Shares in Clearside Biomedical fell as much as 56 percent on Monday after the company announced that a Phase III study of Xipere for the treatment of retinal vein occlusion (RVO) failed to meet its primary endpoint. The SAPPHIRE trial investigated Xipere together with Regeneron Pharmaceuticals' intravitreal anti-VEGF agent Eylea (aflibercept) compared to Eylea monotherapy.
Clearside CEO Daniel White said "approximately 50 percent of patients in both arms showed at least a 15 letter improvement in vision; unfortunately, there was no additional benefit for patients receiving Xipere." White added "in light of these eight-week top-line data, we plan to discontinue clinical development of combination therapy for RVO, which includes SAPPHIRE and its companion Phase III clinical trial, TOPAZ."
The main goal of the SAPPHIRE study, which consisted of 460 patients with treatment-naïve RVO, was the proportion of patients in the combination treatment arm, compared to Eylea alone, with improvements in best-corrected visual acuity from baseline of at least 15 letters on the Early Treatment Diabetic Retinopathy Study scale at eight weeks after initial treatment. The drugmaker noted that the safety profile of Xipere in the study was consistent with prior findings for eight weeks of treatment.
Xipere is a suspension of the corticosteroid triamcinolone acetonide formulated for administration to the back of the eye via the suprachoroidal space. The drug is also being studied in uveitis, where White noted "the opportunity…remains very attractive," adding "we remain on track to submit our [new drug application] for this indication before the end of this year."
Earlier this year, Clearside unveiled late-stage study results illustrating that Xipere, previously known as CLS-TA, met its main goal of the proportion of patients with a 15-letter improvement in best-corrected visual acuity in patients with macular oedema associated with non-infectious uveitis. Meanwhile, the drugmaker later revealed that although a Phase II trial of Xipere given with Eylea met its main goal of improving visual acuity in patients with diabetic macular oedema, the combination failed to provide a clinically meaningful improvement in vision compared to Eylea alone.
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