--- title: "Fitusiran | PepTracker Pro" url: https://peptrackerpro.com/peptides/fitusiran description: "An FDA-approved RNA-interference (RNAi) therapy for hemophilia that works by lowering a natural blood-thinning protein rather than replacing a missing clotting factor. Fitusiran (brand name Qfitlia) is a GalNAc-conjugated small interfering RNA (siRNA) that is taken up by liver cells and silences the gene for antithrombin, the body's main brake on clotting. By reducing antithrombin, fitusiran 'rebalances' hemostasis so that people with hemophilia A or B can generate enough thrombin to form stable clots and bleed less often. It was approved by the U.S. FDA on March 28, 2025 - the first siRNA (RNAi) therapy for hemophilia and the first medicine that treats hemophilia by lowering antithrombin - for routine prophylaxis in adults and children aged 12 and older with hemophilia A or B, with or without factor VIII or IX inhibitors. A key practical advantage is that it is given as an infrequent subcutaneous injection (starting once every two months, as few as about six injections per year) and works regardless of hemophilia type or inhibitor status. In the pivotal Phase 3 ATLAS trials, fitusiran reduced the annualized bleeding rate by about 90% versus on-demand treatment. Because lowering antithrombin shifts the clotting balance, fitusiran carries a boxed warning for thrombotic (clotting) events and gallbladder disease, and it is now dosed to a target antithrombin level (15-35%) to reduce clot risk. Fitusiran is a prescription biologic administered under medical supervision - not a supplement or research chemical." lang: en --- Skip to main content **Educational information only.** This site does not provide medical advice. Read full disclaimer (https://peptrackerpro.com/disclaimer) **Research-only content.** This page is for educational purposes and does not constitute medical advice. Read full disclaimer → (https://peptrackerpro.com/research-disclaimer) # Fitusiran High Evidence An FDA-approved RNA-interference (RNAi) therapy for hemophilia that works by lowering a natural blood-thinning protein rather than replacing a missing clotting factor. Fitusiran (brand name Qfitlia) is a GalNAc-conjugated small interfering RNA (siRNA) that is taken up by liver cells and silences the gene for antithrombin, the body's main brake on clotting. By reducing antithrombin, fitusiran 'rebalances' hemostasis so that people with hemophilia A or B can generate enough thrombin to form stable clots and bleed less often. It was approved by the U.S. FDA on March 28, 2025 - the first siRNA (RNAi) therapy for hemophilia and the first medicine that treats hemophilia by lowering antithrombin - for routine prophylaxis in adults and children aged 12 and older with hemophilia A or B, with or without factor VIII or IX inhibitors. A key practical advantage is that it is given as an infrequent subcutaneous injection (starting once every two months, as few as about six injections per year) and works regardless of hemophilia type or inhibitor status. In the pivotal Phase 3 ATLAS trials, fitusiran reduced the annualized bleeding rate by about 90% versus on-demand treatment. Because lowering antithrombin shifts the clotting balance, fitusiran carries a boxed warning for thrombotic (clotting) events and gallbladder disease, and it is now dosed to a target antithrombin level (15-35%) to reduce clot risk. Fitusiran is a prescription biologic administered under medical supervision - not a supplement or research chemical. Aliases Fitusiran +5 more Evidence High Evidence Last Updated 2026-08-30 Reading Time 9 min ## What It Is Fitusiran (Qfitlia, developed by Sanofi in collaboration with Alnylam Pharmaceuticals) is a subcutaneously administered RNA-interference (RNAi) medicine for hemophilia A and B. It is a small interfering RNA (siRNA) conjugated to N-acetylgalactosamine (GalNAc) so that it is taken up efficiently by liver cells (hepatocytes). Once inside, the siRNA engages the cell's natural gene-silencing machinery (the RNA-induced silencing complex) to degrade the messenger RNA of SERPINC1, the gene that encodes antithrombin - the body's principal endogenous anticoagulant, which normally restrains the clotting enzyme thrombin. Classic hemophilia treatments try to replace what is missing (factor VIII in hemophilia A, factor IX in hemophilia B) or, in the case of the antibody emicizumab, mimic factor VIII. Fitusiran takes the opposite, 'rebalancing' approach: instead of adding a pro-clotting factor, it removes some of the natural anticoagulant brake. By lowering antithrombin, it allows people with hemophilia to generate more thrombin and form more stable clots, reducing bleeding - and because the mechanism sits downstream of the missing factor, it works in hemophilia A and B alike and, crucially, in patients who have developed inhibitors (neutralizing antibodies) against factor replacement, a group that is historically the hardest to treat. Fitusiran was approved by the U.S. FDA on March 28, 2025 for routine prophylaxis to prevent or reduce bleeding episodes in adults and pediatric patients aged 12 years and older with hemophilia A or B, with or without factor VIII or IX inhibitors. It is the first siRNA (RNAi) therapeutic approved for hemophilia and the first