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Clearside Biomedical Inc. study fails to show clinical significance of triamcinolone acetonide plus anti-VEGF treatment

Clearside Biomedical Inc. (NASDAQ:CLSD), head-quartered in Alpharetta, Ga., USA, have announced the results of a Phase II clinical study investiagting the use of triamcinolone acteonide (CST-TA), with and without aflibercept for the treatment of diabetic macular edema (DME). The results of the study showed that patients receiving CST-TA plus aflibercept gained an average of 12.3 ETDRS letters compared to 13.5 ETDRS letters in the aflibercept alone control arm (p = 0.664).  The combination arm was treated at 0 and 3 months, while the aflibercept arm was treated at 0, 1, 2 and 3 months). The absence of clear clinical significance however did not reflect positively among investors as the company fell $6.14/share from a high of $15.33/share on May 30th, to a close of $9.19/share on June 4th, following the company annoucement. While the company has indicated it will continue to discuss a Phase III study with the FDA, the combination treatment remains in question for investors and commentators.


The Phase II clincial trial, named “TYBEE”, was a multicenter, randomized, masked, study of 71 naïve treatment DME patients.  According to the company, trial participants were randomized 1:1 to receive either three-monthly treatments of suprachoroidal CLS-TA, together with intravitreal aflibercept (months 0 and 3) (the “combination arm”), or four-monthly treatments of intravitreal aflibercept plus a sham suprachoroidal procedure (months 0, 1, 2 and 3) (the “control arm”), with patients in either arm receiving intravitreal aflibercept treatment at months 4 and 5 as needed. While the company stated that the study met its primary end-point of a mean improvement in BCVA from baseline over six months, as measured by ETDRS, the market appears to have taken a different view in respect of the results obtained.


CLS-TA is a proprietary suspension of triamcinolone acetonide, a corticosteroid formulated for administration to the back of the eye via the suprachoroidal space. The company uses the drug formulation in its three lead clinical programs, representing a significant asset for the business. The company itself was established in January 2012, on the back of a proprietary micro-injection platform allowing compartmentalization of an API within a specific area of the eye. The proprietary platform was developed from an academic collaboration between the Georgia Institute of Technology and Emory University School of Medicine. The technology was developed from the work of Mark Prausnitz, Ph.D., Regents’ Professor and Love Family Professor of Chemical & Biomolecular Engineering at the Georgia Institute, and Henry Edelhauser, Ph.D., Professor in the Department of Ophthalmology at Emory University School of Medicine. The targeted delivery approach is focused on the use of a micro-needle to deliver agents to the supra-choroidal space (SCS) between the choroid and the sclera in order to more efficiently reach tissues impacted by chorioretinal disease.