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Gilead Sciences (NASDAQ:GILD) is about to find out if the FDA will approve its latest hepatitis C drug, and if it does, then that approval will solidify Gilead Sciences as the Goliath in the hepatitis C treatment market. Gilead Sciences will rack up billions of dollars in hepatitis C drug sales in the next year, but efforts underway at smaller competitors to shorten treatment duration could pose a threat to the biotech giant in a couple years. Will Achillion Pharmaceuticals' (NASDAQ:ACHN) and Regulus Therapeutics' (NASDAQ:RGLS) promising R&D programs dislodge Gilead Sciences' grappling hold on the indication? Read on to learn more about these upstarts and the challenge they're mounting.

The next big battle in hepatitis C

In 2014, Gilead Sciences' Sovaldi and Harvoni revolutionized hepatitis C treatment by delivering functional cure rates that approach 100% while lowering treatment duration to 12 weeks for most patients. That was a marked improvement from the roughly 80% cure rates delivered by previous-generation therapies over treatment periods lasting 24 weeks or longer.

Since then, competitors, including AbbVie Inc. and Merck & Co., have launched products that offer similar efficacy. However, there's been little advance in the duration of treatment. Since patient adherence tends to decline for therapies with longer treatment periods, the future winner in this indication will be the company that can shorten treatment duration, improve adherence, and lower payer costs in the process.

Image source: Gilead Sciences, Inc.

Improving hepatitis C treatment

Hepatitis C drugs hauled in more than $20 billion in combined sales last year, so it's not surprising to learn that drugmakers are plowing billions of dollars per year researching next-generation hepatitis C therapies. Although most of that spending is being done by big players like Gilead Sciences and AbbVie, Achillion Pharmaceuticals and Regulus Therapeutics are aggressively pursuing short-duration cures too.

After Achillion Pharmaceuticals' odalasvir delivered 100% cure rates when paired up with Sovaldi for six weeks, Johnson & Johnson (NYSE:JNJ) licensed the rights to Achillion Pharmaceuticals' hepatitis C drug pipeline last summer.

Johnson & Johnson hopes that pairing up odalasvir with its own in-house compounds will produce similar results over six- or eight-week treatment cycles. The company has a phase 2a multidrug combination therapy trial underway, and results from it are expected in the third quarter. If results are positive, they may suggest that a newly launched 400-person phase 2b study of this combination therapy will also pan out. Results from this larger phase 2b study are expected in July 2017. 

Reducing treatment duration to six or eight weeks would be a nice improvement over the current standard of care, but Regulus Therapeutics' RG-101 hopes to reduce hepatitis C treatment to four weeks or less.

Regulus Therapeutics recently announced that two shots of RG-101 given alongside Harvoni for four weeks produced 100% cure rates 24 weeks later. That's undeniably impressive, but Regulus Therapeutics' big moonshot involves pairing up RG-101 with a long-lasting protein-inhibiting drug made by GlaxoSmithKline (NYSE:GSK) that could cure hepatitis C in one doctor visit. Regulus Therapeutics and GlaxoSmithKline are kicking off that trial soon, and if successful, a registration-ready study of the pairing could begin before the end of 2017.

Looking forward

Johnson & Johnson and Achillion Pharmaceuticals' phase 2a six- and eight-week dosing trial data are on deck, so investors interested in the future of hepatitis C treatment will want to watch closely. It will be a while longer before we know if Regulus Therapeutics' single-visit moonshot works, but investors will get additional insight into RG-101's efficacy in the coming months. Regulus and GlaxoSmithKline expect to report results from a trial combining RG-101 with another GlaxoSmithKline drug over a 12-week treatment period before the end of the year. 

While Achillion Pharmaceuticals' and Regulus Therapeutics' hepatitis C programs could shorten treatment duration, Gilead Sciences isn't going to give up its leadership in the indication without a fight. Gilead Sciences is working on its own short-duration therapies that could allow it to sidestep the risk posed by these companies.

Since Achillion Pharmaceuticals and Regulus Therapeutics are clinical-stage companies without revenue, they're too risky for most investors to buy. However, their R&D programs are advancing, and the threat they pose to Gilead Sciences makes their progress worth tracking.

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