Janney Capital analyst Debjit Chattopadhyay noted that the de novo Hb increase in 50% of patients in an ongoing Phase 2 study of AG-348 reported by Agios Pharmaceuticals was "robust and clinically meaningful," but added that the lack of mechanistic impact on 2,3 DPG and ATP is "perplexing" and the fact that little to no clinical impact in patients with low Hb was shown is "troubling." The analyst, who thinks the commercial opportunity for AG-348/519 at launch could be about 1,000 patients, translating to a commercial opportunity of $200M-$300M, keeps a Neutral rating on shares and lowered his fair value estimate on the stock to $47 from $52.