The stock market is roaring higher, with the Nasdaq and S&P 500 recently extending gains to reach new record highs. But don't worry. It's not too late to get in on this market growth. The indexes confirmed their presence in a bull market earlier this year, but these phases of market optimism tend to last quite some time -- and history shows us they generally go on for much longer than bear markets.

In a study spanning 1926 through 2017, the average bull market period lasted nearly nine years while bear markets lasted 1.4 years, according to Raymond James & Associates, citing First Trust data. So, it's likely that if you buy a stock today, you'll have plenty of time to benefit from bull market gains. But your growth story won't necessarily stop there. If you choose companies with solid long-term prospects, you could win by holding on to their shares well beyond this bull market -- and possibly into the next one.

What makes a top bull market buy? I always like a good growth story that's just getting started. The biotech industry is ripe with possibilities, and two of my favorites are companies that recently won their first product approvals, a vote of confidence for their technologies and a key step along the path to revenue growth. Let's check out these two bull market buys to own for the long run.

An investor seen from behind at a desk cheers while looking at a phone.

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1. CRISPR Therapeutics

CRISPR Therapeutics (CRSP -2.60%) recently scored a big win when regulators approved Casgevy, its treatment for blood disorders sickle cell disease and beta thalassemia. This represents the world's first approval of a treatment based on CRISPR gene editing -- showing regulators are ready to give the nod to this new technology if clinical data are strong.

CRISPR gene editing involves the correcting of faulty genes responsible for disease, so products using the technique have the potential to become functional cures. This is a game-changer for patients -- and could result in significant demand for makers of these products. CRISPR Therapeutics said more than 25 authorized treatment centers are ready to launch Casgevy, and "multiple" patients have already started the process.

The company is also developing a lighter conditioning treatment, or preparatory phase, as well as in vivo gene editing of stem cells that would remove the need for conditioning. This eventually could make Casgevy treatment easier, increasing uptake, and expand treatment into other disease areas. On top of this, CRISPR has several candidates in the pipeline across specialty areas -- so this growth story is just getting started.

CRISPR Therapeutics is trading much lower than it was just a few years ago, when the potential for product revenue was much farther off. So, at today's levels, with the Casgevy launch underway, this biotech stock offers growth investors a terrific buying opportunity.

2. Iovance Biotherapeutics

Iovance Biotherapeutics (IOVA -3.20%) specializes in tumor infiltrating lymphocyte (TIL) treatments, meaning it harnesses the body's own ability to fight cancer. TIL are naturally present in the body, and their job is to fight disease, but when they lose ground, Iovance gets involved. The idea of TIL therapy is to collect a patient's own TIL, reinvigorate these cells, and administer them back to the person.

Regulators recently gave Iovance the nod for Amtagvi, making this the company's first commercialized TIL product. Amtagvi is approved for advanced melanoma, the deadliest of skin cancers -- and this represents the only U.S. Food and Drug Administration approved T cell therapy for a solid tumor indication.

Momentum is looking positive for this new treatment. The company says more than 100 patients have already enrolled for Amtagvi since the February approval. Iovance also says it's on target to bring on board 50 authorized treatment centers by the end of this month and more than 70 by the end of the year.

Iovance also has good news when it comes to another key item that could determine a treatment's success: reimbursements. Payers covering more than 200 million people have given Amtagvi the nod. This is positive because it indicates this treatment is within reach for many of those individuals who need it.

Finally, like CRISPR Therapeutics, Iovance is using its technology throughout its pipeline in other promising candidates -- so additional growth drivers may be down the road. And all of this means it's worth buying this innovative company now and holding on for the long term, to benefit from growth in the bull market and beyond.