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Image source: Amgen via Flickr.

The original biotech blue-chip stock, Amgen (NASDAQ:AMGN), has had nothing short of a phenomenal year. Even though its share price is up a pedestrian 3% year to date, the trailing-12-month period has witnessed Amgen gaining six new approvals or expansions.

Beginning with the approval on Blincyto for a rare form of acute lymphoblastic leukemia in early Dec. 2014, Amgen has since delivered approvals for a number of new molecular entities, including Corlanor, Repatha, and Imlygic, an expanded label for multiple myeloma drug Kyprolis, and approval for the Onpro Kit to deliver Neulasta to patients undergoing chemotherapy.

The approvals are consistent with Amgen's announced plans to report data on 10 late-stage products between 2014 and 2016. What's truly been remarkable is that Amgen has been perfect in hitting its primary endpoints and gaining approval for its late-stage compounds. It's been a nice surprise for investors, and it could fuel years of sustainable growth for Amgen and its shareholders.

The most important drugs in Amgen's pipeline
But Amgen looks to be far from done when it comes to bringing lucrative products to market. Despite its deep pipeline, I would contend that the following three experimental therapies are currently its most important.

ABP 501
Interestingly enough, a "novel" medicine really isn't the most exciting developing drug in Amgen's pipeline. Instead, that distinction goes to ABP 501, one of Amgen's numerous biosimilar drugs in development. Biosimilars have similar active properties to innovator drugs that they're designed to compete with, but unlike a generic drug, they are not "copies" of an innovator drug. Biosimilars are still expected to command a healthy price tag, but they'll offer a discount likely ranging from 10% to as much as 50% from an innovator drug.

Humira

Image source: AbbVie.

ABP 501 is Amgen's biosimilar drug designed to compete with AbbVie's (NYSE:ABBV) anti-inflammatory drug Humira, which is currently the best-selling drug in the world and on pace for more than $13 billion in global sales in 2015. For AbbVie, Humira is expected to lose its patent exclusivity late in 2016, exposing the drug to multiple avenues of potential competition. Considering that Humira is roughly a $13 billion drug, the market for a biosimilar at a discounted price to Humira could become a blockbuster, even in a highly competitive therapeutic indication.

Just last week, Amgen announced that it had filed for U.S. approval of ABP 501 after it demonstrated comparable efficacy and safety to Humira in late-stage clinical studies for rheumatoid arthritis and plaque psoriasis. The irony here is the first biosimilar approved in the U.S. came earlier this year, and it was a biosimilar of Amgen's white blood cell-enhancing drug Neupogen.

Expect a lot of emphasis on Amgen's biosimilar franchise throughout the remainder of this decade and beyond, but look to ABP 501 to be the company's first step forward.

Omecamtiv mecarbil
When it comes to its new cardiovascular franchise, Amgen is breaking out of the box. For Big Pharma and blue-chip biotech companies, it's commonplace to focus on their strengths. For many, that equates to anywhere from one to six therapeutic indications. It's rare for bigger drug developers to deviate from their core indications because it usually means substantial marketing and launch costs, as well as a lot of established competition. Amgen, though, doesn't seem to care.

Cdc Fb
Image source: Centers for Disease Control and Prevention. 

After bringing next-generation LDL-cholesterol-lowering injection Repatha to pharmacy shelves, as well as chronic heart failure drug Corlanor, Amgen and development partner Cytokinetics (NASDAQ:CYTK) are looking for the trifecta with experimental cardiac myosin activator omecamtiv mecarbil. In layman's terms, omecamtiv mecarbil is designed to aid the heart's ability to contract, thus improving its ability to pump blood throughout the body.

In the midstage COSMIC-HF trial, which Amgen and Cytokinetics reported results from a little more than a month ago, omecamtiv mecarbil "showed statistically significant improvements in several measures of cardiac function, including systolic ejection time, stroke volume, and N-terminal-pro-brain natriuretic peptide, at 20 weeks following randomization" in chronic heart failure patients. The trial wasn't modeled to assess cardiovascular outcomes, but from the perspective of safety and initial efficacy, everything is looking good.

If approved, omecamtiv mecarbil could generate north of $1 billion in peak annual sales.

Kyprolis
Finally, we're once again forced to sit on the edge of our seats to find out what happens next to multiple myeloma drug Kyprolis, which Amgen acquired when it purchased Onyx Pharmaceuticals.

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Image source: Amgen.

Amgen shareholders had a bit of a scare last year after the company reported results from its two phase 3 trials, ASPIRE and FOCUS, designed to assess Kyprolis' efficacy and safety in a second-line setting. In ASPIRE, Kyprolis' progression-free survival improvement thumped the control group by a mile. However, in FOCUS Kyprolis didn't deliver a statistically significant survival benefit over the placebo. Nonetheless, Kyprolis was granted its label expansion to a second-line indication a few months prior.

What investors are going to want to monitor are two ongoing late-stage studies known as CLARION and ARROW. In CLARION, Kyprolis is being assessed in combination with melphalan and prednisone in newly diagnosed multiple myeloma patients compared to a control arm consisting of Velcade in combination with melphalan and prednisone. First-line multiple myeloma is where Celgene's Revlimid makes a good chunk of its revenue, and moving into a possible first-line indication would be a major win for Kyprolis and Amgen.

ARROW is trial examining Kyprolis as a weekly dosing regimen for relapsed and refractory multiple myeloma patients.

If Kyprolis can somehow find additional label expansion opportunities from its current label of second-line and beyond, it could potentially see its sales double.

Time to buy Amgen?
Now that you have a good idea of what are arguably Amgen's most important developing drugs, you're probably curious as to whether you should be buying the stock. The answer really comes down to your investing strategy and your tolerance for risk. Biotech stocks, even those with established pipelines, tend to be more volatile than the stock market as a whole. Investors who are squeamish of short-term stock movements may not be suited to own Amgen stock.

However, Amgen does look poised for long-term success. Its new complement of approvals and its deep mid- and late-stage pipeline suggest that patent concerns won't be a huge issue due to improving product diversity. I would therefore encourage long-term investors to give Amgen a closer look.

Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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