What happened

ImmunoGen (NASDAQ:IMGN) closed down 12.6% on Wednesday, following the release of abstracts for the American Society of Hematology (ASH) meeting next month.

So what

The data covers a pair of ImmunoGen's early-stage antibody drug conjugates. IMGN779, which targets CD33, is being developed for acute myeloid leukemia (AML), while IMGN632, which targets CD123, is being developed for blood cancers, including AML and blastic plasmacytoid dendritic cell neoplasm (BPDCN).

The latter hasn't entered the clinic yet, so the ASH presentation will simply go over the expression patterns of CD123 and some preclinical anti-leukemia activity; this will give investors some ideas of potential treatments using IMGN632, but shouldn't be driving the share price.

Micrograph of stained leukemia cells

Image source: Getty Images.

IMGN779 is in a phase 1 trial, but one of the two posters to be presented at ASH is about combining the drug with cytarabine and only has preclinical data. The other poster will cover the phase 1 trial, but the data in the abstract is pretty early-stage. At higher doses, the drug reduced peripheral blasts within three to eight days of first dose in all patients, but the abstract didn't report response rates, which will ultimately determine whether the drug advances into phase 2 development.

Now what

Today's share-price move is a bit perplexing: Perhaps investors were expecting more data in the abstracts. Of course, ImmunoGen's shares have a tendency to move for no particular reason, so maybe the ASH abstracts had nothing to do with today's drop.

Investors itching for data will hopefully get it when the presentations are made at ASH, since the cutoff to submit abstracts was months ago, and ImmunoGen should have more data by the time of the meeting.

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