Phase 1b Trial of the Toll-Like Receptor 8 Agonist, Motolimod (VTX-2337), Combined with Cetuximab in Patients with Recurrent or Metastatic SCCHN.

Publication Type:

Journal Article


Clinical cancer research : an official journal of the American Association for Cancer Research (2016)


PURPOSE: As toll-like receptors (TLRs) are key mediators of immune responses, TLR agonists may be important for augmenting the efficacy of therapies for squamous cell carcinoma of the head and neck (SCCHN). Motolimod (VTX-2337), a selective small-molecule agonist of TLR8, stimulates NK cells, dendritic cells, and monocytes. A Phase 1b clinical trial assessed the safety and anti-tumor activity of motolimod in combination with cetuximab in patients with SCCHN. Correlative biomarkers of immune activity were explored.

EXPERIMENTAL DESIGN: Thirteen patients with recurrent or metastatic SCCHN were enrolled in this open-label, dose-escalation study using a standard 3+3 design. Doses of motolimod (2.5, 3.0, 3.5 mg/m2) were given on days 1, 8, and 15, in combination with fixed weekly doses of cetuximab in 28-day cycles.

RESULTS: There were no protocol-defined dose-limiting toxicities, drug-related deaths, or evidence of synergistic toxicities between motolimod and cetuximab. Clinical tolerability at the 3.5 mg/m2 dose level was not optimal for repeated dosing and 3.0 mg/m2 was identified as the maximum tolerated dose. Two patients achieved partial responses for an overall response rate of 15%. Five patients had disease stabilization equating to a disease control rate of 54%. Statistically significant increases in plasma cytokines and in the frequency and activation of circulating NK cells were observed.

CONCLUSIONS: Motolimod can be safely administered in combination with cetuximab with an acceptable toxicity profile. Encouraging anti-tumor activity and robust pharmacodynamic responses were observed. Motolimod is being further investigated in a Phase 2 trial in patients with SCCHN ( NCT01836029).