The irony here is that SGEN's share appreciation is off of the potential of a small molecule compound which they acquired and tested in combination with Immunogen and Roche's T-DM1 rather than anything they developed themselves. Props to them for making a wise investment, but this speaks better of a company as a biotech hedgefund than a R&D house (not that it's illegitimate to make profits like this of course.)
I still think Immunogen's R&D is undeniably superior to SGEN's and that this is will eventually translate into share appreciation. They have kept a surprising number of irons on the fire in addition to IMGN 853, in IMGN632 and IMGC936. It is promising that they continue to expand enrollment for 632 which bodes well for safety; SGEN's DGN armed ADC had its enrollment suspended and the drug ultimately failed due to delayed toxicity. We'll see how efficacy turns out soon, but I am looking forward to it given the CR's and CRi's they got last year as well as the theoretical promise of 10-20x potency of this linker/payload over 779.