Genentech Inc. and XOMA Ltd. said preliminary data from a long-term study of their psoriasis drug indicates that most patients who complete one year of therapy maintain a 50 percent or greater improvement in their condition.
The companies are jointly developing a psoriasis treatment called Raptiva (efalizumab, formerly named Xanelim), which is injected subcutaneously each week.
Preliminary data from the 339-patient long-term study showed that 79.1 percent of patients participating for a year maintained a 50 percent or greater improvement in Psoriasis Area and Severity Index (PASI) scores while 61 percent had a 75 percent of greater PASI improvement after a year of participation.
"It appears that once patients get on the drug and continue with it, they continue to do well," Colleen Sweeney, manager of corporate communications at South San Francisco-based Genentech, told BioWorld Today. "Obviously, this is a preliminary look, but it gives us an indication that maybe patients who start off responding will continue to respond with continuous treatment."
Raptiva is a humanized monoclonal antibody designed to inhibit the binding of T cells to other cells types and to target the psoriasis processes.
Raptiva had performed well in two previous pivotal Phase III studies, meeting the primary endpoint of achieving a 75 percent or greater improvement in PASI scores over placebo. (See BioWorld Today, May 25, 2001.)
Genentech and XOMA, of Berkeley, Calif., had planned to file a biologics license application (BLA) late last year, but were delayed when the FDA requested a pharmacokinetic study to confirm the equivalence between materials used for testing and manufacturing. (See BioWorld Today, Oct. 8, 2001.)
Several months later, XOMA's stock (NASDAQ:XOMA) dropped 42.1 percent, or $3.21, to close at $4.42 when preliminary results from the pharmacokinetic study came back looking bad. Genentech's stock (NYSE:DNA) fell 8.8 percent, or $4.29, to close at $44.70 that day. (See BioWorld Today, April 8, 2002.)
Sweeney said the pharmacokinetic study showed that Genentech and XOMA materials were not comparable. "There were higher levels of Genentech materials in the blood," she said.
In light of that news, the companies are hoping that other studies, including a 12-week, 500-patient efficacy trial, will help support Raptiva.
"The additional efficacy study will help us provide more information to the FDA before we file, and if everything goes well, we will be filing by the end of the year," she said.
While those studies are short-term, the long-term study showed that after an initial three months of treatment, 85 percent of patients (n=288) achieved PASI 50 or an Overall Lesion Severity score of "mild."
At six months, 77.1 percent of the 288 patients entering the extended treatment phase maintained PASI 50, and 51 percent of the patients had PASI 75. Of the 265 patients completing the nine-month study, 80.5 percent maintained PASI 50, and 58 percent had PASI 75.
Dennis Harp, a biotechnology analyst with Deutsche Bank Securities in New York, told BioWorld Today that Raptiva likely would be designed for chronic use.
Harp added that if there is demonstration of clear improvement over time, "that can only help attract more patients and doctors to use Raptiva."
Deutsche Bank estimates peak U.S. sales of Raptiva will reach $250 million.
Data from the long-term study were to be presented Saturday by Craig Leonardi, clinical associate professor at St. Louis University Medical School, at the general psoriasis session at the American Academy of Dermatology's Academy 2002 meeting in New York.
Genentech's stock closed Friday at $33.23, up 23 cents, while XOMA's closed at $4.33, up 16.2 cents.