Regulus Therapeutics (RGLS) has found it difficult to convince investors that an injectable hepatitis C drug could find a place in a market dominated by convenient and highly effective pills, but promising clinical data announced Wednesday strengthens the company's argument.
A four-week course of treatment consisting of two injections of Regulus' RG-101 combined with four weeks of currently approved oral medicines reduced the level of hepatitis C virus to undetectable levels in 97% of patients after eight weeks of follow-up, the company said.
Regulus shares were up 23% to $7.71 in trading on Wednesday.
Today, drugs sold by Gilead Sciences (GILD) , AbbVie (ABBV) and Merck (MRK) cure nearly all hepatitis C patients with a single, daily pill taken for eight to 12 weeks. These drugs are so effective and safe there's little room for improvement.
Regulus, however, said it believes the RG-101 data announced Wednesday are strong enough to pursue the development of an even shorter, four-week hepatitis C regimen. Combining injections and pills could be more convenient -- and perhaps less expensive -- than current treatment options, the company argued.
In the phase II study, 38 patients with untreated genotype 1 or 4 hepatitis C were injected with RG-101, given four weeks of Harvoni, Olysio or Daklinza (all currently approved hepatitis C drugs) and then a second RG-101 injection. Eight weeks after the treatment ended, 37 of the 38 patients had hepatitis C viral loads below the limit of quantification.
Fourteen of the patients have been followed for 12 weeks and all still have undetectable hepatitis C viral loads. Two patients in the study reported serious adverse events, possibly related to RG-101.
Wednesday's data are encouraging, but significant questions and hurdles remain.
These results are preliminary because Regulus enrolled 79 hepatitis C patients in the study. Final results will come later this year after all the patients are followed for 12 weeks.
On a conference call Wednesday, Regulus said regulators may want patient follow-up longer than 12 weeks to prove RG-101 injections can provide an effective, safe and durable cure for hepatitis C.