Single, Lowest Dose Group of ALN-AT3 Achieves Statistically Significant Knockdown of AT and Increase in Thrombin Generation in “Part A” of Phase 1 Study in Normal Human Volunteers
Results Demonstrate a Greater than 50-Fold Potency Improvement for Enhanced Stabilization Chemistry (ESC)-GalNAc-siRNA Conjugates in Humans, Representing an Unprecedented Advance in Delivery of RNAi Therapeutics with Subcutaneous Dose Administration
Company Initiates Multiple Ascending Dose “Part B” of Phase 1 Study in Patients with Moderate-to-Severe Hemophilia A and B; Interim Results Expected to be Presented in Late 2014
Alnylam Pharmaceuticals, Inc., 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.”
“There are several notable implications of these exciting initial results with ALN-AT3. First, ALN-AT3 now becomes the fourth program in our ‘Alnylam 5×15’ pipeline to demonstrate clinical activity. As such, these results increase our confidence level yet further across the entirety of our pipeline efforts, where we remain focused on genetically defined, liver-expressed disease targets with a modular and reproducible delivery platform. Moreover, these results with ALN-AT3 establish human proof of concept for our ESC-GalNAc conjugate technology, extending and broadening the human results we have previously shown with ALN-TTRsc which employs our standard template chemistry. Our ESC-GalNAc conjugate technology enables subcutaneous dosing with increased potency and durability and a wide therapeutic index, and has now become our primary approach for the delivery of RNAi therapeutics,” said John Maraganore, Ph.D., Chief Executive Officer of Alnylam. “Finally, the achievement of target knockdown at such a low dose of 0.03 mg/kg is unprecedented. Based on our evaluation of datasets from non-human primate (NHP) and human studies, these results demonstrate a 10-fold improved potency for ALN-AT3 as compared with NHP and a 50-fold improved potency in humans as compared with ALN-TTRsc. Based on data we announced earlier this week at TIDES, we believe that this increased potency is the combined result of enhanced stability for ESC-GalNAc conjugates and an attenuated nuclease environment in human tissue compared with other species. If these results extend to other ESC-GalNAc-siRNA conjugates, such as those in our complement C5 and PCSK9 programs, we believe we can expect highly potent clinical activities with very durable target knockdown effects.”
The ongoing Phase 1 trial of ALN-AT3 is being conducted in the U.K. as a single- and multi-dose, dose-escalation study comprised of two parts. Part A – which has now been completed – was a randomized, single-blind, placebo-controlled, single-dose, dose-escalation study, intended to enroll up to 24 healthy volunteer subjects. The primary objective of this part of the study was to evaluate the safety and tolerability of a single dose of ALN-AT3, with the potential secondarily to show changes in AT plasma levels at sub-pharmacologic doses. This part of the study evaluated only low doses of ALN-AT3, with a dose-escalation stopping rule at no more than a 40% level of AT knockdown. Based on the pharmacologic response achieved in this part of the study, only the lowest dose cohort (n=4; 3:1 randomization of ALN-AT3:placebo) was enrolled. Part B of the study is an open-label, multi-dose, dose-escalation study enrolling up to 18 people with moderate-to-severe hemophilia A or B. The primary objective of this part of the study is to evaluate the safety and tolerability of multiple doses, specifically three doses, of subcutaneously administered ALN-AT3 in hemophilia subjects. Secondary objectives include assessment of clinical activity as determined by knockdown of circulating AT levels and increase in thrombin generation at pharmacologic doses of ALN-AT3; thrombin generation is known to be a biomarker for bleeding frequency and severity in people with hemophilia (Dargaud, et al., Thromb Haemost; 93, 475-480 (2005)). In this part of the study, dose-escalation will be allowed to proceed beyond the 40% AT knockdown level.
