Alnylam Pharmaceuticals, Inc. Announces New Results from Phase 2 Open-Label Extension Study of Patisiran
Sep 28 15
Alnylam Pharmaceuticals, Inc. announced new results from the company’s ongoing Phase 2 open-label extension (OLE) study of patisiran, an investigational RNAi therapeutic targeting transthyretin (TTR) for the treatment of TTR-mediated amyloidosis (ATTR amyloidosis) patients with familial amyloidotic polyneuropathy (FAP). In collaboration with investigators at The Scripps Research Institute and Misfolding Diagnostics, Inc., patisiran administration was shown to reduce pathogenic, misfolded TTR monomers and oligomers in FAP patients in the Phase 2 OLE study. Specifically, patisiran administration resulted in a rapid and sustained reduction of approximately 90% in serum non-native conformations of TTR (NNTTR). Since NNTTR is pathogenic in ATTR amyloidosis, these results provide direct mechanistic evidence supporting the therapeutic hypothesis that TTR knockdown has the potential to result in clinical benefit. In addition, Alnylam presented complete 12-month data from all 27 patients initially enrolled in the patisiran OLE study, showing a mean 3.1-point decrease in the modified Neuropathy Impairment Score (mNIS+7) at 12 months as well as sustained mean maximum reductions in total serum TTR of 91% for over 18 months. Moreover, patisiran administration was found to be generally well tolerated out to 21 months of treatment. Alnylam's ongoing Phase 2 OLE study is an open-label, multi-center trial designed to evaluate the long-term safety and tolerability of patisiran administration in FAP patients that were previously enrolled in a Phase 2 study. Patisiran is being administered once every 3 weeks at a dose of 0.3 mg/kg by intravenous infusion. The study is measuring a number of clinical endpoints every six months, including mNIS+7 which is an evaluation of muscle weakness, sensory and autonomic function, and nerve conductance, where neuropathy progression leads to an increased score over time. The change in the mNIS+7 measurement from baseline to 18 months is the primary endpoint in the company's ongoing Phase 3 APOLLO trial of patisiran in FAP patients.
Alnylam Announces Positive Results from Phase I Acute Hepatic Porphyrias Trial
Sep 21 15
Alnylam Pharmaceuticals, Inc. has announced initial positive results from its ongoing Phase I clinical trial with ALN-AS1, an investigational RNAi therapeutic targeting aminolevulinic acid synthase 1, or ALAS1, for the treatment of acute hepatic porphyrias. The Phase I study is being performed in asymptomatic "high excreter" (ASHE) patients, who carry the genetic mutation of acute intermittent porphyria (AIP) and have elevated levels of aminolevulinic acid (ALA) and porphobilinogen (PBG), the toxic heme intermediates that mediate porphyria attacks. Study results showed that single subcutaneous doses of ALN-AS1 resulted in an up to 82% lowering of ALA and an up to 93% lowering of PBG, providing human proof-of-concept for this investigational RNAi therapeutic as a potential therapy for AIP and other acute hepatic porphyrias. In addition, through analysis of exosomal mRNA preparations from serum and urine, it was demonstrated that ALN-AS1 treatment resulted in potent, dose-dependent, and durable silencing of ALAS1 mRNA in liver. Further, ALN-AS1 was found to be generally well tolerated with no clinically significant drug-related adverse events to date. The company has now transitioned to Part B of the Phase I study, in which subjects are receiving monthly subcutaneous dosing, and the company expects to initiate Part C in AIP patients suffering from recurrent attacks in early 2016. In addition, Alnylam presented initial data from the EXPLORE trial, a multinational, prospective observational study of patients with hepatic porphyrias suffering from recurrent attacks. ALN-AS1 is a subcutaneously administered, investigational RNAi therapeutic that employs Alnylam's ESC-GalNAc delivery technology. The Phase I trial is being conducted in three parts. Parts A and B are randomized (3:1, drug:placebo), single-blind, single-dose (Part A) and multi-dose (Part B), dose-escalation studies, designed to enroll up to a total of 40 ASHE subjects. Per protocol, ASHE subjects in the study have a defined mutation in the porphobilinogen deaminase (PBGD) gene and elevated urinary levels of ALA and PBG, but do not have a recent history of porphyria attacks or