Sometimes clinical trials don't work out, and Argenx SE (ARGX) learned that lesson the hard way on Monday. The company announced it's discontinuing its Phase 3 UplighTED studies evaluating efgartigimod subcutaneous in adults with moderate to severe thyroid eye disease (TED).
The decision came after an Independent Data Monitoring Committee took a look at interim data and essentially said, "This isn't going anywhere." Following a pre-specified interim analysis, the committee recommended stopping the trials for futility. Translation: the drug wasn't showing enough promise to justify continuing.
Here's the silver lining, if you can call it that—efgartigimod showed a favorable safety and tolerability profile, with no new safety signals identified. So it wasn't dangerous, just not particularly effective for this specific condition.
"We are disappointed the studies did not meet our desired outcome," said Luc Truyen, Chief Medical Officer at argenx. That's the diplomatic way of saying the results weren't what they hoped for.
The IDMC conducted its futility evaluation using unblinded data from patients who completed 24 weeks in the Phase 3 studies. Now that the studies are being wound down, Argenx plans to conduct a comprehensive analysis of the data and share findings at a future medical meeting. At least the scientific community might learn something from the failure.
What The Studies Were Testing
The Phase 3 UplighTED trials were designed to evaluate efgartigimod PH20 SC administered by prefilled syringe across multiple measures: efficacy, safety, tolerability, pharmacokinetics, pharmacodynamics, and immunogenicity in adults with thyroid eye disease.
The primary endpoint measured the percentage of participants who responded to treatment for proptosis—that's the medical term for bulging eyes, one of the most visible and distressing symptoms of TED.
Key secondary endpoints included changes in proptosis measurement from baseline through week 24, changes in the Graves' Orbitopathy Quality of Life score over the same period, and the percentage of participants whose diplopia (double vision) resolved by week 24.
What Wall Street Thinks
William Blair analysts weighed in on Monday, noting the news came as somewhat surprising given external data in the closely related Graves' disease showing that FcRn inhibition could drive strong response rates. The failure "clearly raising additional questions on the biological differences between the two diseases," they wrote.
Analyst Matt Phipps points out that this development is actually positive news for the IGF-1R antibody class, which remains the most effective treatment approach for TED. Amgen Inc. (AMGN) currently has the only FDA-approved drug for TED with Tepezza, but Phipps expects Viridian Therapeutics Inc. (VRDN) to receive FDA approval for its candidate veligrotug in 2026. With Argenx out of the picture, that competitive landscape just got clearer.
William Blair had previously modeled peak TED sales for Vyvgart at $550 million, assuming a 60% probability of success. But here's the thing—they always viewed TED as a meaningful but secondary opportunity compared with Vyvgart's larger programs in myositis and Sjögren's disease.
That broader context matters. Despite the TED setback, Phipps maintains an Outperform rating on Argenx, citing the strong Vyvgart launch trajectory—especially uptake of the prefilled syringe formulation—and additional commercial expansion opportunities ahead. In other words, losing one battle doesn't mean losing the war.
Argenx shares fell 4.86% to $835.31 on Monday following the announcement.