TSR-033 is a human IgG4 antibody with high affinity for LAG-3 (lymphocyte activation gene-3), a co-receptor linked to diminished T cell activity, frequently co-expressed with PD-1. It bolsters T cell function and augments PD-1 inhibition both in vitro and in vivo, demonstrating anti-tumor activity [1].

TSR-033, at concentrations ranging from 0.01 to 1000 nmol/L over a 48-hour period, has been shown to elevate interleukin-2 (IL2) production in primary human CD4 T cells and dendritic cells, as well as enhance the effector function of T cells [1].

TSR-033 (i.p., 10 mg/kg, twice weekly, 40 days) demonstrated a moderate inhibitory effect on tumor growth in the A549 HuNOG-EXL NSCLC mouse tumor model, achieving a Tumor Growth Inhibition (TGI) of 23% when used as a monotherapy at the end of the treatment period. When combined with TSR-042, a cumulative effect was observed, leading to a greater hindrance of tumor growth with a TGI of 45% at the conclusion of the study [1].