antithrombin-lowering therapy of any kind. A defining feature is its dosing convenience: it is given by subcutaneous injection starting at 50 mg once every two months, with the dose or interval adjusted to keep antithrombin activity in a target range (15-35%) - as few as roughly six injections per year, in sharp contrast to the frequent intravenous factor infusions many patients otherwise need. Efficacy was established in the Phase 3 ATLAS program. In ATLAS-INH (people with inhibitors), fitusiran prophylaxis reduced the mean annualized bleeding rate to about 1.7 versus 18.1 with on-demand bypassing agents - a roughly 90.8% reduction - and 66% of fitusiran-treated participants had zero treated bleeds versus 5% on-demand. In ATLAS-A/B (severe hemophilia without inhibitors), 51% of fitusiran-treated participants had zero treated bleeds versus 5% of those on prior on-demand treatment, with a similar roughly 90% overall reduction in annualized bleeding rate. Because lowering antithrombin tilts the hemostatic balance toward clotting, the central safety issue is thrombosis. In earlier development the original fixed 80 mg once-monthly regimen was associated with serious and sometimes fatal clotting events (thrombotic events in about 2.6% of patients on 80 mg monthly, including a fatal cerebral venous sinus thrombosis), which led Sanofi to switch to a lower, less frequent, antithrombin-based dosing regimen (AT-DR) that targets antithrombin activity of 15-35%; on that regimen the thrombotic-event rate fell to about 1.4%. The approved label carries a boxed warning for thrombotic events and for gallbladder disease (including gallstones and cholecystitis, sometimes requiring gallbladder removal), and also warns about liver enzyme elevations, with monitoring of antithrombin activity using an FDA-cleared companion test and of liver blood tests at baseline and periodically thereafter. The pivotal ATLAS trials (ATLAS-INH, ATLAS-A/B, and the ATLAS-PPX switch study) were published in The Lancet and The Lancet Haematology in 2023, and additional studies (including ATLAS-NEO, ATLAS-PEDS in younger children, and the ATLAS-OLE long-term extension) continue to characterize the newer dosing regimen. Fitusiran is a prescription biologic given under specialist hematology care; it is not a supplement, peptide sold by vendors, or research chemical, and any product marketed as 'fitusiran' or 'antithrombin siRNA' outside a regulated pharmacy or clinical trial is unverified and unsafe. Also known as: Fitusiran, Qfitlia, ALN-AT3, SAR439774, antithrombin siRNA, SERPINC1 siRNA (Sanofi/Alnylam) ## Regulatory Status Approved (prescription) Approved by the U.S. FDA on March 28, 2025 as Qfitlia (fitusiran) for routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adult and pediatric patients aged 12 years and older with hemophilia A or B, with or without factor VIII or IX inhibitors. Fitusiran is the first siRNA (RNAi) therapy approved for hemophilia and the first antithrombin-lowering therapy. The label carries a boxed warning for thrombotic events and gallbladder disease; dosing uses an antithrombin-based regimen targeting antithrombin activity of 15-35%, monitored with an FDA-cleared companion test. Commercialized by Sanofi in collaboration with Alnylam Pharmaceuticals. It is a prescription biologic given under specialist care - not a supplement or research chemical. Effective: 2025-03-28 View FDA Source (https://www.fda.gov/news-events/press-announcements/fda-approves-novel-treatment-hemophilia-or-b-or-without-factor-inhibitors) ## Why Researchers Study It Fitusiran matters because it reframes how hemophilia can be treated. For decades the logic of hemophilia therapy was replacement: give back the clotting factor the patient lacks, whether factor VIII in hemophilia A or factor IX in hemophilia B. That works, but it demands frequent intravenous infusions, is specific to each disease type, and fails in the roughly one in four patients who develop inhibitors - neutralizing antibodies that render factor replacement ineffective and who have long faced the worst bleeding outcomes. Fitusiran tests a different idea borrowed from the natural balance of the clotting system: hemostasis is a tug-of-war between pro-clotting factors and natural anticoagulants, so instead of boosting the pro-clotting side you can lower an anticoagulant. Antithrombin is the body's principal built-in brake on thrombin generation; turning that brake down with an RNAi drug lets even a factor-deficient patient produce enough thrombin to clot. Because this rebalancing happens downstream of the missing factor, a single medicine can help across hemophilia A and B and regardless of inhibitor status - a genuinely unifying approach. Researchers are also drawn to fitusiran as a demonstration of what RNA interference can do beyond the liver-lipid and rare-metabolic diseases where GalNAc-siRNAs first succeeded: here the same chemistry silences a coagulation gene to change a bleeding phenotype, with deep and durable knockdown that allows dosing as infrequently as roughly every two months. Just as important, fitusiran has become a case study in dose optimization for a mechanism with a narrow therapeutic window. Its early fixed-dose regimen caused serious clots, and the program's pivot to an