Poor preliminary Phase II results of Zenapax as a maintenance agent for psoriasis prompted Protein Design Labs Inc. to decide against further development in that indication.
However, the Fremont, Calif.-based company is studying the humanized antibody in several other indications, a fact that may have kept its stock from diving on the news.
Instead, Protein Design Labs’ stock (NASDAQ:PDLI) shot up $3.28 Thursday, or 21.8 percent, to close at $18.30. In a prepared research note, Bill Tanner, of SG Cowen Securities Corp., rated PDL’s stock as a “buy,” saying it is expected to outperform the market during the next 12 to 18 months.
Since 1997, Zenapax (daclizumab) has been marketed for prevention of kidney transplant rejection by PDL partner F. Hoffmann-La Roche Ltd., of Basel, Switzerland. PDL initially licensed Zenapax to Roche in 1989, but regained rights in 1999 to develop it for autoimmune diseases, Robert Kirkman, PDL’s vice president of business development and corporate communications, told BioWorld Today. PDL does receive royalties.
In the Phase II trial, PDL studied Zenapax as maintenance therapy for patients with moderate to severe psoriasis following treatment with cyclosporine. While Zenapax was well tolerated, it did not prolong the time to recurrence of psoriasis, the primary endpoint.
“It’s hard to know what went wrong, but one possibility would be the dosing we selected,” Kirkman said. “We will stop the indication for the maintenance of remission, but we have not yet made a determination on whether we will look at Zenapax as a primary therapeutic agent for psoriasis that decision will be made after looking at the data and considering all the options.”
On a positive note, Daniel Levitt, president, research and development for PDL, said in a prepared statement that there was a “statistically significant prolongation of remission in the subgroup of patients with moderate psoriasis treated with daclizumab every other week for five doses compared with the placebo control.” The note also said the same regimen was less effective than the placebo arm in patients with more severe psoriasis, with statistical significance.
Meanwhile, PDL has other things going with Zenapax. The company is conducting a Phase II trial in asthma, a Phase II trial in Type I diabetes, a Phase I/II trial in multiple sclerosis and later this year, a Phase III trial in uveitis will commence.
Zenapax is directed at the alpha chain of the human IL-2 receptor (CD25).
The Phase II maintenance therapy for psoriasis was a randomized, double-blind, placebo-controlled trial conducted at 12 centers in the U.S. and Canada. Patients with moderate to severe psoriasis were treated with cyclosporine for one to three months. In this trial, 76 percent of patients achieved remission with cyclosporine, defined as a 75 percent reduction in Psoriasis Area and Severity Index (PASI) score. Patients who responded to cyclosporine were then randomized to receive daclizumab in one of two dosing regimens or placebo.
A total of 127 patients were randomized in the trial. The median baseline PASI score of patients was 14.1 and the median body surface area affected was 20 percent.