Piper Jaffray analyst Joseph Catanzaro notes that ImmunoGen presented full data from the failed FORWARD I study for lead asset mirvetuximab in FRalpha-expressing r/r ovarian cancer. The analyst believes that focus following the presentation will like fall on the revelation that a change in methodology to assess biomarker positivity may have contributed to enrollment of patients that did not meet the intended threshold for FRalpha positivity. A retrospective analysis showed that if the original screening method had been used, the trial could have been positive per its statistical design, with the absolute effect size on PFS benefit in FRalpha-high patients increasing modestly to +2.4 months vs. +1.5 months per protocol, he adds. Catanzaro has a Neutral rating and a $2.50 price target on the shares.