What happened

Shares of ImmunoGen (NASDAQ:IMGN) closed down 10.6% on Thursday on no apparent news. The volatile biotech stock is, well, volatile. It's not exactly the first time we've seen a double-digit move on no news.

So what

ImmunoGen's investors are in a wait mode, having fully enrolled the phase 3 Forward 1 clinical trial testing mirvetuximab as a monotherapy in platinum-resistant ovarian cancer. Data from the trial is expected next year. If positive, the data should be enough to gain regulatory approval for mirvetuximab.

The word volatility written under the curled piece of red torn paper

Image source: Getty Images.

Between now and then, investors can expect some earlier-stage data for mirvetuximab. The phase 2 trial, dubbed Forward 2, will read out data for patients treated with mirvetuximab and Merck's (NYSE:MRK) Keytruda at the European Society for Medical Oncology meeting this month.

And in December, data for ImmunoGen's earlier-stage assets IMGN779 and IMGN632 is expected at the American Society of Hematology meeting. Both drugs are only in phase 1, but they give investors an idea of what could follow after mirvetuximab.

Now what

Long-term investors should ignore the daily gyrations in the stock price and focus on ImmunoGen's clinical trial data. Forward 1 is clearly the most important clinical trial to get mirvetuximab on the market, but other data later this year should tide investors over while they wait.

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.