Improvement of the quality of BRAF testing in melanomas with nationwide external quality assessment, for the BRAF EQA group.

BACKGROUND: Knowledge about tumour gene mutation status is essential for the treatment of increasing numbers of cancer patients, and testing quality has a major impact on treatment response and cost. In 2012, 4,629 tests for BRAF p.V600 were performed in France, in patients with melanomas. METHODS: Two batches of unstained melanoma sections were sent, in May and November 2012, to the 46 laboratories supported by the French National Institute of Cancer (INCa). An external quality assessment (EQA) evaluated mutation status, response times and compliance with INCa recommendations. RESULTS: All the French laboratories involved in testing participated in the EQA. Fourteen different methods were used to detect BRAF mutations, most consisting of combinations of in-house techniques. False responses were noted in 25/520 cases (4.8%), 11 of which concerned confusion between p.V600E and p.V600K. Thus, 2.7% of responses would have led to inappropriate treatment. Within six months, mean response times decreased from 22 to 12 days (P<0.001), and the percentage of samples evaluated by a pathologist for tumour cell content increased, from 75.2% to 96.9% (P<0.001). CONCLUSION: Despite the use of non-certified methods, the false response rate was low. Nationwide EQA can improve the quality of molecular pathology tests on tumours.

Mutations in the RAS-MAPK, PI(3)K (phosphatidylinositol-3-OH kinase) signaling network correlate with poor survival in a population-based series of colon cancers.

The RAS-MAPK, PI (3)K signaling pathways form a network that play a central role in tumorigenesis. The BRAF, KRAS and PI3KCA genes code 3 partners of this network and have been found to be activated by mutation in colorectal cancer; these mutations lead to unrestricted cell growth. We evaluated the clinicopathological features and the prognosis of patients with activated-network colon cancers in a population-based study. A total of 586 colon adenocarcinomas were evaluated using sequencing for mutations of KRAS and PI3KCA, and allelic discrimination for mutation of BRAF. Clinicopathological characteristics were correlated to the risk of bearing a mutation of the network using logistic regression. Three-year survival rates were compared with the Log rank test. A multivariate survival analysis using the Cox model was performed. After adjustment for age and microsatellite instability, activation of the network by mutation of at least 1 of the 3 genes was significantly associated with female sex (p = 0.02) and proximal location (p < 0.001). Lower levels of 3-year survival were associated with activation of the network by mutation of at least 1 of the 3 genes (59.4 and 69.4%, respectively; p = 0.009). These results remained significant in a multivariate analysis adjusted for sex, age, location, stage and microsatellite instability (HR = 1.48; CI CI(95%) = [1.07-2.04]). Our study is the first report to underline the potential role of RAS-MAPK, PI (3)K network mutations on survival in colon cancers. Because of the role of this signaling network on anticancer agents, the evaluation of its mutations could have clinical implications.

PIK3CA mutations predict recurrence in localized microsatellite stable colon cancer.

PIK3CA, which encodes the p110α catalytic subunit of PI3Kα, is one of the most frequently altered oncogenes in colon cancer (CC), but its prognostic value is still a matter of debate. Few reports have addressed the association between PIK3CA mutations and survival and their results are controversial. In the present study, we aimed to clarify the prognostic impact of PIK3CA mutations in stage I-III CC according to mismatch repair status. Fresh frozen tissue samples from two independent cohorts with a total of 826 patients who underwent curative surgical resection of CC were analyzed for microsatellite instability and screened for activating point mutations in exon 9 and 20 of PIK3CA by direct sequencing. Overall, 693 tumors (84%) exhibited microsatellite stability (MSS) and 113 samples (14%) harbored PIK3CA mutation. In the retrospective training cohort (n = 433), patients with PIK3CA-mutated MSS tumors (n = 47) experienced a significant increased 5-year relapse-free interval compared with PIK3CA wild-type MSS tumors (n = 319) in univariate analysis (94% vs. 68%, Log-rank P = 0. 0003) and in multivariate analysis (HR = 0.12; 95% confidence interval, 0.029-0.48; P = 0.0027). In the prospective validation cohort (n = 393), the favorable prognostic impact of PIK3CA mutations in MSS tumors (n = 327) was confirmed (83% vs. 67%, Log-rank P = 0.04). Our study showed that PIK3CA mutations are associated with a good prognosis in patients with MSS stage I-III CC.

Response of human renal tubular cells to cyclosporine and sirolimus: a toxicogenomic study.

The molecular mechanisms involved in the potentially nephrotoxic response of tubular cells to immunosuppressive drugs remain poorly understood. Transcriptional profiles of human proximal tubular cells exposed to cyclosporine A (CsA), sirolimus (SRL) or their combination, were established using oligonucleotide microarrays. Hierarchical clustering of genes implicated in fibrotic processes showed a clear distinction between expression profiles with CsA and CsA+SRL treatments on the one hand and SRL treatment on the other. Functional analysis found that CsA and CsA+SRL treatments preferentially alter biological processes located at the cell membrane, such as ion transport or signal transduction, whereas SRL modifies biological processes within the nucleus and related to transcriptional activity. Genome wide expression analysis suggested that CsA may induce an endoplasmic reticulum (ER) stress in tubular cells in vitro. Moreover we found that CsA exposure in vivo is associated with the upregulation of the ER stress marker BIP in kidney transplant biopsies. In conclusion, this toxicogenomic study highlights the molecular interaction networks that may contribute to the tubular response to CsA and SRL. These results may also offer a new working hypothesis for future research in the field of CsA nephrotoxicity. Further studies are needed to evaluate if ER stress detection in tubular cells in human biopsies can predict CsA nephrotoxicity.