In this poster, we present a human QSP model that predicts the tumor response of tipifarnib/alpelisib combination therapy for five distinct genotypes of Head and Neck Squamous Cell Carcinoma (HNSCC) patients: PIK3CA mut, PIK3CA amp, HRAS OE positive, PIK3CA mut/HRAS OE positive, PIK3CA amp/HRAS OE positive.