Mapatumumab (HGS-ETR1) is an experimental human monoclonal antibody undergoing clinical trials for the treatment of cancer.

Early work by the two companies indicated that mapatumumab induced cell death in multiple tumor types both in vitro and in vivo.

[5][6] In two phase 1b clinical trials mapatumumab in combination with chemotherapy was well tolerated by patients with advanced solid tumors.

[8] In 2008 HGS reported initial results of a randomised phase 2 trial of mapatumumab in combination with bortezomib in advanced multiple myeloma.

There was no difference in disease response or progression-free survival rates between patients receiving the drug for multiple myeloma and the control group.