Molecular alterations and poziotinib efficacy,a pan-HER inhibitor,in human epidermal growth factor receptor 2 (HER2)-positive breast cancers: Combined exploratory biomarker analysis from a phase II clinical trial of poziotinib for refractory HER2-positive breast cancer patients

We aimed to investigate the impact of genetic alterations on the efficacy of poziotinib in a phase II clinical trial of patients with heavily treated HER2-positive metastatic breast cancer (BC). We performed targeted ultra-deep sequencing with a customized cancer gene panel and RNA expression assay using BC specimens. Of 106 patients, biomarker data were available for 85. Copy number (CN) amplifications of HER2 were observed in 72 patients (85%), and CN >8 in 50 (59%). Single nucleotide variants (SNVs) of HER2 were found in 16 patients (19%). Genetic alterations of PIK3CA pathway were found in 40 patients (47%). Median progression free survival (PFS) of the biomarker analysis group was 3.61 months. In terms of PFS, HER2 with CN >8 prolonged (hazard ratio (HR) 0.61, 95% CI: 0.38, 0.97, p = 0.037) and alteration of PIK3CA pathway shortened the duration of survival (HR 2.25, 95% CI: 1.39, 3.63, p = 0.001). SNVs of HER2 increased survival duration, but the effect was not significant (HR: 0.58, 95% CI: 0.31, 1.08, p = 0.085). In addition, SNVs in the ERBB3 cytoplasmic domain decreased poziotinib response (HR: 4.58, 95% CI: 2.02, 10.37, p < 0.001). In multigene analysis, BC with HER2 CN >8 and intact PIK3CA pathway had significantly longer PFS compared to others (HR: 0.37, 95% CI: 0.21, 0.66, p = 0.001), while SNVs in the ERBB3 cytoplasmic domain predicted poor prognosis (HR: 4.28, 95% CI: 1.71, 10.71, p < 0.001). In conclusion, HER2 CN amplification, PIK3CA pathway alteration, and ERBB3 cytoplasmic mutation showed predictive roles on clinical outcomes of HER2-positive MBC treated with poziotinib.     

PIK3CA mutation impact on survival in breast cancer patients and in ERα, PR and ERBB2-based subgroups

Introduction

PIK3CA is the oncogene showing the highest frequency of gain-of-function mutations in breast cancer, but the prognostic value of PIK3CA mutation status is controversial.

Methods

We investigated the prognostic significance of PIK3CA mutation status in a series of 452 patients with unilateral invasive primary breast cancer and known long-term outcome (median follow-up 10 years).

Results

PIK3CA mutations were identified in 151 tumors (33.4%). The frequency of PIK3CA mutations differed markedly according to hormone receptor (estrogen receptor alpha [ER??] and progesterone receptor [PR]) and ERBB2 status, ranging from 12.5% in the triple-negative subgroup (ER-/PR-/ERBB2-) to 41.1% in the HR+/ERBB2- subgroup. PIK3CA mutation was associated with significantly longer metastasis-free survival in the overall population (P = 0.0056), and especially in the PR-positive and ERBB2-positive subgroups. In Cox multivariate regression analysis, the prognostic significance of PIK3CA mutation status persisted only in the ERBB2-positive subgroup.

Conclusions

This study confirms the high prevalence of PIK3CA mutations in breast cancer. PIK3CA mutation is an emerging tumor marker which might become used in treatment-choosing process. The independent prognostic value of PIK3CA mutation status in ERBB2-positive breast cancer patients should be now confirmed in larger series of patients included in randomized prospective ERBB2-based clinical trials.     

Prevalence of PIK3CA mutations and the SNP rs17849079 in Arab breast cancer patients