antithrombin-targeted dosing strategy - measure the anticoagulant, aim for a defined range, and adjust - is a template for safely deploying powerful gene-silencing drugs whose effect must be carefully titrated. That combination of a first-in-class mechanism, a hard-to-treat population finally addressed, an unusually convenient dosing schedule, and a real, monitorable safety trade-off is why fitusiran is studied so closely by hematologists and drug developers alike. ## Proposed Mechanisms - Antithrombin (SERPINC1) gene silencing via RNA interference: fitusiran is a GalNAc-conjugated small interfering RNA (siRNA) taken up by liver hepatocytes, where it engages the RNA-induced silencing complex to degrade SERPINC1 messenger RNA and lower production of antithrombin, the body's main natural anticoagulant. - Rebalancing hemostasis by lowering a natural brake: antithrombin normally inhibits thrombin and other clotting enzymes, so reducing it increases the amount of thrombin a person can generate - restoring more effective clot formation in patients who lack factor VIII or IX, rather than replacing the missing factor. - Factor- and inhibitor-independent action: because the effect is downstream of the deficient clotting factor, fitusiran reduces bleeding across both hemophilia A and hemophilia B and works even when neutralizing inhibitors make factor replacement ineffective. - Deep, durable, infrequent-dose knockdown: GalNAc-siRNA chemistry produces long-lasting suppression of antithrombin from subcutaneous dosing as infrequent as once every two months, enabling low-burden prophylaxis compared with frequent intravenous factor infusions. - Antithrombin-targeted dosing to manage a narrow window: because too much antithrombin lowering causes clots, dosing is titrated to keep antithrombin activity within a 15-35% target range measured by an FDA-cleared assay, balancing bleeding prevention against thrombotic risk. ## Evidence Snapshot High Evidence Low Medium High | Study Type | Model | Outcome | Link | | --- | --- | --- | --- | | Phase 3 randomized, open-label trial - fitusiran prophylaxis in hemophilia A or B WITH inhibitors (ATLAS-INH); published in The Lancet (2023) | People with hemophilia A or B and inhibitors randomized to subcutaneous fitusiran 80 mg once monthly prophylaxis versus on-demand bypassing agents, with the annualized bleeding rate as the primary endpoint. | Fitusiran reduced the model-based mean annualized bleeding rate to about 1.7 versus 18.1 with on-demand bypassing agents (about a 90.8% reduction), and 66% of fitusiran-treated participants (25 of 38) had zero treated bleeds versus 5% (1 of 19) on-demand. Suspected or confirmed thromboembolic events occurred in about 5% of fitusiran-treated participants, signalling the mechanism's thrombosis risk. | Source | | Phase 3 randomized, open-label trial - fitusiran prophylaxis in severe hemophilia A or B WITHOUT inhibitors (ATLAS-A/B); published in The Lancet Haematology (2023) | People with severe hemophilia A or B without inhibitors randomized to subcutaneous fitusiran 80 mg once monthly prophylaxis versus continued on-demand factor treatment, with annualized bleeding rate as the primary endpoint. | 51% of fitusiran-treated participants (40 of 79) had zero treated bleeds versus 5% (2 of 40) on prior on-demand treatment, with an overall roughly 90% reduction in annualized bleeding rate across the ATLAS program versus on-demand comparators. | Source | | Dose-regimen optimization and safety - transition to the antithrombin-based dosing regimen (AT-DR) | Analyses across the fitusiran program comparing the original fixed 80 mg once-monthly regimen with a lower, less frequent antithrombin-targeted regimen (start 50 mg every 2 months) titrated to keep antithrombin activity at 15-35%. | Thrombotic events occurred in about 2.6% of patients on 80 mg once monthly (including a fatal cerebral venous sinus thrombosis) versus about 1.4% on the antithrombin-based regimen, supporting antithrombin-guided dosing to reduce clot risk while maintaining bleed protection. The approved label carries a boxed warning for thrombotic events and gallbladder disease. | Source | | Regulatory milestone - U.S. FDA approval (March 28, 2025) | FDA review of the ATLAS Phase 3 program supporting Qfitlia (fitusiran) for routine bleeding prophylaxis in patients aged 12 and older with hemophilia A or B, with or without inhibitors. | Fitusiran became the first siRNA (RNAi) therapy and the first antithrombin-lowering therapy approved for hemophilia, given subcutaneously starting once every two months with antithrombin-based dose adjustment (target activity 15-35%) and monitoring using an FDA-cleared companion test. | Source | ## Commonly Discussed Benefits Hematology: https://peptrackerpro.com/benefits/hematology Rare Disease Treatment: https://peptrackerpro.com/benefits/rare-disease-treatment Researching Fitusiran? Track it, set reminders, and keep notes in the free app. Track in App (https://app.peptrackerpro.com/?add=fitusiran) ## Safety & Cautions - Fitusiran (Qfitlia) carries a boxed warning for thrombotic (blood clot) events. Because it works by lowering the natural anticoagulant antithrombin, it can tip the balance toward clotting; serious and even fatal clots (including cerebral venous sinus