Aduhelm

6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in the labeling: Amyloid Related Imaging Abnormalities [see Warnings and Precautions ( 5.1 )] Hypersensitivity Reactions [see Warnings and Precautions ( 5.2 )] Most common adverse reactions (at least 10% and higher incidence compared to placebo): ARIA-Edema, headache, ARIA-H microhemorrhage, ARIA-H superficial siderosis, and fall. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Biogen at 1-833-425-9360 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in 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 clinical practice. The safety of ADUHELM has been evaluated in 3,078 patients who received at least one dose of ADUHELM. In two placebo-controlled studies (Studies 1 and 2) in patients with Alzheimer's disease, a total of 1105 patients received ADUHELM 10 mg/kg [see Clinical Studies ( 14 )] . Of these 1105 patients, approximately 52% were female, 76% were White, 10% were Asian, and 3% were of Hispanic or Latino ethnicity. The mean age at study entry was 70 years (range from 50 to 85). In the combined placebo-controlled and long-term extension periods of Studies 1 and 2, 834 patients received at least one dose of ADUHELM 10 mg/kg once monthly for at least 6 months, 551 patients for at least 12 months, and 309 patients for at least 18 months. In the combined placebo-controlled and long-term extension periods, 5% (66 out of 1386) of patients in the 10 mg/kg dose group withdrew from the study because of an adverse reaction. The most common adverse reaction resulting in study withdrawal in the combined placebo-controlled and long-term extension periods was ARIA-H superficial siderosis. Table 5 shows adverse reactions that were reported in at least 2% of patients treated with ADUHELM and at least 2% more frequently than in patients on placebo. Table 5: Adverse Reactions Reported in at Least 2% of Patients Treated with ADUHELM 10 mg/kg and at Least 2% Higher Than Placebo in Studies 1 and 2 Adverse Reaction ADUHELM 10 mg/kg N=1105 % Placebo N=1087 % a Headache includes the adverse reaction related terms headache, head discomfort, migraine, migraine with aura, and occipital neuralgia. b Diarrhea includes the adverse reaction related terms diarrhea and infectious diarrhea. c Confusion/Delirium/Altered Mental Status/Disorientation includes the adverse reaction related terms confusional state, delirium, altered state of consciousness, disorientation, depressed level of consciousness, disturbance in attention, mental impairment, mental status changes, postoperative confusion, and somnolence. ARIA-E 35 3 Headache a 21 16 ARIA-H microhemorrhage 19 7 ARIA-H superficial siderosis 15 2 Fall 15 12 Diarrhea b 9 7 Confusion/Delirium/Altered Mental Status/Disorientation c 8 4

4 CONTRAINDICATIONS None. None. ( 4 )

11 DESCRIPTION Aducanumab-avwa is a recombinant human immunoglobulin gamma 1 (IgG1) monoclonal antibody directed against aggregated soluble and insoluble forms of amyloid beta, and is expressed in a Chinese hamster ovary cell line. Aducanumab-avwa has an approximate molecular weight of 146 kDa. ADUHELM (aducanumab-avwa) injection is a preservative-free, sterile, clear to opalescent, and colorless to yellow solution for intravenous infusion after dilution supplied in single-dose vials available in concentrations of 170 mg/1.7 mL (100 mg/mL) or 300 mg/3 mL (100 mg/mL) of ADUHELM. Each mL of solution contains 100 mg of aducanumab-avwa and L-arginine hydrochloride (31.60 mg), L-histidine (0.60 mg), L-histidine hydrochloride monohydrate (3.39 mg), L-methionine (1.49 mg), polysorbate 80 (0.50 mg), and Water for Injection at an approximate pH of 5.5.