Carcinomas initiate and progress due to genetic and epigenetic alterations in epithelial cells. However, recently, these alterations have also been reported in stromal fibroblasts. The gain-of-function mutations in the PI3K p110 catalytic subunit (PIK3CA) have been identified in many cancers with a current global incidence of 26% (18–40%) in breast carcinomas. We analyzed the mutational frequency of PIK3CA of three hotspots (exons 1, 9, and 20) in 81 primary invasive breast cancers (BC) and 25 cultured breast cancer-associated fibroblast (CAF) samples by Sanger sequencing in Arab breast cancer patients. Associations between the incidence of any PIK3CA mutation and several clinicopathologic characteristics were assessed using chi-square tests for categorical or t test for continuous variables. Furthermore, survival curves were estimated using the Kaplan–Meier method with the log rank test to evaluate the significance of their differences. We identified a total of 21 PIK3CA missense mutations with a frequency of 25.9%. The majority of the mutations, 17 out of 21 (81%), were in exon 20 (p.His1047Arg, p.His1047Lys, p.Thr1025Ala, p.Gly1049Arg, p.Asp1056Asn) while the remainder, 4 out of 21 (19%) were in exon 9 (p.Glu545Lys). PIK3CA mutations were significantly associated with lower grade and hormone receptor positivity. Although there was a favorable trend in overall survival for patients whose tumor harbored PIK3CA mutations, the difference was not statistically significant (P = 0.10). However, we did not detect any somatic mutations in CAFs. Furthermore, we have shown a high prevalence (8.2-fold) of a silent variant (SNP, rs17849079) in the Arab breast cancer population compared with disease-free individuals.     

Next generation sequencing in lung cancer: An initial experience from India

Introduction: Approximately 35% of NSCLC patients in East Asia have EGFR mutations. Next-generation sequencing (NGS) provides a comprehensive mutational profile in lung cancer patients. Material and Method: Clinicopathologic characteristics and mutational profiling data was analyzed from nonsmall cell lung carcinoma /Adenocarcinoma over a duration of 42 months (October 2014 to March 2018) using next-generation sequencing Ion Ampliseq Cancer Hotspot panel v2 (Ampliseq, Life Technologies) on the Ion torrent PGM platform. Results: A total of 154 cases were processed during this period. The average number of mutations/case varied from one to four 72.07% (111/154), of these cases had minimum one genetic alteration. The most common mutated gene was TP53 gene (37.6%, n = 58) followed by EGFR (32.4%, n = 50), KRAS (18.18%, n = 28), ERBB2 (3.2%, n = 5), BRAF (1.94%, n = 3). EGFR positivity was more in females (43.3%) and non-smokers (52.08%) in comparison to males (26.7%) and smokers (16.1%). Conclusion: In this paper, we have described the comprehensive mutational profiling of a large cohort of advanced lung adenocarcinoma patients from the eastern part of India. To the best of our knowledge, this is one of the largest studies from the country describing mutations in BRAF, ERBB2, TP53 genes and their clinicopathologic/histopathologic associations in lung cancers.     

The Role of <Emphasis Type="Italic">PIK3CA</Emphasis> Mutations as A Predictor of Outcomes and A Therapeutic Target

The development of individualized therapies for the treatment of breast cancer continues to evolve at a rapid pace. Recent genome-wide efforts have uncovered new information regarding common genetic alterations that are present at high frequencies in human breast cancers. Among these, mutations in the gene encoding the p110α catalytic subunit of PI3kinase, PIK3CA, are commonly present in breast cancers, with a mutational frequency of approximately 25%. Importantly, three “hotspot” mutations comprise 80% to 90% of PIK3CA mutations, allowing for rapid analysis of tumor samples to determine the mutational status of a patient’s cancer. In this article, we discuss the current views regarding the use of PIK3CA mutations as biomarkers for prognosis as well as predictors of response to therapies. We also review ongoing efforts to target mutant PIK3CA and the PI3kinase pathway and briefly discuss how mutant PIK3CA status may be useful as a predictive marker of response to these newer therapies.     

PIK3CA mutations rarely demonstrate genotypic intratumoral heterogeneity and are selected for in breast cancer progression

PIK3CA gene mutations are the most common activating mutations in human breast cancer. Its association with hormone receptor-positive breast cancer makes it a prime target for clinical therapeutic advances to maintain anti-estrogen responsiveness. In anticipation of this therapeutic approach, we have evaluated intratumoral heterogeneity in primary breast cancers with regard to PIK3CA mutation status. In addition, we have assessed for the presence of the mutation in paired pre-invasive breast cancer and metastases. To assess for intratumoral heterogeneity, separate tumor blocks from primary breast cancers (n = 63) were genotyped for PIK3CA mutations. Available paired tissue samples from breast tumors known to harbor mutations underwent massARRAY genotyping (n = 70) to identify PIK3CA and AKT1(E17K) mutations. Cores were macro-dissected from matched tissue, including normal breast, benign lymph nodes (LN), ductal carcinoma in situ, regional LN metastases, and distant metastases. Matched samples underwent genetic fingerprinting by multiple SNP genotyping to confirm genetic identity. Intratumoral heterogeneity is minimal with a concordance rate of 95.2% between two different blocks from primary breast cancers. Complete concordance of PIK3CA mutations is noted between primary breast cancer and DCIS. PIK3CA mutations in primary breast cancer are detected in matched regional LNs (91.7%) and distant metastases (100%). Mutation detection by massARRAY genotyping is sensitive but may be affected by sample quality. Intratumoral heterogeneity as measured by PIK3CA genotype is rare; PIK3CA mutations occur early and are selected for in breast cancer progression. HapMap analysis is an essential control for paired sample analysis. This data is clinically important, particularly, for the design of therapies targeting the PI3K/AKT pathway, as it offers confidence that the detection of PIK3CA mutations in the invasive primary tumor will accurately reflect breast cancer biology.     