thrombosis) occurred with the original 80 mg once-monthly dose, which is why the approved regimen uses lower, less frequent, antithrombin-targeted dosing. - It also carries a boxed warning for gallbladder disease (gallstones and cholecystitis), which sometimes requires gallbladder removal, and a warning for liver enzyme elevations; antithrombin activity and liver blood tests are monitored during treatment. - Fitusiran is a prescription biologic used only under specialist hematology supervision, with antithrombin monitored using an FDA-cleared test and dose adjusted to keep antithrombin activity in a 15-35% target range; it is not self-directed therapy, a supplement, or a research chemical. - Any product sold as 'fitusiran', 'Qfitlia', or 'antithrombin siRNA' outside a licensed pharmacy or regulated clinical trial is unverified and unsafe; do not source or use it from peptide vendors or gray-market suppliers. - Managing breakthrough bleeds and surgery requires care: because antithrombin is already lowered, replacement factor or bypassing-agent dosing for bleeds must follow specific bleed-management guidance to avoid excessive clotting, and use in the post-operative setting has been linked to thrombotic risk when those guidelines were not followed. - Decisions about hemophilia prophylaxis - including whether to switch from factor replacement or emicizumab to fitusiran - should be made with a hematologist; this is educational background about an approved medicine, not medical advice. ## Comparisons See how Fitusiran compares to related peptides: Fitusiran vs Inclisiran: https://peptrackerpro.com/compare/fitusiran-vs-inclisiran Fitusiran vs Olpasiran: https://peptrackerpro.com/compare/fitusiran-vs-olpasiran Fitusiran vs Plozasiran: https://peptrackerpro.com/compare/fitusiran-vs-plozasiran Fitusiran vs Rusfertide: https://peptrackerpro.com/compare/fitusiran-vs-rusfertide Fitusiran vs Vutrisiran: https://peptrackerpro.com/compare/fitusiran-vs-vutrisiran Fitusiran vs Zilebesiran: https://peptrackerpro.com/compare/fitusiran-vs-zilebesiran Fitusiran vs Donidalorsen: https://peptrackerpro.com/compare/fitusiran-vs-donidalorsen Fitusiran vs Nucresiran: https://peptrackerpro.com/compare/fitusiran-vs-nucresiran Fitusiran vs Garadacimab: https://peptrackerpro.com/compare/fitusiran-vs-garadacimab Fitusiran vs Sebetralstat: https://peptrackerpro.com/compare/fitusiran-vs-sebetralstat ## Calculator Tools Use our research tools to explore dosing and reconstitution data: Reconstitution Calculator: https://peptrackerpro.com/calculators ## Citations 1. [1] FDA Approves Novel Treatment for Hemophilia A or B, with or without Factor Inhibitors - U.S. Food & Drug Administration (March 28, 2025) PubMed (https://www.fda.gov/news-events/press-announcements/fda-approves-novel-treatment-hemophilia-or-b-or-without-factor-inhibitors) 2. [2] Qfitlia approved as the first therapy in the US to treat hemophilia A or B with or without inhibitors - Sanofi (March 28, 2025) PubMed (https://www.sanofi.com/en/media-room/press-releases/2025/2025-03-28-20-07-38-3051637) 3. [3] FDA Approves Qfitlia (fitusiran), the First siRNA (RNAi Therapeutic) for the Treatment of Hemophilia A or B - Alnylam Pharmaceuticals (March 28, 2025) PubMed (https://investors.alnylam.com/press-release?id=28901) 4. [4] QFITLIA (fitusiran) injection - full U.S. Prescribing Information (boxed warning), DailyMed / NIH PubMed (https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=6dd2f8ac-6f90-4cbf-b197-97d74964135c) 5. [5] QFITLIA (fitusiran) label - FDA Approval reference PDF (Reference ID 5560676, 2025) PubMed (https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/219019s000lbl.pdf) 6. [6] Young G, et al. Efficacy and safety of fitusiran prophylaxis in people with haemophilia A or B with inhibitors (ATLAS-INH): a phase 3 trial - The Lancet (2023) PubMed (https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(23)00284-2/abstract) 7. [7] Srivastava A, et al. Fitusiran prophylaxis in people with severe haemophilia A or B without inhibitors (ATLAS-A/B): a phase 3 trial - The Lancet Haematology (2023) PubMed (https://www.thelancet.com/journals/lanhae/article/PIIS2352-3026(23)00037-6/abstract) ### Keep researching in the app - Log Fitusiran to your private tracker - Set a dosing reminder - Compare it side-by-side with your stack Open PepTracker Pro Free: https://app.peptrackerpro.com/?add=fitusiran Browse more peptides: https://peptrackerpro.com/peptides ## Related Peptides ### Inclisiran High Evidence An approved, twice-yearly subcutaneous GalNAc-conjugated small interfering RNA (siRNA) from Novartis (originally discovered by Alnylam) that lowers LDL cholesterol by silencing PCSK9 (proprotein convertase subtilisin/kexin type 9), the liver protein that destroys LDL receptors. By switching off PCSK9 production inside hepatocytes, inclisiran leaves more LDL receptors on the liver surface to pull LDL cholesterol out of the blood - achieving roughly a 50% LDL reduction with an injection given only twice a year after a loading dose. Marketed as Leqvio, it was the first siRNA medicine approved for a chronic cardiovascular condition: the EU cleared it in December 2020 and the FDA in December 2021, and in July 2025 the FDA expanded the U.S. label to first-line monotherapy, dropping the requirement