2 DOSAGE AND ADMINISTRATION Confirm the presence of amyloid beta pathology prior to initiating treatment. ( 2.1 ) Titration is required for treatment initiation. ( 2.2 ) The recommended maintenance dosage is 10 mg/kg administered as an intravenous infusion over approximately one hour every four weeks. ( 2.2 ) Obtain a recent (within one year) brain MRI prior to initiating treatment. ( 2.3 , 5.1 ) Obtain MRIs prior to the 5 th , 7 th , 9 th , and 12 th infusions; if radiographically observed ARIA occurs, treatment recommendations are based on type, severity, and presence of symptoms. ( 2.3 , 5.1 ) Dilution in 100 mL of 0.9% Sodium Chloride Injection, USP, is required prior to administration. ( 2.4 ) Administer as an intravenous infusion over approximately one hour via a 0.2 or 0.22 micron in-line filter. ( 2.5 ) 2.1 Patient Selection Confirm the presence of amyloid beta pathology prior to initiating treatment [see Clinical Pharmacology ( 12.1 )] . 2.2 Dosing Instructions After an initial titration, the recommended dosage of ADUHELM is 10 mg/kg (see Table 1 ). ADUHELM must be diluted and is administered as an intravenous infusion over approximately one hour every four weeks. Table 1: Dosing Schedule Intravenous Infusion (every 4 weeks) ADUHELM Dosage (administered over approximately one hour) Infusion 1 and 2 1 mg/kg Infusion 3 and 4 3 mg/kg Infusion 5 and 6 6 mg/kg Infusion 7 and beyond 10 mg/kg If an infusion is missed, resume administration at the same dose as soon as possible and at least 21 days apart. 2.3 Monitoring and Dosing Interruptions for Amyloid Related Imaging Abnormalities ADUHELM can cause amyloid related imaging abnormalities -edema (ARIA-E) and hemosiderin deposition (ARIA-H) [see Warnings and Precautions ( 5.1 )] . Monitoring for ARIA Obtain recent (within one year) brain magnetic resonance imaging (MRI) prior to initiating treatment with ADUHELM. Obtain MRIs prior to the 5 th infusion (first dose of 6 mg/kg), 7 th infusion (first dose of 10 mg/kg), 9 th infusion (third dose of 10 mg/kg), and 12 th infusion (sixth dose of 10 mg/kg). Recommendations for Dosing Interruptions in Patients with ARIA If dosing is resumed following a temporary suspension, dosing may resume at that same dose and titration schedule prior to the dosing suspension. The benefits of reaching and maintaining the 10 mg/kg dosage should be considered when evaluating a potential dose suspension. ARIA-E The recommendations for dosing interruptions for patients with ARIA-E are provided in Table 2 . Table 2: Dosing Recommendations for Patients with ARIA-E 1 Mild: discomfort noticed, but no disruption of normal daily activity. Moderate: discomfort sufficient to reduce or affect normal daily activity. Severe: incapacitating, with inability to work or to perform normal daily activity. 2 Suspend until MRI demonstrates radiographic resolution and symptoms, if present, resolve; consider a follow-up MRI to assess for resolution 2 to 4 months after initial identification. Resumption of dosing should be guided by clinical judgment. 3 See table 4 . Clinical Symptom Severity 1 ARIA-E Severity on MRI 3 Mild Moderate Severe Asymptomatic May continue dosing at current dose and schedule Suspend dosing 2 Suspend dosing 2 Mild May continue dosing based on clinical judgment Suspend dosing 2 Moderate or Severe Suspend dosing 1 ARIA-H The recommendations for dosing interruptions for patients with ARIA-H are provided in Table 3 . Table 3: Dosing Recommendations for Patients with ARIA-H 1 Suspend until MRI demonstrates radiographic stabilization and symptoms, if present, resolve; resumption of dosing should be guided by clinical judgment; consider a follow-up MRI to assess for stabilization 2 to 4 months after initial identification. 2 Suspend until MRI demonstrates radiographic stabilization and symptoms, if present, resolve; use clinical judgment in considering whether to continue treatment or permanently discontinue ADUHELM. 3 See table 4 . Clinical Symptom Severity ARIA-H Severity on MRI 3 Mild Moderate Severe Asymptomatic May continue dosing at current dose and schedule Suspend dosing 1 Suspend dosing 2 Symptomatic Suspend dosing 1 Suspend dosing 1 In patients who develop intracerebral hemorrhage greater than 1 cm in diameter during treatment with ADUHELM, suspend dosing until MRI demonstrates radiographic stabilization and symptoms, if present, resolve. In Studies 1 and 2, dosing was permanently discontinued in patients who developed intracerebral hemorrhage greater than 1 cm in diameter. Use clinical judgment in considering whether to continue treatment after radiographic stabilization and resolution of symptoms or permanently discontinue ADUHELM. 2.4 Dilution Instructions Prior to administration, ADUHELM must be diluted in 100 mL of 0.9% Sodium Chloride Injection, USP. Use aseptic technique when preparing the ADUHELM diluted solution for intravenous infusion. Calculate the dose, total volume of ADUHELM solution required, and the number of vials needed based on the patient's actual body weight. Each vial contains an ADUHELM concentration of 100 mg per mL. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Check that the ADUHELM solution is clear to opalescent and colorless to yellow solution. Do not use if opaque particles, discoloration, or other foreign particles are present. Remove the flip-off cap from the vial. Insert the syringe needle into the vial through the center of the rubber stopper. Withdraw the required volume of ADUHELM from the vial(s) and add to an infusion bag of 100 mL of 0.9% Sodium Chloride Injection, USP. Do not use other intravenous diluents to prepare the ADUHELM diluted solution. Each vial is for single-dose only. Discard any unused portion. Gently invert the infusion bag containing the ADUHELM diluted solution to mix completely. Do not shake. After dilution, immediate use is recommended. If not administered immediately, store the diluted solution of ADUHELM in 0.9% Sodium Chloride Injection, USP refrigerated at 2°C to 8°C (36°F to 46°F) for up to 3 days, or at room temperature up to 30°C (86°F) for up to 12 hours. Do not freeze. 2.5 Administration Instructions Visually inspect the ADUHELM diluted solution for particles or discoloration prior to administration. Do not use if it is discolored, or opaque or foreign particles are seen. Prior to infusion, allow the ADUHELM diluted solution to warm to room temperature. Infuse ADUHELM diluted solution intravenously over approximately one hour through an intravenous line containing a sterile, low-protein binding, 0.2 or 0.22 micron in-line filter. Promptly discontinue the infusion upon the first observation of any signs or symptoms consistent with a hypersensitivity-type reaction [see Warnings and Precautions ( 5.2 )] .

1 INDICATIONS AND USAGE ADUHELM is indicated for the treatment of Alzheimer's disease. Treatment with ADUHELM should be initiated in patients with mild cognitive impairment or mild dementia stage of disease, the population in which treatment was initiated in clinical trials. There are no safety or effectiveness data on initiating treatment at earlier or later stages of the disease than were studied. This indication is approved under accelerated approval based on reduction in amyloid beta plaques observed in patients treated with ADUHELM [see Clinical Studies ( 14 )] . Continued approval for this indication may be contingent upon verification of clinical benefit in confirmatory trial(s). ADUHELM is an amyloid beta-directed antibody indicated for the treatment of Alzheimer's disease. Treatment with ADUHELM should be initiated in patients with mild cognitive impairment or mild dementia stage of disease, the population in which treatment was initiated in clinical trials. There are no safety or effectiveness data on initiating treatment at earlier or later stages of the disease than were studied. This indication is approved under accelerated approval based on reduction in amyloid beta plaques observed in patients treated with ADUHELM. Continued approval for this indication may be contingent upon verification of clinical benefit in confirmatory trial(s). ( 1 )

