In first-line therapy, mice survival was significantly longer in the 2mAbs group compared with gemcitabine (P < 0.0001 for BxPC-3, P = 0.0679 for MiaPaCa-2 and P = 0.0019 for Capan-1) and with controls (P < 0.0001). In second-line therapy, tumor regressions were observed after replacing gemcitabine by 2mAbs treatment, resulting in significantly longer animal survival compared with mice receiving continuous gemcitabine injections (P = 0.008 for BxPC-3, P = 0.05 for MiaPaCa-2 and P < 0.001 for Capan-1). Therapeutic benefit of 2mAbs was observed despite K-Ras mutation. Interestingly, concerning the mechanism of action, coinjection of F(ab')(2) fragments from 2mAbs induced significant tumor growth inhibition, compared with controls (P = 0.001), indicating that the 2mAbs had an Fc fragment-independent direct action on tumor cells. This preclinical study demonstrated a significant improvement of survival and tumor regression in mice treated with anti-EGFR/anti-HER2 2mAbs in first- and second-line treatments, compared with gemcitabine, independently of the K-Ras status.
BackgroundReverse transcription-quantitative polymerase chain reaction (RT-qPCR) is the gold standard technique for mRNA quantification, but appropriate normalization is required to obtain reliable data. Normalization to accurately quantitated RNA has been proposed as the most reliable method for in vivo biopsies. However, this approach does not correct differences in RNA integrity.ResultsIn this study, we evaluated the effect of RNA degradation on the quantification of the relative expression of nine genes (18S, ACTB, ATUB, B2M, GAPDH, HPRT, POLR2L, PSMB6 and RPLP0) that cover a wide expression spectrum. Our results show that RNA degradation could introduce up to 100% error in gene expression measurements when RT-qPCR data were normalized to total RNA. To achieve greater resolution of small differences in transcript levels in degraded samples, we improved this normalization method by developing a corrective algorithm that compensates for the loss of RNA integrity. This approach allowed us to achieve higher accuracy, since the average error for quantitative measurements was reduced to 8%. Finally, we applied our normalization strategy to the quantification of EGFR, HER2 and HER3 in 104 rectal cancer biopsies. Taken together, our data show that normalization of gene expression measurements by taking into account also RNA degradation allows much more reliable sample comparison.ConclusionWe developed a new normalization method of RT-qPCR data that compensates for loss of RNA integrity and therefore allows accurate gene expression quantification in human biopsies.
The aberrant hypermethylation of BRCA1 promoter CpG islands induces the decreased expression of BRCA1 (Breast Cancer 1) protein. It can be detected in sporadic breast cancer without BRCA1 pathogenic variants, particularly in triple-negative breast cancers (TNBC). We investigated BRCA1 hypermethylation status (by methylation-specific polymerase chain reaction (MS-PCR) and MassARRAY® assays), and BRCA1 protein expression using immunohistochemistry (IHC), and their clinicopathological significance in 248 chemotherapy-naïve TNBC samples. Fifty-five tumors (22%) exhibited BRCA1 promoter hypermethylation, with a high concordance rate between MS-PCR and MassARRAY® results. Promoter hypermethylation was associated with reduced IHC BRCA1 protein expression (p = 0.005), and expression of Programmed death-ligand 1 protein (PD-L1) by tumor and immune cells (p = 0.03 and 0.011, respectively). A trend was found between promoter hypermethylation and basal marker staining (p = 0.058), and between BRCA1 expression and a basal-like phenotype. In multivariate analysis, relapse-free survival was significantly associated with N stage, adjuvant chemotherapy, and histological subtype. Overall survival was significantly associated with T and N stage, histology, and adjuvant chemotherapy. In addition, patients with tumors harboring BRCA1 promoter hypermethylation derived the most benefit from adjuvant chemotherapy. In conclusion, BRCA1 promoter hypermethylation is associated with TNBC sensitivity to adjuvant chemotherapy, basal-like features and PD-L1 expression. BRCA1 IHC expression is not a good surrogate marker for promoter hypermethylation and is not independently associated with prognosis. Association between promoter hypermethylation and sensitivity to Poly(ADP-ribose) polymerase PARP inhibitors needs to be evaluated in a specific series of patients.
Neoadjuvant radiochemotherapy followed by total mesorectal excision is now the standard treatment for locally advanced rectal cancer. However, tumor response to chemoradiation varies widely among individuals and cannot be determined before the final pathologic evaluation. The aim of this study was to identify germline genetic markers that could predict sensitivity or resistance to preoperative radiochemotherapy (RT-CT) in rectal cancer. We evaluated the predictive value of 128 single-nucleotide polymorphisms (SNPs) in 71 patients preoperatively treated by RT-CT. The selected SNPs were distributed over 76 genes that are involved in various cellular processes such as DNA repair, apoptosis, proliferation or immune response. The SNPs superoxide dismutase 2 (SOD2) rs4880 (P ¼ 0.005) and interleukin-13 (IL13) rs1800925 (P ¼ 0.0008) were significantly associated with tumor response to chemoradiation. These results reinforce the idea of using germline polymorphisms for personalized treatment.
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