In addition to reporting positive top-line results from the Phase 1 trial with ALN-AT3, Alnylam presented new pre-clinical data with ALN-AT3. First, in a saphenous vein bleeding model performed in hemophilia A (HA) mice, a single subcutaneous dose of ALN-AT3 that resulted in an approximately 70% AT knockdown led to a statistically significant (p < 0.0001) improvement in hemostasis compared to saline-treated HA mice. The improved hemostasis was comparable to that observed in HA mice receiving recombinant factor VIII. These are the first results in what can be considered a genuine bleeding model showing that AT knockdown with ALN-AT3 can control bleeding. Second, a number of in vitro studies were performed in plasma from hemophilia donors. Stepwise AT depletion in these plasma samples was shown to achieve stepwise increases in thrombin generation. Furthermore, it was shown that a 40-60% reduction of AT resulted in peak thrombin levels equivalent to those achieved with 10-15% levels of factor VIII in HA plasma and factor IX in hemophilia B (HB) plasma. These levels of factor VIII or IX are known to significantly reduce bleeding in hemophilia subjects. As such, these results support the hypothesis that a 40-60% knockdown of AT with ALN-AT3 could be fully prophylactic. Finally, a modified Activated Partial Thromboplastin Time (APTT) assay – an ex vivomeasure of blood coagulation that is significantly prolonged in hemophilia – was developed, demonstrating sensitivity to AT levels. Specifically, depletion of AT in HA plasma led to a shortening of modified APTT. This modified APTT assay can be used to routinely and simply monitor functional activity of AT knockdown in further ALN-AT3 clinical studies.
“The unmet need for new therapeutic options to treat hemophilia patients remains very high, particularly in those patients who experience multiple annual bleeds such as patients receiving replacement factor ‘on demand’ or patients who have developed inhibitory antibodies. Indeed, I believe the availability of a safe and effective subcutaneously administered therapeutic with a long duration of action would represent a marked improvement over currently available approaches for prophylaxis,” said Claude Negrier, M.D., head of the Hematology Department and director of the Haemophilia Comprehensive Care Centre at Edouard Herriot University Hospital in Lyon. “I continue to be encouraged by Alnylam’s progress to date with ALN-AT3, including these initial data reported from the Phase 1 trial showing statistically significant knockdown of antithrombin and increased thrombin generation, which has been shown to correlate with bleeding frequency and severity in hemophilia. I look forward to the advancement of this innovative therapeutic candidate in hemophilia subjects.”
About Hemophilia and Rare Bleeding Disorders
Hemophilias are hereditary disorders caused by genetic deficiencies of various blood clotting factors, resulting in recurrent bleeds into joints, muscles, and other major internal organs. Hemophilia A is defined by loss-of-function mutations in Factor VIII, and there are greater than 40,000 registered patients in the U.S. and E.U. Hemophilia B, defined by loss-of-function mutations in Factor IX, affects greater than 9,500 registered patients in the U.S. and E.U. Other Rare Bleeding Disorders (RBD) are defined by congenital deficiencies of other blood coagulation factors, including Factors II, V, VII, X, and XI, and there are about 1,000 patients worldwide with a severe bleeding phenotype. Standard treatment for hemophilia patients involves replacement of the missing clotting factor either as prophylaxis or on-demand therapy. However, as many as one third of people with severe hemophilia A will develop an antibody to their replacement factor – a very serious complication; these ‘inhibitor’ patients become refractory to standard replacement therapy. There exists a small subset of hemophilia patients who have co-inherited a prothrombotic mutation, such as Factor V Leiden, antithrombin deficiency, protein C deficiency, and prothrombin G20210A. Hemophilia patients that have co-inherited these prothrombotic mutations are characterized as having a later onset of disease, lower risk of bleeding, and reduced requirements for Factor VIII or Factor IX treatment as part of their disease management. There exists a significant need for novel therapeutics to treat hemophilia patients.
About Antithrombin (AT)
Antithrombin (AT, also known as “antithrombin III” and “SERPINC1”) is a liver expressed plasma protein and member of the “serpin” family of proteins that acts as an important endogenous anticoagulant by inactivating Factor Xa and thrombin. AT plays a key role in normal hemostasis, which has evolved to balance the need to control blood loss through clotting with the need to prevent pathologic thrombosis through anticoagulation. In hemophilia, the loss of certain procoagulant factors (Factor VIII and Factor IX, in the case of hemophilia A and B, respectively) results in an imbalance of the hemostatic system toward a bleeding phenotype. In contrast, in thrombophilia (e.g., Factor V Leiden, protein C deficiency, antithrombin deficiency, amongst others), certain mutations result in an imbalance in the hemostatic system toward a thrombotic phenotype. Since co-inheritance of prothrombotic mutations may ameliorate the clinical phenotype in hemophilia, inhibition of AT defines a novel strategy for improving hemostasis.