disease activity. The primary objective of Parts A and B is to evaluate safety and tolerability of single and multiple subcutaneous doses of ALN-AS1. Secondary objectives include evaluation of clinical activity for ALN-AS1 as measured by reduction in plasma and urinary levels of ALA and PBG. Exploratory objectives include the impact of ALN-AS1 on liver ALAS1 mRNA as measured from circulatory or excreted exosomal mRNA preparations in serum or urine, respectively. Part C will be a multi-dose study in up to eight AIP patients who experience recurrent porphyria attacks, and will assess safety, tolerability, pharmacodynamics (i.e., lowering of serum and urine ALA and PBG, as well as liver ALAS1 mRNA) and clinical activity of multiple doses of ALN-AS1. In addition, this part of the study will include an exploratory evaluation of the effects of ALN-AS1 on the number and severity of attacks and other disease symptoms, use of hematin and pain medications, number and duration of hospitalizations, and quality of life. Initial Phase I study results were presented. All results are based on data in the database as of September 2, 2015. A total of 16 ASHE patients were enrolled in four single ascending dose (SAD) cohorts (N=4 per group), with subjects receiving 0.035, 0.1, 0.35, or 1.0 mg/kg doses of ALN-AS1. In all dose cohorts, the volume of injection was less than 1.0 mL. The 0.035 mg/kg cohort was added to explore a lower dose after initial results were obtained from the 0.1 and 0.35 mg/kg cohorts. The multi-dose Part B of the study has now been initiated with monthly subcutaneous doses of 0.35 mg/kg. Alnylam expects to report initial data from this part of the study in 2016. Measurement of ALAS1 mRNA levels employed a method previously described by Alnylam scientists known as circulating extracellular mRNA detection (cERD) (Sehgal et al., RNA, 20:1-7(2014)), and was performed using serial serum and urine samples. At baseline, ASHE patients enrolled in the study were found to have substantially higher levels of liver ALAS1 mRNA detected in serum and urine relativ e to normal healthy volunteers. Specifically, there was an approximate 3-fold increase in liver ALAS1 mRNA (p less than 0.001, unpaired t test) relative to levels observed in healthy subjects. ALN-AS1 administration resulted in potent, dose-dependent, and durable silencing of liver ALAS1 mRNA. An up to 59% maximal and 44 + 8% mean maximum (p less than 0.01, relative to placebo) silencing of liver ALAS1 mRNA was observed in the 0.35 mg/kg dose cohort; as of the data cut-off date, mRNA silencing data are pending for the top 1.0 mg/kg dose. Nadir silencing was achieved at approximately day 21, and effects were highly durable lasting over 42 days after a single dose. While it has been speculated that ASHE patients have increased liver ALAS1 mRNA levels compared to that of healthy subjects, these data represent the first definitive evidence that this is in fact the case in humans. In addition, to the company's knowledge, these mRNA silencing and time course data are the first to ever be presented from any human study with RNAi therapeutics, marking another milestone in Alnylam's efforts to advance this potential new class of medicines to patients. In AIP, loss-of-function mutations in PBGD can result in excessive accumulation of ALA and PBG, the toxic heme synthesis intermediates that mediate porphyria attacks. ASHE patients are asymptomatic, but have increased ALA and PBG levels that, while lower than those seen in AIP patients during an acute attack, are still significantly higher than normal reference values. In the Phase I ASHE patient study, mean baseline urinary levels of ALA and PBG were 11.0 and 21.7 mmol/mol creatinine, respectively. Compared to normal, these levels were elevated by approximately 3-fold for ALA and 14-fold for PBG. A single subcutaneous dose of ALN-AS1 resulted in potent, dose-dependent, and highly durable lowering of ALA of up to 82% and PBG of up to 93%. An up to 77 + 7% and 73 + 6% mean maximum lowering of urinary ALA and PBG, respectively, was achieved in the 0.35 mg/kg cohort (p less than 0.01 for ALA and p equal to 0.06 for PBG, both relative to placebo). A greater mean maximum lowering of ALA and PBG is expected to be achieved at the 1.0 mg/kg dose, but current data are limited to 2 subjects through day 14. Even at the lowest dose of 0.035 mg/kg, an approximately 33% lowering of ALA and PBG was observed.