ERBB2 gene as a potential therapeutic target in small bowel adenocarcinoma

Aim of the studySmall bowel adenocarcinoma (SBA) is a rare and aggressive tumour with poor outcomes. Because of its low incidence, the number prospective studies remains insufficient leading to poor knowledge and absence of standard of care. Aiming to better understand small bowel carcinogenesis we investigated the frequency of somatic mutations in a large data set of patients in more than 740 mutational hotspots among 46 genes.MethodsIn total, 83 SBA cases were selected from two European databases. The sequencing was performed using the Ion 316 Chip. Additionally we looked into ERBB2 expression and microsatellite instability (MSI) status.ResultsThe tumours most frequently were duodenal (47%) and stage ⩾3 (63%). Eight genes were mutated with a frequency >5%: KRAS, TP53, APC, SMAD4, PIK3CA, ERBB2, BRAF and FBXW7. ERBB2 alterations are present in 10 patients (12%) through mutations (7 cases) or amplifications (3 cases). ERBB2 mutations were significantly associated with duodenal tumour location (P = 0.04). In this group, there was a positive association with dMMR status (P = 0.006) and APC mutation (P = 0.02) but negative association with p53 mutations (P = 0.038).ConclusionsThis study describes the first large screening of somatic mutations in SBA using next generation sequencing. The ERBB2 mutation was revealed to be one of the most frequent alterations in SBA with a distribution dependent on tumour location. In most cases ERBB2 mutation was identical (p.L755S). In clinical practice, this may suggest that more than 10% of the patients with SBA could be treated using an anti-ERBB2-targeted agent.     

Genomic profile of pseudomyxoma peritonei analyzed using next‐generation sequencing and immunohistochemistry

Pseudomyxoma peritonei (PMP) is a relatively rare clinical syndrome characterized by neoplastic epithelial cells growing in the peritoneal cavity and secreting mucinous ascites. Our aim was to explore the molecular events behind this fatal but under‐investigated disease. We extracted DNA from 19 appendix‐derived PMP tumors and nine corresponding normal tissues, and analyzed the mutational hotspot areas of 48 cancer‐related genes by amplicon‐based next‐generation sequencing (NGS). Further, we analyzed the protein expression of V600E mutated BRAF, MLH1, MSH2, MSH6 and p53 from a larger set of PMP tumors (n = 74) using immunohistochemistry. With NGS, we detected activating somatic KRAS mutations in all of the tumors studied. GNAS was mutated in 63% of the tumors with no marked difference between low‐grade and high‐grade tumors. Only one (5.3%) tumor showed oncogenic PIK3CA mutation, one showed oncogenic AKT1 mutation, three (15.8%) showed SMAD4 mutations and none showed an APC mutation. P53 protein was aberrantly expressed in higher proportion of high‐grade tumors as compared with low‐grade ones (31.3 vs. 7.1%, respectively; p = 0.012) and aberrant expression was an independent factor for reduced overall survival (p = 0.002). BRAF V600E mutation was only found in one (1.4%) high‐grade tumor by immunohistochemistry (n = 74). All the studied tumors expressed mismatch repair proteins MLH1, MSH2 and MSH6. Our results indicate that KRAS mutations are evident in all and GNAS mutations in most of the PMPs, but BRAF V600E, PIK3CA and APC mutations are rare. Aberrantly expressed p53 is associated with high‐grade histology and reduced survival.     

