What were you doing on Friday, Jan. 2, 2015? It's OK if you don't remember. I certainly can't.

But there were some investors who did something on that date who probably recall it with a smile. Anyone who bought shares of Exelixis (NASDAQ:EXEL) at the beginning of 2015 and held on to the stock are now sitting on a return of 1,560%. A $10,000 investment in the biotech less than three years ago would now be worth $166,000. 

Exelixis has been one of the hottest biotech stocks in recent years. But can buying this stock still make you rich? It just might.

Man wearing suit holding giant red magnet with cash flowing toward the magnet

Image source: Getty Images.

Outlook for Cabometyx is better than ever

Exelixis already claims a 35% market share with Cabometyx approved as a second-line treatment for renal cell carcinoma (RCC), the most common type of kidney cancer. The company made net product revenue of more than $143 million in the first half of 2017 from the drug. But that's just the start.

A few days ago, Exelixis submitted a supplemental New Drug Application (sNDA) to the U.S. Food and Drug Administration (FDA) for Cabometyx as a first-line treatment for RCC. Cabometyx was found to be more effective in a late-stage clinical study than Pfizer's (NYSE:PFE) Sutent, one of the current leading treatments for the disease. The odds for approval in the first-line indication appear to be quite good, although anything can happen in the regulatory process. 

Bad news recently for Bristol-Myers Squibb (NYSE:BMY) could indicate that the outlook for Cabometyx is better than ever, assuming the drug wins approval. The big drugmaker reported disappointing results from its late-stage study of a combination of Opdivo and Yervoy in treating first-line RCC. Although more patients taking Bristol's combo achieved tumor shrinkage than did patients taking Sutent, there wasn't a statistically significant difference between the two treatments in progression-free survival.

The mixed results for Bristol-Myers Squibb should mean that Exelixis will be able to capture more of the first-line RCC market than originally thought. It also positions Cabometyx as the go-to drug for combo therapies in the indication. Bristol-Myers Squibb and Roche are both testing Exelixis' drug in combination with their respective cancer drugs in RCC and other types of cancer.

Exelixis is also hoping to score wins in other indications as well. Besides the combo studies with Bristol-Myers Squibb and Roche, the company is evaluating Cabometyx in a late-stage study targeting treatment of advanced hepatocellular carcinoma (HCC). A second interim analysis of this study is expected before the end of 2017. 

Corporate tax reform would open intriguing possibilities

With hopes of healthcare reform apparently dead, the GOP majority in Congress really needs something to point to as a positive accomplishment. Many think that corporate tax reform is the ideal area for the GOP to make its mark.

Now that it's profitable, any reduction in corporate tax rates would help Exelixis. The biotech spent over $35 million in the first half of the year on income taxes. A nice tax cut would mean a better bottom line. Exelixis CEO Michael Morrissey has already stated that he'd like to buy early stage or pre-clinical-stage pipeline candidates to beef up the company's oncology portfolio. But the direct impact on Exelixis of potential tax reform isn't what intrigues me the most. 

So far, 2017 has been a dud when it comes to biotech acquisitions. I recently wrote about why I thought that was the case. The main reason, in my view, behind the relatively low number of deals is that big drugmakers are waiting to see what happens with corporate tax reform.

I suspect that if efforts to reduce corporate taxes are successful, and particularly if there is a one-time repatriation of oversees cash at a discounted rate, we will see the buyout floodgates open soon thereafter. Exelixis would be one of the top acquisition targets, in my view.

Exelixis is in a sweet spot from a valuation perspective, with a current market cap of around $8 billion. Cabometyx would be an attractive addition to any number of big pharma companies' portfolios, including Bristol-Myers Squibb, Pfizer, and quite a few others. Even Exelixis' less-discussed drug, MEK inhibitor Cotellic, would probably be appealing to several larger companies. 

Even if corporate tax reform fails to gain traction (a real possibility), I still think Exelixis could be up for grabs. As I mentioned earlier, drugmakers have held off on making deals because they wanted to see what would happen in Washington. If they see nothing happen, my hunch is that there will nonetheless be several big pharma companies that will go into acquisition mode.

Get rich -- slow

Early in my career, I bought furniture for my apartment with the salesperson being the owner of the large furniture store himself. The prices for the furniture I bought were pretty reasonable, so I told the owner that I appreciated the deal I was getting. He immediately responded, "I want to get rich, but get rich slow."

It's possible that Exelixis could still be a get-rich-quick kind of stock. That would probably be the case if the biotech becomes the subject of a bidding war, which could very well happen. However, even if not, the tremendous potential for Cabometyx and the things Exelixis can do with the cash the drug generates should still allow investors who buy the stock and hold for the long term to become relatively rich. They just might get rich slow.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.