Phase III study, however, did not meet overall primary endpoint of reducing dependency on standard-of-care within five weeks to 50%.
Celtic Pharma reports that even though its treatment for brain tumor-associated cerebral edema did not meet its overall primary endpoint, it showed statistical significance in those with metastatic disease.
Xerecept® is a synthetic version of the natural peptide hormone corticotropin-releasing factor, which reduces the permeability of blood vessel walls. The therapy was being tested for its ability to wean patients off conventional steroid therapies such as dexamethasone and improve conditions compared to treatment with dexamethasone alone. It is being evaluated as a mono-therapy and in conjunction with steroid drugs.
In the placebo-controlled North American Phase III trial, the primary composite endpoint of 50% reduction in dexamethasone, stable/improved Karnofsky performance status, and stable/improved 10-item neurological examination scores, was not reached during weeks two through five of treatment. Celtic explains that this was primarily because placebo-treated patients coped with a 50% reduction in dexamethasone dosing better than anticipated.
Results did, however, show that at two, five, and eight weeks, patients in the Xerecept treatment group were able to use less dexamethasone. Additionally, a statistically significant improvement was seen when compared to placebo after 12 weeks in reducing dexamethasone dose levels. Fifteen percent of patients on Xerecept were able to reach 0 mg of dexamethasone within the 12-week period.
Approximately 20% of the patients enrolled had metastatic brain tumors. In this patient population, the primary and all secondary endpoints achieved a statistically significant advantage.
Also, there were significant reductions in steroid-related adverse events including myopathy and Cushingoid syndrome along with concomitant increases in muscle strength.
Results from the open-label Phase III extension study, which included patients from previous trials, confirmed the long-term tolerability of Xerecept. Of 113 patients enrolled in the extension, more than 32 completed one year or more of treatment. Dexamethasone dosing in all participants was reduced progressively over time. Over 50% of patients who completed six months of treatment achieved a virtual or complete sustained elimination of corticosteroids.
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