Piper Sandler initiated coverage of Upstream Bio (UPB) with an Overweight rating and $75 price target The analyst believes Upstream’s verekitug has a differentiated mechanism of action that targets the TSLP receptor versus ligand. Accordingly, the TSLP ligand has been de-risked by Tezspire’s 2021 approval in severe asthma, which represents a rapidly growing biologic market opportunity of $7.5B, the analyst tells investors in a research note.