Givosiran

12.1 Mechanism of Action Givosiran is a double-stranded small interfering RNA that causes degradation of aminolevulinate synthase 1 ( ALAS1 ) mRNA in hepatocytes through RNA interference, reducing the elevated levels of liver ALAS1 mRNA. This leads to reduced circulating levels of neurotoxic intermediates aminolevulinic acid (ALA) and porphobilinogen (PBG), factors associated with attacks and other disease manifestations of AHP.

1 INDICATIONS AND USAGE GIVLAARI is indicated for the treatment of adults with acute hepatic porphyria (AHP). GIVLAARI is an aminolevulinate synthase 1-directed small interfering RNA indicated for the treatment of adults with acute hepatic porphyria (AHP). ( 1 )

2 DOSAGE AND ADMINISTRATION The recommended dose of GIVLAARI is 2.5 mg/kg once monthly by subcutaneous injection. ( 2.1 ) 2.1 Recommended Dosage The recommended dose of GIVLAARI is 2.5 mg/kg administered via subcutaneous injection once monthly. Dosing is based on actual body weight. Missed Dose Administer GIVLAARI as soon as possible after a missed dose. Resume dosing at monthly intervals following administration of the missed dose. Dose Modification for Adverse Reactions In patients with severe or clinically significant transaminase elevations, who have dose interruption and subsequent improvement, reduce the dose to 1.25 mg/kg once monthly [see Warnings and Precautions (5.2) ] . In patients who resume dosing at 1.25 mg/kg once monthly without recurrence of severe or clinically significant transaminase elevations, the dose may be increased to the recommended dose of 2.5 mg/kg once monthly. 2.2 Administration Instructions Ensure that medical support is available to appropriately manage anaphylactic reactions when administering GIVLAARI [see Warnings and Precautions (5.1) ]. GIVLAARI is intended for subcutaneous use by a healthcare professional only. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. GIVLAARI is a sterile, preservative-free, clear, colorless-to-yellow solution. It is supplied in a single-dose vial, as a ready-to-use solution that does not require additional reconstitution or dilution prior to administration. Use aseptic technique. Calculate the required volume of GIVLAARI based on the recommended weight-based dosage [see Dosage and Administration (2.1) ] . Withdraw the indicated injection volume of GIVLAARI using a 21-gauge or larger needle. Divide doses requiring volumes greater than 1.5 mL equally into multiple syringes. Replace the 21-gauge or larger needle with either a 25-gauge or 27-gauge needle with 1/2" or 5/8" needle length. Avoid having GIVLAARI on the needle tip until the needle is in the subcutaneous space. Administer injection into the abdomen, the back or side of the upper arms, or the thighs. Rotate injection sites. An injection should never be given into scar tissue or areas that are reddened, inflamed, or swollen. If injecting into the abdomen, avoid a 5 cm diameter circle around the navel. If more than one injection is needed for a single dose of GIVLAARI, the injection sites should be at least 2 cm apart from previous injection locations. Discard unused portion of the drug.

6 ADVERSE REACTIONS The following clinically significant adverse reactions are discussed in greater detail in other sections of the labeling: Anaphylactic Reaction [see Warnings and Precautions (5.1) ] Transaminase Elevations [see Warnings and Precautions (5.2) ] Serum Creatinine Increase [see Warnings and Precautions (5.3) ] Injection Site Reactions [see Warnings and Precautions (5.4) ] Blood Homocysteine Increased [see Warnings and Precautions (5.5) ] Pancreatitis [see Warnings and Precautions (5.6) ] The most common adverse reactions (≥20% of patients) included nausea and injection site reactions. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Alnylam Pharmaceuticals at 1-877-256-9526 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trial Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In the pivotal placebo-controlled, double-blind study (ENVISION), 48 patients received 2.5 mg/kg GIVLAARI and 46 patients received placebo, administered once monthly via subcutaneous injection for up to 6 months. Patients received GIVLAARI for a median of 5.5 months (range 2.7-6.4 months). Of these, 47 patients received ≥5 months of treatment. The most frequently occurring (≥20% incidence) adverse reactions reported in patients treated with GIVLAARI were nausea (27%) and injection site reactions (25%). Permanent discontinuation occurred in one patient due to elevated transaminases. Table 1: Adverse Reactions that Occurred at Least 5% More Frequently in Patients Treated with GIVLAARI Compared to Patients Treated with Placebo Adverse Reaction GIVLAARI N=48 N (%) Placebo N=46 N (%) Nausea 13 (27) 5 (11) Injection site reactions 12 (25) 0 Rash Grouped term includes pruritus, eczema, erythema, rash, rash pruritic, urticaria 8 (17) 2 (4) Serum creatinine increase Grouped term includes blood creatinine increased, glomerular filtration rate decreased, chronic kidney disease (decreased eGFR) 7 (15) 2 (4) Transaminase elevations 6 (13) 1 (2) Fatigue 5 (10) 2 (4) Adverse reactions observed at a lower frequency occurring in placebo-controlled and open-label clinical studies included anaphylactic reaction (one patient, 0.9%) and hypersensitivity (one patient, 0.9%). In the ENVISION study, during the open label extension, adverse reactions of blood homocysteine increased were reported in 15 of 93 (16%) patients treated with GIVLAARI [see Warnings and Precautions (5.5) ]. 6.2 Immunogenicity As with all oligonucleotides, there is a potential for immunogenicity. The detection of antibody formation is highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of antibody (including neutralizing antibody) positivity in an assay may be influenced by several factors, including assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies in the studies described below with the incidence of antibodies in other studies or to other products may be misleading. In placebo-controlled and open-label clinical studies, 1 of 111 patients with AHP (0.9%) developed treatment-emergent anti-drug antibodies (ADA) during treatment with GIVLAARI. No clinically significant differences in the clinical efficacy, safety, pharmacokinetic, or pharmacodynamic profiles of GIVLAARI were observed in the patient who tested positive for anti-givosiran antibodies. 6.3 Postmarketing Experience The following additional adverse reactions have been reported during post-approval use. Because these events are reported voluntarily from a population of uncertain size, it is generally not possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Gastrointestinal Disorders: Acute pancreatitis

7 DRUG INTERACTIONS Sensitive CYP1A2 and CYP2D6 Substrates: Avoid concomitant use with CYP1A2 and CYP2D6 substrates for which minimal concentration changes may lead to serious or life-threatening toxicities. ( 7.1 ) 7.1 Effect of GIVLAARI on Other Drugs Sensitive CYP1A2 and CYP2D6 Substrates Concomitant use of GIVLAARI increases the concentration of CYP1A2 or CYP2D6 substrates [see Clinical Pharmacology (12.3) ] , which may increase adverse reactions of these substrates. Avoid concomitant use of GIVLAARI with CYP1A2 or CYP2D6 substrates, for which minimal concentration changes may lead to serious or life-threatening toxicities. If concomitant use is unavoidable, decrease the CYP1A2 or CYP2D6 substrate dosage in accordance with approved product labeling.