Viridian looks over Horizon after eye disease med notches early improvements

Viridian Therapeutics is trying to carve out a portion of a simmering market for eye disease treatments, releasing phase 1/2 data on a small group of patients that suggests its candidate could rival Amgen-acquired Horizon. 

The new results from the Massachusetts biotech indicate that lead asset VRDN-001 spurred a decline in protrusion of the eye in patients with chronic thyroid eye disease (TED). Viridian’s candidate surprisingly showed more significant declines in proptosis in the 3 mg/kg group compared to the larger 10 mg/kg, with six patients reporting an average decline from baseline of 1.5 mm when measured by exophthalmometry. Among four out of six patients treated with the 3-mg/kg dose that have had proptosis measured by MRI, the mean reduction is 2.6 mm. Horizon's Tepezza, by comparison, had average reductions (PDF) of 2.5 and 2.8 in two studies. 

In an interview with Fierce Biotech, Viridian executives chalked up the better results in the 3-mg/kg dose group to the fact that those patients had larger eye protrusion on average. The mean baseline of proptosis in the patients receiving the smaller amount was 23.4 mm compared to 21.1 mm for patients in the 10-m/kg arm. The execs affirmed their intention to use the 10-mg/kg dose in a future phase 3 trial.

“We know as clinicians, we know in real-world conditions, the amount of response in proptosis is partially a function of the extent of the proptosis at baseline entry,” said Chief Medical Officer Barrett Katz, M.D.

The phase 1/2 trial was placebo-controlled but was not powered to assess the statistical significance of the proptosis reductions in treated patients versus those receiving placebo. The average reduction in proptosis among five patients given a placebo was -0.2 mm as measured by MRI. 

Tepezza appears to have the upper hand in remedying diplopia, also known as double vision. Almost half of the 12 patients treated with VRDN-001 had diplopia, but none of them recorded a complete resolution of the condition at Week 6 following treatment. In Tepezza's studies, more than 50% of patients with diplopia that received the therapy recorded a complete resolution by Week 24. 

The data set the stage for the launch of Viridian's second phase 3 trial, THRIVE-2, in patients with chronic TED in the third quarter of 2023. CEO Scott Myers wouldn’t disclose yet how many patients the company plans to recruit. An ongoing phase 2/3 trial for patients with active TED is set to recruit some 90 patients. 

But what Viridian is most excited about in its pipeline is a subcutaneous version of VRDN-001, which should be ready for an application for phase 1 testing sometime in the third quarter. The company is also working on a subcutaneous next-gen version, VRDN-003, that has a longer half-life than its predecessor. Viridian plans to select a lead subcutaneous candidate before the end of the year and advance that asset into a phase 2/3 trial in 2024. 

“We shouldn't just follow the standard, we should look at what's the best for the patient two years from now when it’s approved,” said Myers. “That’s what’s really driving us.” 

Viridian's new data and future aspirations come as Tepezza continues to rake in hundreds of millions of dollars for Horizon and, potentially, Amgen. The larger pharmaceutical giant bought Horizon for $27.8 billion at the end of 2022,  but the Federal Trade Commission has since sued to block the deal. Tepezza revenue was $405.3 million in the first quarter of 2023, a 19% decline from the first quarter of 2022. 

Editor's note: This story was corrected to reflect that Viridian plans to advance one subcutaneous TED treatment into a phase 2/3 trial in 2024, not two. A press contact for the company corrected CEO Scott Myers' previous comment.