What

Shares of ImmunoGen (NASDAQ:IMGN) are up 10.4% at 3:10 p.m. EDT on no apparent news. Most likely, shares of the highly volatile biotech are up as investors jump in ahead of the American Society of Clinical Oncology (ASCO) meeting set to start tomorrow.

So what

In an abstract for ASCO that was released earlier this month, ImmunoGen disclosed data from the phase 1b/2 Forward II trial testing its lead drug, mirvetuximab soravtansine, in combination with a variety of other cancer medications.

In 23 ovarian cancer patients with medium or high expression of FRalpha, which mirvetuximab soravtansine targets, treatment with mirvetuximab soravtansine plus Roche's Avastin produced an overall response rate (ORR) of 48% with a median duration of response of 10.6 months. That's not bad considering these patients could have failed up to three previous treatments.

Woman in a head scarf holding hands with another woman

Image source: Getty Images.

A separate set of 10 patients received mirvetuximab soravtansine plus the chemotherapy carboplatin, which produced an ORR of 80% with a median duration of response that hadn't been reached at the cutoff. These patients haven't progressed as far as the Avastin combination group, so it's certainly not an apples-to-apples comparison. In fact, ImmunoGen thought both sets of data were promising enough to justify testing a triplet combination of mirvetuximab soravtansine plus carboplatin and Avastin, which began recently.

Now what

ASCO abstracts have to be turned in months before the meeting, so presentation of the data -- especially the Avastin data on Monday -- could have updated results further solidifying the combination as a potential treatment for ovarian cancer.

The combination data is important to ImmunoGen's long-term future, but investors shouldn't forget about the Forward I trial, testing mirvetuximab soravtansine as a monotherapy since results from that trial, which are due out in the first half of next year, are the quickest way for ImmunoGen to get the drug on the market.

Brian Orelli has no position in any of the stocks mentioned. The Motley Fool recommends ImmunoGen. The Motley Fool has a disclosure policy.