OXBRYTA

2.1 Recommended Dosage for Adults and Pediatric Patients 12 Years and Older

The recommended dosage of OXBRYTA is 1,500 mg orally once daily.

2.2 Recommended Dosage for Pediatric Patients 4 Years to Less Than 12 Years

For pediatric patients 4 years to less than 12 years, select the appropriate product (OXBRYTA tablets or OXBRYTA tablets for oral suspension) based on patient's ability to swallow tablets and patient's weight.

The recommended dosage of OXBRYTA for pediatric patients 4 years to less than 12 years is shown in Table 1.

2.3 Recommended Dosage for Adults and Pediatric Patients 12 Years and Older with Hepatic Impairment

The recommended dosage of OXBRYTA in adults and pediatric patients 12 years and older with severe hepatic impairment (Child Pugh C) is 1,000 mg orally once daily.

No dosage adjustment of OXBRYTA is required for patients with mild or moderate hepatic impairment [see Use in Specific Populations (8.6) and Clinical Pharmacology (12.3)].

2.4 Recommended Dosage for Pediatric Patients 4 Years to Less Than 12 Years with Hepatic Impairment

The recommended dosage of OXBRYTA in pediatric patients 4 years to less than 12 years with severe hepatic impairment (Child Pugh C) is described in Table 2.

No dosage adjustment of OXBRYTA is required for patients with mild or moderate hepatic impairment [see Use in Specific Populations (8.6) and Clinical Pharmacology (12.3)].

2.5 Recommended Dosage of OXBRYTA for Adults and Pediatric Patients 12 Years and Older When Used with Concomitant Strong or Moderate CYP3A4 Inducers

2.6 Recommended Dosage of OXBRYTA for Pediatric Patients 4 Years to Less Than 12 Years When Used with Concomitant Strong or Moderate CYP3A4 Inducers

2.7 Important Administration Instructions

Administer OXBRYTA orally, once daily with or without food. If a dose is missed, or not administered entirely, resume dosing the following day.

OXBRYTA may be given with or without hydroxyurea.

5.1 Hypersensitivity Reactions

Serious hypersensitivity reactions after administration of OXBRYTA have occurred in <1% of patients treated. Clinical manifestations may include generalized rash, urticaria, mild shortness of breath, mild facial swelling, and eosinophilia [see Adverse Reactions (6.1)].

Drug reaction with eosinophilia and systemic symptoms (DRESS) has been reported in postmarketing experience with OXBRYTA [see Adverse Reactions (6.2)]. Patients who develop a combination of skin rash, fever, peripheral eosinophilia, and internal systemic organ involvement (e.g., hepatic, renal, pulmonary) while receiving OXBRYTA should undergo medical evaluation.

Advise patients of the signs and symptoms of severe hypersensitivity reactions, including DRESS. If hypersensitivity reactions occur, discontinue OXBRYTA and administer appropriate medical therapy. Do not reinitiate OXBRYTA in patients who experience these symptoms with previous use.

5.2 Laboratory Test Interference

OXBRYTA administration may interfere with measurement of Hb subtypes (HbA, HbS, and HbF) by high-performance liquid chromatography (HPLC) [see Drug Interactions (7.3)]. If precise quantitation of Hb species is required, chromatography should be performed when the patient has not received OXBRYTA therapy in the immediately preceding 10 days.

6.1 Clinical Trials 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.

6.2 Postmarketing Experience

The following adverse reactions have been identified during postapproval use of OXBRYTA. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure:

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Drug reaction with eosinophilia and systemic symptoms (DRESS), Pruritis, Angioedema (including swelling of eyelid, face edema, lip swelling, and periorbital swelling).

7.1 Effect of Other Drugs on Voxelotor

7.2 Effect of Voxelotor on Other Drugs

Voxelotor increased the systemic exposure of midazolam (a sensitive CYP3A4 substrate) [see Clinical Pharmacology (12.3)]. Avoid coadministration of OXBRYTA with sensitive CYP3A4 substrates with a narrow therapeutic index. If concomitant use is unavoidable, consider dose reduction of the sensitive CYP3A4 substrate(s).

7.3 Laboratory Test Interference

OXBRYTA administration may interfere with measurement of Hb subtypes (HbA, HbS, and HbF) by HPLC [see Warnings and Precautions (5.2)]. If precise quantitation of Hb species is required, chromatography should be performed when the patient has not received OXBRYTA therapy in the immediately preceding 10 days.

8.1 Pregnancy

8.2 Lactation

8.4 Pediatric Use

The safety and effectiveness of OXBRYTA for SCD have been established in pediatric patients aged 4 years and older. The safety and efficacy of OXBRYTA in pediatric patients with SCD below the age of 4 years have not been established.

Use of OXBRYTA in pediatric patients 12 to <17 years for SCD is supported by evidence from an adequate and well-controlled study in adults and pediatric patients (HOPE trial). The HOPE trial enrolled 26 pediatric patients aged 12 to <17 years, in which 12 pediatric patients received OXBRYTA 1,500 mg once daily and 14 pediatric patients received OXBRYTA 900 mg once daily [see Adverse Reactions (6.1), Clinical Pharmacology (12.3), and Clinical Studies (14.1)].

