Shares of ImmunoGen fell more than 4% late Tuesday as investors mulled the announcement. The stock traded lower in pre-market trade Wednesday, opening in the red at US$10.90, but it recovered to trend 1.7% higher to US$11.66 in morning trade.
Underwriters will be granted a 30-day option to buy up to an additional 15% of the shares, the company said.
Plans for the proceeds include research and development activities, clinical trial activities, manufacturing, and commercialization preparation, the company said.
ImmunoGen develops targeted anticancer therapeutics using its expertise in tumor biology, monoclonal antibodies, potent cancer-cell killing agents and engineered linkers.