that it be added on top of a statin. Its Phase 3 ORION-9, ORION-10 and ORION-11 trials established the LDL benefit; a large cardiovascular outcomes program (VICTORION-2-PREVENT and others) is still running to test whether that LDL lowering prevents heart attacks and strokes. Inclisiran is the approved, real-world proof-of-concept for the GalNAc-siRNA cardiometabolic platform that newer investigational agents like zodasiran, solbinsiran, olpasiran and plozasiran build on. Cardiovascular: https://peptrackerpro.com/benefits/cardiovascular Cholesterol Management: https://peptrackerpro.com/benefits/cholesterol-management Disease Modification: https://peptrackerpro.com/benefits/disease-modification View Details: https://peptrackerpro.com/peptides/inclisiran \+ Compare: https://peptrackerpro.com/compare?select=inclisiran Track in App: https://app.peptrackerpro.com/?add=inclisiran ### Olpasiran Medium Evidence An investigational, once-every-12-weeks injectable small interfering RNA (siRNA) from Amgen that lowers lipoprotein(a) [Lp(a)] by up to ~97% by silencing the LPA gene in the liver. Its Phase 3 OCEAN(a)-Outcomes cardiovascular outcomes trial (~7,000 patients) is one of the pivotal readouts — due December 2026 — that will help decide whether lowering Lp(a) prevents heart attacks and strokes. View Details: https://peptrackerpro.com/peptides/olpasiran \+ Compare: https://peptrackerpro.com/compare?select=olpasiran Track in App: https://app.peptrackerpro.com/?add=olpasiran ### Plozasiran High Evidence An approved subcutaneous RNA interference (RNAi) therapy from Arrowhead Pharmaceuticals, branded Redemplo, that silences the gene for apolipoprotein C-III (apoC-III) to lower triglycerides. Given once every three months, it cut triglycerides by roughly 80% in familial chylomicronemia syndrome (FCS) and sharply reduced acute pancreatitis events. The FDA approved it on November 18, 2025 for FCS, and Phase 3 SHASTA-3 and SHASTA-4 (reported July 2026) extended those results to the far larger severe hypertriglyceridemia population. View Details: https://peptrackerpro.com/peptides/plozasiran \+ Compare: https://peptrackerpro.com/compare?select=plozasiran Track in App: https://app.peptrackerpro.com/?add=plozasiran ### Rusfertide High Evidence A first-in-class synthetic hepcidin-mimetic (mini-hepcidin) peptide given as a weekly subcutaneous injection to control red-blood-cell overproduction in polycythemia vera (PV). By mimicking the iron-regulating hormone hepcidin, rusfertide binds the iron exporter ferroportin and restricts iron availability, reducing the need for therapeutic phlebotomy. Developed by Protagonist Therapeutics and partnered with Takeda, it met its primary endpoint in the Phase 3 VERIFY trial and, in March 2026, received FDA acceptance of its New Drug Application with Priority Review, with a decision expected in the third quarter of 2026. Hematology: https://peptrackerpro.com/benefits/hematology View Details: https://peptrackerpro.com/peptides/rusfertide \+ Compare: https://peptrackerpro.com/compare?select=rusfertide Track in App: https://app.peptrackerpro.com/?add=rusfertide ### Vutrisiran High Evidence An approved, quarterly (once-every-three-months) subcutaneous GalNAc-conjugated small interfering RNA (siRNA) from Alnylam that treats transthyretin-mediated (ATTR) amyloidosis by silencing the TTR gene in the liver. Transthyretin is a liver-made transport protein that can misfold and pile up as amyloid deposits in nerves and, critically, the heart; vutrisiran uses RNA interference (RNAi) to degrade both mutant and wild-type TTR messenger RNA before the protein is made, lowering circulating TTR by roughly 80% and starving the amyloid of its raw material. Marketed as Amvuttra, it was first FDA-approved in June 2022 for the polyneuropathy of hereditary ATTR amyloidosis (HELIOS-A), and in March 2025 the FDA expanded the label to ATTR cardiomyopathy (ATTR-CM) of wild-type or hereditary disease - making vutrisiran the first RNAi therapeutic shown to reduce cardiovascular death and cardiovascular events, on the strength of the HELIOS-B outcomes trial. It shares the exact GalNAc-siRNA delivery platform that underlies the cardiometabolic RNAi medicine inclisiran and the investigational agents olpasiran, lepodisiran, zerlasiran, zilebesiran, zodasiran, solbinsiran and plozasiran, and it is the direct successor to Alnylam's earlier intravenous TTR siRNA patisiran (Onpattro). Cardiovascular: https://peptrackerpro.com/benefits/cardiovascular Neuroprotection: https://peptrackerpro.com/benefits/neuroprotection Disease Modification: https://peptrackerpro.com/benefits/disease-modification Rare Disease Treatment: https://peptrackerpro.com/benefits/rare-disease-treatment View Details: https://peptrackerpro.com/peptides/vutrisiran \+ Compare: https://peptrackerpro.com/compare?select=vutrisiran Track in App: https://app.peptrackerpro.com/?add=vutrisiran ### Zilebesiran Medium Evidence An investigational subcutaneous GalNAc-conjugated small interfering RNA (siRNA) from Alnylam Pharmaceuticals and Roche/Genentech that lowers blood pressure by silencing angiotensinogen (AGT), the single upstream precursor of the renin-angiotensin-aldosterone system (RAAS). Designed for dosing as infrequently as once or twice a year, it is the first RNА