Use of OXBRYTA in pediatric patients 4 to <12 years for SCD is supported by evidence from an open-label, Phase 2 study. The study enrolled 45 pediatric patients aged 4 to <12 years and 11 patients aged 12 to <17 years with SCD. Patients 12 to <17 years received OXBRYTA 1,500 mg once daily. Patients 4 to <12 years were administered OXBRYTA based on body weight. OXBRYTA doses of 600 mg, 900 mg, or 1,500 mg once daily were administered to patients weighing 10 kg to <20 kg, 20 kg to <40 kg, or ≥40 kg, respectively [see Adverse Reactions (6.1), Clinical Pharmacology (12.3), and Clinical Studies (14.2)].

Pharmacokinetics, safety and efficacy were similar across the pediatric age groups and across pediatric and adult patients [see Dosage and Administration (2), Clinical Pharmacology (12.3) and Clinical Studies (14)].

The adverse reactions observed were similar across the pediatric age groups and across pediatric and adult patients [see Adverse Reactions (6.1)].

8.5 Geriatric Use

Clinical studies of OXBRYTA did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects.

8.6 Hepatic Impairment

Severe hepatic impairment increases voxelotor exposures [see Clinical Pharmacology (12.3)]. Reduce OXBRYTA dose [see Dosage and Administration (2.3, 2.4)].

12.1 Mechanism of Action

Voxelotor is a hemoglobin S (HbS) polymerization inhibitor that binds to HbS with a 1:1 stoichiometry and exhibits preferential partitioning to red blood cells (RBCs). By increasing the affinity of Hb for oxygen, voxelotor demonstrates dose-dependent inhibition of HbS polymerization. Nonclinical studies suggest that voxelotor may inhibit RBC sickling, improve RBC deformability, and reduce whole blood viscosity.

12.2 Pharmacodynamics

The pharmacodynamic effect of voxelotor treatment demonstrated a dose-dependent increase in Hb oxygen affinity as determined by the change in p50 (partial pressure of oxygen at which Hb oxygen saturation of 50% is achieved) that was linearly correlated with voxelotor exposure.

The pharmacodynamic effect of voxelotor treatment also demonstrated a dose-dependent reduction in clinical measures of hemolysis (indirect bilirubin and % reticulocytes).

12.3 Pharmacokinetics

Voxelotor is absorbed into plasma and is then distributed predominantly into RBCs due to its preferential binding to Hb. The major route of elimination of voxelotor is by metabolism with subsequent excretion of metabolites into urine and feces. The PK are linear and voxelotor exposures increased proportionally with either single or multiple doses (Table 5) in whole blood, plasma, and RBCs. Steady-state after repeated administration is reached within 8 days and exposures of voxelotor are consistent with accumulation predicted based on single dose data in patients with SCD.

In healthy subjects, voxelotor exposures were comparable when administered as tablet for oral suspension dispersed in water or as oral tablet swallowed whole.

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Voxelotor was not carcinogenic in a 26-week study in RasH2 transgenic mice at oral doses of 30, 150, or 500 mg/kg/day.

Voxelotor was not genotoxic in the reverse mutation bacterial (Ames) test, rat Comet assay, or rat micronucleus assay.

In a fertility and early embryonic development study, voxelotor was administered orally to rats at 15, 50, and 250 mg/kg/day. Males were dosed 28 days prior to mating through cohabitation and females were dosed 14 days prior to mating through gestation Day 7. Voxelotor had no effect on fertility or reproductive function. Sperm motility was decreased and changes in sperm morphology occurred at 250 mg/kg/day (approximately 5-times the human exposure at 1,500 mg/day).

14.1 Adults and Pediatric Patients 12 Years and Older

The efficacy and safety of OXBRYTA in SCD was evaluated in HOPE, a Phase 3 randomized, double-blind, placebo-controlled, multicenter trial [NCT 03036813]. In this study, 274 patients were randomized to daily oral administration of OXBRYTA 1,500 mg (N=90), OXBRYTA 900 mg (N=92), or placebo (N=92). Patients were included if they had from 1 to 10 vasoocclusive crisis (VOC) events within 12 months prior to enrollment and baseline hemoglobin (Hb) ≥5.5 to ≤10.5 g/dL. Eligible patients on stable doses of hydroxyurea for at least 90 days were allowed to continue hydroxyurea therapy throughout the study. Randomization was stratified by patients already receiving hydroxyurea (yes, no), geographic region (North America, Europe, Other), and age (12 to <17 years, 18 to 65 years). The trial excluded patients who received red blood cell (RBC) transfusions within 60 days and erythropoietin within 28 days of enrollment, had renal insufficiency, uncontrolled liver disease, were pregnant, or lactating.

