As previously reported, RBC Capital analyst Brian Abrahams downgraded Proteostasis to Sector Perform and cut his price target for shares to $5 from $11 following "mixed" data for PTI-801 in CF patients on background Orkambi therapy. In a research note to investors, Abrahams said that while there were signs of activity in the trial, given a lack of clear FEV1 benefit, he believes more work will need to be done to fully de-risk the asset, and does not have enough confidence in the profiles of PTI-428 or PTI-808 to be constructive on shares should PTI-801 ultimately not succeed. He said he is moving to the sidelines until their assets are further de-risked.