Replies to post #97104 on Biotech Values

[mcbio]

Re: ACH-1625

No, because 26 hours is not that long—it’s just about perfect for qD dosing. ACH-1625, on the other hand, has a half-life of several days, which is suboptimal for an oral drug.

Do we know for certain that the half-life is several days for ACH-1625? I realize that the HCV virus takes several days to begin to rebound once ACH-1625 treatment is ceased whereas the virus quickly rebounds once treatment with other PIs is ceased. However, isn't it possible that ACH-1625 has suppressed the virus sufficiently enough that it need not be active in the body to keep the virus in check? I.e., the virus is suppressed enough to where it needs more time to properly rebound.

Also, assuming half-life is in fact several days, couldn't ACHN push the ability to only dose ACH-1625 once every several days to prospective partners? I.e., who needs qD when we have once every several days' dosing? I guess that wouldn't be able to be co-formulated into one HCV drug when the other components must be taken daily. Also, for some patients that do have some reaction, I guess there's still the issue of having to wait several days for the drug to clear.

I do see your point on how a long half-life could be a potential negative for a partner, but I still think ACHN has a decent chance to land a nice deal for the drug. I think there are plenty of positives with the drug to hopefully outweigh that one potential negative. I also don't think the market is really pricing in any positive expectations for ACH-1625 given ACHN's $90M market cap. (Obviously, there's still ACH-2684 too.)

I would like to check back on ACHN's pre-clinical data to double-check the half-life of ACH-1625 in animals, keeping in mind the discrepancy of half-life of IDX320 in humans vs. animals.

p.s. I had a feeling you would bring up ACH-1625 :- )

LOL

p.s. Given the recent appreciation of IDIX coupled with the depreciation in ACHN, IDIX actually represents about a 50% greater position in my biofolio than ACHN. I'm still not selling any IDIX shares though.

[turtlepower]

ACH-1625, on the other hand, has a half-life of several days, which is suboptimal for an oral drug.

I don't remember any clinical information that directly leads to the conclusion that the half-life was several days. Slide 17 from the link below appears to indicate a half-life of a few hours for a 50mg/kg dose with the caveat that the dosing was done in rats

http://www.achillion.com/PL/pdf/1625_0905.pdf

and this is part of the conclusion of a ach-1625 presentation at EASL in april

While active uptake is an apparent mechanism for liver partitioning, the data show that < 1% of the dose remains in the liver after 24 hr post dose, indicating that elimination/redistribution of the drug occurs. There was no indication of prolonged half-life in the liver compared to plasma.

http://www.natap.org/2010/EASL/EASL_69.htm

What is the basis for your assertion that the half-life is "several days" for ACH-1625? TIA