It's been a banner year for patients, drugmakers, and their regulators. The U.S. Food and Drug Administration has approved an impressive 43 new drugs in 2015. While all represent a tremendous effort on behalf of the companies developing them, some are better positioned for success than others.

In particular, the second half of the year yielded three new drugs that you'll want to watch in the new year. In July, Novartis (NYSE:NVS) was greenlighted for a heart failure combination with impressive bragging rights. About one-third of cystic fibrosis sufferers finally have a treatment option with Vertex Pharmaceuticals' (NASDAQ:VRTX) groundbreaking Orkambi. Recent attention for Gilead Sciences (NASDAQ:GILD) may be focused on its hepatitis program, but Genvoya, which was approved in November, has an important advantage in the HIV antiviral space.

Here's why I expect all three of these new drugs to enjoy rapidly expanding sales in the year ahead.

All about the benefits
To the uninitiated, "heart failure" might sound more like a cause of death than a chronic medical condition. For about 5.1 million Americans with hearts that fail to meet their bodies' demands, it's a daily struggle. Luckily, many of them have a new option that's been shown to help these patients live longer.

Image source: Novartis.

This summer, the FDA approved Entresto for treatment of reduced ejection fraction heart failure, after seeing results from an enormous study that pitted the drug against the ACE-inhibitor (enalapril) typically prescribed to this patient population. Entresto mopped the floor with enalapril. Patients receiving Novartis' twice-a-day tablet were 20% less likely to die from cardiovascular causes, and 21% less likely to be hospitalized for heart failure. The results were such a slam dunk that independent data monitors overseeing the study recommended it be shut down early so patients in the control arm could enjoy the benefit as well.

The U.S. list price of $12.50 per day, or about $4,560 per year, is high enough to draw complaints from payers, but Novartis is unfazed. The Swiss drug giant is so confident of the drug's abilities that it has offered end payers a value-based pricing model.

Although Novartis probably won't find many payers willing to adopt such a model, we should see sales figures for this program ramp up in the new year. In addition to the U.S., Entresto is also approved for marketing in the EU.

Novartis is expecting peak annual sales of $4 billion for Entresto. Now that the word is out about its proven mortality benefit, I'd say it has a good chance of getting there.

Successful launch
Even without Entresto, Novartis is on pace to record over $39 billion in sales this year. As big as its latest megablockbuster might be, it isn't going to move the needle that far for the Swiss drug giant. One company with a recently approved, potential megablockbuster that could move the needle much further is Vertex Pharmaceuticals.

Image source: Vertex Pharmaceuticals.

After being horribly unfortunate with its groundbreaking hepatitis treatment, Incivek, this innovation powerhouse is back with a big winner in cystic fibrosis. Approved in July, Orkambi combines lumacaftor with previously marketed Kalydeco to treat roughly 8,500 cystic fibrosis patients with the F580del mutation.

This might be a far smaller patient base than Entresto's, but an eye-popping $259,000 price per patient per year should make up the difference. Orkambi's predecessor, Kalydeco, is only approved for roughly 2,000 patients. After nearly three years on the market, third-quarter sales of Kalydeco reached $166 million. Despite launching in July, Orkambi reached $131 million in sales during the same period. With cystic fibrosis community relationships established, and four times the available patient population, sales of Orkambi are ready for lift-off.

Room to grow
While Orkambi is the first therapy to treat the underlying cause of cystic fibrosis, usage of HIV targeting antivirals has grown steadily for years. Strides have been made, but among an estimated 36.9 million people living with HIV, only about 40% are on an antiretroviral therapy.

Image source: Gilead Sciences.

That's more than enough to push Gilead's latest offering into blockbuster territory in the near future. Approved by the FDA in November, Genvoya is a four-part cocktail nearly identical to Stribild with one important difference: a new formulation of tenofovir that is effective at smaller doses. Genvoya contains 10 mg of tenofovir alafenamide while Stribild contains 300 mg of tenofovir disoproxil.

Genvoya isn't significantly more effective than Stribild, but the lower tenofovir dosage makes it safer. In head-to-head phase 3 trials, patients taking Stribild showed significantly higher impairment of kidney function compared with those on Genvoya. The new formulation is also better tolerated, with half as many Genvoya patients exiting the trial because of adverse events.

Launched three years ago, Stribild sales are tracking at a $2 billion annual run rate. With an improved safety and tolerability profile, I think that Genvoya should have no trouble eclipsing this figure.

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.