**5. Conclusions**

In conclusion, we confirmed that *TP53* exon 8 mutations identify a subgroup of patients with primary resistance to *EGFR* TKIs, and that this is true also in relation to third generation TKIs such as osimertinib. These data suggest that patients with concomitant *EGFR* and exon 8 *TP53* mutations should be candidates for more aggressive therapeutic schemes and should be monitored with a stricter follow-up.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2077-0383/9/4/1047/s1, Table S1: Demographic, clinicopathological and molecular characteristics of patients according to *EGFR* mutations (*n* = 136); Table S2: Demographic, clinicopathological and molecular characteristics by *TP53* mutation; Table S3: Best clinical response according to *TP53* mutations; Table S4: Univariate Cox analyses for PFS and OS.

**Author Contributions:** Conceptualization, A.D. (Angelo Delmonte) , L.C. and P.U.; methodology, M.C., E.P., E.C., V.L. and S.B.; validation, M.C., E.C., V.L., S.B. and P.U.; formal analysis, M.C., E.P., A.D. (Angelo Delmonte), A.D. (Alessandra Dubini) R.C., L.C. and P.U.; investigation, all authors; resources, A.D. (Angelo Delmonte), V.L., R.C., L.C. and P.U.; data curation, A.D. (Angelo Delmonte), A.D. (Alessandra Dubini) G.B., M.P., N.D.L., A.V., R.C., L.L., G.M. and M.A.B.; writing—original draft preparation, M.C., E.P., L.C. and P.U.; writing—review and editing, all authors; visualization, M.C., E.P. A.D. (Angelo Delmonte), L.C. and P.U.; supervision, A.D. (Angelo Delmonte), L.C. and P.U. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
