Investigational drug shrinks fibroids in early trials. (Also Reduces Bleeding).

WASHINGTON -- An investigational drug shows great promise not only in decreasing the symptoms associated with leiomyomas, but in shrinking them as well.

Unlike other drugs used to treat fibroids, asoprisnil does not induce a hypoestrogenic state and is not associated with vasomotor symptoms and bone density loss, Dr. Kristof Chwalisz said at the annual meeting of the Society for Gynecologic Investigation.

Dr. Chwalisz, therapeutic area head for women's health at TAP Pharmaceutical Products Inc., Lake Forest, Ill., also presented data from a phase II clinical trial showing the drug's ability to shrink fibroids in a dose-dependent manner. It reduced tumor volume by an average of 36% over the course of 12 weeks.

A selective progesterone receptor modulator (SPRM), asoprisnil is thought to work by inhibiting blood flow at the endometrial level, thus significantly reducing bleeding associated with leiomyomas. SPRMs are a new class of drugs with selective endometrial effects. The compounds suppress endometrial growth without decreasing estradiol levels, so they do not induce hot flashes or cause adverse bone effects. Their target appears to be the spiral arteries, and they either suppress angiogenesis or increase vasoconstriction. Asoprisnil is the first of this class to reach phase III trials.

"This compound could have the potential to reduce the number of surgeries performed each year for symptomatic uterine fibroids," Dr. Chwalisz said, noting that there is now no approved medical treatment for fibroids.

During the 12-week placebo-controlled study 129 women with uterine leiomyomas were randomized to placebo or one of three oral asoprisnil doses: 5 mg, 10 mg, or 25 mg. The women took the drug or placebo once daily for 12 weeks, beginning during ...