What happened

ImmunoGen (NASDAQ:IMGN) is up 10.1% at 3:27 p.m. EDT, having been up as much as 13.5% today with no obvious news to justify a double-digit move.

So what

The biotech's shares haven't been this high since last Thursday, when ImmunoGen closed at $3.24.

In other words, while this is a big one-day move, it's not necessarily a reset of the company's valuation. The move is more likely just day-traders piling on perceived momentum after shares fell earlier in the week -- again for no apparent reason. Where it'll stop on Monday is anyone's guess.

Electronic stock chart with map of world in the background

Image source: Getty Images.

Investors interested in focusing on fundamentals should be paying attention to ImmunoGen's lead drug mirvetuximab soravtansine -- specifically a phase 1b/2 trial called FORWARD II testing the drug in combination with Avastin, carboplatin, Doxil, or Keytruda. Management has previously disclosed that the data would be released during the second quarter, which started 12 days ago.

Management also said to expect pooled data from phase 1 trials testing mirvetuximab soravtansine in patients with ovarian cancer, including some data for patients taking steroid eye drops to manage a side effect of the drug.

Ultimately, investors should be focused on ImmunoGen's phase 3 FORWARD I trial in patients with platinum-resistant ovarian cancer that's required to gain marketing approval, but the trial only enrolled its first patient in January, so it'll be a few years until data from that trial is available.

Now what

While investors have a long time to wait for mirvetuximab soravtansine to get approved -- management is shooting for 2020 -- if the data from FORWARD II and the pooled phase 1 data are positive, investors should have more confidence that FORWARD I will ultimately succeed.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.