Antiretroviral Therapy II (Poster Session 194)

  • Long-Term Efficacy and Safety of Emtricitabine (FTC) in HIV-Positive Adults Switching from a Lamivudine (3TC)-Containing HAART Regimen
    Abstract 1932
    Authored by C. Van Der Horst (UNC, Chapel Hill, NC), C. Benson (Univ. of Colorado Health Sciences Center, Denver, CO), A. Rodriguez (Univ. of Miami, Miami, FL), L. Hulett (Triangle Pharmaceuticals, Inc.), C. Wakeford (Triangle Pharmaceuticals, Inc.), J. Quinn (Triangle Pharmaceuticals, Inc.)
    View the original abstract

Emtricitabine (FTC) is an investigational NRTI which has a greater than five-fold potency against HIV compared to 3TC, with which it shares a similar resistance pattern. Its long half life allows once-daily dosing. The drug is currently in phase III clinical trials. This poster reviewed the long term safety and efficacy of emtricitabine in a study of over 200 patients.

Study 303 randomized patients who were currently on 3TC-containing regimens to either continue 3TC or switch to emtricitabine. At the end of the 48-week study, they were offered the opportunity to continue emtricitabine treatment in a study extension. The follow-up for efficacy and safety continued out to 72 weeks.

Two hundred fourteen patients were randomized to receive emtricitabine. Patients who had a viral load <400 copies elected to continue the drug after week 48. One hundred seventy-nine patients maintained viral suppression of less than 400 copies at week 72, and 157 had viral loads of less than 50 copies. The drug-related severe or potentially life-threatening side effects were five percent and less than one percent respectively. Asymptomatic and transient elevations in creatine phosphokinase (CPK) were the most commonly observed adverse effect.

The results of this study suggest that emtricitabine is safe and effective. Additionally, its once-daily dosing is certainly an advantage. The major challenges facing emtricitabine for clinician and patient acceptance are:

  1. its resistance pattern is identical to 3TC;

  2. 3TC is by and large an extraordinarily well tolerated drug; and

  3. 3TC will likely be approved for once-daily dosing soon.

Nonetheless, we eagerly await the results of the pivotal phase III study of emtricitabine, which compared emtricitabine with d4T, both in combination with ddI and efavirenz. This large double-blind, randomized trial has completed enrollment, and may have results for preliminary presentation in 2002.