Shares of Celgene (NASDAQ:CELG), a biotech blue-chip stock that generates most of its revenue from the development of oncology, inflammation, and immunology drugs, dipped 11% in November, based on data from S&P Capital IQ, after the company reported disappointing third-quarter earnings results.

Normally known for thumping Wall Street's projections, Celgene's Q3 results were ultimately mixed. Sales for the quarter improved 18% year-over-year to $2.33 billion, and adjusted net income rose 26% to $1.01 billion. Adjusted EPS also grew to $1.23 from $0.97 in the year-ago period. Celgene's EPS topped forecasts for a seventh straight quarter, this time by $0.01; however, Wall Street was expecting $2.4 billion in revenue, meaning Celgene came up short.

What went wrong for Celgene in the third quarter? Look no further than cancer drug Abraxane, which is approved to treat breast cancer, first-line non-small cell lung cancer, and advanced pancreatic cancer. Celgene had previously forecast that Abraxane sales would total between $1 billion and $1.25 billion in 2015, but have since lowered that forecast to a range of $950 million to $1 billion.

Image source: Celgene.

Although Celgene was pretty tight-lipped regarding the reasons why Abraxane's U.S. sales fell 4% year-over-year, I proposed last month that cancer immunotherapies may be to blame. There are clinical trials under way right now for Merck's Keytruda and Bristol-Myers Squibb's Opdivo in NSCLC and other indications that Abraxane covers. While there's no guarantee these immunotherapies will find success, some consumers and physicians may be holding off on prescribing Abraxane in the hope of securing access to one of these immunotherapies.

Now that you have a better idea of why Celgene stumbled in November, you might be wondering if the latest dip should potentially be used as a buying opportunity. I would certainly argue that doing so might be a good idea.

Celgene has everything that an investor could want in a biotech stock. It primarily grows organically, through the label expansion of Abraxane, multiple myeloma drug Revlimid, and anti-inflammatory drug Otezla. It also has the ability to purchase growth intelligently, as it did when it paid $7.2 billion for Receptos. This acquisition gave Celgene access to next-generation multiple sclerosis drug ozanimod, which is expected to generate $4 billion to $6 billion in peak annual sales if approved. Lastly, Celgene can lean on its more than 30 collaborations to locate the next big thing in cancer or anti-inflammatory research.

Combined, these three factors are what allow Celgene to forecast double-digit sales percentage growth per year through 2020. Celgene's forward P/E of 19 may not give off the impression that it's an undervalued stock on the surface, but its 20% five-year growth rate and subsequent PEG ratio of 0.94 might change your tune.

I would strongly encourage long-term growth-seeking investors to give Celgene a closer look.