In particular, the highest levels of p65BTK were expressed by cell lines with both a p53 mutation and a mutation in KRAS or in the RAS/MAPK pathway. growth and clonogenicity were assessed by crystal violet and colony assays, respectively. Cell toxicity assays were performed to study the effect of the combination of non-toxic concentrations of BTK-TKIs with EGFR-TKIs and standard-of-care (SOC) chemotherapy (Cisplatin, Gemcitabine, Pemetrexed). Results p65BTK was significantly over-expressed in EGFR-wild type (wt) adenocarcinomas (AdC) from non-smoker patients and its expression was also preserved at the metastatic site. p65BTK was also over-expressed in cell lines mutated for KRAS or for a component of the RAS/MAPK pathway and in tumors from null mice. BTK-TKIs were more effective than EGFR-TKIs in decreasing cancer cell viability and significantly impaired cell proliferation and clonogenicity. Moreover, nontoxic doses of BTK-TKIs re-sensitized drug-resistant NSCLC cell lines to both target- and SOC therapy, independently from EGFR/KRAS status. Conclusions p65BTK results as an emerging actionable target in non-smoking EGFR-wt AdC, also at advanced stages of disease. Notably, these patients are not eligible for EGFR-TKIs-based therapy due to a lack of EGFR mutation. The combination of BTK-TKIs with EGFR-TKIs is cytotoxic for EGFR-wt/KRAS-mutant/p53-null tumors and BTK-TKIs re-sensitizes drug-resistant NSCLC to SOC chemotherapy. Therefore, our data suggest that adding BTK-TKIs to SOC chemotherapy and EGFR-targeted therapy may open new avenues for clinical trials in currently untreatable NSCLC. Electronic supplementary material The online version of this article (10.1186/s13046-019-1199-7) contains supplementary material, which is available to authorized users. Nafarelin Acetate test with or without Welch correction unless otherwise specified. A probability (p) value less than 0.05 was considered as statistically significant. Results Nafarelin Acetate p65BTK is overexpressed in advanced lung adenocarcinomas with wild type Nafarelin Acetate EGFR from never-smoker patients Using the BN30 isoform-specific polyclonal antibody we previously developed and characterized in the lab we examined p65BTK expression in cancer tissues derived from a cohort of chemo- and/or radio-na?ve NSCLC patients (Additional file 2: Table S1). To this end, 382 out of 383 cases were available. Overall, p65BTK Tgfb3 was expressed in 51% of NSCLC (Table?1). Interestingly, p65BTK was more expressed in AdC than in SCC cases (adenocarcinoma, squamous cell carcinoma In bold are indicated the number of samples completely negative or positive (any positivity) for p65BTK expression Open in a separate window Fig. 1 p65BTK is overexpressed in advanced lung adenocarcinomas with wild type EGFR from never-smoker patients. a IHC analysis of p65BTK in lung cancer tissue samples from a cohort of NSCLC patients using the BN30 antibody. Representative images of normal lung and lung cancer tissues are shown. SCC: squamous cell carcinoma; AdC/S: adenocarcinoma from smoker patient; AdC/NS: adenocarcinoma from non-smoker patient. Scale bar 100?M. b Quantification of p65BTK expression in SCC and AdC patients. ***, test with Welchs correction. c Quantification of p65BTK expression in smoker and non-smoker patients AdC and SCC patients. NS: non-smoker; S: smoker. Quantification of p65BTK expression. d Quantification of p65BTK expression in smoker and non-smoker AdC patients with either wild type (WT) or mutated (MT) EGFR. *, test. e Quantification of p65BTK expression in primary NSCLC according to pN status. *, test with Welchs correction. f IHC analysis of p65BTK in metastatic lymph nodes of lung adenocarcinomas (AdC) or squamous cell carcinoma (SCC). Representative images show different expression levels of the kinase in the metastatic setting. Scale bars 500?m (top panels) or 200?m (lower panels) NSCLC cells with activated KRAS express high levels of p65BTK We then analysed p65BTK expression in NSCLC cell lines. By using the BN49 isoform-specific polyclonal antibody that we previously developed and characterized , we showed that p65BTK was abundantly expressed at the protein level by several NSCLC cell lines with a mutation in KRAS or in the RAS/MAPK pathway (Fig.?2a). In particular, the highest levels of p65BTK were expressed by cell lines with both a p53 mutation and a mutation in KRAS or in the RAS/MAPK pathway. The highest expressing cell lines, ie KRAS-mutated Calu-6 and SK-Lu-1, EGFR-doubly mutated NIH-H1975, and ALK-translocated NIH-H2228 were analysed by qPCR for p65BTK and p77BTK.