Rezolute has posted midphase data on its oral eye disease drug candidate, sparking a share price jump as investors assessed its chances of rivaling Bayer and Regeneron’s injectable Eylea for the diabetic macular edema market.
Investigators randomized 94 participants to receive placebo or one of three doses of RZ402 orally once a day for 12 weeks. Participants had, at most, received limited anti-VEGF injections. The trial linked RZ402 to significant reductions in central subfield thickness (CST), a biomarker linked to visual acuity, leading Rezolute to hail the drug candidate as the first oral therapy to demonstrate reduction in macular edema.
There were no significant differences in CST results between the three doses of RZ402, although the middle, 200 mg dose performed best numerically. The reduction in CST was smallest at the top dose.
“We probably had sufficient concentrations at all three dose levels. RZ402 is potent in vivo, so it may well be that we’re not getting much benefit beyond 200 mg,” Chief Medical Officer Brian Roberts, M.D., said on a call with investors. “The differences that are seen are … likely just due to group sizes of 20 to 25 patients and inherent differences between them.”
Roberts said improvements were more pronounced in patients who had a CST of more than 400 µm at baseline. There were more of those patients, who Roberts classed as having more severe CST, in the 200 mg arm than the other cohorts. While Roberts said baseline CST may explain the results, the biotech is continuing to analyze the data and is yet to settle on an answer.
There was no significant improvement in vision in the study but Rezolute attributed that to the length of the trial, rather than a limitation of the drug candidate. The biotech said the CST changes would predict vision benefits in a longer trial.
“Any drug that gets rid of … the fluid and gets rid of the thickening of the retina is, almost by definition, going to have visual benefits for the patient. I think in a six-month study, a 12-month study, that would give enough time to the clinical trial to demonstrate effects on the visual acuity.”
Rezolute is now evaluating the next steps for the program. Nevan Charles Elam, the biotech’s CEO, said he will “definitely explore all viable options” but it is unlikely the company will advance into late-stage development independently. A larger partner could explore opportunities identified by Rezolute, such as the potential for a lower dose given over a longer period of time to be efficacious.