12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Aducanumab-avwa is a human, immunoglobulin gamma 1 (IgG1) monoclonal antibody directed against aggregated soluble and insoluble forms of amyloid beta. The accumulation of amyloid beta plaques in the brain is a defining pathophysiological feature of Alzheimer's disease. ADUHELM reduces amyloid beta plaques, as evaluated in Studies 1, 2, and 3 [see Clinical Studies ( 14 )]. 12.2 Pharmacodynamics Effect of ADUHELM on Amyloid Beta Pathology ADUHELM reduced amyloid beta plaque in a dose- and time-dependent manner in Study 1, Study 2, and Study 3, compared with placebo [see Dosage and Administration ( 2.2 ) and Clinical Studies ( 14 )] . The effect of ADUHELM on amyloid beta plaque levels in the brain was evaluated using PET imaging ( 18 F-florbetapir tracer). The PET signal was quantified using the Standard Uptake Value Ratio (SUVR) method to estimate brain levels of amyloid beta plaque in composites of brain areas expected to be widely affected by Alzheimer's disease pathology (frontal, parietal, lateral temporal, sensorimotor, and anterior and posterior cingulate cortices), compared to a brain region expected to be spared of such pathology (cerebellum). The SUVR was also expressed on the Centiloid scale. In substudies of Study 1 and Study 2, ADUHELM reduced amyloid beta plaque levels in the brain, producing reductions at both ADUHELM low dose and high dose levels and at both Weeks 26 and 78 (p < 0.0001), compared to placebo. The magnitude of reduction was time- and dose-dependent. In the long-term extension of Study 1 and Study 2, a continued decrease in brain amyloid beta plaque levels was observed at Week 132 in patients initially randomized to ADUHELM. In Study 3, ADUHELM reduced amyloid beta plaque levels in the brain, producing statistically significant dose- and time-dependent reductions compared to placebo in the 3 mg/kg, 6 mg/kg, and 10 mg/kg ADUHELM treatment groups at Week 26, and in all ADUHELM treatment groups at Week 54. Among those dosed with ADUHELM during the placebo-controlled period in Study 3, amyloid beta plaque levels in the brain continued to decline in a time- and dose-dependent manner in the long-term extension period through Week 222. Effect of ADUHELM on Tau Pathophysiology ADUHELM reduced markers of tau pathophysiology (CSF p-Tau 181, plasma p-Tau 181, and Tau PET) and neurodegeneration (CSF t-Tau) in Study 1 and Study 2 [see Clinical Studies ( 14 )] . ADUHELM reduced CSF levels of p-Tau 181 in substudies conducted in Study 1 and Study 2. The adjusted mean change from baseline in CSF p-Tau 181 levels relative to placebo was in favor of the ADUHELM low (p<0.01) and high (p<0.001) dose groups at Week 78 in Study 1. Results in Study 2 numerically favored ADUHELM but were not statistically significant. In Study 1 and Study 2, ADUHELM reduced plasma p-tau 181 levelscompared to placebo. In the long-term extension of Study 1 and Study 2, a continued decrease in plasma p-Tau 181 levels was observed at the high dose through Week 128 in patients initially randomized to ADUHELM. ADUHELM reduced CSF levels of t-Tau in substudies conducted in Study 1 and Study 2. The adjusted mean change from baseline in CSF t-Tau levels relative to placebo was in favor of the ADUHELM low (p<0.05) and high (p<0.01) dose groups at Week 78 in Study 1. Results in Study 2 numerically favored ADUHELM but were not statistically significant. Substudies were conducted in both Study 1 and Study 2 to evaluate the effect of ADUHELM on neurofibrillary tangles composed of tau protein using PET imaging ( 18 F-MK6240 tracer). The PET signal was quantified using the SUVR method to estimate brain levels of tau in brain regions expected to be affected by Alzheimer's disease pathology (medial temporal, temporal, frontal, cingulate, parietal, and occipital cortices) in the study population compared to a brain region expected to be spared of such pathology (cerebellum). Data from the substudies were pooled, comprising 37 patients with longitudinal follow-up. The adjusted mean change from baseline in tau PET SUVR relative to placebo at follow-up was in favor of ADUHELM high dose in the medial temporal (p<0.001), temporal (p<0.05), and frontal (p<0.05) brain regions. No statistically significant differences were observed for the cingulate, parietal, or occipital cortices. Exposure-Response Relationships Model based exposure-response analyses for Studies 1 and 2 demonstrated that higher exposures to ADUHELM were associated with greater reduction in clinical decline on CDR-SB, ADAS-Cog13, and ADCS-ADL-MCI. In addition, higher exposures to ADUHELM were associated with greater reduction in amyloid beta plaque in Studies 1 and 2. An association between reduction in amyloid beta plaque and clinical decline on CDR-SB was also observed. Higher exposures to ADUHELM were associated with greater reduction in plasma p-Tau 181. An association between reduction in plasma p-Tau 181 and reduction in Amyloid PET SUVR was observed. An association between reduction in plasma p-Tau 181 and reduced clinical decline on CDR-SB, ADAS-Cog 13, and ADCS-ADL-MCI was also observed. 12.3 Pharmacokinetics The pharmacokinetics (PK) of ADUHELM were characterized using a population PK analysis with concentration data collected from 2961 subjects with Alzheimer's disease who received ADUHELM in single or multiple doses. Steady-state concentrations of ADUHELM were reached by 16 weeks of repeated dosing with an every 4-week regimen, and the systemic accumulation was 1.7-fold. The peak concentration (C max ), trough concentration (C min ), and area under the plasma concentration versus time curve at steady state (AUC ss ) of ADUHELM increased dose proportionally in the dose range of 1 to 10 mg/kg every 4 weeks. Distribution The mean value (95% CI) for volume of distribution at steady state is 9.63 L (9.48, 9.79). Elimination ADUHELM is expected to be degraded into small peptides and amino acids via catabolic pathways in the same manner as endogenous IgG. ADUHELM clearance (95% CI) is 0.0159 (0.0156, 0.0161) L/hr. The terminal half-life is 24.8 (14.8, 37.9) days. Specific Populations Body weight, age, sex, and race were found to impact exposure to ADUHELM. However, none of these covariates were found to be clinically significant. Patients with Renal or Hepatic Impairment No studies were conducted to evaluate the pharmacokinetics of ADUHELM in patients with renal or hepatic impairment. ADUHELM is not expected to undergo renal elimination or metabolism by hepatic enzymes. 12.6 Immunogenicity The observed incidence of anti-drug antibodies is highly dependent on the sensitivity and specificity of the assay. Differences in assay methods preclude meaningful comparisons of the incidence of anti-drug antibodies in other studies, including those of aducanumab-avwa or of other aducanumab products. The immunogenicity of ADUHELM has been evaluated using an in vitro assay for the detection of binding anti-aducanumab-avwa antibodies. In up to 41 months of treatment in the combined placebo-controlled and long-term extension periods of Studies 1 and 2, up to 0.6% (15/2689) of patients receiving ADUHELM once monthly developed anti-aducanumab-avwa antibodies. Based on the limited number of patients who tested positive for anti-aducanumab-avwa antibodies, no observations were made concerning a potential effect of neutralizing activity of anti-aducanumab-avwa antibodies on exposure or efficacy; however, the available data are too limited to make definitive conclusions regarding an effect on pharmacokinetics, safety, or efficacy of ADUHELM. Quantification of neutralizing anti-aducanumab-avwa antibodies has not been assessed.