Impact of KRAS,BRAF, PIK3CA,TP53 status and intraindividual mutation heterogeneity on outcome after liver resection for colorectal cancer metastases

We determined prognostic impact of KRAS, BRAF, PIK3CA and TP53 mutation status and mutation heterogeneity among 164 colorectal cancer (CRC) patients undergoing liver resections for metastatic disease. Mutation status was determined by Sanger sequencing of a total of 422 metastatic deposits. In univariate analysis, KRAS (33.5%), BRAF (6.1%) and PIK3CA (13.4%) mutations each predicted reduced median time to relapse (TTR) (7 vs. 22, 3 vs. 16 and 4 vs. 17 months; p < 0.001, 0.002 and 0.023, respectively). KRAS and BRAF mutations also predicted a reduced median disease‐specific survival (DSS) (29 vs. 51 and 16 vs. 49 months; p <0.001 and 0.008, respectively). No effect of TP53 (60.4%) mutation status was observed. Postoperative, but not preoperative chemotherapy improved both TTR and DSS (p < 0.001 for both) with no interaction with gene mutation status. Among 94 patients harboring two or more metastatic deposits, 13 revealed mutation heterogeneity across metastatic deposits for at least one gene. Mutation heterogeneity predicted reduced median DSS compared to homogeneous mutations (18 vs. 37 months; p = 0.011 for all genes; 16 vs. 26 months; p < 0.001 analyzing BRAF or KRAS mutations separately). In multivariate analyses, KRAS or BRAF mutations consistently predicted poor TRR and DSS. Mutation heterogeneity robustly predicted DSS but not TTR, while postoperative chemotherapy improved both TTR and DSS. Our findings indicate that BRAF and KRAS mutations as well as mutation heterogeneity predict poor outcome in CRC patients subsequent to liver resections and might help guide treatment decisions.     

Genomic landscape and its prognostic significance in stage III colorectal cancer: JCOG1506A1, an ancillary of JCOG0910

Large-scale genomic sequencing of colorectal cancers has been reported mainly for Western populations. Differences by stage and ethnicity in the genomic landscape and their prognostic impact remain poorly understood. We investigated 534 Japanese stage III colorectal cancer samples from the Phase III trial, JCOG0910. Targeted-capture sequencing of 171 potentially colorectal cancer-associated genes was performed, and somatic single-nucleotide variants and insertion–deletions were determined. Hypermutated tumors were defined as tumors with MSIsensor score >7 and ultra-mutated tumors with POLE mutations. Genes with alterations associated with relapse-free survival were analyzed using multivariable Cox regression models. In all patients (184 right-sided, 350 left-sided), mutation frequencies were TP53, 75.3%; APC, 75.1%; KRAS, 43.6%; PIK3CA, 19.7%; FBXW7, 18.5%; SOX9, 11.8%; COL6A3, 8.2%; NOTCH3, 4.5%; NRAS, 4.1%; and RNF43, 3.7%. Thirty-one tumors were hypermutated (5.8%; 14.1% right-sided, 1.4% left-sided). Modest associations were observed: poorer relapse-free survival was seen with mutant KRAS (hazard ratio 1.66; p = 0.011) and mutant RNF43 (2.17; p = 0.055), whereas better relapse-free survival was seen with mutant COL6A3 (0.35; p = 0.040) and mutant NOTCH3 (0.18; p = 0.093). Relapse-free survival tended to be better for hypermutated tumors (0.53; p = 0.229). In conclusion, the overall spectrum of mutations in our Japanese stage III colorectal cancer cohort was similar to that in Western populations, but the frequencies of mutation for TP53, SOX9, and FBXW7 were higher, and the proportion of hypermutated tumors was lower. Multiple gene mutations appeared to impact relapse-free survival, suggesting that tumor genomic profiling can support precision medicine for colorectal cancer.     

PIK3CA mutation profiling in patients with breast cancer,using a highly sensitive detection system

