desnick
authors.affiliation: Alnylam Pharmaceuticals, Cambridge, Massachusetts, USA.
authors.forename: William
authors.initials: W
authors.lastname: Querbes