Few big pharma stocks excited investors in the first half of 2018. Sure, there were a few stocks that performed pretty well. Overall, though, the year has been at best mediocre for the stocks of major drugmakers. Could the rest of 2018 be a better picture? Maybe so.

Three big pharma stocks, in particular, could be set to move higher. Here's why I think AbbVie (NYSE:ABBV), Celgene (NASDAQ:CELG), and Gilead Sciences (NASDAQ:GILD) are the three best big pharma stocks to buy for the second half of 2018. 

Three scientists working in a lab

Image source: Getty Images.

1. AbbVie

AbbVie stock was on a roll this year until the company's announcement in March of disappointing phase 2 study results for Rova-T in treating small-cell lung cancer. The drugmaker's shares tanked on the news and still haven't recovered. But better things could be in store for AbbVie.

An FDA decision on approval for elagolix in treating endometriosis-associated pain is expected by early August. AbbVie thinks elagolix could become its next blockbuster drug. The company is also evaluating elagolix in a phase 3 clinical study targeting the treatment of uterine fibroids.

AbbVie has a major regulatory filing on the way in the next few months as well. The big pharma company reported overwhelmingly positive results from multiple late-stage clinical studies of upadacitinib in treating rheumatoid arthritis with the most recent results announced in June. Upadacitinib appears likely to be AbbVie's second-most successful immunology drug, trailing only Humira, which ranks as the top-selling drug in the world.

More good news could be on the way in the future. Market research firm EvaluatePharma views AbbVie's pipeline as No. 2 overall in the biopharmaceutical industry.  

2. Celgene

It's been a rough year so far for Celgene, with shares down around 20%. Celgene committed the pharma equivalent of an unforced error earlier in 2018, with its filing for ozanimod in treating multiple sclerosis (MS) rejected by the FDA right out of the gate. There are plenty of things to like about the company and its stock, though.

Celgene has had some good news lately. A few days ago, the company and its partner, Acceleron Pharma, announced great results from a late-stage study of luspatercept in treating rare blood disorder beta-thalassemia. Less than two weeks earlier, Celgene and Acceleron reported positive phase 3 results for the drug in treating myelodysplastic syndromes (MDS). Luspatercept could generate peak annual sales topping $2 billion if approved for both indications. The partners plan to submit for FDA approval of luspatercept in the first half of 2019.

Two acquisitions could also pay off nicely for Celgene. The company acquired Impact Biomedicines in January. Celgene plans to submit for FDA approval of Impact's fedratinib as a treatment for myelofibrosis this year. The acquisition of Juno Therapeutics enabled Celgene to control full rights to liso-cel (JCAR017), a CAR-T therapy that could be best-in-class.

Don't forget about ozanimod. Although Celgene hit a bump in the road, the biotech still plans to file for approval of the drug in treating MS in early 2019. Despite the delay, ozanimod is still projected to become a blockbuster success for Celgene.

3. Gilead Sciences

Gilead Sciences has experienced an up-and-down year thus far. The stock jumped more than 20% early in 2018, and then proceeded to give up all those gains and more. Gilead has rebounded somewhat lately, with its share price up by a single-digit percentage year to date.

There are several potential catalysts for Gilead that could be around the corner, however. The company's management thinks that sales for its hepatitis C virus (HCV) franchise will stabilize this year after several years of steep declines. If they're right, it would shift the focus to the company's other drugs -- and that should be great news for Gilead stock.

One key area to watch is Gilead's HIV franchise. The company launched Biktarvy in Q1. Expect sales for the powerful HIV therapy to rapidly gain momentum. Analysts think Biktarvy could eventually generate peak annual sales of around $6 billion. 

Gilead could also make a splash in the immunology market. The company expects to announce results in the near future from a phase 3 study evaluating filgotinib in treating rheumatoid arthritis. Gilead also is conducting late-stage studies for the drug in treating Crohn's disease and ulcerative colitis.

Best buy of all

I like all three of these stocks -- and I own all three of them. If I had to pick just one of them as the best to buy, though, it would probably be AbbVie.

AbbVie claims a solid product lineup with Humira, cancer drug Imbruvica, and HIV drug Mavyret. It has a great pipeline. The stock trades at less than 11 times expected earnings. On top of all that, AbbVie's dividend yields nearly 4%. These factors together are enough to make AbbVie an exciting stock regardless of its mediocre performance so far in 2018. 

Keith Speights owns shares of AbbVie, Celgene, and Gilead Sciences. The Motley Fool owns shares of and recommends Celgene and Gilead Sciences. The Motley Fool has a disclosure policy.