The majority of patients had HbSS or HbS/beta0-thalassemia genotype (90%) and were receiving background hydroxyurea therapy (65%). The median age was 24 years (range: 12 to 64 years); 46 (17%) patients were 12 to <17 years. Median baseline Hb was 8.5 g/dL (5.9 to 10.8 g/dL). One hundred and fifteen (42%) had 1 VOC event and 159 (58%) had 2 to 10 events within 12 months prior to enrollment. In the OXBRYTA 1,500 mg group, 63 (70%) patients completed the study through Week 72.

Efficacy was based on Hb response rate defined as a Hb increase of >1 g/dL from baseline to Week 24 in patients treated with OXBRYTA 1,500 mg versus placebo. The response rate for OXBRYTA 1,500 mg was 51.1% (46/90) compared to 6.5% (6/92) in the placebo group (p < 0.001). No outlier subgroups were observed. The distribution of Hb change from baseline for individual patients completing 24 weeks of treatment with OXBRYTA 1,500 mg or placebo is depicted in Figure 1.

* Approximately 83% of all randomized patients completed 24 weeks of treatment.

Figure 1: Subject-level Change from Baseline in Hemoglobin at Week 24 in Patients Who Completed 24 Weeks of Treatment*

Additional efficacy evaluation included change in Hb and percent change in indirect bilirubin and percent reticulocyte count from baseline to Week 24 (Table 6).

14.2 Pediatric Patients 4 to <12 Years

The efficacy and safety of OXBRYTA in patients 4 to <12 years with SCD was evaluated in an open-label, multi-center, Phase 2 trial [NCT 02850406]. In this study, 45 patients 4 to <12 years and 11 patients 12 to <17 years received OXBRYTA. Patients 4 to <12 years received tablets for oral suspension based on body weight at baseline. OXBRYTA doses of 600 mg, 900 mg, or 1,500 mg once daily were administered to patients weighing 10 kg to <20 kg, 20 kg to <40 kg, or ≥40 kg, respectively. Patients 12 to <17 years received OXBRYTA 1,500 mg once daily.

Patients were included if their baseline hemoglobin (Hb) was ≤10.5 g/dL. Eligible patients on stable doses of hydroxyurea for at least 90 days were allowed to continue hydroxyurea therapy throughout the study. The trial excluded patients who had a VOC event within 14 days prior to enrollment, received red blood cell (RBC) transfusions within 30 days of enrollment, and had renal insufficiency or uncontrolled liver disease.

All patients had HbSS or HbS/beta0-thalassemia genotype (100%) and most were receiving background hydroxyurea therapy (80%). The median age was 8 years (range: 4 to 15 years); 45 (80%) patients were 4 to <12 years. In this age group, mean baseline Hb was 8.6 g/dL (range: 6.1 to 10.5 g/dL).

Efficacy was based on Hb response rate, which is defined as a Hb increase of >1 g/dL from baseline to Week 24. Hb response rate for OXBRYTA in patients aged 4 to <12 years who took at least one dose of OXBRYTA was 36% (16/45) (95% CI: 21.6%, 49.5%).

Store OXBRYTA at 20°C to 30°C (68°F to 86°F).

Hypersensitivity Reactions

Advise patients that serious hypersensitivity reactions including DRESS may occur, and to notify their healthcare providers if they develop generalized rash, urticaria, shortness of breath, facial swelling, swelling around their eyes, lips, or tongue, fever, fatigue, muscle and/or joint pain, swollen glands, and eosinophilia [see Warnings and Precautions (5.1)]. Inform patients that some severe hypersensitivity reactions may affect their internal organs (such as liver, kidneys, lungs) and their blood cells. Advise patients to stop OXBRYTA if a severe hypersensitivity reaction is suspected.

Breastfeeding

Advise women not to breastfeed while they are on OXBRYTA therapy [see Use in Specific Populations (8.2)].

Dosage and Administration

To avoid a dosing error from using the wrong formulation of OXBRYTA, strongly advise patients and caregivers to visually inspect the tablets to verify the correct formulation each time the prescription is filled [see Dosage and Administration (2) and How Supplied/Storage and Handling (16)].

Advise patients to:

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Store OXBRYTA at 20°C to 30°C (68°F to 86°F).

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Continue taking OXBRYTA every day for as long as their physician tells them.

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Do not take St John's wort while taking OXBRYTA.

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Swallow OXBRYTA tablets whole. Do not cut, crush, or chew the tablets.

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Do not swallow whole, cut, crush, or chew OXBRYTA tablets for oral suspension. Disperse OXBRYTA tablets for oral suspension in room temperature clear drink (such as drinking water, clear soda, apple juice, clear electrolyte drinks, clear flavored drinks, or clear sports drinks) before administration. The amount of liquid needed to disperse the tablets for oral suspension will depend on the dose (number of tablets prescribed) [see Dosage and Administration (2.7)].

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Take OXBRYTA with or without food.

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If a dose is missed or not consumed entirely, resume dosing the following day [see Dosage and Administration (2.7)].