96-week RESIST Data Show Boosted Tipranavir Produces Superior and Durable Treatment Response

In the RESIST 1 and 2 studies, ritonavir-boosted tipranavir/ritonavir (Aptivus) demonstrated potent activity and superior efficacy relative to comparator boosted protease inhibitors (PIs) in highly treatment-experienced patients at Weeks 24 and 48.

At the 46th Interscience Conference on Antimicrobial Agents and Chemotherapy, taking place this week in San Francisco, researchers presented 96-week data on virological responses in the 2 studies.

Study participants had prior experience with at least 3 classes of antiretroviral drugs (including at least 2 PI-based regimens) and had at least 1 primary PI-resistance mutation. Patients were randomized to receive 500/200 mg tipranavir/ritonavir or a comparator PI plus an optimized background regimen (OBR). Treatment response rates, time to treatment failure, and virological response rates (below 400 and below 50 copies/mL) were determined.

Results

1483 patients were randomized: 746 to tipranavir/ritonavir and 737 to comparator PIs.

20% of participants also took enfuvirtide (T-20; Fuzeon).

In an intent-to-treat analysis at Week 96, treatment response (viral load reduction of at least 1 log) rates were 26.7% in the tipranavir/ritonavir arm and 10.4% in the comparator PI arm (P < 0.0001).

26.9% of patients achieved viral loads below 400 copies/mL in the tipranavir/ritonavir arm, compared with 10.7% in the comparator PI arm.

The corresponding percentages achieving HIV RNA below 50 copies/mL were 20.4% (tipranavir/ritonavir) and 9.0% (comparator PI) (P < 0.0001).

In patients taking enfuvirtide, proportions of patients with viral load below 400 and below 50 copies/mL for were 38.2% and 28.8% in the tipranavir/ritonavir arm, compared with 14.1% and 12.6% for comparator PIs (P </= 0.0002).

The median time to treatment failure was 115 days in the tipranavir/ritonavir arm and 0 days in the comparator PI arm (P < 0.0001).

Conclusion

According to the researchers, these results confirm the durable superiority of tipranavir/ritonavir versus comparator PI regimens in highly treatment-experienced patients. "Tipranavir/ritonavir plus OBR was significantly better than comparator PI/ritonavir in achieving Week 96 treatment and virologic responses and delaying treatment failure," they wrote. "Combining tipranavir/ritonavir with another active agent resulted in a greater rate of virologic response in this population."

AIDS Healthcare Foundation, Los Angeles, CA; Dupont Circle Physicians Group, Washington, DC; Duke Univ. Med. Ctr., Durham, SC; Royal Free Hospital, London, U.K.; Università Cattolica del Sacro Cuore, Roma, Italy; Fundación Huesped, Buenos Aires, Argentina.

09/26/06

Reference
C Farthing, D Ward, C Hicks, and others. Tipranavir/r Demonstrates Superior and Durable Treatment Response Compared with Comparator PI/r in Highly Treatment Experienced (HTE) Patients: Week 96 RESIST 1 and 2 Results. 46th Interscience Conference on Antimicrobial Agents and Chemotherapy. San Francisco, CA. September 27-30, 2006. Abstract H-1385.

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