- Regulus Therapeutics' stock dove on Monday after revealing the termination of two clinical programs, including one for its lead candidate, as well as the loss of a big pharma partner on the third.
- The two sidelined drugs are RG-101 and RGLS5040 . The former is Regulus' lead therapy, currently in Phase 2 testing as a treatment for hepatitis C (HCV). The latter is a pre-clinical medication aimed at addressing cholestatic disease. RG-125, meanwhile, is under Phase 2 investigation in patients with type 2 diabetes, and comes from a drug discovery and development agreement with AstraZeneca.
- Regulus nixed RGLS5040 due to pharmcology study results and the "competitive landscape" it would fall into, according to a Monday statement. Meanwhile, RG-101 has been on clinical hold for almost a year because of safety concerns related to two serious cases of jaundice. The company is now looking into other compounds that target an miRNA called miR-122. No reasoning was given for why AstraZeneca pulled out of RG-125 development.
This is the latest bad news to hit the La Jolla, Calif.-based drugmaker. The clinical hold back in mid-2016, as well as the Food and Drug Administration's decision in January to maintain it despite a response from Regulus, sent shares plummeting on multiple occasions.
History repeated itself yet again on Monday, with the company's stock down 16% to $1.17 in morning trading.
There is only one remaining clinical trial to wrap up before development of RG-101 comes to a complete close. That study should end next month, according to the June 12 statement. The move to end the RG-101 program is the most relatively clear cut of the new announcements, given the series of setbacks the drug has had. Still, Regulus appears confident that it has identified why its lead compound failed, and says there's still promise in miR-122 inhibition for the treatment of HCV.
"Applying the learnings from the RG-101 program, alternative compounds targeting miR-122 have been identified that maintain potent HCV antiviral activity while lacking inhibition of the bilirubin transporter," the company said. "These compounds have the potential for rapid clinical proof-of-concept of a novel, markedly shortened treatment regimen for HCV and will be considered for further development pending an updated global commercial market assessment for HCV."
The other program setbacks were a little more surprising. Regulus, for instance, planned on submitting an Investigational New Drug filing for RGLS5040 by the end of 2017. As for RG-125, the company had already received $12.5 million in milestones from AstraZeneca for the drug, and another $160 million in milestones was up for grabs, according to Regulus' most recent 10-Q filing.
AstraZeneca's rights to the drug will now head back to Regulus in 12 months time, as stipulated by the terms of their 2012 licensing agreement. Neither company immediately responded to request for more details about that decision.
Their licensing deal was for compounds acting on three microRNA alliance targets. It's unclear how AstraZeneca's pull out will affect the remaining parts of the deal.