Alnylam Pharmaceuticals, Inc. (Nasdaq: ALNY), a leading RNAi therapeutics company, announced today positive top-line results from its ongoing Phase 1 trial of ALN-AT3, a subcutaneously administered RNAi therapeutic targeting antithrombin (AT) in development for the treatment of hemophilia and rare bleeding disorders (RBD). These top-line results are being presented at the World Federation of Hemophilia (WFH) 2014 World Congress being held May 11 – 15, 2014 in Melbourne, Australia. In Part A of the Phase 1 study, human volunteer subjects received a single subcutaneous dose of ALN-AT3 and, per protocol, the maximum allowable level of AT knockdown was set at 40%. Initial results show that a single, low subcutaneous dose of ALN-AT3 at 0.03 mg/kg resulted in an up to 28-32% knockdown of AT at nadir that was statistically significant relative to placebo (p < 0.01 by ANOVA). This led to a statistically significant (p < 0.01) increase in peak thrombin generation, that was temporally associated and consistent with the degree of AT knockdown. ALN-AT3 was found to be well tolerated with no significant adverse events reported. With these data, the company has transitioned to the Multiple Ascending Dose (MAD) Part B of the study in moderate-to-severe hemophilia subjects. Consistent with previous guidance, the company plans to present initial clinical results from the Phase 1 study, including results in hemophilia subjects, by the end of the year. These human study results are the first to be reported for Alnylam’s Enhanced Stabilization Chemistry (ESC)-GalNAc conjugate technology, which enables subcutaneous dosing with increased potency, durability, and a wide therapeutic index. Further, these initial clinical results demonstrate a greater than 50-fold potency improvement with ESC-GalNAc conjugates relative to standard template chemistry conjugates.
“We are excited by these initial positive results for ALN-AT3 in the human volunteer ‘Part A’ of our Phase 1 study. Indeed, within the protocol-defined boundaries of single doses that provide no more than a 40% knockdown of AT in normal subjects, we were able to demonstrate a statistically-significant knockdown of AT of up to 28-32% and an associated increase in thrombin generation. Remarkably, this result was achieved at the lowest dose tested of 0.03 mg/kg, demonstrating a high and better than expected level of potency for ALN-AT3, our first ESC-GalNAc conjugate to enter clinical development,” said Akshay Vaishnaw, M.D., Ph.D., Executive Vice President and Chief Medical Officer of Alnylam. “With these results in hand, we are now proceeding to ‘Part B’ of the study, where we will administer multiple ascending doses to up to 18 patients with moderate-to-severe hemophilia A or B. Patients will receive three weekly doses, and we fully expect to achieve robust levels of AT knockdown as we dose escalate. In addition, we will aim to evaluate a once-monthly dosing regimen in future clinical studies, as we believe this could provide a highly attractive prophylactic regimen for patients. We look forward to sharing our detailed Phase 1 results, including data in hemophilia subjects, later this year, consistent with our original guidance.”