Biotech Values

[DewDiligence]

Rationale for IDX320 HCV Protease Inhibitor

IDIX revealed at the JPM conference last week that IDX320 is not the same drug as IDX316 (as I previously thought); rather, IDX320 is a more potent and longer lasting protease inhibitor with the same macrocyclic structure.

While IDIX was talking about IDX316 to investors last year, IDX320 was lurking as the backup compound. Presumably, IDIX never mentioned IDX320 to investors until last week in order to keep the competition off guard.

JP Sommadossi expects IDX320 to be effective at a cumulative daily dose of 50-400 mg, which is extremely low for an HCV protease inhibitor. By comparison, the daily doses of Telaprevir and Boceprevir being tested in phase-3 are 2250 mg and 2400 mg, respectively. The lower dose of IDX320 dose enhances the practicality of combining IDX320 with other oral agents in an all-in-one pill similar to Atripla in the HIV market; such a product is the stated goal of most major developers of HCV drugs.

The following graphics from the JPM webcast last week present the rationale for IDX320:



In summary, IDX320 is a better candidate than IDX316 (the PI that IDX320 superseded) insofar as it:

• is more potent against the major HCV genotypes.

• has better oral bioavailability (nearly 100% for IDX320 vs ~20% for IDX316: #msg-37246670).

• has a longer half-life (8-10 hrs for IDX320 vs 4-5.2 hrs for IDX316: #msg-37246670), which facilitates qD dosing.