Shares of ImmunoGen Inc. (IMGN) lost steam in afternoon trading on Monday but were up as much as 7.7% earlier in the session on news that the company saw improvements in the safety of an investigational treatment for non-Hodgkin's lymphoma.

The company said a Phase I assessment of its investigational compound SAR3419 – which it hopes will be used to treat non-Hodgkin’s lymphoma and other B-cell malignancies – was administered on an alternative schedule that demonstrated “an improved safety profile compared to prior tested schedules.”

"We believe the findings reported today support that SAR3419 has the potential to become an important new therapy for key B-cell malignancies,” said ImmunoGen CEO  Daniel Junius in a release.

The investigational SAR3419 compound uses the company’s Targeted Antibody Payload (TAP) technology to bind to and kill cancer cells.

The stock was up 0.6% as of 1:05 p.m. ET.