• Efficacy of Quad Therapy in Antiretroviral-Naive Adults With Very Low CD4 Cell Counts: The Tetra Study
  Authored by Wilkins E., Gazzard B., Easterbrook P., Gordon D., Loughrey U., Bhatowa K., and Cheesbrough A.
  Poster P13

It is well known that antiretroviral-naive patients with low CD4 counts are less likely to respond well to an initial triple-drug regimen than patients who possess higher CD4 counts at time of initiation of therapy. In this context, the Tetra study represents an attempt to determine whether first-line treatment with four instead of three drugs will yield superior results. Accordingly, patients with CD4 counts less than 200 received Trizivir (ZDV/3TC/ABC) in combination with the NNRTI efavirenz (EFV, Sustiva). In the event of efavirenz-related toxicities, patients were permitted to switch to Trizivir/nevirapine (NVP, Viramune), and this was included in an intent-to-treat (ITT) analysis. Results were analyzed after 4, 8, 16 and 24 weeks. The data showed that over 50 percent of patients achieved viral loads below 50 copies RNA/ml after 24 weeks. During this time, the mean CD4 count rose from 66 to 211.

Of the 55 subjects enrolled, 82 percent had CD4 counts less than 100 at baseline (mean = 64), while baseline viral load was 554,548 RNA copies/ml plasma. The authors believe that the success rate of more than 50 percent of patients achieving less than 50 copies RNA/ml at week 24 will probably continue to increase during follow-up and that the regimen of Trizivir/EFV represents a good option in naive patients with profound immunosuppression.

Interestingly, the results of an as-treated analysis proved equally convincing. This was based, in part, on individuals who were intolerant of efavirenz and who switched to nevirapine and who had less than 50 copies viral RNA/ml at the time of the switch.

This is an important study that is one of the first of its type involving initiation of antiviral therapy with a four-drug regimen. Accordingly, it is interesting that this study was not selected for oral presentation. However, it is also likely, given the abstract deadline for this conference (late July 2002), that 48-week (or at least 36-week) data might have been available for presentation at this meeting had the authors of the study so desired. Nor did they apparently avail themselves of the opportunity to submit this paper for consideration as a late-breaker abstract containing results accumulated over a longer period of time.

One suspects that they may have preferred to save these data for a different meeting to take place during 2003. The data presented here should be considered to be both preliminary and encouraging.