Antibody therapy appears powerful against psoriasis

A biotechnology therapeutic for psoriasis appears to clear most of the symptoms in many patients, according to recently published results of clinical trials.

The therapeutic is “ixekizumab,” an antibody that inactivates a “cytokine” or signaling molecule produced by a subset of white blood cells called type 17 helper T cells.* Researchers at the pharmaceutical company Eli Lilly and university colleagues published the Phase 2 results in the New England Journal of Medicine in March. I learned about ixekizumab from a JACI paper published last week, reporting on aspects of the earlier Phase 1 trial.

Th17 are thought to be overactive in psoriasis patients. That is not the case in patients with atopic dermatitis, for whom helper T cells of types 2 and 22 generally exist in higher numbers and are more active than they are in the average person. The authors of the JACI paper speculate that tailored antibody therapy could prove as effective in controlling eczema as ixekizumab has for psoriasis.

In the Phase 2 trial, researchers injected 142 patients with various doses of ixekizumab at regular intervals over a 16-week period. They found that, for all but the lowest dosage, the antibody mostly cleared up psoriasis—as measured by a standard set of measures—for more than 75% of the patients in the trial.

The authors did not present data showing how long the effects lasted. But they did note that hardly anyone dropped out of the trial because of adverse effects. (From what I can tell, those who dropped out came from the lowest dosage group.)

Nor was there any indication how expensive ixekizumab might be. I imagine that, compared to drugs such as steroids, custom-produced antibodies would be extremely expensive for patients and insurers.

Nevertheless, the results are unusually positive. A blog post on the JACI website called the results “near-astonishing.” Keeping in mind that all trials and papers published on them are bankrolled by pharma companies (who else can pay for clinical trials?) this area of antibodies against T cell cytokines seems worth watching closely.

* I am pretty sure that Th17 cells are not the seventeenth type of helper T cells. The only ones I've ever heard of are Th1, Th2, Th17, and Th22. I don't know why the last two are numbered 17 and 22 instead of 3 and 4. This sort of thing is why I got out of immunology.