Shares of CRISPR Therapeutics are up by 26% over the past three months. That coincides with the company's first regulatory approval, that of Casgevy, for the treatment of sickle cell disease (SCD) and transfusion-dependent beta-thalassemia (TDT). These two rare blood diseases are hard to treat, but Casgevy, developed in collaboration with Vertex Pharmaceuticals, is a one-time cure. Casgevy's approval in the U.S. and several other countries is a significant step forward for CRISPR Therapeutics.

The company can now brag that its gene-editing platform, arguably so far unproven, can lead to breakthrough therapies. And thanks to Casgevy's enormous potential, CRISPR Therapeutics should start to generate the funds necessary to advance its most promising programs. What is Casgevy's total addressable market? It's hard to come up with a definitive figure, but a lower bound of $70 billion seems fair. CRISPR Therapeutics and Vertex plan to initially target 32,000 patients in the U.S. and Europe.

Gene-editing therapies take even longer to ramp up than everyday oral drugs since they are complex to administer. Still, things are looking good for CRISPR's future. The company is going after challenging targets, from several forms of cancer to type 1 diabetes and Duchenne muscular dystrophy (a rare, progressive disease that weakens patients' muscles). CRISPR Therapeutics should have strong sales of Casgevy within the next couple of years and record meaningful clinical progress.

CRISPR Therapeutics' market capitalization is currently $5 billion – it's a growth story, and it has just started. This company is well-positioned to become a leader in the biotech industry in time, which makes it an excellent stock to buy and hold.