Pfizer's (NYSE: PFE) pipeline has had a string of disappointments lately, but the pharma giant's luck might be turning around. Data from a phase 2 trial testing tasocitinib against psoriasis, a painful autoimmune skin disease, looks promising even given its small size.

Tasocitinib reduced patients' psoriasis by 75% compared with the pretreatment levels in 25%, 40.8%, and 66.7% of patients at the three different doses given to patients. That's exactly what you'd like to see: a nice escalation of efficacy as the dose increased. More importantly, just 2% of the patients that received placebo saw their rash decrease by 75%, so the drug is clearly working.

There are quite a few drugs to treat autoimmune diseases like psoriasis and rheumatoid arthritis, but the most powerful ones all need to be injected or infused. As an oral compound, tasocitinib should have an easy time taking market share from Abbott Labs' (NYSE: ABT) Humira, Merck (NYSE: MRK) and Johnson & Johnson's (NYSE: JNJ) Remicade, and Pfizer and Amgen's (Nasdaq: AMGN) Enbrel.

Don't pencil in the revenue just yet, though. Tasocitinib still needs to pass larger phase 3 trials in psoriasis and rheumatoid arthritis to get on the market. After seeing the data released yesterday and previous data in rheumatoid arthritis, positive efficacy results seem fairly likely.

The bigger risk for investors is the safety profile. Fewer than 200 patients were enrolled in this trial, but the phase 3 trials for psoriasis will enroll 3,400 patients combined. It's a lot easier to detect a safety issues in the larger patient populations -- that's why the Food and Drug Administration makes drugmakers run them -- and inhibiting the immune system to stop the autoimmune reaction can be a tricky affair.

We may not have to wait long to get a look at the phase 3 rheumatoid arthritis data; Pfizer may release it next month at a medical conference. Investors could certainly use a rash of good news.

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