In vitro activity: VTX-2337 (Motolimod) stimulates the production of both TNFα with EC50 of 140 nM and IL-12 with EC50 of 120 nM in PBMCs. In monocytes and mDCs, VTX-2337 selectively induces the production of TNFα and IL-12 via NF-κB activation. VTX-2337 also stimulates IFNγ production from NK cells, augments the lytic function of NK cells and enhances ADCC.

Kinase Assay: The activity of specific TLR agonists is assessed using the secretory embryonic alkaline phosphatase (SEAP) reporter gene that is linked to NF-κB activation in response to TLR stimulation. Measurement of SEAP activity using the Quanti-blue substrate (InvivoGen) after TLR agonist treatment is carried out.

Cell Assay: PBMCs or purified NK cells are prepared as previously described, and the purity of NK cells was approximately 99%. NK cell–mediated cytotoxicity is assessed by Calcein AM release from labeled target cells. In brief, PBMCs or purified NK cells are cultured for 48 hours in RPMI medium in the presence of VTX-2337 (167 or 500 nmol/L) before incubation with target cells.