Achillion said the patient with elevated liver enzymes and bilirubin levels had significant liver damage at baseline due to "binge" drinking and use of cannabis and ibuprofen -- all mitigating factors that could contribute to liver toxicity. This meaningfully lessens my anxiety about sovaprevir, as does the fact that the highest 800 mg dose will not be used in future studies. Nonetheless, investors should remain vigilant for possible signals of hepatic toxicity as additional patients are treated. Sovaprevir may actually have some safety advantages, at least over marketed protease inhibitors. Unlike Vertex Pharmaceuticals' ( VRTX) first-generation compounds Incivek or Merck's ( MRK) Victrelis, the drug does not cause any significant rash. That's a definite plus, especially since future hepatitis C development efforts seem likely to rely on combinations of multiple direct acting antivirals. ACH-3102 Achillion is also developing ACH-3102, an NS5A inhibitor in the same class as Bristol-Myers' daclatasvir (formerly BMS-052) and Abbott's ( ABT) ABT-267. Although clinical data for the drug remain limited, ACH-3102 has reasonable efficacy and an intriguing resistance profile, retaining potency against mutations to which daclatasvir seems sensitive. For those not obsessing over hepatitis C, ACH-3102's induces a 3.52 log to 3.93 log reduction in viral load after a single dose, which compares favorably to ABT-267. The combination of solid efficacy and a robust resistance profile could prove a distinguishing characteristic. Within the next few months, Achillion will initiate a dose-ranging Phase IIa study of sovaprevir plus ACH-3102 and ribavirin in treatment-naive patients with genotype 1 disease, the most common variant found in the U.S. The company also plans to initiate studies of ACH-3012 plus ribavirin and ACH-3012 plus sovaprevir next year. These studies set up 2013 as a catalyst-rich period for Achillion. As investor attention shifts from Hurricane Sandy to next month's American Association for the Study of Liver Diseases (AASLD) conference, hepatitis C will likely yet again receive widespread scrutiny. Achillion won't present any major new data at the conference, but the company could benefit from investor excitement about other multi-drug combination regimens that exclude a nucleoside polymerase inhibitor, such as Abbott Laboratories' AVIATOR study. Scheduled as a late breaker presentation at AASLD, AVIATOR combined three direct acting antivirals (along with ribavirin) -- a protease inhibitor, NS5A inhibitor, and non-nucleoside polymerase inhibitor -- and showed SVR12 rates in the 93% to 99% range, depending on the patient subgroup. Presentation of these data will further raise the profile of "non-nuc" treatment alternatives, which could benefit Achillion.