Investing in biotech stocks can be a leap of faith. Many of those in the sector with the most promising therapies aren’t profitable, and some have taken a drubbing so far this year. If you’re investing for the long term, however, biotech companies can provide huge potential.

Instead of just looking at a company’s bottom line, follow the science. Companies with breakthrough therapies offer upside for patient investors. Consider Sarepta Therapeutics (SRPT -1.30%), CRISPR Therapeutics (CRSP -1.92%) and Myriad Genetics (MYGN -1.41%). All three companies have been able to expand their pipelines by building off proprietary data.

1. Sarepta’s pipeline offers an opportunity

Sarepta’s stock is up more than 27% this year. It is the first company to get Food and Drug Administration (FDA) approval for therapies to treat Duchenne muscular dystrophy (DMD). This is a rare and deadly illness, with most patients dying in their 20s, and it affects six individuals in every 100,000, mostly young males, according to the Muscular Dystrophy Association.

But that’s not all. Sarepta also has more than 40 other genetic therapies in development.

In the second quarter, the company reported revenue of $233.5 million, up 42% year over year. It is still ramping up its research and development and said it had a net loss of $231.5 million, or $2.65 per share, compared to a net loss of $81.4 million ($1.02 per share) in the same quarter a year ago. It also raised its guidance for the…