Gilead issues letter about virologic failure

Gilead Sciences Inc. in Forest City, CA, has issued a "Dear Health Care Professional" letter describing high rates of virologic failure in patients treated with a once-daily triple NRTI regimen containing Didanosine (ddI, Videx EC), Lamivudine (3TC, Epivir), and Tenofovir (Viread).

Here’s a copy of the Oct. 14 letter from Jay Toole, MD, PhD, senior vice president of clinical research for Gilead:

"Gilead Sciences Inc. is writing to inform you of a high rate of early virologic failure and emergence of nucleoside reverse transcriptase inhibitor [NRTI] resistance associated mutations observed in a clinical study of HIV-infected treatment-naive patients receiving a once-daily triple NRTI regimen containing didanosine enteric coated beadlets [Videx EC, Bristol-Myers Squibb], lamivudine [Epivir, Glaxo-SmithKline], and Tenofovir disoproxil fumarate [Viread, Gilead].

"These new data are consistent with the high rates of virologic failure observed in several recent clinical studies that have evaluated the use of triple NRTI regimens.

"Based on these results: Tenofovir DF in combination with didanosine and lamivudine is not recommended when considering a new treatment regimen for therapy-naive or experienced patients with HIV infection. Patients currently on this regimen should be considered for treatment modification.

"In a 24-week, single-site, pilot study (N=3D24) designed to evaluate the safety and efficacy of a triple NRTI once-daily regimen of didanosine EC (250 mg), lamivudine (300 mg), and Tenofovir DF (300 mg) in HIV-infected treatment-naive patients, Jemsek, et al. (Oral Communication, September 2003) have identified a high frequency of virologic failure (91%), which was defined as < 2 log10 reduction in plasma HIV RNA level by Week 12. Resistance testing was performed on 21 patients; 20 patients (95%) had M184I/V, and 10 of these patients (50%) had K65R in addition to M184V. As a result of this high early failure rate, study enrollment was stopped.

"Suboptimal virologic response has also been reported with the use of the triple NRTI regimen abacavir/lamivudine/zidovudine (Trizivir) (Gulick 2003) and abacavir/didanosine/stavudine (Gerstoft 2003), and similarly early virologic failure and high rates of resistance mutations have been reported with abacavir/lamivudine/ tenofovir DF (Farthing 2003, Gallant 2003). Overall, these studies demonstrate a lower response rate in patients on a triple NRTI regimen.

"Furthermore, they indicate that patients who achieve viral suppression on a triple NRTI regimen have a higher rate of virologic failure.

"Please report all adverse events, following or coincident with the use of Viread, to Gilead Global Drug Safety at (800) GILEAD-5, option 3 — or to the FDA MedWatch Program by phone at (800) FDA-1088; by fax at (800) FDA-0178); by mail (using postage-paid form) to MedWatch, FDA, 5600 Fishers Lane, Rockville, MD 20852-9787; or via the Internet at www.accessdata.fda.gov/scripts/medwatch."