Biotech Values

[DewDiligence]

VX-950 phase-2 program:

Katie et al: The 24-week dosing that was the subject of the Forbes piece pertains to the phase-2 trial in treatment-refractory patients. This trial will not begin until 4Q06 because six-month animal tox studies started only a month ago.

In treatment-naïve patients, the phase-2 program will test VX-950 for 12 weeks only; this duration of testing is already supported by results from 3-month tox studies and hence it can proceed immediately.

An odd wrinkle of the phase-2 treatment-naïve study is that there will be arms that continue peg-interferon+ribavirin without VX-950 for 12 or 36 weeks following 12 weeks of treatment with VX-950, for a total treatment duration of 24 or 48 weeks. The rationale, as it was explained on today’s CC, is to see if the additional time on peg-interferon+ribavirin will allow the immune system to clean out any remnants of HCV that might remain after reducing the viral load to the limits of detection during the 12 weeks of VX-950. VRTX thinks this treatment epilogue is unnecessary, but they want to test such a regimen in phase-2 to preempt a demand that it be tested later in the development program.

The plan is to begin a phase-3 trial in treatment-naïve patients in mid 2007 that will test for SVR at six months and follow patients for one year. VRTX hopes to augment this with a large phase-2 trial in treatment-refractory patients to begin in 4Q06 so that an NDA submitted in 2008 could seek approval in both patient populations based on one phase-3 and one phase-2 study.