For Patients & Caregivers

Safety data were generally consistent with the well-established safety profile1

Adverse reactions occurring in 5% or more of patients treated with ENSPRYNG® and greater incidence than placebo1

In SATRAGO-1 and SATRAGO-2 there were no reports of hearing loss or hyperglycemia adverse events through Week 24.1*

Neutropenia was also reported with less than 5% occurrence.1

Injection-related reactions1

  • In both trials, reactions in patients on ENSPRYNG were predominantly mild to moderate in severity and no serious reactions were reported1
  • The most frequently reported systemic symptoms were fatigue and headache, and the most commonly reported local injection site reaction was pruritus. The majority of these events did not require dose interruption or treatment discontinuation, with the exception of two cases (pruritus and injection site reaction) that resulted in the discontinuation of treatment1
  • Reactions were generally self-limiting and resolved without specific treatment1
  • In an open label trial in healthy adults, in which a single injection of 180 mg/1.5 mL by autoinjector was compared to two injections of 60 mg/0.5 mL and 120 mg/1 mL by prefilled syringe, the most commonly reported local injection site reactions were erythema, edema, induration, and pain. All local injection site reactions were mild to moderate in severity and most were resolved with 24 hours1

Infections1

  • In both trials, the rate of infections was lower in patients treated with ENSPRYNG compared with patients receiving placebo1
  • The rate of serious infections was 0.00 events/100 patient-years (95% CI, 0, 6.2) treated with ENSPRYNG, compared with 1.90 events/100 patient-years (95% CI, 0.05, 10.58) receiving placebo1

Laboratory abnormalities1

  • Neutrophil count: In both trials, decreased neutrophil counts through Week 24 were observed in 28.2% of patients treated with ENSPRYNG compared with 9.7% of patients receiving placebo. Of these patients in the ENSPRYNG group, 2.3% had a neutrophil count decreased below 1 x 109/L compared to no patients in the placebo group. The decreased neutrophil counts were not associated with serious infections1
  • Platelet count: In both trials, decreases in platelet count through Week 24 were reported in 8.4% of patients treated with ENSPRYNG compared with 2.4% with placebo. All decreases in the ENSPRYNG group were characterized by a platelet count in the range of below the lower limit of normal (LLN) to 75 x 109/L. In the placebo group, two patients experienced decreases in platelet counts to the range of <LLN to 75 x 109/L, and one patient experienced a decrease in platelet count to the range of <75 to 50 x 109/L. None of the patients had a decrease in platelet count to less than 50 x 109/L, and decreases were not associated with bleeding events1
  • Liver enzymes: In both trials, elevations in ALT or AST through Week 24 occurred in 25.2% and 11.5% of patients treated with ENSPRYNG respectively, compared with 7.3% and 4.8% of patients receiving placebo. The majority of elevations were characterized by an elevation above upper limit of normal (ULN) to 3 x ULN. One patient (0.8%) in the placebo group experienced an AST elevation of >3 to 5 x ULN. No transaminase elevations of >5 to 20 x ULN or >20 x ULN were reported. Most events of ALT and AST elevation resolved without requiring dose modification or discontinuation of ENSPRYNG.  Elevations in ALT or AST were not associated with an increase in total bilirubin. Overall post-baseline, liver function test abnormalities were infrequent, predominantly of low grade, with no evidence of drug-induced liver injury or hepatotoxicity1
  • Lipid abnormalities: In both trials, increases in total cholesterol through Week 24 were reported in 19.8% of patients treated with ENSPRYNG compared with 9.7% of patients receiving placebo. Elevations in cholesterol above 7.75 mmol/L were observed in 9.2% of these patients treated with ENSPRYNG compared with 2.4% of corresponding patients receiving placebo. Increases in triglycerides through Week 24 were reported in 33.6% of patients treated with ENSPRYNG compared with 27.4 % of patients receiving placebo. Elevations in triglycerides above 3.42 mmol/L were observed in 1.5% of patients treated with ENSPRYNG compared with 3.2% of patients receiving placebo. The elevations in lipid parameters did not require treatment discontinuation1

*Based on a clinical cutoff date of July 24, 2025.

ALT=alanine aminotransferase; AST=aspartate aminotransferase; CI=confidence interval; LLN=lower limit of normal; TED=thyroid eye disease; ULN=upper limit of normal.

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How ENSPRYNG is thought to work

Discover the role of IL-6 in TED.4

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Next: Dosing & administration

Important Safety Information & Indication

Indication

ENSPRYNG® (satralizumab-mwge)  is indicated for the treatment of thyroid eye disease (TED) regardless of TED activity or duration in adult patients.

Contraindications

ENSPRYNG is contraindicated in patients with a known hypersensitivity to satralizumab or any of the inactive ingredients, an active hepatitis B infection, or active or untreated latent tuberculosis.

Warnings and Precautions

Infections
An increased risk of infections, including serious and potentially fatal infections, has been observed in patients treated with IL-6 receptor antagonists, including ENSPRYNG. The most common infections reported in a randomized clinical trial of patients treated with ENSPRYNG who were not on other chronic immunosuppressant therapies, and that occurred more often than in patients receiving placebo, were nasopharyngitis (12%) and cellulitis (10%). The most common infections in patients who were on an additional concurrent immunosuppressant, and that occurred more often than in patients receiving placebo, were nasopharyngitis (31%), upper respiratory infection (19%), and pharyngitis (12%). Delay ENSPRYNG administration in patients with an active infection, including localized infections, until the infection is resolved.