interference (RNAi) therapeutic developed for hypertension. In Phase 2 KARDIA-1 and KARDIA-2 trials it produced durable, clinically meaningful reductions in systolic blood pressure sustained for up to 6 months from a single dose, and in 2025 it advanced into the large Phase 3 ZENITH cardiovascular outcomes trial. Cardiovascular: https://peptrackerpro.com/benefits/cardiovascular Disease Modification: https://peptrackerpro.com/benefits/disease-modification View Details: https://peptrackerpro.com/peptides/zilebesiran \+ Compare: https://peptrackerpro.com/compare?select=zilebesiran Track in App: https://app.peptrackerpro.com/?add=zilebesiran ### Donidalorsen High Evidence An FDA-approved RNA-targeted therapy that prevents hereditary angioedema (HAE) attacks by turning down production of a single blood protein rather than blocking it after it forms. Donidalorsen (brand name Dawnzera) is a GalNAc-conjugated antisense oligonucleotide (ASO) taken up by liver cells, where it binds the messenger RNA for prekallikrein (the gene KLKB1) and triggers its degradation, lowering circulating prekallikrein. Because prekallikrein sits at the top of the kallikrein-kinin cascade that generates bradykinin - the peptide that drives the swelling of HAE - reducing it prevents the runaway bradykinin surges responsible for painful, sometimes life-threatening attacks. It was approved by the U.S. FDA on August 21, 2025 as the first and only RNA-targeted prophylactic medicine for HAE, for routine prevention of attacks in adults and children aged 12 and older. It is given as an 80 mg subcutaneous self-injection by autoinjector once every four weeks, with the option to move to once every eight weeks in well-controlled patients. In the pivotal Phase 3 OASIS-HAE trial, donidalorsen reduced monthly HAE attacks by about 81% versus placebo over 24 weeks, and in the OASISplus switch study most patients who moved from other long-term prophylaxis preferred donidalorsen. Donidalorsen is a prescription biologic developed by Ionis Pharmaceuticals and administered under specialist care - not a supplement or research chemical. Immune Modulation: https://peptrackerpro.com/benefits/immune-modulation Rare Disease Treatment: https://peptrackerpro.com/benefits/rare-disease-treatment View Details: https://peptrackerpro.com/peptides/donidalorsen \+ Compare: https://peptrackerpro.com/compare?select=donidalorsen Track in App: https://app.peptrackerpro.com/?add=donidalorsen ### Nucresiran Medium Evidence An investigational next-generation RNA interference (RNAi) therapeutic from Alnylam Pharmaceuticals designed to silence the transthyretin (TTR) gene and treat transthyretin amyloidosis (ATTR) - the same disease targeted by Alnylam's approved drugs patisiran and vutrisiran (Amvuttra) and by Ionis/AstraZeneca's eplontersen (Wainua/Wainzua). Nucresiran (formerly ALN-TTRsc04) is a subcutaneous GalNAc-conjugated small interfering RNA (siRNA) built on Alnylam's newer IKARIA platform, engineered for deeper, more durable knockdown of both mutant and wild-type TTR with the potential for once- or twice-yearly dosing - a substantial step beyond the current quarterly (vutrisiran) or monthly (eplontersen) schedules. In an interim Phase 1 single-ascending-dose study in 48 healthy volunteers (presented at AHA 2024), a single dose of 300 mg or higher rapidly lowered serum TTR by more than 90% by Day 15 and by more than 96% at peak (Day 29), with more than 70% reduction still present at one year after a single 300 mg dose and low patient-to-patient variability; all doses were well tolerated with no injection-site reactions and no liver safety signals. Alnylam has moved nucresiran into a Phase 3 TRITON program: TRITON-PN (NCT07223203) in hereditary ATTR with polyneuropathy, an open-label study using vutrisiran as an active comparator, and TRITON-CM (NCT07052903), a large event-driven cardiovascular outcomes trial in ATTR cardiomyopathy dosing nucresiran 300 mg subcutaneously once every six months. Nucresiran is investigational and not approved by the FDA, EMA or any regulator; it is studied only in clinical trials and is not a supplement or research chemical. View Details: https://peptrackerpro.com/peptides/nucresiran \+ Compare: https://peptrackerpro.com/compare?select=nucresiran Track in App: https://app.peptrackerpro.com/?add=nucresiran ### Garadacimab High Evidence Garadacimab (brand name Andembry; garadacimab-gxii) is a first-in-class, fully human monoclonal antibody that inhibits activated Factor XII (FXIIa), used once monthly to prevent attacks of hereditary angioedema (HAE). HAE is a rare, potentially life-threatening genetic disease in which unchecked activation of the plasma contact system floods the body with bradykinin, causing sudden, recurrent swelling of the skin, gut and airway. FXIIa is the very first enzyme in that contact-system cascade, so garadacimab shuts the pathway off at its source - blocking FXIIa before it can activate plasma kallikrein and generate the bradykinin that drives swelling. It is given as a 400 mg subcutaneous loading dose followed by 200 mg once-monthly subcutaneous self-injection with an autoinjector (an injection that takes about 15 seconds), making it the only HAE prophylaxis that targets FXIIa and offers once-monthly dosing for all eligible patients