12.1 Mechanism of Action Aducanumab-avwa is a human, immunoglobulin gamma 1 (IgG1) monoclonal antibody directed against aggregated soluble and insoluble forms of amyloid beta. The accumulation of amyloid beta plaques in the brain is a defining pathophysiological feature of Alzheimer's disease. ADUHELM reduces amyloid beta plaques, as evaluated in Studies 1, 2, and 3 [see Clinical Studies ( 14 )].

12.2 Pharmacodynamics Effect of ADUHELM on Amyloid Beta Pathology ADUHELM reduced amyloid beta plaque in a dose- and time-dependent manner in Study 1, Study 2, and Study 3, compared with placebo [see Dosage and Administration ( 2.2 ) and Clinical Studies ( 14 )] . The effect of ADUHELM on amyloid beta plaque levels in the brain was evaluated using PET imaging ( 18 F-florbetapir tracer). The PET signal was quantified using the Standard Uptake Value Ratio (SUVR) method to estimate brain levels of amyloid beta plaque in composites of brain areas expected to be widely affected by Alzheimer's disease pathology (frontal, parietal, lateral temporal, sensorimotor, and anterior and posterior cingulate cortices), compared to a brain region expected to be spared of such pathology (cerebellum). The SUVR was also expressed on the Centiloid scale. In substudies of Study 1 and Study 2, ADUHELM reduced amyloid beta plaque levels in the brain, producing reductions at both ADUHELM low dose and high dose levels and at both Weeks 26 and 78 (p < 0.0001), compared to placebo. The magnitude of reduction was time- and dose-dependent. In the long-term extension of Study 1 and Study 2, a continued decrease in brain amyloid beta plaque levels was observed at Week 132 in patients initially randomized to ADUHELM. In Study 3, ADUHELM reduced amyloid beta plaque levels in the brain, producing statistically significant dose- and time-dependent reductions compared to placebo in the 3 mg/kg, 6 mg/kg, and 10 mg/kg ADUHELM treatment groups at Week 26, and in all ADUHELM treatment groups at Week 54. Among those dosed with ADUHELM during the placebo-controlled period in Study 3, amyloid beta plaque levels in the brain continued to decline in a time- and dose-dependent manner in the long-term extension period through Week 222. Effect of ADUHELM on Tau Pathophysiology ADUHELM reduced markers of tau pathophysiology (CSF p-Tau 181, plasma p-Tau 181, and Tau PET) and neurodegeneration (CSF t-Tau) in Study 1 and Study 2 [see Clinical Studies ( 14 )] . ADUHELM reduced CSF levels of p-Tau 181 in substudies conducted in Study 1 and Study 2. The adjusted mean change from baseline in CSF p-Tau 181 levels relative to placebo was in favor of the ADUHELM low (p<0.01) and high (p<0.001) dose groups at Week 78 in Study 1. Results in Study 2 numerically favored ADUHELM but were not statistically significant. In Study 1 and Study 2, ADUHELM reduced plasma p-tau 181 levelscompared to placebo. In the long-term extension of Study 1 and Study 2, a continued decrease in plasma p-Tau 181 levels was observed at the high dose through Week 128 in patients initially randomized to ADUHELM. ADUHELM reduced CSF levels of t-Tau in substudies conducted in Study 1 and Study 2. The adjusted mean change from baseline in CSF t-Tau levels relative to placebo was in favor of the ADUHELM low (p<0.05) and high (p<0.01) dose groups at Week 78 in Study 1. Results in Study 2 numerically favored ADUHELM but were not statistically significant. Substudies were conducted in both Study 1 and Study 2 to evaluate the effect of ADUHELM on neurofibrillary tangles composed of tau protein using PET imaging ( 18 F-MK6240 tracer). The PET signal was quantified using the SUVR method to estimate brain levels of tau in brain regions expected to be affected by Alzheimer's disease pathology (medial temporal, temporal, frontal, cingulate, parietal, and occipital cortices) in the study population compared to a brain region expected to be spared of such pathology (cerebellum). Data from the substudies were pooled, comprising 37 patients with longitudinal follow-up. The adjusted mean change from baseline in tau PET SUVR relative to placebo at follow-up was in favor of ADUHELM high dose in the medial temporal (p<0.001), temporal (p<0.05), and frontal (p<0.05) brain regions. No statistically significant differences were observed for the cingulate, parietal, or occipital cortices. Exposure-Response Relationships Model based exposure-response analyses for Studies 1 and 2 demonstrated that higher exposures to ADUHELM were associated with greater reduction in clinical decline on CDR-SB, ADAS-Cog13, and ADCS-ADL-MCI. In addition, higher exposures to ADUHELM were associated with greater reduction in amyloid beta plaque in Studies 1 and 2. An association between reduction in amyloid beta plaque and clinical decline on CDR-SB was also observed. Higher exposures to ADUHELM were associated with greater reduction in plasma p-Tau 181. An association between reduction in plasma p-Tau 181 and reduction in Amyloid PET SUVR was observed. An association between reduction in plasma p-Tau 181 and reduced clinical decline on CDR-SB, ADAS-Cog 13, and ADCS-ADL-MCI was also observed.