Hepatitis B Virus (HBV) Reactivation
Risk of HBV reactivation has been observed with other immunosuppressant therapies. Patients with chronic HBV infection were excluded from clinical trials. Perform HBV screening in all patients before initiation of treatment with ENSPRYNG. Do not administer ENSPRYNG to patients with active hepatitis. For patients who are chronic carriers of HBV [HBsAg+] or are negative for HBsAg and positive for HB core antibody [HBcAb+], consult liver disease experts before starting and during treatment with ENSPRYNG.

Tuberculosis
Tuberculosis has occurred in patients treated with other IL-6 receptor antagonists. Patients should be evaluated for tuberculosis risk factors and tested for latent infection prior to initiating ENSPRYNG. Consider anti-tuberculosis therapy prior to initiation of ENSPRYNG in patients with a history of latent or active tuberculosis in whom an adequate course of treatment cannot be confirmed, and for patients with a negative test for latent tuberculosis but having risk factors for tuberculosis infection. Consult infectious disease experts regarding whether initiating anti-tuberculosis therapy is appropriate before starting treatment. Patients should be monitored for the development of signs and symptoms of tuberculosis with ENSPRYNG, even if initial tuberculosis testing is negative.

Vaccinations
Live or live-attenuated vaccines should not be given concurrently with ENSPRYNG because clinical safety has not been established. Administer all immunizations according to immunization guidelines at least 4 weeks prior to initiation of ENSPRYNG for live or live-attenuated vaccines and, whenever possible, at least 2 weeks prior to initiation of ENSPRYNG for non-live vaccines.

Elevated Liver Enzymes
Mild and moderate elevations of liver enzymes have been observed in patients treated with ENSPRYNG at a higher incidence than in patients receiving placebo. ALT and AST levels should be monitored every 4 weeks for the first 3 months of treatment, followed by every 3 months for one year, and thereafter, as clinically indicated.

Decreased Neutrophil Counts
Decreases in neutrophil counts were observed in patients treated with ENSPRYNG at a higher incidence than placebo. Neutrophil counts should be monitored 4 to 8 weeks after initiation of therapy, and thereafter at regular clinically determined intervals.

Hypersensitivity Reactions
Hypersensitivity reactions, including rash, urticaria, and fatal anaphylaxis, have occurred with other IL-6 receptor antagonists.


Use in Specific Populations

Pregnancy
There are no adequate data on the developmental risk associated with the use of ENSPRYNG in pregnant women. In an animal reproduction study, no adverse effects on maternal animals or fetal development were observed in pregnant monkeys and their offspring, with administration of ENSPRYNG at doses up to 50 mg/kg/week. In the U.S. general population, the estimated background risk of major birth defect and miscarriage in clinically recognized pregnancies is 2 – 4% and 15 – 20%, respectively. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. ENSPRYNG should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus.

Lactation
No information is available on the presence of ENSPRYNG in human milk, the effects of ENSPRYNG on the breastfed infant, or the effects of ENSPRYNG on milk production. ENSPRYNG was excreted in the milk of lactating monkeys administered ENSPRYNG throughout pregnancy. Human IgG is excreted in human milk and the potential for absorption in the infant is unknown. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for ENSPRYNG and any potential adverse effects on the breastfed infant from ENSPRYNG or from the underlying maternal condition.

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

Geriatric Use
Clinical studies of ENSPRYNG did not include sufficient numbers of patients aged 65 years and older to determine whether they respond differently from younger patients. However, population pharmacokinetic analyses in patients with NMOSD did not show that age affected the pharmacokinetics of ENSPRYNG. In general, caution should be used when dosing the elderly, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant diseases or other drug therapy.

Most Common Adverse Reactions
The most common adverse reactions in patients with TED (incidence ≥5% and greater than placebo) were upper respiratory tract infection (5%), and alanine aminotransferase increased (5%).

You may report side effects to the FDA at (800) FDA-1088 or www.fda.gov/medwatch. You may also report side effects to Genentech at (888) 835-2555.

For additional safety information, please see the full Prescribing Information and Medication Guide.

    • ENSPRYNG [package insert]. South San Francisco, CA: Genentech, Inc; 2026.

      ENSPRYNG [package insert]. South San Francisco, CA: Genentech, Inc; 2026.

    • Subramanian P, et al. Presented at North American Neuro-Ophthalmology Society (NANOS) 52nd Annual Meeting. March 20-24, 2026.

      Subramanian P, et al. Presented at North American Neuro-Ophthalmology Society (NANOS) 52nd Annual Meeting. March 20-24, 2026.

    • Bennett JL, et al. Neurol Neuroimmunol Neuroinflamm. 2025;12(5):e200450.

      Bennett JL, et al. Neurol Neuroimmunol Neuroinflamm. 2025;12(5):e200450.

    • Murdock J, et al. Front. Ophthalmol. 2025; 5:1544436.

      Murdock J, et al. Front. Ophthalmol. 2025; 5:1544436.

    • Ezra DG, et al. Rev Endocr Metab Disord. 2026; 27(2):237-253.

      Ezra DG, et al. Rev Endocr Metab Disord. 2026; 27(2):237-253.

    • Ezra DG, et al. Ophthalmol Ther. 2025; 14(12):3119-3132.

      Ezra DG, et al. Ophthalmol Ther. 2025; 14(12):3119-3132.

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