Monrovia-based Xencor, a developer of antibody engineering technology, reported today that the firm has received a milestone payment from Pfizer, as part of the firm's antibody technology license agreement with Pfizer. Amount of the payment was not disclosed. According to Xencor, the payment came because of the initiation of human clinical trials of a novel monoclonal antibody therapeutic which uses Xencor's technologies. Xencor and Pfizer entered into a deal in March of 2009, to use Xencor's antibody optimization technology on a number of its drug discovery projects.