These Biotech Stocks Are Pricey, but Investors Can Still Buy Them

Sarepta Therapeutics (NASDAQ: SRPT) and Amicus Therapeutics (NASDAQ: FOLD) are two fast-growing biotech stocks that are trading at price-to-sales multiples north of 50, yet biotech investors may still want to add them to their portfolios despite their sky-high valuations. Both companies already market fast-growing, FDA-approved drugs and each is developing new drugs for rare diseases that could significantly expand their peak sales opportunity.

Small start, big finish

Sarepta Therapeutics markets Exondys 51, an exon-skipping drug that helps restore dystrophin production in about 13% of Duchenne's muscular dystrophy (DMD) patients.

A gold pill rest on top of a pile of gold coins.
A gold pill rest on top of a pile of gold coins.

IMAGE SOURCE: GETTY IMAGES.

DMD is a rare, life-shortening, muscle-wasting disease, and when Exondys 51 won FDA approval last year, it became the first FDA-approved therapy in this indication. Despite a small addressable market totaling about 3,400 patients, sales of Exondys 51 are already tracking at an annualized pace of about $140 million, and sales are growing rapidly. Its second-quarter revenue more than doubled its revenue in the first quarter.

However, Exondys 51's growth isn't why I think Sarepta Therapeutics shares could continue higher. Instead, it's the company's progress toward developing additional exon-skipping drugs that make me optimistic.

The company is evaluating drugs that skip exon 53 and exon 45, and in September, it reported its exon 53 skipping drug boosted dystrophin levels in a small phase 1/2 trial. If this news leads to the FDA eventually giving a green light to the use of drugs that skip exon 53 and exon 45, then Sarepta Therapeutics' addressable market increases to about 30% of all DMD patients, or roughly 7,600 patients.

Since Exondys 51 costs $300,000 per year, and future exon-skipping drugs will likely command similar prices, additional approvals could push Sarepta Therapeutics' annual sales over $1 billion after rebates and discounts. Peak revenue could end up being even higher than that, though, because Sarepta Therapeutics is also developing exon-skipping drugs that could allow it to address 47% of DMD patients, or about 12,000 patients per year.

A chart showing the breakdown of patients with various exon mutations.
A chart showing the breakdown of patients with various exon mutations.

IMAGE SOURCE: SAREPTA THERAPEUTICS.

The company's current $3.2 billion market cap becomes far less frightening if these efforts pan out. Admittedly, there's no telling if it will win more approvals, or when it may turn a profit -- it lost more than $60 million last quarter -- but I do think the opportunity here can justify a higher price.

Second time a charm?

Amicus Therapeutics' shares have been on a roller-coaster ride since the FDA rejected the company's first attempt to file for approval of Galafold, its Fabry disease drug.