Actinium Pharmaceuticals (ATNM) said Tuesday it is launching a clinical program consisting of trials studying Actimab-A in combination with either Merck's (MRK) Keytruda or Bristol Myers Squibb's (BMY) Opdivo for the treatment of multiple solid tumors.

Actimab-A is meant to improve the efficacy of the immunotherapies by targeting myeloid derived suppressor cells, the company said.

The Actimab-A trials will include several controlled, head-to-head studies that will evaluate the combination of Actimab-A with Keytruda and Opdivo in comparison with the two drugs alone.