Biotechnology was one of the market's shining stars in 2014. The Nasdaq Biotechnology Index ETF returned an impressive 33% last year, significantly outpacing the performance of the S&P 500. Of course, no one can know if biotechnology stocks will put up similar returns again, or what will or won't happen with any particular company in this highly volatile industry, but if 2014 is any indication, perhaps these five predictions may be worth watching in 2015.

Source: Celgene Corp.

No. 1. Celgene Corporation (NASDAQ:CELG) will buy somebody
I don't have any idea which company Celgene could buy in 2015, but the company's getting flush with cash, and it's been kicking a lot of tires over the past two years. The company has inked collaboration deals with a host of promising emerging biotechs, including Bluebird bio, but it's also taken equity stakes in a number of them, too, including Agios, in which it owns a 14% equity stake, Acceleron, in which it also owns a 14% stake, and Epizyme, in which it owns an 11% position. I don't know if any of those are on Celgene's short list of potential acquisitions, but it wouldn't shock me if Celgene ends up making a splash with an acquisition this year.

No. 2. Investors will decide that Alkermes (NASDAQ:ALKS) is worth more than it is today
Alkermes isn't a household biotechnology company, but it may be a lot better known by the end of 2015. Alkermes has a string of intriguing drugs coming through its product pipeline, including a novel, long-lasting injectable formulation of the billion-dollar blockbuster schizophrenia drug Abilify. That drug, aripiprazole lauroxil, has already been filed for FDA approval, and if the FDA gives it the green light, it could significantly improve patient adherence rates. Alkermes also recently reported solid phase 3 results from one of three ongoing studies of ALKS-5461, a treatment for depression. If ALKS-5461 can deliver similar results throughout its phase 3 trials, it could also have billion-dollar blockbuster potential since it is dosed alongside top selling antidepressants like Cymbalta, rather than instead of them. Since Alkermes expects sales of between $580 million and $610 million this year, these new drugs could have investors thinking that the company is worth more at year end than the $9.75 billion it is today, especially since Actavis paid 7 times sales to buy Alkermes' peer Forest Labs in 2014.

Source: The Motley Fool.

No. 3. Marijuana drugs will make headway, but GW Pharmaceuticals (NASDAQ:GWPH) won't
One of the most intriguing trends in 2014 was the rise of medical marijuana. Increasing awareness of medical marijuana, which is now legal in 23 states, caused shares in GW Pharmaceuticals to soar by 63% in 2014.

GW Pharmaceuticals is developing a slate of marijuana-derived medicine for cancer pain and epilepsy, and those programs are without a doubt intriguing. However, its far from certain whether or not these programs will deliver on their promise. For example, GW Pharmaceuticals and its partner Otsuka recently reported that Sativex failed the first of three ongoing phase 3 trials designed to evaluate its ability to control cancer pain versus placebo. The company still has two remaining trials ongoing, so there's still hope for Sativex in this indication, but investors are probably best served focusing their attention elsewhere for two reasons.

First, I think that this recent failure casts far too much doubt on Sativex making its way to market and secondly, even if the remaining two studies show Sativex does work, any eventual approval would only be for its use as a second-line therapy, rather than as a first-line therapy. Additionally, the company's collaboration deal with Otsuka means that GW Pharmaceuticals will only collect a royalty on sales of Sativex in the United States, which suggests that it's Otsuka, not GW Pharmaceuticals, that would stand to benefit most from any eventual approval.

Arguably, a bigger opportunity for GW Pharmaceuticals may be in treating epilepsy, but the epilepsy indications that GW Pharmaceuticals is targeting are very small patient populations. As a result, I think that investors may decide that GW Pharmaceuticals' current $1.4 billion market cap is a bit rich.

No. 4. Gilead Sciences (NASDAQ:GILD) and AbbVie's (NYSE:ABBV) hepatitis C battle will change
In 2014, Gilead Sciences top-selling hepatitis C drug, Sovaldi, notched $8.5 billion in sales during the first nine months of the year. That set the stage for a battle between Gilead Sciences and AbbVie into year's end that included the FDA approval of Gilead Sciences' second-generation hepatitis C drug Harvoni in October, the approval of AbbVie's competing hep C drug cocktail Viekira Pak in December, an exclusivity pact between AbbVie and pharmacy benefit manager Express Scripts in December, and the inking of a similar exclusivity deal between Gilead Sciences and CVS Health's pharmacy benefit manager earlier this month.

Since the battle has shifted from fiction to non-fiction, and investors tend to look ahead rather than behind, I wouldn't be shocked if attention begins to be focus elsewhere, such as toward finding the companies most likely to deliver functional cures in far less time than the current eight- and 12-week protocols. A number of companies (including these two) are working on solutions that may reduce treatment time, but it could be programs at Merck & Co, Achillion Pharmaceuticals, and Regulus Therapeutics that prove to be of greater interest by year end.

No. 5. Investors will flock to companies with biosimilar programs
As industry watchers get a clearer understanding of the regulatory pathway to approval of biosimilars, their allure may prove to be too great for investors to ignore in 2015. A number of companies, including Novartis' Sandoz unit and Hospira, are at the forefront of the push toward winning approval for biosimilars, which are similar to, but not exact copies of, some of the globe's top-selling medicines.

Pushing along for their speedy arrival will be health care payers that are desperate to find ways to slow health care cost inflation in the face of increasingly expensive medicine. According to Express Scripts, the approval of biosimilars for Amgen's cancer drug Neupogen and Johnson & Johnson's rheumatoid arthritis drug Remicade could save payers $22.7 billion alone during the first 10 years following their approval. Of course, it still remains to be seen if or when these biosimilars make it to market, and it's not clear whether biosimilars can capture the majority of market share even if they are approved. In overseas markets, where some biosimilars have been available for years, they've captured about a third of prescription volume. Regardless, this could be the early stages of a major market shift that is similar to the advance of generic drugs 15 years ago. If so, investors may be right to be getting more interested in 2015.

Tying it all together
If there's one thing that's certain, it's that there's little certainty in making stock market predictions. Any number of things can and will happen this year, many of which will likely be big surprises. Having said that, investors may want to dig a bit deeper into these companies, given that a compelling argument can be made for each.