12.3 Pharmacokinetics The pharmacokinetics (PK) of ADUHELM were characterized using a population PK analysis with concentration data collected from 2961 subjects with Alzheimer's disease who received ADUHELM in single or multiple doses. Steady-state concentrations of ADUHELM were reached by 16 weeks of repeated dosing with an every 4-week regimen, and the systemic accumulation was 1.7-fold. The peak concentration (C max ), trough concentration (C min ), and area under the plasma concentration versus time curve at steady state (AUC ss ) of ADUHELM increased dose proportionally in the dose range of 1 to 10 mg/kg every 4 weeks. Distribution The mean value (95% CI) for volume of distribution at steady state is 9.63 L (9.48, 9.79). Elimination ADUHELM is expected to be degraded into small peptides and amino acids via catabolic pathways in the same manner as endogenous IgG. ADUHELM clearance (95% CI) is 0.0159 (0.0156, 0.0161) L/hr. The terminal half-life is 24.8 (14.8, 37.9) days. Specific Populations Body weight, age, sex, and race were found to impact exposure to ADUHELM. However, none of these covariates were found to be clinically significant. Patients with Renal or Hepatic Impairment No studies were conducted to evaluate the pharmacokinetics of ADUHELM in patients with renal or hepatic impairment. ADUHELM is not expected to undergo renal elimination or metabolism by hepatic enzymes.

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6

3 DOSAGE FORMS AND STRENGTHS ADUHELM is a clear to opalescent and colorless to yellow solution, available as: Injection: 170 mg/1.7 mL (100 mg/mL) in a single-dose vial Injection: 300 mg/3 mL (100 mg/mL) in a single-dose vial Injection: 170 mg/1.7 mL (100 mg/mL) solution in a single-dose vial ( 3 ) 300 mg/3 mL (100 mg/mL) solution in a single-dose vial ( 3 )

Aduhelm Aducanumab aducanumab aducanumab arginine hydrochloride histidine histidine monohydrochloride monohydrate methionine polysorbate 80 Water Aduhelm Aducanumab aducanumab aducanumab arginine hydrochloride histidine histidine monohydrochloride monohydrate methionine polysorbate 80 Water

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility Carcinogenesis Carcinogenicity studies have not been conducted. Mutagenesis Genotoxicity studies have not been conducted. Impairment of Fertility Intravenous administration of aducanumab-avwa (0, 100, 300, or 1000 mg/kg/week) to male and female rats prior to and during mating and continuing in females to gestation day 7 resulted in no adverse effects on fertility or reproductive performance. The relevance of these data to humans is limited because aggregated amyloid beta, the pharmacological target of aducanumab-avwa, is not present in rat.

13 NONCLINICAL TOXICOLOGY 13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility Carcinogenesis Carcinogenicity studies have not been conducted. Mutagenesis Genotoxicity studies have not been conducted. Impairment of Fertility Intravenous administration of aducanumab-avwa (0, 100, 300, or 1000 mg/kg/week) to male and female rats prior to and during mating and continuing in females to gestation day 7 resulted in no adverse effects on fertility or reproductive performance. The relevance of these data to humans is limited because aggregated amyloid beta, the pharmacological target of aducanumab-avwa, is not present in rat.

BLA761178

Aduhelm

Aducanumab

64406-101

HUMAN PRESCRIPTION DRUG

INTRAVENOUS

Principal Display Panel – 1.7 mL Carton Label Rx Only NDC 64406- 101 -01 Aduhelm ® (aducanumab-avwa) Injection 170 mg/1.7 mL (100 mg/mL) For Intravenous Infusion Only Must be diluted prior to use ATTENTION: Dispense the enclosed Medication Guide to Each Patient. Principal Display Panel – 1.7 mL Carton Label

Dosage and Administration ( 2.1 , 2.2 , 2.3 , 2.4 , 2.5 ) 2/2023 Warnings and Precautions ( 5.1 ) 2/2023

17 PATIENT COUNSELING INFORMATION Advise the patient and/or caregiver to read the FDA-approved patient labeling ( Medication Guide ). Amyloid Related Imaging Abnormalities Inform patients that ADUHELM may cause Amyloid Related Imaging Abnormalities or “ARIA”. ARIA most commonly presents as temporary swelling in areas of the brain that usually resolves over time. Some people may also have small spots of bleeding in or on the surface of the brain. Inform patients that most people with swelling in areas of the brain do not experience symptoms, however, some people may experience symptoms such as headache, confusion, dizziness, vision changes, nausea, aphasia, weakness, or seizure. Instruct patients to notify their healthcare provider if these symptoms occur. Inform patients that events of intracerebral hemorrhage greater than 1 cm in diameter have been reported infrequently in patients taking ADUHELM, and that the use of antithrombotic or thrombolytic medications while taking ADUHELM may increase the risk of bleeding in the brain. Notify patients that their healthcare provider will perform MRI scans to monitor for ARIA [see Warnings and Precautions ( 5.1 )] . Inform patients that although ARIA can occur in any patient treated with ADUHELM, there is an increased risk in patients who are ApoE ε4 homozygotes, and that there is a test available to determine ApoE ε4 genotype. Patient Registry Advise patients that the Alzheimer's Network for Treatment and Diagnostics (ALZ-NET) is a voluntary provider-enrolled patient registry that collects information on treatments for Alzheimer's disease, including ADUHELM. Encourage patients to participate in the ALZ-NET registry [see Warnings and Precautions ( 5.1 )] . Hypersensitivity Reactions Inform patients that ADUHELM may cause hypersensitivity reactions, including angioedema and urticaria, and to contact their healthcare provider if hypersensitivity reactions occur [see Warnings and Precautions ( 5.2 )]. 55093-05 Manufactured by: Biogen Inc. Cambridge, MA 02142 US License #1697 ADUHELM is a registered trademark of Biogen. © 2023 Biogen

