Nearly five years ago, Abbott Labs spun off its biopharmaceutical unit into a separate entity. That new company, AbbVie (NYSE:ABBV), enjoyed a tremendous first year, with its share price soaring more than 50% in 2013. However, the following years weren't as great for AbbVie. Until now.

Granted, AbbVie stock isn't up more than 50% year to date. But it's really close. And there's plenty of time remaining in the year. Here's why 2017 could be the stock's best year yet.

Large outlines of numbers forming 2017, with silhouette of woman with raised hands in the 1 position.

Image source: Getty Images.

Humongous wins for Humira

It's been a great year for Humira. AbbVie's blockbuster autoimmune-disease drug appears to be on track to once again reign as the top-selling prescription drug in the world. In the first half of 2017, Humira generated sales totaling more than $8.8 billion. That's up 14% from the prior-year period. 

AbbVie remains heavily dependent on Humira -- the drug accounts for roughly 64% of the company's total revenue. This reliance on Humira has concerned some investors, especially after Amgen (NASDAQ:AMGN) gained approval from the U.S. Food and Drug Administration for its biosimilar to Humira, Amjevita, last year. 

Any worries have been largely dismissed now, however, thanks to a deal announced by AbbVie at the end of September. Amgen agreed to hold off on marketing Amjevita in the U.S. until Jan. 31, 2023, and will launch its biosimilar in Europe on Oct. 16, 2018. The biotech acknowledged AbbVie's intellectual property rights to Humira and will pay royalties to AbbVie on all sales of Amjevita.

That's huge news for AbbVie. The deal clears the deck for Humira to keep on rocking in the U.S., where around two-thirds of the drug's sales are made. While there are other companies trying to get their biosimilars on the U.S. market, the agreement with Amgen makes it much more likely that AbbVie will be able to protect Humira for a few more years.

Rapid rise for Imbruvica 

While Humira is AbbVie's top-selling drug, it can't claim the fastest sales growth. That honor belongs to Imbruvica. The cancer drug made nearly $1.2 billion in the first half of 2017 for AbbVie. That represents year-over-year growth of more than 43%.

Market research firm EvaluatePharma believes that Imbruvica will rank as the No. 4 cancer drug in terms of sales by 2022, with annual revenue of $7.5 billion. This estimate includes the five indications for which Imruvica is already approved, plus prospects of gaining approval for three additional indications for which the drug is being evaluated in late-stage studies.

AbbVie won't make all of that money, since it partners with Johnson & Johnson on Imbruvica. However, the split between the two companies is close to 60-40, with AbbVie receiving the higher share of sales. If the EvaluatePharma projection becomes reality, AbbVie could be looking at nearly doubling its revenue from Imbruvica in the next five years.

Percolating pipeline 

AbbVie's good news in 2017 hasn't been limited to its current product lineup. The company has also enjoyed several positive developments with its pipeline.

Probably the most important is winning FDA approval in August for hepatitis C virus (HCV) drug Mavyret. Although sales are steadily falling for AbbVie's first HCV drug, Viekira, Mavyret could be more successful. The drug is approved to treat all genotypes of HCV and is priced at a discount to current HCV therapies.

Another pipeline candidate could be on the way to getting a green light from the FDA. AbbVie submitted for approval of elagolix in treating endometriosis in September based on positive results from two late-stage studies. The drug is also being evaluated in late-stage studies for the management of uterine fibroids. 

In June, AbbVie announced positive results from a late-stage study evaluating experimental drug upadacitinib in treating rheumatoid arthritis. The company followed up with more good news in September from another late-stage study of the drug in treating the indication.

One negative -- sort of

Barring a stumble when the company reports its third-quarter results later this month, AbbVie appears to be solidly on track to turn in its best stock performance ever. There's only one negative: The dividend yield ain't what it used to be. Right now, AbbVie's dividend yields just north of 2.8%. For most of the past two years, the yield stood well above 3.25%.

But AbbVie hasn't cut its dividend; in fact, it has raised the dividend every year since being spun off from Abbott Labs. The lower yield is simply a reflection of how much AbbVie stock has soared. That's the kind of "negative" that investors could get used to.

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.