XOMA Ltd.'s stock plunged 35.1 percent Tuesday when the firm said preliminary data from a Phase II trial of XMP.629 gel in the treatment of acne was inconclusive.
The firm's stock (NASDAQ:XOMA) fell $1.23 to close at $2.27.
While the candidate appeared to be safe and well tolerated, Deb McManus, XOMA's manager of corporate communications, told BioWorld Today there was no statistical significance showing any difference between the patients using XMP.629 and those using the vehicle gel in the control group.
XOMA will not pursue development in acne, she said, adding that the candidate likely will be studied by dermatology experts to determine whether it has any other uses.
XMP.629, discovered by Berkeley, Calif.-based XOMA, is a synthetic peptide compound derived from bactericidal/permeability-increasing protein (BPI), a human host-defense protein that is part of the body's line of defense against invading microorganisms. The compound is designed to kill acne-causing bacteria, the company said.
XOMA's Phase II study was a double-blind, randomized, controlled trial that enrolled 253 patients who were dosed with either placebo or one of three dosages of an XMP.629 gel (0.01 percent, 0.05 percent and 0.1 percent), administered nightly for 12 weeks.
The primary endpoint was to compare the percentage change from baseline at week 12 in inflammatory lesion counts, non-inflammatory lesion counts and total lesion counts between patients applying XMP.629 gel and those receiving vehicle gel. The study also evaluated the percentage of patients who were clear or almost clear after 12 weeks of treatment.
McManus said there were patients who were clear after 12 weeks, but not enough to warrant moving forward with XMP.629.
At the July American Academy of Dermatology meeting in New York, XOMA reported results from Phase I studies showing that use of the compound in healthy volunteers and acne patients caused no significant skin irritation, lacked systemic absorption and showed a reduction in lesion counts as early as two weeks after daily dosing.
In preclinical studies, XOMA evaluated antibacterial activity of XMP.629 against P. acnes and other skin flora. It was determined that the compound, in a proprietary formulation buffer, showed bactericidal activity against P. acnes, including strains resistant to other antibiotics such as erythromycin or clindamyacin, the company said.
Meanwhile, XOMA and partner Genentech Inc., of South San Francisco, expect Raptiva to be cleared for marketing in Europe during the third quarter. Raptiva (efalizumab) is approved in the U.S. as a treatment for chronic moderate to severe plaque psoriasis in adults aged 18 years or older who are candidates for systemic therapy or phototherapy.
Serono SA, of Geneva, has rights to Raptiva outside the U.S., except in Japan, where Genentech has rights.
Approval in Europe requires Genentech to pay XOMA a milestone. McManus said the companies would not disclose the amount.