This Medication Guide has been approved by the U.S. Food and Drug Administration Approved: 2/2023 MEDICATION GUIDE ADUHELM ® (AD-yew-helm) (aducanumab-avwa) injection, for intravenous use What is the most important information I should know about ADUHELM? ADUHELM can cause serious side effects, including: Amyloid Related Imaging Abnormalities or “ARIA”. ARIA is a common side effect that does not usually cause any symptoms but can be serious. It is most commonly seen as temporary swelling in areas of the brain that usually resolves over time. Some people may also have small spots of bleeding in or on the surface of the brain, and infrequently, larger areas of bleeding in the brain can occur. Most people with this type of swelling in the brain do not get symptoms, however some people may have symptoms, such as: headache confusion Dizziness Vision changes nausea difficulty walking seizures Your healthcare provider will do magnetic resonance imaging (MRI) scans before and during your treatment with ADUHELM to check you for ARIA. Some people have a genetic risk factor (homozygous apolipoprotein E gene carriers) that may cause an increased risk for ARIA. Talk to your healthcare provider about testing to see if you have this risk factor. Call your healthcare provider or go to the nearest hospital emergency room right away if you have any of the symptoms listed above. What is ADUHELM? ADUHELM is a prescription medicine used to treat people with Alzheimer's disease. It is not known if ADUHELM is safe and effective in children. Before receiving ADUHELM, tell your healthcare provider about all of your medical conditions, including if you: are pregnant or plan to become pregnant. It is not known if ADUHELM will harm your unborn baby. Tell your healthcare provider if you become pregnant during your treatment with ADUHELM. are breastfeeding or plan to breastfeed. It is not known if aducanumab-avwa (the active ingredient in ADUHELM) passes into your breast milk. Talk to your healthcare provider about the best way to feed your baby while receiving ADUHELM. Tell your healthcare provider about all of the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Especially tell your healthcare provider if you take medicines to reduce blood clots from forming (antithrombotic medicines, including aspirin). Ask your healthcare provider for a list of these medicines if you are not sure. Know the medicines you take. Keep a list of them to show your healthcare provider and pharmacists when you get a new medicine. How will I receive ADUHELM? ADUHELM is given through a needle placed in your vein (intravenous (IV) infusion) in your arm. ADUHELM is given every 4 weeks. Each infusion will last about 1 hour. What are the possible side effects of ADUHELM? ADUHELM can cause serious side effects, including: See above “ What is the most important information I should know about ADUHELM? ” Serious allergic reactions. Swelling of the face, lips, mouth, or tongue and hives have happened during an ADUHELM infusion. Tell your healthcare provider if you have any of the symptoms of a serious allergic reaction during or after ADUHELM infusion. The most common side effects of ADUHELM include: swelling in areas of the brain, with or without small spots of bleeding in or on the surface of the brain (ARIA) headache fall These are not all the possible side effects of ADUHELM. For more information, ask your healthcare provider or pharmacist. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. General Information about the safe and effective use of ADUHELM. Medicines are sometimes prescribed for purposes other than those listed in this Medication Guide. You can ask your pharmacist or healthcare provider for more information about ADUHELM that is written for health professionals. There is a registry that collects information on treatments for Alzheimer's disease. The registry is named ALZ-NET (Alzheimer's Network for Treatment and Diagnostics). Your healthcare provider can help you become enrolled in this registry. For more information, go to www.aduhelm.com or call at 1-833-425-9360. What are the ingredients in ADUHELM? Active ingredient: aducanumab-avwa Inactive ingredients: L-arginine hydrochloride, L-histidine, L-histidine hydrochloride monohydrate, L-methionine, polysorbate 80, and water for injection Manufactured by: Biogen Inc., Cambridge, MA 02142, U.S. License #1697 ADUHELM is a registered trademark of Biogen. ©2023 Biogen

