Collaboration revenues for the second quarter of 2012 were $12.1 million, compared to $6.6 million for the second quarter of 2011, an increase of $5.5 million, or 83%. This increase was a result of increases in development, milestone and manufacturing revenues recognized under the 2009 license and collaboration agreement with Sanofi for the development and commercialization of drug candidate MM-121.
Research and development expenses for the second quarter of 2012 were $28.8 million, compared to $31.2 million for the second quarter of 2011, a decrease of $2.4 million, or 8%. This decrease was primarily attributable to decreased overall spending on the MM-398 program resulting from the absence of a $10.0 million upfront license payment to PharmaEngine, Inc. which was made by Merrimack during 2011, partially offset by overall increases in spending on the MM-121, MM-111 and MM-302 programs.
General and administrative expenses for the second quarter of 2012 were $3.6 million, compared to $4.8 million for the second quarter of 2011, a decrease of $1.2 million, or 25%. This decrease was primarily attributable to a decrease in stock compensation expense allocable to general and administrative activities.
In April 2012, Merrimack closed the initial public offering of its common stock. Merrimack sold an aggregate of 15,042,459 shares of common stock at a public offering price of $7.00 per share, including 742,459 shares pursuant to the exercise by the underwriters of an over-allotment option. Net proceeds were approximately $98.1 million, after deducting underwriting discounts and commissions and other offering expenses but prior to the one-time payment of dividends of $4.3 million which became payable upon conversion of Merrimack's Series B convertible preferred stock into common stock at the time of the IPO.Merrimack expects its existing cash and cash equivalents and investments on hand as of June 30, 2012 of $106.7 million to be sufficient to fund operations into the second half of 2013.