from the start. Approval rests on the pivotal Phase 3 VANGUARD trial (NCT04656418), a global, randomized, double-blind, placebo-controlled study of 64 patients aged 12 and older, in which garadacimab cut the monthly HAE attack rate by a least-squares mean of 89.2% versus placebo (median reduction greater than 99%) over the 6-month treatment period, with 62% of treated patients attack-free; the results were published in The Lancet in 2023. The FDA approved Andembry on June 16, 2025 to prevent HAE attacks in people aged 12 and older, following European (February 2025), Australian and Canadian approvals. On July 27, 2026 CSL reported positive top-line Phase 3b results in children aged 2 to 11, with most young participants remaining attack-free over a 12-month treatment period, supporting a planned expanded pediatric filing. Discovered and optimized at CSL's Bio21 research site and developed by CSL Behring, garadacimab sits alongside the antisense prekallikrein-lowering drug donidalorsen, the anti-plasma-kallikrein antibody lanadelumab, the oral kallikrein inhibitor berotralstat and C1-esterase-inhibitor concentrates in the modern HAE prevention toolkit. immunology: https://peptrackerpro.com/benefits/immunology rare-disease: https://peptrackerpro.com/benefits/rare-disease hereditary-angioedema: https://peptrackerpro.com/benefits/hereditary-angioedema attack-prevention: https://peptrackerpro.com/benefits/attack-prevention View Details: https://peptrackerpro.com/peptides/garadacimab \+ Compare: https://peptrackerpro.com/compare?select=garadacimab Track in App: https://app.peptrackerpro.com/?add=garadacimab ### Sebetralstat High Evidence Sebetralstat (brand name Ekterly) is a first-in-class, orally administered small-molecule inhibitor of plasma kallikrein and the first and only oral on-demand treatment approved for acute attacks of hereditary angioedema (HAE). HAE is a rare, sometimes life-threatening genetic disease in which unchecked activation of the plasma contact system floods the body with bradykinin, causing sudden, recurrent swelling of the skin, gut and airway. Plasma kallikrein is the enzyme that liberates bradykinin, so sebetralstat stops an attack by blocking kallikrein the moment symptoms begin - delivered as a tablet that can be taken at home rather than as an injection or infusion. The approved dose is 600 mg (two 300 mg tablets) at the earliest recognition of an attack, with a second 600 mg dose allowed at least 3 hours later if the response is inadequate or symptoms recur, up to a maximum of 1200 mg in 24 hours. Approval rests on the pivotal Phase 3 KONFIDENT trial (NCT05259917) - the largest HAE trial ever conducted, with 136 patients at 66 sites across 20 countries - a randomized, double-blind, placebo-controlled, event-driven crossover study in which sebetralstat cut the median time to the beginning of symptom relief to 1.61 hours (300 mg) and 1.79 hours (600 mg) versus 6.72 hours for placebo (p<0.0001 and p=0.0013), and also shortened the time to reduced attack severity and to complete resolution; results were published in the New England Journal of Medicine in 2024. The FDA approved Ekterly on July 7, 2025 for patients aged 12 and older, followed by European Commission and Swissmedic approvals on September 19, 2025 and UK MHRA approval. In 2026 the program widened further: an international pediatric HAE guideline named sebetralstat a first-line on-demand option for adolescents aged 12 and older, and in March 2026 KalVista reported positive interim Phase 3 results from the KONFIDENT-KID study in children aged 2 to 11 using an orally disintegrating tablet, with a US filing planned for late 2026. Developed by KalVista Pharmaceuticals, sebetralstat is a rescue (on-demand) therapy that complements the prophylactic HAE drugs garadacimab, donidalorsen, lanadelumab and berotralstat rather than replacing them. immunology: https://peptrackerpro.com/benefits/immunology rare-disease: https://peptrackerpro.com/benefits/rare-disease hereditary-angioedema: https://peptrackerpro.com/benefits/hereditary-angioedema acute-treatment: https://peptrackerpro.com/benefits/acute-treatment View Details: https://peptrackerpro.com/peptides/sebetralstat \+ Compare: https://peptrackerpro.com/compare?select=sebetralstat Track in App: https://app.peptrackerpro.com/?add=sebetralstat ## Structured data ```json [ { "@context": "https://schema.org", "@type": "Organization", "name": "PepTracker Pro", "url": "https://peptrackerpro.com", "logo": "https://peptrackerpro.com/favicon.png", "description": "Evidence-based educational resource dedicated to improving peptide research literacy.", "contactPoint": { "@type": "ContactPoint", "email": "hello@peptrackerpro.com", "contactType": "customer support" }, "sameAs": [] }, { "@context": "https://schema.org", "@type": "MedicalWebPage", "name": "Fitusiran", "description": "An FDA-approved RNA-interference (RNAi) therapy for hemophilia that works by lowering a natural blood-thinning protein rather than replacing a missing clotting factor. Fitusiran (brand name Qfitlia) is a GalNAc-conjugated small interfering RNA (siRNA) that is taken up by liver cells and silences the gene for antithrombin, the body's main brake on clotting. By reducing antithrombin, fitusiran 'rebalances' hemostasis so that