by Ben Adams
Ultragenyx Pharmaceutical saw its shares jump around 25% in trading Friday after announcing positive top-line data out of its gene therapy trial.
It’s a small number, just three patients that form part of a third cohort for the phase 1/2 study, as well as another small test but a longer-term look from the second cohort.
In cohort three testing the biotech’s drug DTX301, an adeno-associated virus gene therapy for the treatment of ornithine transcarbamylase (OTC) deficiency, there were two confirmed female responders as well a third potential male responder who requires longer-term follow-up to confirm response status.
Meanwhile, in cohort two, one female patient saw a new response after a year. The biotech added that the two previously disclosed responders in cohort one and two “also remain clinically and metabolically stable at 104 and 78 weeks, respectively. Across all nine patients dosed in the study, up to six patients have demonstrated a response,” it said in a statement.
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OTC deficiency is a rare X-linked genetic disorder characterized by complete or partial lack of the enzyme OTC. Excess ammonia, which is a neurotoxin, travels to the central nervous system through the blood,
According to the National Organization for Rare Disorders, the severity and age of onset of OTC deficiency varies from person to person, even within the same family. “A severe form of the disorder affects some infants, typically males, shortly after birth (neonatal period). A milder form of the disorder affects some children later in infancy. Both males and females may develop symptoms of OTC deficiency during childhood. Most carrier females are healthy, but may be prone to severe headaches following protein intake.”
Analysts at Jefferies said the data “looked better than expected” and could “be a positive spark to help turn the stock heading into 2020 events.” It certainly did in the immediate term, with the biotech’s shares up by 25% in mid-morning trading Friday.
“We are encouraged to see a more uniform response at the higher doses including three female responders. To date, three patients in the study have discontinued alternate pathway medication and liberalized their diets while remaining clinically and metabolically stable,” said Eric Crombez, M.D., chief medical officer of the Ultragenyx Gene Therapy development unit.
“We are moving to prophylactic steroid use in the next cohort as we believe this could further enhance the level and consistency of expression that we have demonstrated so far.”