Regulus Therapeutics ($RGLS) upped the dosage of its microRNA hepatitis C therapy RG-101 in a small study and gathered evidence of a bigger impact on patients' viral loads. But investigators also added new evidence that its single treatment was far less durable than the new therapies hitting the marketplace, sending a shiver through the market this morning.
After 29 days there was a mean reduction in viral load of 4.8 log10 among 14 patients receiving the 4 mg/kg dose. At day 57, 9 of the 15 were below the limit of qualification, or BLOQ. Tracking the 2 mg/kg cohort in an extended study researchers said that four of 14 patients had undetectable levels of the target at day 85, with two of the four BLOQ patients at day 57 relapsing "shortly thereafter."
The biotech adopted a sunny outlook on the results, but it didn't get much traction as its stock quickly slid about 17% in premarket trading on the numbers.
Hepatitis C treatment is being transformed by a wave of new therapies that hit the market with much better performance numbers. Harvoni led the way with a widely effective combo from Gilead ($GILD), with AbbVie ($ABBV) following up with its rival cocktail. Just last week Merck ($MRK) found itself in the spotlight as the FDA began the process of stripping its breakthrough drug title for its promising hep C remedy, as regulators cited the revolution that is now well underway in the marketplace.
Analysts may be quick to pick apart its argument, but Regulus--which saw its shares soar a year ago on its first results for this drug--is insisting that it has a big future in hepatitis C, with plans to shake up its development strategy by launching combination studies of its injectable as an add-on with existing oral therapies. The company also plans to try dosing patients with its therapy more frequently. Their drug, slated to be in Phase II in a matter of weeks, targets microRNA-122, which the virus uses to replicate.
"The profile of RG-101 has been significantly enhanced with these top-line data, making it an ideal pan-genotypic asset to investigate further in combination with all classes of oral agents to shorten the duration of treatment, increase patient compliance and maintain viral response, and also as monotherapy in certain underserved HCV populations," said Regulus CEO Kleanthis Xanthopoulos.
- here's the release