ICI PHARMA ZOLADEX LAUNCH SET FOR JAN. 15 FOLLOWING LATE 1989 APPROVAL; FIRM WILL PIT LHRH ANALOG AGAINST TAP’s LUPRON IN PROSTATE CANCER MARKET

ICI Pharma will launch Zoladex on Jan. 15, following the late Dec. 29 approval of the monthly injectable luteinizing hormone releasing hormone (LH-RH) analog for the treatment of advanced prostate cancer. Zoladex (goserelin acetate) is the second cancer product for ICI Pharma and will be marketed along with ICI's breast cancer drug Nolvadex by the company's 60-rep oncology sales force. Zoladex will appear on the market almost one year after the approval of Takeda Abbott Pharmaceutical's (TAP) Lupron Depot, a monthly dosage form of the company's LH-RH analog Lupron (leuprolide acetate). Lupron was originally approved in 1985 for daily administration. Zoladex received a 1C rating from FDA, which indicates no therapeutic advantage over existing therapies. A question mark raised by the Zoladex approval is the effect the new LH-RH analog will have on Schering's Eulexin (flutamide), which was approved in January 1989. Eulexin is indicated "for use in combination with LH-RH agonistic analogs (such as leuprolide)." ICI has not yet conducted studies with the combination. The combination of Eulexin with Lupron demonstrated a 25% increased survival rate over that of Lupron alone in a study conducted by the NCI ("The Pink Sheet" Feb. 6, T&G-5). Like Lupron, Zoladex is indicated for "the treatment of advanced carcinoma of the prostate," with the added statement that "Zoladex offers an alternative treatment of prostatic cancer when orchiectomy [castration] or estrogen administration are either not indicated or unacceptable to the patient." Therapies for prostrate cancer have included surgical castration and treatment with DES (diethylstilbestrol). Zoladex is administered in a 3.6 mg dose by subcutaneous injection "with continuous release over a 28 day period." The drug is dispersed in a copolymer matrix. Labeling explains that "chronic administration of Zoladex leads to sustained suppression of pituitary gonadotropins, and serum levels of testosterone consequently fall into the range normally seen in surgically castrated men approximately 2-4 weeks after initiation of therapy." In controlled trials comparing Zoladex and orchiectomy, the two treatments were found to be equally effective. Additionally, "duration of survival was similar between the two treatment arms in a major comparative trial," labeling states. Adverse reactions reported in the trials were "rarely severe enough to result in the patients withdrawal from Zoladex," labeling notes, and "were due to the expected physiological effects from decreased testosterone levels." Side effects included hot flashes, sexual dysfunction and decreased erections. The major contraindication for both Zoladex and Lupron Depot is the use in "women who are or may become pregnant" due to the potential abortifacient effects of the drugs. However, while Lupron Depot produced an increase in major fetal abnormalities in rabbits, Zoladex labeling states that "there was no evidence that Zoladex possessed the potential to cause teratogenicity." Studies suggest that LH-RH analogs may have potential use in the treatment of pelvic tumors in women. TAP has been pursuing an indication for Lupron for the treatment of these tumors, leiomyoma uteri. In October, FDA's Fertility and Maternal Health Drugs Advisory Committee recommended against the new indication for Lupron because TAP's clinical trials showed that Lupron reduced the size of the uterine tumors but was not able to completely eliminate them.