EGFR and non-small cell lung carcinoma: However, while cut-off values for VAF to predict progression-free survival were calculated both for activating EGFR (act-EGFR) mutations and for the ratio T790M/act-EGFR [8], further studies are needed to calculate SQI cut-offs with clinical relevance for the management of NSCLC patients, especially to detect TKI response failure or MDR.