Genentech, a member of the Roche Group, announced that the FDA has accepted and granted priority review for a supplemental Biologics License Application (BLA) for Enspryng (satralizumab) for the treatment of thyroid eye disease (TED).
More TED news?! It’s been a busy week …
It really has—especially considering our coverage on the FDA’s recent approval of Viridian Therapeutics’ Lumvoa (veligrotug-vvze).
To kick things off: Tell me about Enspryng.
Developed by Chugai (another member of the Roche Group), this is a humanized monoclonal antibody that targets the receptor activity of interleukin-6 (IL-6).
- Important to know: IL-6 plays a critical role as a chemical messenger involved in the body’s inflammatory response
The basis for its design is a novel recycling antibody technology that enables sustained IL-6 inhibition by “binding strongly and repeatedly to the IL-6 receptor,” which in turn allows for rapid and sustained suppression of inflammatory pathways.
Now hold up—isn’t this already approved by the FDA?
Yes … but not for TED. The therapy was actually approved in 2020 as an at-home, subcutaneous (SC) prescription-based treatment for adults with anti-aquaporin-4 (AQP4) antibody-positive neuromyelitis optica spectrum disorder (NMOSD).
- See its official product page (and full prescribing information).
- Also take note: Enspryng is approved in an estimated 90 countries worldwide as the first and only IL-6 inhibitor treatment for this indication
- It’s also currently under clinical investigation for two new indications: autoimmune encephalitis (AIE) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD)
So … what do we know about the clinical data for this TED indication?
It’s (obviously) different from the clinical trial data used for its NMOSD data.
More specifically: The data included in Enspryng’s TED sBLA package are based on the phase 3 SatraGO program consisting of two randomized, placebo-controlled global studies:
- SatraGO-1(NCT05987423)
- SatraGO-2 (NCT06106828)
Talk details.
Collectively, these trials evaluated the safety and efficacy of Enspryng administered every 4 weeks (Q4W) via SC injection versus placebo in nearly 300 patients with moderate-to-severe TED.
- Primary endpoint: proptosis response (achieving a ≥ 2mm reduction) from baseline to week 24
- See here for secondary endpoints
And the results?
Reported last October during the American Society of Ophthalmic Plastic and Reconstructive Surgery (ASOPRS) meeting, Genentech noted that the “totality of data” from the phase 3 program demonstrated that Enspryng showed:
- Consistent, clinically meaningful improvements across key TED signs and symptoms
- A favorable and differentiated safety profile compared to currently available TED treatments
Tell me more.
Looking at the primary outcome:
- In SatraGO-1: 49% of Enspryng-treated patients achieved a proptosis reduction (versus 39% of placebo-treated)
- This did not meet statistical significance
- In SatraGO-2: 53% of Enspryng-treated patients achieved a proptosis reduction (versus 23% of placebo-treated)
- This met statistical significance
To note: While SatraGO-1’s improvements were lacking, the company stated that the data “offers additional confirmatory evidence regarding the potential benefit of satralizumab in this setting.”
How about those secondary endpoints?
Notable improvements were also observed across both studies. Case in point: Among patients with active TED:
- In SatraGO-1: 78% achieved reduction in clinical activity score (CAS) and 44% improved diplopia
- In SatraGO-2: 90% achieved reduction in CAS and 61% improved diplopia
And its safety profile?
This was consistent with its known profile for NMOSD.To be more specific: Investigators noted that the safety results from both SatraGO trials “reaffirm the highly favorable profile of satralizumab, as demonstrated in > 10,000 patients for up to 7 years”—while its safety profile in TED was highly favorable and had no adverse events (AEs) commonly associated with other TED treatments.
The most common adverse events among Enspryng-treated patients: nasopharyngitis, headache, influenza, abdominal pain, back pain, diarrhea, and nausea.
- See here for more.
Alrighty, so in regards to this sBLA … what does priority review mean?
This essentially accelerates (shortens) the FDA’s application review process from the standard 10-month timeframe to just 6 months.
And in this case?
The FDA is expected to make its approval decision for Enspryng’s TED indication by Oct. 15, 2026.
- As Genentech’s Levi Garraway, MD, PhD, chief medical officer and head of Global Product Development, noted: “This (SC) therapy has the potential to introduce a new treatment approach that combines clinical efficacy and a favorable safety profile with the convenience of at-home administration.”
But keep in mind: It’s not the only SC therapy for TED seeking FDA approval …