Cullinan Management Inc. priced its upsized IPO of 11.9 million common shares at $21 apiece.

Cambridge, Mass.-based Cullinan, which develops targeted oncology and immuno-oncology therapies, expects proceeds of about $249.9 million from the offering.

Underwriters have a 30-day option to purchase up to an additional 1,785,000 shares at the IPO price.

The shares are expected to commence trading on the Nasdaq Global Select Market under the ticker CGEM on Jan. 8. The offering is anticipated to close Jan. 12, subject to closing conditions.

Morgan Stanley & Co. LLC, SVB Leerink LLC and Evercore Group LLC are joint bookrunning managers for the offering. H.C. Wainwright & Co. LLC is the lead manager.