senior analyst says hcv is a sweet spot

TLSR: Going back to HCV for just a moment, what is it about the disease that allows you to derisk a proposed drug so early in a phase 2 trial powered with as few as 100–200 patients, say compared to an oncology candidate?

GM: When you have an oncology asset, most companies will look at a drug in a variety of tumor types. So they will do a phase 1 all-comers’ trial that could include breast cancer, colon cancer and lung cancer, and these are going to be very, very refractory patients. Usually, you’ll see the drug have some activity, and that guides you for the next trial, which would be a dose-finding study. Then you try to figure out if there’s a subset within a certain tumor type that looks good. Then your larger phase 3 trial is oftentimes based on tenuous assumptions when it comes to either overall survival (OS) or progression-free survival (PFS). A lot of companies will go into a phase 3, having very good response rate data, but not really knowing whether that is going to lead to PFS or OS net benefit.

With hepatitis C in a phase 1 or phase 2 trial you gain experience in a much more finite number of variables, and so you can figure out who your best and worst responders are. Oftentimes, if you have data in 100 patients, that actually turns out to be very predictive of something in a much larger phase 3 setting of 500 or 800 patients. Although the rate of clinical trial failures is probably higher due to unforeseen toxicities, you can derisk on the efficacy side, in other words, whether your drug works or not. You can determine that very early in hepatitis C. That’s a lot different than, say, oncology or multiple sclerosis or other biotech markets.