PIK3CA mutations are common activating mutations associated with breast cancer (occurring in 20–30% of all cases) and are potent predictive markers for responses to PI3K inhibitors. Thus, it is important to develop sensitive methods to detect these mutations. We established a novel detection method using a quenching probe (QP) system to identify PIK3CA mutations, using DNA from 309 breast cancer tissues. In a developmental cohort, we determined the optimal detection threshold of the QP system with human tumor DNA from 119 freshly frozen tumor samples. We found a 96% concordance rate with the QP system between DNA from 26 matching fresh‐frozen specimens and formalin‐fixed paraffin‐embedded (FFPE) specimens from the same patients, and known PIK3CA mutation status in the developmental cohort. In a validation cohort, we evaluated whether the threshold for judging mutations using the QP system with frozen specimen‐derived DNA was applicable with FFPE‐derived DNA. In the validation cohort, 30 DNA samples from 190 FFPE‐derived DNA samples with known PIK3CA mutation status were analyzed by direct sequencing (DS) and droplet digital PCR, in a blinded manner. The sensitivity and specificity of the droplet digital PCR results were 100% and 100% (QP system), and 60% and 100% (DS), respectively. We also analyzed the relationship between clinical outcomes and the PIK3CA mutational status of 309 breast cancer samples, including the developmental cohort and validation cohort samples. Multivariate analysis suggested that PIK3CA mutations, especially H1047R, were prognostic factors of relapse‐free survival. Our novel detection system could be more useful than DS for detecting clinical PIK3CA mutations.     

Mutation Profiles of Ovarian Seromucinous Borderline Tumors in Japanese Patients

Ovarian seromucinous tumors (SMBTs) are relatively rare, and their carcinogenesis is largely unknown. In this study, the molecular features of SMBTs in Japan are assessed. DNA was extracted from microdissected paraffin-embedded sections from 23 SMBT cases. Genetic mutations (KRAS, BRAF, PIK3CA, and ERBB2) were evaluated using Sanger sequencing. Immunohistochemistry for p53, ARID1A, and PTEN was also performed as a surrogate for the loss of functional mutations in these tumor suppressor genes. The prevalence of KRAS, BRAF, PIK3CA, and ERBB2 mutations was 4.3% (1/23), 8.6% (2/23), 8.6% (2/23), and 17.3% (4/23), respectively. Overexpression or loss of p53 expression occurred in 26% (6/23), loss of ARID1A expression in 4.3% (1/23), and none of the cases showed expression of PTEN loss. These findings suggest that KRAS/BRAF/PIK3CA and PTEN mutations are rare carcinogenic events in SMBTs. The high frequency of positive p53 staining and a low frequency of loss of ARID1A staining suggests that SMBT carcinogenesis may be related to the alteration of p53 rather than that of ARID1A. ERBB2 oncogenic mutations may play an important role in the tumorigenesis of Japanese SMBTs.     

Specific genomic alterations and prognostic analysis of perihilar cholangiocarcinoma and distal cholangiocarcinoma

BackgroundCholangiocarcinoma (CCA), which consists of intrahepatic CCA (iCCA), perihilar CCA (pCCA), and distal CCA (dCCA), is an aggressive malignancy worldwide. PCCA and dCCA are often classified as extrahepatic CCA (exCCA). However, the differences in mutational characteristics between pCCA and dCCA remain unclear.MethodsDeep sequencing targeting of 450 cancer genes was performed for genomic alteration detection. The tumor mutational burden (TMB) was measured by an algorithm developed in-house. Correlation analysis was conducted using Fisher’s exact test.ResultsFGFR2 and ERBB2 mutations mainly occurred in iCCA and exCCA, respectively. In exCCA, the frequencies of PIK3CA, FAT4, KDM6A, MDM2, and TCF7L2 mutations were significantly higher in pCCA compared to dCCA, while the frequencies of TP53 and KRAS mutations were markedly lower in pCCA than those in dCCA. The prognosis-related mutations were different among the CCA subtypes. NF1 mutation was associated with short disease-free survival (DFS) and overall survival (OS), and ERBB2 mutation was associated with short DFS in dCCA patients. Meanwhile, MAP2K4 mutation was associated with long DFS and OS, and TERT mutation was associated with short DFS in pCCA. A series of mutations in genes, including ARID1A, ARID2, SMAD4, TERT, TP53, and KRAS, were found to be associated with the TMB.ConclusionsIn this study, we investigated the comprehensive genomic characterizations of CCA patients, identified the significant alterations in each subtype, and identified potential biomarkers for prognosis prediction. These results provide molecular evidence for the heterogeneity of CCA subtypes and evidence for further precision targeted therapy of CCA patients.     

