RegenxBio rally fades fast after biotech reports setbacks, hospitalization in gene therapy study

RegenxBio $RGNX has some explaining to do today.

In its quarterly report the gene therapy company reported that it experienced several setbacks during its Phase I/II study of RGX-501, one of 4 pipeline programs at the biotech that’s being developed for homozygous familial hypercholesterolemia (HoFH) in a trial underway at the University of Pennsylvania. In addition to reporting adverse events, the interim analysis failed to produce evidence of LDL reduction in one cohort — and may not be able to in the other.

The biotech’s stock initially popped 10%, then began to slide back down as news of the setbacks spread. Within minutes, the stock was 11% in the red.

Ken Mills, RegenxBio CEO

Researchers say that following an earlier reported immune response in a patient accompanied by transient hypotension and elevation in transaminases, a second patient was hospitalized to treat transaminases while all three in that group “experienced an elevation in transaminases 4-6 weeks post-dosing. The peak ALTs were 165, 388 and 1469 IU/L in the three subjects. All three subjects were asymptomatic and responded rapidly to the initiation of prednisone followed by a slow taper, with normalization of the transaminases.”

This therapy uses an AAV vector to deliver the human low-density lipoprotein receptor gene to liver cells.

It was Cohort 1 that failed to produce signs of efficacy, while for Cohort 2:

RegenxBio believes that the ability to assess LDL-C levels at 12 weeks in the three subjects in Cohort II may be confounded by the potential effects on the liver and the resulting steroid therapy.

As a result of the problems, the company says it will change up the study design, going in early with steroids and pushing back the efficacy timeline from 12 weeks to 26 weeks while adding more patients to the trial.

The biotech much preferred to report on some mixed but positive early results from another effort it has underway for RGX-314 for wet, age-related macular degeneration. The therapy is designed to replace anti-VEGF injections, and after injections 3 patients in one cohort were free of the injections with some early signs of visual improvements among the patients in the early-stage study.



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Research Scientist - Immunology
Recursion Pharmaceuticals Salt Lake City, UT
Director of Operations
Atlas Venture Cambridge, MA

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