Waltham, MA-based ImmunoGen (NASDAQ: IMGN) said today it has netted about $67.4 million through a stock offering. The company sold 9 million shares to investors at $8 apiece, for a gross of $72 million, then subtracted underwriting discounts and expenses. Underwriters of the deal have a 30-day option to buy another 1.35 million shares. JP Morgan Securities is the sole book-runner for the offering while Oppenheimer & Co., RBC Capital Markets, Cantor Fitzgerald and Morgan Joseph are co-managers. The deal provides a big new cushion for ImmunoGen, which expects to burn through about $38 million to $41 million during the fiscal year ending June 30.