Aimmune shares sank 5% in early trade today despite a largely positive US FDA advisory committee hearing on Friday for its peanut allergy immunotherapy, AR101; the outcome means that approval in January looks likely. But investors’ reaction shows how prospects for the project, to be branded Palforzia, are still very hard to call, even before considering the usual concerns about a solo launch by a small company. Factors in Aimmune’s favour include a relatively large and motivated pool of patients and a dataset that many believe establishes Palforzia’s safety and effectiveness, at least in the short term. Questions remain about long-term benefits, however, particularly versus peanut avoidance; a critical report by the cost watchdog Icer raised this point earlier in the year and, although it was widely dismissed by the company and supportive analysts at the time, payers will look closely at the issues raised when Palforzia’s price emerges. EvaluatePharma’s consensus revenue forecast shows that the sellside expects commercial success, though even here the spread of numbers shows that views vary considerably. It seems that not all investors want to wait around to find out how AR101 actually fares in the market.