Abstract
Predicting individual radiotherapy (RT) response is valuable in managing head and neck squamous cell carcinoma (HNSCC). We assessed the feasibility of our novel 3D culture platform to measure radioresponse using patient-derived cells (PDCs) from HNSCC patients. Cells from the FaDu line and tumor samples from 39 HNSCC patients were cultivated serially in MatrigelTM on a 3D pillar/well array culture system. The 3D tumor models were exposed to 0 to 8 Gy of radiation dose, and the radioresponse index (RTauc, area under the dose-response curve) was measured quantitatively with Calcein AM staining of live tumor cells. Calcein AM fluorescence showed reduced density and the number of FaDu colonies as radiation increased, implying a dose-dependent effect on cell viability in the 3D pillar/well culture system. 3D tumor models using PDCs were established successfully from 39 HNSCC patient tumor samples, maintaining original genomic and pathological characteristics. These 3D tumor models were exposed to ionizing radiation on a 3D pillar/well array, with a mean period of 12 days from tumor harvest to the measurement of RTauc. The RTauc of all PDCs varied from 3.5 to 9.4, and the lower 40th percentile (Z-score = -0.26) was considered a good radioresponse group with a threshold RTauc of 4.6. The good radioresponse group showed fewer adverse features than others. As of the last follow-up, recurrence-free survival was better in the good radioresponse group (p = 0.037). 3D pillar/well array platforms using PDC could rapidly quantify radioresponse index in patients with HNSCC, showing potential as a novel prognosticator.