Nimotuzumab shows an additive effect to inhibit cell growth of ALA-PDT treated oral cancer cells.

Oral squamous cell carcinoma (OSCC) can be characterized by severe functional impairment and a poor prognosis. The epidermal growth factor receptor (EGFR) is highly expressed in OSCC and is a promising target for cancer therapy. In addition, aminolevulinic acid-induced photodynamic therapy (ALA-PDT) has produced robust clinical effects in oral cancer. Here, an EGFR inhibitor, nimotuzumab, was administered to 2 OSCC cell lines, CAL-27 and SCC-25, treated with ALA-PDT. Cell growth, apoptosis, and reactive oxygen species (ROS) generation were used to measure the antitumor activity of the combination therapy. The in vivo effect of nimotuzumab plus ALA-PDT was done using a mouse OSCC xenograft model (SCC-25). EGFR expression was further compared by Western blotting in different groups. We observed that nimotuzumab combined with ALA-PDT could enhance inhibition of OSCC cell growth in vitro and in vivo. We also observed an enhanced effect after combination on cell apoptosis in CAL-27 and SCC-25 cells. Furthermore, combined therapy significantly reduced the protein expression levels of EGFR in vitro. However, we observed that nimotuzumab plus ALA-PDT did not increase ROS generation substantially in OSCC cells compared to the ALA-PDT group alone. These observations indicate that nimotuzumab combined with ALA-PDT has valuable applications for OSCC treatment.