Replies to post #114917 on Biotech Values

[DewDiligence]

Thanks for the clarification re NEJM. This could be a nice ancillary indication for Promacta, but I doubt that the incremental revenue will be material for a company of GSK’s size.

[dewophile]

re promacta in HCV

Up to 12 weeks of antiviral therapy were completed by 36% (5/14), 53% (10/19) and 65% (15/23) of patients in the 30mg, 50mg and 75mg PROMACTA groups, respectively, versus 6% in the placebo group

it should be noted this was on an ITT basis. the numbers look less impressive if you note that only 4/18 placebo patients started therapy (i.e 25% of patients on placebo who initiated therapy were able to complete 12 weeks)

this is going to be the relevant metric in the phase 3 because ALL patients get promacta pretreatment (entry criteria is thrombocytopenia), and are then randomized to SOC or SOC+promacta
also note that in the phase 3 the entry criteria for initiating therapy is a higher platelet count than in the phase 2 - and since none in the placebo arm in the phase 2 started therapy with >100K platelets dropouts in placebo are expected to be lower in the phase 3
lastly i would be a bit concerned about a drug that has a black box warning for hepatotoxicity in a population of patients with liver disease

on the plus side thrombocytopenia is relatively common during treatment and if successful i don't see why the drug won't see off label use in patients who develop thrombocytopenia on treatment (i.e. in practice use may not just be limited to patients with pretreatment thrombocytopenia)

the other thing to watch out for is the evolving treatment landscape - if interferon is supplanted by DAAs the need for promacta during treatment probably disappears. also inf lambda does not cause myelosuppression so if that makes it to market the commercial opportunity will also shrink