Biotech Values

[DewDiligence]

VX-950 trial-design notes from VRTX’s GS conference:

Because the GS webcast was mostly Q&A, there was a lot of color on the design parameters of the phase-3 VX-950 trials. There are three main cases, depending on what happens in the phase-2b trials called PROVE-1 and PROVE-2 (#msg-11248731), which together are testing 580 treatment-naïve, genotype-1 patients:

1. If the SVR rate after 3 months of 950+ifn is <65%, Boger will be disappointed and VRTX will probably have to drop the idea of stopping VX-950 after only three months. In this case, the phase-3 trials will almost certainly include one or more arms that test 950+ifn (and perhaps ribavirin) for at least 6 months.

2. If the SVR rate after 3 months of 950+ifn is >=85%, Boger will be delighted and VRTX will probably forego trying to get the SVR rate even higher by testing 950 treatment for longer than 3 months. In this case, the phase-3 trials will effectively become safety trials rather than efficacy trials and they will include a SoC arm only to the extent needed to establish that 950+ifn is as safe as SoC for a 3-month duration.

3. If the SVR rate after 3 months of 950+ifn is >=65% and <85%, Boger will be neither disappointed nor delighted and VRTX will have to include manifold arms in the phase-3 trials to ferret out the optimal treatment regimen. In this case, the phase-3 trials will compare the efficacy of 3 months of 950+ifn vs 6 months of 950+ifn. The role of ribavirin and the use of SoC following 3 months of 950+ifn remain open questions.

Dew