On February 9th, 2015 shares of Regulus Therapeutics (RGLS) were down 7% despite reporting good final results from the phase 1 study treating patients with Hepatitis C using their injection drug RG-101. Regulus Therapeutics is a biotechnology company focused on creating new treatments for patients with Hepatitis C using microRNA technology. The trial tested patients with all genotypes of the Hepatitis C virus, including patients who had relapsed from an interferon treatment regimen. One trial had tested a single shot injection of RG-101 for 2 mg/kg and another trial had tested single shot injection of RG-101 for 4 mg/kg.

The 2 mg/kg showed some good efficacy where 4 out of 14 patients, in total 85 were TND -- target not detected  -- which means no detection of HCV RNA levels in the patients' bodies. Although this group did have 2 patients that were shown to be below the limit of quantification -- BLOQ -- in total 57 but these 2 patients had relapsed with their disease. The patients condition will be monitored for one year to determine RG-101 efficacy as a viral cure over that period. The 4 mg/kg group showed that 9 out of 14 patients had achieved BLOQ in total 57 and these patients will be monitored for the next 6 months to determine if the RG-101 single shot can act as a cure for the Hepatitis C virus.

As of right now, these results are pretty good but Regulus is nowhere near achieving a single shot cure with RG-101. What may end up happening is that the company will probably have to combine RG-101 in combination studies with oral hepatitis C drugs to boost efficacy. We can't say that the jury is out on RG-101 as a monotherapy but the company may be able to adjust dosage if needed or add additional injections since safety is not an issue. This is because even at the highest dose of RG-101  4 mg/kg there have been no adverse events reported to date and no discontinuation by patients for excessive amounts of toxicity. Regulus will now have to conduct studies to test RG-101 with oral therapies to determine if it can achieve greater efficacy than RG-101 alone as a monotherapy.