Celgene (NASDAQ:CELG) has been hard at work building a franchise of drugs to complement its blockbuster cancer drug Revlimid. It has been enjoying a wave of success with Abraxane, which was approved as a breast cancer treatment in 2005 and has also recently been approved for non-small-cell lung cancer and pancreatic cancer patients. It hopes to have similar success with apremilast.

It hasn't been all smooth sailing for apremilast. Celgene had high hopes the drug could prove a solid competitor to AbbVie's (NYSE:ABBV) Humira across a range of autoimmune diseases. But some of those hopes were dashed in 2011 when apremilast failed to reach endpoints in a critical rheumatoid arthritis study.

Not all hopes were dashed
There are still some solid opportunities for sales and market share growth in a host of different autoimmune diseases.

In June, Celgene updated data from a phase 3 trial treating psoriatic arthritis sufferers. That data, while not a slam-dunk beat of Humira, showed similar efficacy and safety. That's compelling given that apremilast is taken orally, rather than injected like Humira. Apremilast may also benefit from the potential for fewer side effects than Humira. As a result, the drug could serve as an important bridge between standard treatment and biologics.

Earlier this year, Celgene filed with the Food and Drug Administration for approval of apremilast as a treatment for psoriatic arthritis. The updated data showed that 31.3% of patients had at least a 20% reduction in pain after 16 weeks of treatment. After 52 weeks, 63% of patients saw a reduction in pain. Importantly, the 504 patients in the study had tried -- and failed -- anti-TNF drugs like Humira previously.

The positive data helps support Celgene's optimistic outlook for apremilast. The company thinks apremilast can eventually generate up to $2 billion in annual sales, and as part of the company's strategy to reach that goal, Celgene plans to file apremilast as a treatment for both psoriasis and psoriatic arthritis in Europe later this year.

Puffed up autoimmune pipelines
Celgene isn't the only drugmaker advancing new autoimmune drugs through its pipelines. In July, Novartis (NYSE:NVS) reported positive results for secukinumab as it met primary endpoints in treating psoriasis. Novartis will release additional results for secukinumab for other arthritic conditions by year's end. Additional diseases being studied include rheumatoid arthritis and multiple sclerosis. 

That puts Novartis head to head against Enbrel; the blockbuster auto immune drug racked up more than $8 billion in sales for Amgen (NASDAQ:AMGN) in 2012. But Enbrel is facing biosimilar competition from Novartis' Sandoz unit, which has a phase 3 study under way, and Amgen is unlikely to roll over in the indication. It's partnered with AstraZeneca on brodalumab. That drug is in various mid- stage studies for psoriasis and asthma. In phase 2 studies, patients treated with brodalumab saw an 86% average improvement versus just 16% for a placebo.

Eli Lilly (NYSE:LLY) is also in the hunt with ixekizumab. That drug showed promise in mid-stage trials. Roughly 80% of patients receiving the drug saw an improvement of at least 75% in symptoms, versus just 8% on placebo. In phase 3 trials, Lilly is studying the drug head to head against Enbrel.

All of these drugs are vying for share in a big market. In addition to blockbusters Humira and Enbrel, Johnson & Johnson sells Remicade and Simponi. U.S. sales of Simponi were $175 million in the second quarter, while sales of Remicade were just under $1 billion.

The Foolish final take
Celgene has a big opportunity to carve out a share of the autoimmune market. Psoriasis affects some 125 million people worldwide. 

Of course, there are risks. In addition to current competitors vying to supplant Humira, AbbVie is advancing its own promising drug ALX-0061 through clinic. But, if Celgene can position the drug as a pre-biologics alternative, it may be on its way toward meeting its optimistic sales goal.