14 CLINICAL STUDIES The efficacy of ADUHELM was evaluated in two double-blind, randomized, placebo-controlled, parallel group studies (Study 1, NCT 02484547 and Study 2, NCT 02477800) in patients with Alzheimer's disease (patients with confirmed presence of amyloid pathology and mild cognitive impairment or mild dementia stage of disease, consistent with Stage 3 and Stage 4 Alzheimer's disease, stratified to include 80% Stage 3 patients and 20% Stage 4 patients). The effects of ADUHELM were also supported by a double-blind, randomized, placebo-controlled, dose-ranging study (Study 3, NCT 01677572) in patients with Alzheimer's disease (patients with confirmed presence of amyloid pathology and prodromal or mild dementia stage of disease, consistent with Stage 3 and Stage 4 Alzheimer's disease, with an enrolled distribution of 43% Stage 3 patients and 57% Stage 4 patients), followed by an optional, dose-blind, long-term extension period. In Studies 1 and 2, patients were randomized to receive ADUHELM low dose (3 or 6 mg/kg for ApoE ε4 carriers and noncarriers, respectively), ADUHELM high dose (10 mg/kg), or placebo every 4 weeks for 18 months, followed by an optional, dose-blind, long-term extension period. Both studies included an initial titration period of up to 6 months to the maximum target dose. At the beginning of the study, ApoE ε4 carriers were initially titrated up to a maximum of 6 mg/kg in the high dose group, which was later adjusted to 10 mg/kg. In Studies 1 and 2, patients were enrolled with a Clinical Dementia Rating (CDR) global score of 0.5, a Repeatable Battery for Assessment of Neuropsychological Status (RBANS) delayed memory index score ≤ 85, and a Mini-Mental State Examination (MMSE) score of 24-30. In Study 3, patients were enrolled with a global CDR score of 0.5 or 1.0 and an MMSE score of 20-30. Patients were enrolled with or without concomitant approved therapies (cholinesterase inhibitors and the N-methyl-D-aspartate antagonist memantine) for Alzheimer's disease. Studies 1 and 2 were terminated prior to their planned completion. Study endpoints were analyzed based on the prespecified statistical analysis plan. Study 1 In Study 1, 1638 patients were randomized 1:1:1 to receive ADUHELM low dose, ADUHELM high dose, or placebo. At baseline, the mean age of patients was 71 years, with a range of 50 to 85 years. A subgroup of 488 patients were enrolled in the amyloid PET substudy; of these, 302 were evaluated at week 78. Results from the amyloid beta PET substudy are described in Figure 1 and Table 6 . CSF and plasma biomarkers are described in Table 6 . Figure 1: Reduction in Brain Amyloid Beta Plaque (Change from Baseline in Amyloid Beta PET Composite, SUVR and Centiloids) in Study 1 *** p<0.001 Table 6: Biomarker Results of ADUHELM in Study 1 1 P-values were not statistically controlled for multiple comparisons. 2 The analysis results on plasma p-Tau 181 should be interpreted with caution because of uncertainties related to stability of stored samples. Biomarker Endpoint at Week 78 1 ADUHELM High dose Placebo Amyloid Beta PET Composite SUVR N=170 N=159 Mean baseline 1.383 1.375 Change from baseline Difference from placebo -0.264 -0.278, p<0.0001 0.014 Amyloid Beta PET Centiloid N=170 N=159 Mean baseline 85.3 83.5 Change from baseline (%) Difference from placebo -60.8 (-71%) -64.2, p<0.0001 3.4 CSF p-Tau 181 (pg/mL) N=17 N=28 Mean baseline 100.11 72.55 Change from baseline Difference from placebo -22.93 -22.44, p=0.0005 -0.49 Plasma p-Tau 181 (pg/mL) 2 N=294 N=294 Mean baseline 3.342 3.181 Change from baseline Difference from placebo -0.424 -0.669, p<0.0001 0.245 CSF t-Tau (pg/mL) N=17 N=28 Mean baseline 686.65 484.00 Change from baseline Difference from placebo -112.44 -112.05, p=0.0088 -0.39 The primary efficacy endpoint was the change from baseline on the CDR-Sum of Boxes (CDR-SB) at Week 78. In Study 1, treatment with ADUHELM high dose demonstrated reduced clinical decline, as evidenced by a statistically significant treatment effect on change from baseline in CDR-SB compared to placebo (-0.39 [-22%], p = 0.0120), as shown in Figure 2 and Table 7 . The estimate of the treatment effect favored ADUHELM across all prespecified subgroups of interest. Figure 2: Line Plot of Primary Efficacy Endpoint (Change From Baseline in CDR Sum of Boxes) in Study 1 * p<0.05 Secondary efficacy endpoints included the change from baseline in MMSE score at Week 78, the change from baseline in the Alzheimer's Disease Assessment Scale-Cognitive Subscale (13 items) (ADAS-Cog 13) at Week 78, and the change from baseline in the Alzheimer's Disease Cooperative Study – Activities of Daily Living Inventory (Mild Cognitive Impairment version) (ADCS-ADL-MCI) score at Week 78. In Study 1, statistically significant differences from placebo were observed in the ADUHELM high dose group on all secondary efficacy endpoints evaluated. The estimate of the treatment effect favored ADUHELM across most prespecified subgroups of interest for the secondary efficacy endpoints. The Neuropsychiatric Inventory-10 item (NPI-10) was the only tertiary endpoint that assessed efficacy. The results of the high dose group, compared to placebo, are presented in Table 7 . Differences from placebo observed in the ADUHELM low dose group numerically favored ADUHELM but were not statistically significant. Table 7: Clinical Results of ADUHELM in Study 1 1 P-value was not statistically controlled for multiple comparisons. Clinical Endpoint at Week 78 ADUHELM High dose (N=547) Placebo (N=548) CDR-SB Mean baseline 2.51 2.47 Change from baseline Difference from placebo (%) 1.35 -0.39 (-22%) p=0.0120 1.74 MMSE Mean baseline 26.3 26.4 Change from baseline Difference from placebo (%) -2.7 0.6 (-18%) p=0.0493 -3.3 ADAS-Cog 13 Mean baseline 22.246 21.867 Change from baseline Difference from placebo (%) 3.763 -1.400 (-27%) p=0.0097 5.162 ADCS-ADL-MCI Mean baseline 42.5 42.6 Change from baseline Difference from placebo (%) -2.5 1.7 (-40%) p=0.0006 -4.3 NPI-10 1 Mean baseline 4.5 4.3 Change from baseline Difference from placebo (%) 0.2 -1.3 (-87%) p=0.0215 1.5 Figure 1 Figure 2 Study 2 In Study 2, 1647 patients were randomized 1:1:1 to receive ADUHELM low dose, ADUHELM high dose, or placebo. At baseline, the mean age of patients was 71 years, with a range of 50 to 85 years. A subgroup of 585 patients were enrolled in the amyloid PET subgroup; of these, 374 were evaluated at week 78. Results from the amyloid beta PET substudy are described in Figure 3 and Table 8 . CSF and plasma biomarkers are described in Table 8 . Figure 3: Reduction in Brain Amyloid Beta Plaque (Change from Baseline in Amyloid Beta PET Composite, SUVR and Centiloids) in Study 2 *** p<0.001 Table 8: Biomarker Results of ADUHELM in Study 2 1 P-values were not statistically controlled for multiple comparisons. 2 The analysis results on plasma p-Tau 181 should be interpreted with caution because of uncertainties related to stability of stored samples. Biomarker Endpoint at Week 78 1 ADUHELM High dose Placebo Amyloid Beta PET Composite SUVR N=183 N=204 Mean baseline 1.407 1.376 Change from baseline Difference from placebo -0.235 -0.232, p<0.0001 -0.003 Amyloid Beta PET Centiloid N=183 N=204 Mean baseline 90.8 83.8 Change from baseline (%) Difference from placebo -54.0 (-59%) -53.5, p<0.0001 -0.5 CSF p-Tau 181 (pg/mL) N=18 N=15 Mean baseline 121.81 94.53 Change from baseline Difference from placebo -13.19 -10.95, p=0.3019 -2.24 Plasma p-Tau 181 (pg/mL) 2 N = 285 N = 334 Mean baseline 3.131 3.180 Change from baseline Difference from placebo -0.484 -.0769, p<0.0001 0.286 CSF t-Tau (pg/mL) N=16 N=14 Mean baseline 618.50 592.57 Change from baseline Difference from placebo -102.51 -69.25, p=0.3098 -33.26 No statistically significant differences were observed between the ADUHELM-treated and placebo-treated patients on the primary efficacy endpoint, the change from baseline in CDR-SB score at 78 weeks. Figure 3 Study 3 In Study 3, 197 patients were randomized to receive a fixed dose of ADUHELM 1 mg/kg (n=31), 3 mg/kg (n=32), 6 mg/kg (n=30), 10 mg/kg (n=32), titration of ADUHELM to 10 mg/kg over 44 weeks (n=23), or placebo (n=48) for 12 months. At baseline, the mean age of patients was 73 years, with a range of 51-91 years. Results from the amyloid beta PET substudy are described in Figure 4 and Table 9 . Figure 4: Reduction in Brain Amyloid Beta Plaque (Change from Baseline in Amyloid Beta PET Composite, SUVR and Centiloids ) in Study 3 * p<0.05, ** p<0.01, *** p<0.001 Table 9: Biomarker Results of ADUHELM in Study 3 1 P-values were not statistically controlled for multiple comparisons. Biomarker Endpoint at Week 54 1 ADUHELM 10 mg/kg Placebo Amyloid Beta PET Composite SUVR N=28 N=42 Mean baseline 1.432 1.441 Change from baseline Difference from placebo -0.263 -0.277, p<0.0001 0.014 Amyloid Beta PET Centiloid N=28 N=42 Mean baseline 94.5 96.5 Change from baseline (%) Difference from placebo -58.0 (-61%) -61.1, p<0.0001 3.1 Clinical assessments in Study 3 were exploratory. Results for clinical assessments were directionally aligned with the findings from Study 1, with less change from baseline in CDR-SB and MMSE scores at 1 year in the ADUHELM 10 mg/kg fixed-dose group than in patients on placebo (CDR-SB: -1.26, 95% CI [-2.356, -0.163]; MMSE: 1.9, 95% CI [0.06, 3.75]). Figure 4

