Anti-RB1 monoclonal antibody, clone IF8

Background: The etiology and the molecular basis of lung adenocarcinomas (LuADs) in nonsmokers are currently unknown. Furthermore, the scarcity of available primary cultures continues to hamper our biological understanding of non-smoking-related lung adenocarcinomas (NSK-LuADs). Patients and methods: Weestablished patient-derived cancer cell (PDC) cultures frommetastaticNSK-LuADs, including two pairs of matched EGFR-mutant PDCs before and after resistance to tyrosine kinase inhibitors (TKIs), and then performed whole-exome and RNA sequencing to delineate their genomic architecture. For validation, we analyzed independent cohorts of primary LuADs. Results: In addition to known non-smoker-associated alterations (e.g. RET, ALK, EGFR, and ERBB2), we discovered novel fusions and recurrentlymutated genes, including ATF7IP, a regulator of gene expression, that was inactivated in 5% of primary LuADcases. We also found germline mutations at dominant familiar-cancer genes, highlighting the importance of genetic predisposition in the origin of a subset of NSK-LuADs. Furthermore, there was an over-representation of inactivating alterations at RB1, mostly through complex intragenic rearrangements, in treatment-naive EGFR-mutant LuADs. Three EGFR-mutant and one EGFR-wild-type tumors acquired resistance to EGFR-TKIs and chemotherapy, respectively, and histology on re-biopsies revealed the development of small-cell lung cancer/squamous cell carcinoma (SCLC/LuSCC) transformation. These features were consistent with RB1 inactivation and acquired EGFR-T790M mutation or FGFR3-TACC3 fusion in EGFR-mutant tumors. Conclusions: We found recurrent alterations in LuADs that deserve further exploration. Our work also demonstrates that a subset of NSK-LuADs arises within cancer-predisposition syndromes. The preferential occurrence of RB1 inactivation, via complex rearrangements, found in EGFR-mutant tumors appears to favor SCLC/LuSCC transformation under growth inhibition pressures. Thus RB1 inactivation may predict the risk of LuAD transformation to a more aggressive type of lung cancer, and may need to be considered as a part of the clinical management of NSK-LuADs patients.

OBJECTIVE: The microRNAs (miRNAs) -26a, -24, and -21 have been reported as regulators of the P15/P16/RB1/E2F pathway, which plays a major role in glioblastoma multiforme (GBM) progression. In the present study, their predictive marker for the progression of GBMs is evaluated and described. METHODS: The expression of miRNA-21, -24, and -26a was analyzed as fold change (FC) in tumor specimens of 104 patients with GBM and 8 specimen of non-neoplastic brain tissue as control group. The results were referred to the individual clinical data sets and evaluated statistically. RESULTS: The FC of miRNA-21, -24, and -26a was 1.51 +/- 1.35, 0.75 +/- 0.67, and 0.39 +/- 0.24 in the tumor samples. Within the control group, FC of miRNA-21, -24, and -26a was 0.31 +/- 0.51, 0.66 +/- 0.33, and 0.18 +/- 0.11, respectively. MiRNA-26a and -21 were significantly overexpressed in GBM samples compared with healthy brain tissue (miRNA-21: P < 0.001; miRNA-26a: P = 0.011). High expression ofmiRNA-24 trended for a prolonged overall survival (P = 0.07). Patients with high miRNA-26a expression showed a significantly prolonged progression-free survival (hazard ratio 0.21; 95% confidence interval 0.09-0.51], P < 0.001) and overall survival (hazard ratio 0.3; 95% confidence interval 0.136-0.682], P = 0.003). The effect of miRNA-26a was mediated via regulation of mRNA of RB1. There was a significant inverse correlation between mRNA-26a and mRNA expression of RB1. CONCLUSIONS: The expression levels of miRNA-26a and -24 turned out to be promising predictors of further clinical course in patients with GBM multiforme.