Biotech Values

[DewDiligence]

Musings on Telaprevir approval based on PROVE-3:

>VRTX – Do you think if Prove-3 is in the 16% range that would be compelling enough for approval for that [second-line] patient population just on the 2B results?<

For the sake of simplicity, let’s restrict the discussion to the “24+24” arm of PROVE-3 because this is the arm most likely to show impressive results.

The problem with comparing PROVE-3 to Roche’s REPEAT study (#msg-24270257) is that the PROVE-3 includes anyone who failed to have an SVR in the first line while REPEAT was restricted to patients who never responded to first-line therapy, i.e. patients who never became PCR-negative. Clearly, the patient pool in REPEAT was more difficult to treat than the patient pool in PROVE-3.

Still, I would say that if VRTX can achieve a 30% SVR in the 24+24 arm of PROVE-3 with no major safety problems, they would be a big favorite to get approval in the second-line setting without further trials.

With a 25% SVR rate, I think the chance of approval without additional trials would be about even money.

With an SVR rate of 20% in the 24+24 arm of PROVE-3, this arm would be roughly comparable to the efficacy attained by SGP using 48 weeks of second-line therapy with Peg-Intron (#msg-23123038). (SGP actually got a 23% SVR rate, but this rate was boosted to some degree by including in the trial some patients who had received non-pegylated interferon in the first line.) Hence, I think a 20% SVR rate in PROVE-3 would still give VRTX a fighting chance of approval without further trials, but it’s more likely that the FDA would ask for phase-3 data in the second-line setting.

With an SVR rate of less than 20%, I think the chance of approval based on PROVE-3 would be slim to none.

Here’s a table that summarizes the above:

 
      Probability of 2nd-line 
 SVR   approval w/o phase-3 
 30%+    80%+ 
 25%     50% 
 20%     20% 
 <20%    Slim to none

JMHO, FWIW