This phase II clinical trial will evaluate the safety and efficacy of adding APX005M (a CD40
agonistic monoclonal antibody) to doxorubicin for the treatment of patients with advanced
soft tissue sarcoma. The investigators believe that doxorubicin, which is currently the
standard of care for most advanced sarcomas, could work better when combined with APX005M,
which is a type of immunotherapy.