Merrimack Pharmaceuticals, Inc. (NasdaqGM:MACK) announced the completion of its previously announced strategic pipeline review resulting in the identification of the three most promising clinical programs to focus its development efforts on going forward. In assessing the clinical and financial prioritization of its programs, Merrimack determined that MM-121, MM-141 and MM-310 are the programs with the highest probability of success and the highest return on investment.