Gilead Sciences Inc., whose lead product Vistide is slated for reviewFriday at an FDA advisory panel meeting, said a third Phase II/IIItrial of the drug was halted after a preliminary analysis confirmedpositive findings from two previous studies showing the antiviralnucleotide was safe and effective in treating AIDS-relatedcytomegalovirus (CMV) retinitis.

The trial was conducted by a Studies of the Ocular Complications ofAIDS (SOCA) research group established by the National Institutesof Health. The evaluation was stopped after 64 of the anticipated 90patients were enrolled based on a recommendation from anindependent policy and data monitoring board.

Gilead said it was told by the SOCA group the data revealed Vistide(cidofovir) achieved statistical significance in slowing progression ofCMV retinitis in AIDS patients at two doses (5 mg/kg and 3 mg/kg).However, details were not disclosed. AIDS patients participating inthe trial were newly diagnosed with CMV retinitis.

Gilead, of Foster City, Calif., filed for market approval of Vistide inthe U.S. in October 1995 and in Europe in December 1995 withsafety and efficacy data from two previous Phase III studies: onetested the drug in patients newly diagnosed with CMV retinitis andthe other evaluated Vistide in relapsed patients. Both showed thedrug slowed progression of the potentially blinding disease.

Lana Lauher, spokeswoman for Gilead, said some safety data fromthe third study was submitted to the FDA, but the efficacy results,revealed last Friday, have not been incorporated in the new drugapplication (NDA). A combined antiviral and ophthalmic drugsadvisory committee will review Vistide this week.

In addition to confirming findings of previous studies, the SOCAtrials demonstrated Vistide was effective at a lower dose for newlydiagnosed patients. In the previous trial, safety and efficacy wereproved at 5 mg/kg for that class of patients.

A dose-limiting side effect of Vistide is kidney toxicity and patientsin the SOCA study received treatments to minimize potential forcomplications.

In the two Vistide studies supporting the NDA, median time toprogression, with a 5mg/kg dose, was 120 days for newly diagnosedpatients and 115 days for patients who had relapsed after receivingthe current standard therapies. The drug is administered once a weekfor the first two weeks and then once every other week.

Typically AIDS patients receiving the current standard CMV retinitistreatments, which are administered daily, experience diseaseprogression in 50 to 70 days. Without treatment the potentiallyblinding infection progresses in 22 days.

Anticipation of marketing approval for Vistide, a nucleotidecompound, and excitement about Gilead Science's other drugcandidates have fueled investor interest in the company and helped itraise about $250 million in two equity financings in six months.Another nucleotide drug, GS 840, is expected to begin Phase III trialsthis year for AIDS.

Gilead's stock (NASDAQ:GILD) closed Monday at $35.75, up $1. n

-- Charles Craig

(c) 1997 American Health Consultants. All rights reserved.