It's now a new ballgame for CRISPR Therapeutics (CRSP 0.34%). The company, along with its big partner, Vertex Pharmaceuticals (VRTX -0.06%), won U.S. regulatory approval for Casgevy (exa-cel) in treating sickle cell disease (SCD) on Dec. 8, 2023. Casgevy picked up U.K. approval for SCD and transfusion-dependent beta thalassemia last month.

Despite the milestone U.S. approval, CRISPR Therapeutics stock sank nearly 19% after the Food and Drug Administration (FDA) made its decision. Shares have rebounded somewhat but remain close to 15% below the previous high.

We could be seeing a textbook case of "buy the rumor, sell the news" with CRISPR Therapeutics. But here's the one key reason why you might want to buy the gene-editing stock on the dip.

It has little to do with Casgevy

Before we get to that reason for buying CRISPR Therapeutics, I'll let you know upfront that it has little to do with Casgevy. There's a simple explanation why that's the case.

CRISPR Therapeutics currently has a market cap of close to $5 billion even with the recent sell-off. That's a steep valuation for a biotech that has yet to rake in a penny of product sales. The reality is that the revenue prospects for Casgevy are already largely baked into CRISPR Therapeutics' share price.

Goldman Sachs analysts think that Casgevy could generate worldwide peak annual sales of $3.9 billion. However, that's higher than what other analysts project. The consensus is that Casgevy will achieve peak annual sales in the ballpark of $2.2 billion, according to Bloomberg. That's still a lot of money, but there are two important things to keep in mind.

First, it's going to take years to come anywhere close to reaching that level. Analysts don't expect Casgevy to hit $1 billion in sales until 2027. Vertex also hinted in its latest quarterly conference call that the ramp-up could be slow.

Second, CRISPR Therapeutics will receive only 40% of the net profits from Casgevy. So when you see a peak sales estimate of $2.2 billion, it means that CRISPR Therapeutics' part will be much lower.

Next up for CRISPR Therapeutics

Note that I said that the key reason you might want to buy CRISPR Therapeutics has little to do with Casgevy but didn't state that it has nothing to do with the already-approved gene-editing therapy. That's because the money the company will make from Casgevy will help fund its ongoing research and development.

I don't think investors should buy CRISPR Therapeutics primarily to capitalize on the likely success of Casgevy. Instead, the main reason to consider buying the stock is for what the company could have on the way.

CRISPR Therapeutics' pipeline features six clinical-stage programs in addition to Casgevy. The company owns all of the rights to five of them. CTX110 and CTX112 are allogeneic ("off-the-shelf") CAR-T therapies targeting CD19+ malignancies and autoimmune diseases. CTX130 and CTX131 are off-the-shelf CAR-T therapies targeting CD70 in T-cell malignancies and solid tumors. CTX310 is in phase 1 testing for treating cardiovascular disease.

The company teamed up with ViaCyte (which is now owned by Vertex) to develop allogeneic stem-cell therapies for treating type 1 diabetes. VCTX-211 is currently being evaluated in a phase 1/2 clinical study with results set to potentially be announced in 2025.

In addition, CRISPR Therapeutics has several preclinical programs. One of them -- CTX320 -- is on track to advance into early-stage clinical testing in the first half of 2024.

Not a stock for everyone

CRISPR Therapeutics is emphatically not a stock for everyone. The company's pipeline candidates could fail miserably. It's also possible that Casgevy won't achieve the commercial success that analysts predict. Risk-averse investors should look elsewhere.

Aggressive investors, on the other hand, could find this stock attractive. I wouldn't say that CRISPR Therapeutics offers the best risk-reward proposition even among biotech stocks. However, it could have plenty of room to run over the next few years if Casgevy fulfills its potential and the pipeline programs succeed in clinical studies.