Optimal Contact Concentration of Paclitaxel in the Collagen Gel Droplet-Embedded Culture Drug Sensitivity Test for Human Oral Squamous Cell Carcinoma and Evaluation of Combination with Cetuximab

<b><i>Objective:</i></b> A combination of the taxane anticancer drug paclitaxel (PTX) and molecular target drug cetuximab (cMab) is effective for the treatment of head and neck squamous cell carcinoma (HNSCC). However, its use is associated with serious side effects, such as neuropathy and myelosuppression. In addition, it is administered regardless of patient sensitivity because biomarkers indicating its efficacy are unavailable. Therefore, we investigated the usefulness of setting the indicated contact concentration of PTX and predicted the antitumor effect of combined contact with cMab using the collagen gel droplet-embedded culture drug sensitivity test (CD-DST). <b><i>Method:</i></b> Twelve human oral squamous cell carcinoma (OSCC) cell lines (i.e., SAS, HSC-2, HSC-3, HSC-4, OSC-19, OSC-20, KON, HO-1-N-1, HO-1-u-1, SAT, SCC-4, and Nialym) were used. Using the CD-DST, we calculated the optimal contact concentration of the cells with PTX based on the clinical response rate of HNSCC and evaluated the combined contact with cMab. Furthermore, nude mice were treated with standalone PTX and PTX + cMab, and the results were compared with those of the CD-DST. <b><i>Results:</i></b> Based on the CD-DST, 0.1 μg/mL was the optimal contact concentration of PTX, to which the cells showed dose-dependent sensitivity. Moreover, the CD-DST method was used to evaluate the antitumor effects on OSCC even when PTX was used in combination with cMab. The antitumor effects in the CD-DST and nude mice were correlated (<i>p</i> &#x3c; 0.05). <b><i>Conclusion:</i></b> The CD-DST results suggested that it was possible to predict the clinical effects of single-contact PTX and the enhancing effect of cMab + PTX.