people with hemophilia A or B can generate enough thrombin to form stable clots and bleed less often. It was approved by the U.S. FDA on March 28, 2025 - the first siRNA (RNAi) therapy for hemophilia and the first medicine that treats hemophilia by lowering antithrombin - for routine prophylaxis in adults and children aged 12 and older with hemophilia A or B, with or without factor VIII or IX inhibitors. A key practical advantage is that it is given as an infrequent subcutaneous injection (starting once every two months, as few as about six injections per year) and works regardless of hemophilia type or inhibitor status. In the pivotal Phase 3 ATLAS trials, fitusiran reduced the annualized bleeding rate by about 90% versus on-demand treatment. Because lowering antithrombin shifts the clotting balance, fitusiran carries a boxed warning for thrombotic (clotting) events and gallbladder disease, and it is now dosed to a target antithrombin level (15-35%) to reduce clot risk. 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An FDA-approved RNA-interference (RNAi) therapy for hemophilia that works by lowering a natural blood-thinning protein rather than replacing a missing clotting factor. Fitusiran (brand name Qfitlia) is a GalNAc-conjugated small interfering RNA (siRNA) that is taken up by liver cells and silences the gene for antithrombin, the body's main brake on clotting. By reducing antithrombin, fitusiran 'rebalances' hemostasis so that people with hemophilia A or B can generate enough thrombin to form stable clots and bleed less often. It was approved by the U.S. FDA on March 28, 2025 - the first siRNA (RNAi) therapy for hemophilia and the first medicine that treats hemophilia by lowering antithrombin - for routine prophylaxis in adults and children aged 12 and older with hemophilia A or B, with or without factor VIII or IX inhibitors. A key practical advantage is that it is given as an infrequent subcutaneous injection (starting once every two months, as few as about six injections per year) and works regardless of hemophilia type or inhibitor status. In the pivotal Phase 3 ATLAS trials, fitusiran reduced the annualized bleeding rate by about 90% versus on-demand treatment. Because lowering antithrombin shifts the clotting balance, fitusiran carries a boxed warning for thrombotic (clotting) events and gallbladder disease, and it is now dosed to a target antithrombin level (15-35%) to reduce clot risk. 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It was approved by the U.S. FDA on March 28, 2025 - the first siRNA (RNAi) therapy for hemophilia and the first medicine that treats hemophilia by lowering antithrombin - for routine prophylaxis in adults and children aged 12 and older with hemophilia A or B, with or without factor VIII or IX inhibitors. A key practical advantage is that it is given as an infrequent subcutaneous injection (starting once every two months, as few as about six injections per year) and works regardless of hemophilia type or inhibitor status. In the pivotal Phase 3 ATLAS trials, fitusiran reduced the annualized bleeding rate by about 90% versus on-demand treatment. Because lowering antithrombin shifts the clotting balance, fitusiran carries a boxed warning for thrombotic (clotting) events and gallbladder disease, and it is now dosed to a target antithrombin level (15-35%) to reduce clot risk. 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It was approved by the U.S. FDA on March 28, 2025 - the first siRNA (RNAi) therapy for hemophilia and the first medicine that treats hemophilia by lowering antithrombin - for routine prophylaxis in adults and children aged 12 and older with hemophilia A or B, with or without factor VIII or IX inhibitors. A key practical advantage is that it is given as an infrequent subcutaneous injection (starting once every two months, as few as about six injections per year) and works regardless of hemophilia type or inhibitor status. In the pivotal Phase 3 ATLAS trials, fitusiran reduced the annualized bleeding rate by about 90% versus on-demand treatment. Because lowering antithrombin shifts the clotting balance, fitusiran carries a boxed warning for thrombotic (clotting) events and gallbladder disease, and it is now dosed to a target antithrombin level (15-35%) to reduce clot risk. 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It was approved by the U.S. FDA on March 28, 2025 - the first siRNA (RNAi) therapy for hemophilia and the first medicine that treats hemophilia by lowering antithrombin - for routine prophylaxis in adults and children aged 12 and older with hemophilia A or B, with or without factor VIII or IX inhibitors. A key practical advantage is that it is given as an infrequent subcutaneous injection (starting once every two months, as few as about six injections per year) and works regardless of hemophilia type or inhibitor status. In the pivotal Phase 3 ATLAS trials, fitusiran reduced the annualized bleeding rate by about 90% versus on-demand treatment. Because lowering antithrombin shifts the clotting balance, fitusiran carries a boxed warning for thrombotic (clotting) events and gallbladder disease, and it is now dosed to a target antithrombin level (15-35%) to reduce clot risk. 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