8.5 Geriatric Use In Studies 1 and 2, the age of patients ranged from 50 to 85 years, with a mean age of 70 years; 79% were 65 and older, and 32% were 75 and older. There were no notable differences in the incidence of adverse reactions between these age groups, and no additional safety concerns in patients 65 years of age and older compared to younger patients.

8.4 Pediatric Use Safety and effectiveness of ADUHELM in pediatric patients have not been established.

8.1 Pregnancy Risk Summary There are no adequate data on ADUHELM use in pregnant women to evaluate for a drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown. Data Animal Data Intravenous administration of aducanumab-avwa (0, 100, 300, or 1000 mg/kg/week) to female rats through organogenesis had no adverse effect on embryofetal development. Intravenous administration of aducanumab-avwa (0, 100, 300, or 1000 mg/kg/week) to female rats throughout pregnancy and lactation had no adverse effects on pre- or postnatal development. The relevance of these data to humans is limited because aggregated amyloid beta, the pharmacological target of aducanumab-avwa, is not present in rat.

8 USE IN SPECIFIC POPULATIONS 8.1 Pregnancy Risk Summary There are no adequate data on ADUHELM use in pregnant women to evaluate for a drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown. Data Animal Data Intravenous administration of aducanumab-avwa (0, 100, 300, or 1000 mg/kg/week) to female rats through organogenesis had no adverse effect on embryofetal development. Intravenous administration of aducanumab-avwa (0, 100, 300, or 1000 mg/kg/week) to female rats throughout pregnancy and lactation had no adverse effects on pre- or postnatal development. The relevance of these data to humans is limited because aggregated amyloid beta, the pharmacological target of aducanumab-avwa, is not present in rat. 8.2 Lactation Risk Summary There are no data on the presence of aducanumab-avwa in human milk, the effects on the breastfed infant, or the effects of the drug on milk production. Published data from other monoclonal antibodies generally indicate low passage of monoclonal antibodies into human milk and limited systemic exposure in the breastfed infant. The effects of this limited exposure are unknown. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for ADUHELM and any potential adverse effects on the breastfed infant from ADUHELM or from the underlying maternal condition. 8.4 Pediatric Use Safety and effectiveness of ADUHELM in pediatric patients have not been established. 8.5 Geriatric Use In Studies 1 and 2, the age of patients ranged from 50 to 85 years, with a mean age of 70 years; 79% were 65 and older, and 32% were 75 and older. There were no notable differences in the incidence of adverse reactions between these age groups, and no additional safety concerns in patients 65 years of age and older compared to younger patients.

16 HOW SUPPLIED/STORAGE AND HANDLING 16.1 How Supplied ADUHELM (aducanumab-avwa) injection is a preservative-free, sterile, clear to opalescent, and colorless to yellow solution. ADUHELM is supplied one vial per carton as follows: 170 mg/1.7 mL (100 mg/mL) single-dose vial (with red flip cap) – NDC 64406-101-01 300 mg/3 mL (100 mg/mL) single-dose vial (with blue flip cap) – NDC 64406-102-02 16.2 Storage and Handling Unopened Vial Store in original carton until use to protect from light. Store in a refrigerator at 2°C to 8°C (36°F to 46°F). not freeze or shake. If no refrigeration is available, ADUHELM may be stored unopened in its original carton to protect from light at room temperature up to 25°C (77°F) for up to 3 days. Prior to dilution, unopened vials of ADUHELM may be removed from and returned to the refrigerator if necessary, when kept in the original carton. Total combined time out of refrigeration with protection from light should not exceed 24 hours at room temperature up to 25°C (77°F).

16.2 Storage and Handling Unopened Vial Store in original carton until use to protect from light. Store in a refrigerator at 2°C to 8°C (36°F to 46°F). not freeze or shake. If no refrigeration is available, ADUHELM may be stored unopened in its original carton to protect from light at room temperature up to 25°C (77°F) for up to 3 days. Prior to dilution, unopened vials of ADUHELM may be removed from and returned to the refrigerator if necessary, when kept in the original carton. Total combined time out of refrigeration with protection from light should not exceed 24 hours at room temperature up to 25°C (77°F).