1. Based on data from the final Phase 1b ACH-1625 cohorts, additional doses at the QD level are warranted (presumably below 600mg QD) in the upcoming Phase 2a trials. I should note that later in the call during Q&A, management was hesitant to firmly commit to testing additional QD cohorts in the upcoming Phase 2a trials. Among other things, management noted that they are still awaiting final PK data from the Phase 1b final cohorts, so presumably they are just being conservative in not affirming definitively that additional QD cohorts will be tested in the upcoming Phase 2a trials.
2. Phase 2a trials for ACH-1625 still expected to commence in September 2010 and will likely test out to 28 days in genotype 1 HCV patients. Results from these trials should be available 1Q2011. During Q&A, a caller noted that historical discussions between himself and likely partners for ACH-1625 have revealed that these partners consider 12 week safety data (presumably clinical, not just pre-clinical) as important. ACHN does not expect to test out to 12 weeks in the upcoming Phase 2a because it's such a big leap to go from 5 days to 12 weeks, but could potentially roll over the 28 day data into 12 week data given the adaptive trial design protocols that they expect to use that were also used in Phase 1 trials. Notwithstanding, I inferred that ACHN will stick to 28 day testing of ACH-1625 in the upcoming Phase 2a trials.
3. An EASL poster (http://www.achillion.com/PL/pdf/ach1625_clinica.pdf ) showed more detail behind the mild and moderate AEs experienced by ACH-1625 and placebo-treated patients in the Phase 1b trials (there were no SAEs and no patients discontinued treatment due to the AEs). The linked poster shows 3/6 patients in the 500mg BID ACH-1625 cohort had pruritis (rash), although 0 of 6 patients in the 600mg BID ACH-1625 cohort experienced this. By contrast, 1/6 patients in the placebo groups experienced pruritis. I imagine this caused some of the sell-off in ACHN immediately after EASL, although I don't think it's clear that this data proves that ACH-1625 causes a rash. Also, the rash experienced by these patients was a mild/moderate AE and not an SAE. Finally, inasmuch as ACHN demonstrated roughly equivalent efficacy in a 600mg QD cohort (close to half the daily dose of those where rash was reported), it's presumable that ACHN will have an even greater room for safety margin of error with ACH-1625 going forward.
4. Dr. Doug Dietrich, whom I believe may have been a clinical investigator in the Phase 1b trials, commented on the recent results during the call. He believes that the results clearly indicate that ACH-1625 will be a QD drug. He believes that the tail of sustained viral suppression after cessation of ACH-1625 treatment (i.e. not a quick viral rebound) is unique among HCV PIs and is similar to that of a nuke. He also believes that this may be evidence that ACH-1625 is highly resistant to resistance development.
5. Dr. Dietrich also believes that this data moves ACH-1625 into the big leagues of the second round of HCV PIs, alongside TMC435 (Medivir/JNJ) and BI 201335 (Boehringer Ingelheim). These two HCV PIs are apparently the only ones to demonstrate the potential for QD dosing, although ITMN-191 may be able to as well with ritonavir boosting. (Dr. Dietrich seemed to express some skepticism regarding the safety of ITMN-191, however, as has been previously discussed on here.) He also pointed out the tail of sustained viral suppression as possibly being a differentiating point for ACH-1625 among these drugs.
6. Management believes that the new data greatly enhances its strategic position with respect to the partnering of ACH-1625 and the QD attribute is quite a bit more important to most potential partners than ACHN initially believed. There was no clear indication on whether management expects to partner ACH-1625 before the start of Phase 2a trials in September or after. Mangement believes that 28 day data can result in at least 50% greater value for partnering purposes. ACHN still in discussions with north of a half-dozen partners and is open to partnering before or after the start of Phase 2a.
7. Dr. Dietrich placed a large degree of significance on the ability to have QD dosing, namely due to patient compliance matters. Also, he commented on the fact that it may be even more important given that there is the potential that ribavirin itself can potentially be dosed QD as it has a half life of 320 hours. Studies are ongoing now to prove this apparently.
8. ACHN will not seek to participate in ex-U.S. commercialization of ACH-1625, but that could be a possibility for the U.S. itself.