These three biotech stocks have produced some tremendous gains over the past year, and investors are wondering if there’s any more fuel in these rockets.

If these high-flying drugmakers are going to continue their climb, they have to cross some well-defined hurdles in front of them. Here’s a look at what’s ahead.

DATA SOURCE: YAHOO! FINANCE.

Arrowhead Pharmaceuticals: Making a comeback

A clinical hold placed on a new drug candidate aimed at treating chronic hepatitis B virus sent this clinical-stage biotech stock into a tailspin near the end of 2016. That set the stage for a tremendous run-up on the back of new-and-improved candidates. Arrowhead is still developing drugs that use RNA interference to silence specific genes, but the delivery method has been given an update.

In June, investigators showed investors that a single dose of ARO-AAT reduced a target enzyme dramatically, albeit in a small group of healthy volunteers. Arrowhead’s ill-fated hepatitis B candidate appeared to work well among patients allowed to take it before the FDA halted its study. The new-and-improved version, ARO-HBV, has the same new delivery mechanism as ARO-AAT, and recently presented data suggests it effectively clears the virus without any safety concerns.

Currently there are around 16 million Americans with chronic hepatitis B virus that require lifelong treatment. Further signs that Arrowhead’s candidate truly provides a functional cure that frees them from treatment — and reduces their chances of needing a liver transplant down the line — could help this stock continue its climb…

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