About GalNAc Conjugates and Enhanced Stabilization Chemistry (ESC)-GalNAc Conjugates
GalNAc-siRNA conjugates are a proprietary Alnylam delivery platform and are designed to achieve targeted delivery of RNAi therapeutics to hepatocytes through uptake by the asialoglycoprotein receptor. Alnylam’s Enhanced Stabilization Chemistry (ESC)-GalNAc-conjugate technology enables subcutaneous dosing with increased potency and durability, and a wide therapeutic index. This delivery platform is being employed in several of Alnylam’s genetic medicine programs, including programs in clinical development.
RNAi (RNA interference) is a revolution in biology, representing a breakthrough in understanding how genes are turned on and off in cells, and a completely new approach to drug discovery and development. Its discovery has been heralded as “a major scientific breakthrough that happens once every decade or so,” and represents one of the most promising and rapidly advancing frontiers in biology and drug discovery today which was awarded the 2006 Nobel Prize for Physiology or Medicine. RNAi is a natural process of gene silencing that occurs in organisms ranging from plants to mammals. By harnessing the natural biological process of RNAi occurring in our cells, the creation of a major new class of medicines, known as RNAi therapeutics, is on the horizon. Small interfering RNA (siRNA), the molecules that mediate RNAi and comprise Alnylam’s RNAi therapeutic platform, target the cause of diseases by potently silencing specific mRNAs, thereby preventing disease-causing proteins from being made. RNAi therapeutics have the potential to treat disease and help patients in a fundamentally new way.
About Alnylam Pharmaceuticals
Alnylam is a biopharmaceutical company developing novel therapeutics based on RNA interference, or RNAi. The company is leading the translation of RNAi as a new class of innovative medicines with a core focus on RNAi therapeutics as genetic medicines, including programs as part of the company’s “Alnylam 5x15TM” product strategy. Alnylam’s genetic medicine programs are RNAi therapeutics directed toward genetically defined targets for the treatment of serious, life-threatening diseases with limited treatment options for patients and their caregivers. These include: patisiran (ALN-TTR02), an intravenously delivered RNAi therapeutic targeting transthyretin (TTR) for the treatment of TTR-mediated amyloidosis (ATTR) in patients with familial amyloidotic polyneuropathy (FAP); ALN-TTRsc, a subcutaneously delivered RNAi therapeutic targeting TTR for the treatment of ATTR in patients with TTR cardiac amyloidosis, including familial amyloidotic cardiomyopathy (FAC) and senile systemic amyloidosis (SSA); ALN-AT3, an RNAi therapeutic targeting antithrombin (AT) for the treatment of hemophilia and rare bleeding disorders (RBD); ALN-CC5, an RNAi therapeutic targeting complement component C5 for the treatment of complement-mediated diseases; ALN-AS1, an RNAi therapeutic targeting aminolevulinate synthase-1 (ALAS-1) for the treatment of hepatic porphyrias including acute intermittent porphyria (AIP); ALN-PCS, an RNAi therapeutic targeting PCSK9 for the treatment of hypercholesterolemia; ALN-AAT, an RNAi therapeutic targeting alpha-1 antitrypsin (AAT) for the treatment of AAT deficiency-associated liver disease; ALN-TMP, an RNAi therapeutic targeting TMPRSS6 for the treatment of beta-thalassemia and iron-overload disorders; ALN-ANG, an RNAi therapeutic targeting angiopoietin-like 3 (ANGPTL3) for the treatment of genetic forms of mixed hyperlipidemia and severe hypertriglyceridemia; ALN-AC3, an RNAi therapeutic targeting apolipoprotein C-III (apoCIII) for the treatment of hypertriglyceridemia; and other programs yet to be disclosed. As part of its “Alnylam 5×15” strategy, as updated in early 2014, the company expects to have six to seven genetic medicine product candidates in clinical development – including at least two programs in Phase 3 and five to six programs with human proof of concept – by the end of 2015. Alnylam is also developing ALN-HBV, an RNAi therapeutic targeting the hepatitis B virus (HBV) genome for the treatment of HBV infection. The company’s demonstrated commitment to RNAi therapeutics has enabled it to form major alliances with leading companies including Merck, Medtronic, Novartis, Biogen Idec, Roche, Takeda, Kyowa Hakko Kirin, Cubist, GlaxoSmithKline, Ascletis, Monsanto, The Medicines Company, and Genzyme, a Sanofi company. In March 2014, Alnylam acquired Sirna Therapeutics, a wholly owned subsidiary of Merck. In addition, Alnylam holds an equity position in Regulus Therapeutics Inc., a company focused on discovery, development, and commercialization of microRNA therapeutics. Alnylam scientists and collaborators have published their research on RNAi therapeutics in over 200 peer-reviewed papers, including many in the world’s top scientific journals such as Nature, Nature Medicine, Nature Biotechnology, Cell, the New England Journal of Medicine, and The Lancet. Founded in 2002, Alnylam maintains headquarters in Cambridge, Massachusetts. For more information, please visit www.alnylam.com.
