PT199 is an anti-CD73 mAb with a differentiated mechanism of action. PT199 is designed to counter the adenosine-mediated immunosuppressive tumor microenvironment, rendering anti-tumor immune cells to be more responsive to checkpoint immunotherapies, such as PD-1/PD-L1 inhibitors. PT199 fully inhibits both soluble and membrane-bound CD73, unlike some other CD73 inhibitors which may inhibit only one form of enzyme or exhibit incomplete inhibition. Moreover, at higher concentrations no loss of inhibition or hook effect is observed with PT199. Hence, PT199 is expected to increase antitumor immune activation, especially in combination with PD-1 pathway inhibition, and thus offer a new treatment option for cancer patients.
This is a first-in-human, Phase I, open-label, dose-escalation and expansion study designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy of PT199 (an Anti-CD73 mAb) alone and in combination with a PD-1 inhibitor, in patients with locally advanced or metastatic solid tumors that have progressed after all available standard therapy or for which standard therapy has proven to be ineffective, intolerable, or is considered inappropriate.