An experimental drug developed by Annexon Biosciences failed its main goal in a study testing it for a common type of vision loss known as geographic atrophy, though the small biotechnology company plans to continue development after claiming positive signs.
Annexon said its drug, ANX007, didn’t slow the growth of retinal lesions compared to a placebo after one year of treatment in the Phase 2 trial. Participants who received monthly injections of Annexon’s drug had a 6.2% reduction in the rate of lesion growth compared to a placebo, while those who were treated every other month had a 1.3% reduction. Neither result was statistically significant.
The data set Annexon’s drug apart from two other geographic atrophy medicines. Earlier this year, the Food and Drug Administration made Apellis Pharmaceuticals’ Syfovre the first approved treatment for the disease based on its ability to slow lesion growth. A second medicine from Iveric Bio also impacted eye lesions and is currently being reviewed by regulators. Iveric recently agreed to be acquired by Astellas Pharma for nearly $6 billion, largely because of its drug’s potential.
But neither Apellis nor Iveric have clearly shown that their drugs’ effects on geographic atrophy lesions translates to preservation of vision — a point Annexon CEO Douglas Love used to defend the results for ANX007.
“Slowing lesion growth has not been clinically correlated with visual function,” he said on a Wednesday conference call.
Annexon claims its drug is preserving vision. The company pointed to a secondary analysis showing patients who received a placebo were more likely to lose the ability to read at least 15 letters on a standardized eye chart after one year. According to that analysis, treated patients had a 59% lower risk of a 15-letter-loss overall, with a greater risk reduction in those who were treated more frequently.
Nineteen, or 21%, of the 89 participants who received placebo experienced greater than a 15 letter loss after one year, compared to 15, or 8%, of the 181 who were given Annexon’s drug. Annexon didn't disclose average letter loss by group in its presentation.
The company said that finding reflected its drug’s “differentiated mechanism of action” compared to its rival medicines. Like Apellis’ and Iveric’s drugs, ANX007 blocks activation of the complement pathway, a part of the innate immune system, but does so in a different way.
“What we’re seeing here is a non-significant effect on a very specific biomarker,” said study investigator Jeffrey Heier, the director of the retina service and retina research at Ophthalmic Consultants of Boston, on the conference call hosted by Annexon. “To see preservation of vision in a way that we have not seen in any other study is quite meaningful.”
The finding doesn’t change the study’s outcome, though, and Annexon’s shares fell more than 48%, to about $2.70 apiece, in pre-market trading Thursday. Additionally, the FDA has already established that an effect on eye lesions is an approvable study goal for geographic atrophy, a point analysts questioned the company about on the conference call.
Love, the company’s CEO, responded that Annexon’s anticipated effect on visual acuity would be an acceptable endpoint. “That being said, we’ll go and talk to the regulators about this,” he said.