Stifel analyst Stephen Willey says his "gut reaction" to today's more-detailed Sophia data appears to align with how the stock is trading post this morning's presentation. Shares of MacroGenics are down 19%, or $3.55, to $15.17 in midday trading. The analyst found the overall survival data of margetuximab the most disappointing. He had hoped the large absolute median OS benefit in low-affinity CD16A-158 patients favoring margetuximab would offset some of the concern around the clinical relevance of the progression free survival benefit. Unfortunately, however, this benefit appears to be less compelling when viewed in the context of the full Kaplan-Meier curve, Willey tells investors in a research note titled "First Take on SOPHIA Data Presentation - Don't Expect OS to Pick Up the PFS Slack." The analyst continues to believe the Sophia data represents an approvable data set, but he admits the addressable market opportunity is "likely now amplified following today's presentation." The continued perception of margetuximab as an overhang could serve to keep near-term enthusiasm in MacroGenics shares "muted," says Willey. He keeps a Buy rating on the shares.