The Psoriasis Wars

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Dueling news releases from Amgen (Nasdaq: AMGN) and Abbott Laboratories (NYSE: ABT) on their psoriasis (an immune-mediated chronic skin disease) drug candidates show that the psoriasis wars are heating up. With a market of more than 1.5 million moderate-to-severe psoriasis sufferers, it's a large target for the big biotech and pharma companies.

Amgen is touting the latest data from its Phase III trial of Enbrel, a drug that doubles as a rheumatoid arthritis (RA) treatment. The data show that 49% of higher dose patients achieved the benchmark 75% improvement in psoriasis severity (PASI 75). Interestingly, after 12 weeks, 54% of the high-dose patients who were "stepped-down" to half the dose for the next 12 weeks achieved the benchmark improvement. With Enbrel, improvement started at about the second week of twice-weekly injections.

In comparison, Abbott pushed promising Phase II results from its candidate, Humira, another RA drug being pressed into double duty as a psoriasis treatment. Similar to Enbrel, more than 50% of patients receiving Humira reached the benchmark PASI 75 score.

However, they achieved this level with every other week dosing, compared to Enbrel's twice-weekly dosing. When dosing was stepped up to weekly administration, 76% of patients achieved "clear" or "almost clear" assessments by a different physician's test. Additionally, when the dose was increased, 80% of patients achieved the PASI 75 score.

Judging on these results alone, it appears that Humira has an advantage over Enbrel. However, Humira is only in Phase II testing, so Enbrel has a head start on the approval process.

Waiting in the wings is perhaps the most effective medicine of them all in Johnson & Johnson's (NYSE: JNJ) Remicade, also in Phase II trials. Depending on the dose, more than 70% to nearly 90% of patients achieved PASI 75 in recent studies. There are concerns, though, that patients may produce antibodies to Remicade and limit its effectiveness. Also, three long (two hour) IV infusions are required to receive Remicade.

Abbott, Amgen, and J&J aren't the only players in the psoriasis market. Genentech (NYSE: DNA) partnered with Xoma (Nasdaq: XOMA), and Biogen IDEC (Nasdaq: BIIB) already have drugs on the market with Raptiva and Amevive, respectively. Raptiva brought up to 39% of patients to the PASI 75 level after 12 weeks. Amevive brought just 21% of patients to this level, but Amevive has some of the longest-lasting effects in patients.

Since all these companies have big pipelines, investors needs to carefully analyze the other products and drug candidates and shouldn't make an investing decision based solely on the psoriasis market. If I were handicapping this race, I think Enbrel will dominate the market at first. I assume Amgen will develop a once-weekly formulation to compete with Humira's dosing. I also suspect that many patients will not want to sit in the doctor's office at the other end of an IV line for two hours, unless they are not responding to the other agents. As a result, Remicade will probably not dominate the market, unless J&J can figure out a different formulation.

David Nierengarten , Ph.D., works with a biotechnology venture capital fund. He often contributes to Fool.com, is an active member of the TMF community as DavidMN, and enjoys the Biotechnology discussion board. He owns shares of Johnson & Johnson.