About “Alnylam 5×15™” and Genetic Medicines
The “Alnylam 5×15” strategy, launched in January 2011, establishes a path for development and commercialization of novel RNAi therapeutics as genetic medicines. Alnylam’s genetic medicine programs are RNAi therapeutics directed toward genetically defined targets for the treatment of diseases with high unmet medical need. These programs share several key characteristics including: a genetically defined target and disease expressed in the liver; the potential to have a major impact in a high unmet need population; the ability to leverage the existing Alnylam RNAi platform with clinically proven delivery to the liver; the opportunity to monitor an early biomarker in Phase 1 clinical trials for human proof of concept; and the existence of clinically relevant endpoints for the filing of a new drug application (NDA) with a focused patient database and possible accelerated paths for commercialization. As updated in early 2014, the company expects to have six to seven genetic medicine product candidates in clinical development – including at least two programs in Phase 3 and five to six programs with human proof of concept – by the end of 2015. The “Alnylam 5×15” programs include: patisiran (ALN-TTR02), an intravenously delivered RNAi therapeutic targeting transthyretin (TTR) in development for the treatment of TTR-mediated amyloidosis (ATTR) in patients with familial amyloidotic polyneuropathy (FAP); ALN-TTRsc, a subcutaneously delivered RNAi therapeutic targeting TTR in development for the treatment of ATTR in patients with TTR cardiac amyloidosis, including familial amyloidotic cardiomyopathy (FAC) and senile systemic amyloidosis (SSA); ALN-AT3, an RNAi therapeutic targeting antithrombin (AT) in development for the treatment of hemophilia and rare bleeding disorders (RBD); ALN-CC5, an RNAi therapeutic targeting complement component C5 in development for the treatment of complement-mediated diseases; ALN-AS1, an RNAi therapeutic targeting aminolevulinate synthase-1 (ALAS-1) in development for the treatment of hepatic porphyrias including acute intermittent porphyria (AIP); ALN-PCS, an RNAi therapeutic targeting PCSK9 in development for the treatment of hypercholesterolemia; ALN-AAT, an RNAi therapeutic targeting alpha-1 antitrypsin (AAT) for the treatment of AAT deficiency-associated liver disease; ALN-TMP, an RNAi therapeutic targeting TMPRSS6 in development for the treatment of beta-thalassemia and iron-overload disorders; ALN-ANG, an RNAi therapeutic targeting angiopoietin-like 3 (ANGPTL3) for the treatment of genetic forms of mixed hyperlipidemia and severe hypertriglyceridemia; ALN-AC3, a subcutaneously administered RNAi therapeutic targeting apolipoprotein C-III (apoCIII) for the treatment of hypertriglyceridemia; and other programs yet to be disclosed. In 2014, Alnylam and Genzyme, a Sanofi company, formed a multi-product geographic alliance on Alnylam’s genetic medicine programs. Specifically, Alnylam will lead development and commercialization of programs in North America and Europe, while Genzyme will develop and commercialize products in the rest of world. In addition, Alnylam and Genzyme will co-develop and co-commercialize ALN-TTRsc in North America and Europe.