Clearside Biomedical Shares Plunge as Phase III Xipere Failure Forces the Company to Discontinue Study

Shares of Alpharetta, Georgia-based Clearside Biomedical, Inc. are down more than 50 percent in premarket trading after the company announced its late-stage eye disease treatment added to Regeneron’s Eylea failed to distinguish itself against the established drug in the treatment of retinal vein occlusion.

Shares fell from Friday’s close of $5.56 to $2.65 after the company made the announcement. Clearside was investigating its treatment Xipere (formerly known as suprachoroidal CLS-TA) used in conjunction with Eylea, an anti-VEGF agent, against Eylea alone, in the treatment of retinal vein occlusion. In its announcement, Clearside said the primary endpoint of the trial was the improvement in best corrected visual acuity from baseline of at least 15 letters on the Early Treatment Diabetic Retinopathy Study between the two treatment arms. The company said that the Phase III SAPPHIRE trial showed that approximately 50 percent of patients in both arms showed at least a 15 letter improvement in vision. The company said there was no additional benefit for patients receiving Xipere alongside intravitreal Eylea.

With that data in hand, Clearside Chief Executive Officer Daniel White said the company plans to discontinue clinical development of the combination therapy for retinal vein occlusion. Not only will the SAPPHIRE trial be discontinued, but White said the companion Phase III clinical trial known as TOPAZ would also be shut down. The TOPAZ trial aimed to demonstrate the combination of Xipere and Eylea was a superior treatment to Eylea alone in patients with macular edema secondary to retinal vein occlusion.

“We believe the opportunity in our primary indication, uveitis, remains very attractive. Awareness and acceptance of the strong clinical profile of Xipere as a potential monotherapy in treating uveitic macular edema is growing, and we remain on track to submit our NDA for this indication before the end of this year,” White added in a statement. 

Xipere is a proprietary suspension of the corticosteroid triamcinolone acetonide formulated for administration to the back of the eye via the suprachoroidal space. The approach is designed to enable rapid dispersion of medicine to the back of the eye so that adequate medicine reaches and stays at the site of disease and has potential to act longer, according to Clearside data. Xipere is being studied for unmet or underserved sight-threatening eye diseases that manifest in the retina and the choroid. 

In the company’s Phase III treatment for uveitic MD, at week 24, 40.9 percent of patients experienced resolution in the Xipere arm, compared to 0 percent of patients in the control arm who underwent a sham procedure, the company said last week at the American Academy of Ophthalmology meeting. Additionally, in the Xipere arm, 68 percent of patients with any baseline level of vitreous haze, 72 percent of patients with anterior chamber cell inflammation and 74 percent of patients with anterior chamber flare  had their inflammation resolve, compared to 23 percent, 17 percent and 20 percent, respectively, of patients in the control arm, the company said.