Five days on two days off: Biktarvy in pilot FOTO study

12 August 2024. Related: Conference reports, Antiretrovirals, World AIDS 25 Munich 2024.

Simon Collins, HIV i-Base

A small open-label study randomised 60 people on stable BIC/F/TAF to continue daily ART or switch to only taking treatment five days a week.

The same FOTO strategy (Five-On Two-Off) was studied over 15 years ago using Atripla, with all participants remaining undetectable over 52 weeks.

Even though low drug trough levels were reported in some people at some time points, viral suppression was maintained over 52 weeks. See Table 1.

Table 1: ITT FOTO results <50 c/mL   

Bictegravir trough levels were above the protein-adjusted 95%EC target of 162 ng/ml at week 4, 28 and 52 in 90%, 93.3% and 100% of FOTO participants.

Although median BIC trough levels were 649, 835 and 637 ng/mL at weeks 4, 28 and 52 respectively, these were <162 ng/mL in 3 participants at week 4 (85, 116, and 108) and in 2 participants at week 28 (23 vs. 70).

The median intracellular levels of tenofovir-diphosphate were also lower in the FOTO arm at week 4 (103 vs 224), 28 (23 vs 70) and week 52 (79 vs 101).

At week 84, 57/60 participants in the extension phase (control participants switched to FOTO) maintained viral load <50 copies/mL.

Although these results are useful to show the stability of BIC/F/TAF if doses are sometimes missed, results need to be confirmed in larger studies before FOTO could be recommended.

References

1. Lui W-C et al. Five-day-on-two-day-off (FOTO) vs daily BIC/FTC/TAF: a proof-of-concept randomized clinical trial. AIDS 2024.
   https://programme.aids2024.org/Abstract/Abstract/?abstractid=5033
2. Cohen C et al. The FOTO study: The 48 week extension to assess durability of the strategy of taking efavirenz, tenofovir and emtricitabine Five days On, Two days Off (FOTO) each week in virologically suppressed patients. IAS 2009, Cape Town. Abstract MOPEB063.
   http://library.iasociety.org/AbstractView.aspx?confID=2009&abstractId=3046