ATM and head and neck squamous cell carcinoma: Using the Loewe Synergy Score [38, 39], we found a synergistic interaction between olaparib and AZD6738 selectively in ATM-deficient cells, with the strongest synergy score (7.09) observed in the isogenic FaDu HNSCC ATM-KO cells and a modest score (3.14) in the ATM-mutated NCI-H23 NSCLC cells (Fig. 1ai-ii).