Clonal origins and parallel evolution of regionally synchronous colorectal adenoma and carcinoma

Although the colorectal adenoma-to-carcinoma sequence represents a classical cancer progression model, the evolution of the mutational landscape underlying this model is not fully understood. In this study, we analyzed eight synchronous pairs of colorectal high-grade adenomas and carcinomas, four microsatellite-unstable (MSU) and four -stable (MSS) pairs, using whole-exome sequencing. In the MSU adenoma-carcinoma pairs, we observed no subclonal mutations in adenomas that became fixed in paired carcinomas, suggesting a ‘parallel’ evolution of synchronous adenoma-to-carcinoma, rather than a ‘stepwise’ evolution. The abundance of indel (in MSU and MSS pairs) and microsatellite instability (in MSU pairs) was noted in the later adenoma- or carcinoma-specific mutations, indicating that the mutational processes and functional constraints operative in early and late colorectal carcinogenesis are different. All MSU cases exhibited clonal, truncating mutations in ACVR2A, TGFBR2, and DNA mismatch repair genes, but none were present in APC or KRAS. In three MSS pairs, both APC and KRAS mutations were identified as both early and clonal events, often accompanying clonal copy number changes. An MSS case uniquely exhibited clonal ERBB2 amplification, followed by APC and TP53 mutations as carcinoma-specific events. Along with the previously unrecognized clonal origins of synchronous colorectal adenoma-carcinoma pairs, our study revealed that the preferred sequence of mutational events during colorectal carcinogenesis can be context-dependent.     

<Emphasis Type="Italic">PIK3CA</Emphasis> mutation occurs in nasopharyngeal carcinoma but does not significantly influence the disease-specific survival

This study was aimed to test whether PIK3CA, BRAF and RAS are mutated in nasopharyngeal carcinomas (NPCs) and, if so, to further determine whether such mutations affect patients’ survival. For this purpose, a total of 73 NPCs were subjected to mutational analyses for PIK3CA (exons 4, 7, 9, and 20), BRAF (codon 600), and RAS (codons 12, 13 and 61). Clinicopathological characteristics were correlated to the mutation data. Survival rates were compared with the log-rank test. The result showed that the mutation rate of PIK3CA in NPC (n = 73) was 9.6%, whereas both BRAF (n = 65) and RAS (n = 45) were wild type in every specimen with adequate DNA for analysis. PIK3CA mutation was slightly influenced by sex (P = 0.0418, Fisher’s exact test), but had no significant relationship to other clinicopathological characteristics. Disease-specific survival was not significantly affected by PIK3CA mutations (P = 0.8825, log-rank test), albeit it was slightly better in younger patients (≤35 vs. >35 years of age) (P = 0.0477). These findings show that mutated PI3K may be involved in the NPC tumorigenesis but does not affect patient’s prognosis, suggesting that PI3K is a potential target in NPC for targeted therapeutics using specific kinase inhibitors.     

Loss of FBXW7, a cell cycle regulating gene,in colorectal cancer: Clinical significance

This study focused on a cell cycle regulatory gene, FBXW7, which ubiquitinates c‐Myc and cyclin E and promotes exit from the cell cycle. We determined the expression level of FBXW7 in colorectal cancer (CRC) cases, correlated those values with clinicopathologic features, and characterized the molecular mechanism of reduced expression of FBXW7 in CRC cells in vitro. FBXW7 mRNA and protein expression were evaluated in 93 CRC cases. Using CGH array, the copy number aberrations of the flanking region of FBXW7 were evaluated in another 130 CRC specimens. In vitro analysis of FBXW7 gene silencing in CRC cells was conducted. FBXW7 mRNA expression was significantly lower in tumor tissues than the corresponding normal tissues. The low FBXW7 expression group showed a significantly poorer prognosis than patients in the high expression group. A concordant relationship was observed between the incidence of FBXW7 repression and the genetic alteration. The incidence of genetic alteration was associated with the stage of disease progression. In vitro, FBXW7‐specific siRNA enhanced expression of c‐MYC and cyclin E proteins and up‐regulated cell proliferation. Genetic alterations in tumors led to the loss of FBXW7 expression and increased cell proliferation. FBXW7 expression provides a prognostic factor for patients with CRC.     

Somatic mutations of ERBB2 kinase domain in gastric, colorectal, and breast carcinomas.

PURPOSE: Recent reports revealed that the kinase domain of the ERBB2 gene is somatically mutated in lung adenocarcinoma, suggesting the mutated ERBB2 gene as an oncogene in human cancers. However, because previous reports focused the mutational search of ERBB2 primarily on lung cancers, the data on ERBB2 mutations in other types of human cancers have been largely unknown. EXPERIMENTAL DESIGN: Here, we did a mutational analysis of the ERBB2 kinase domain by PCR single-strand conformational polymorphism assay in gastric, colorectal, and breast carcinoma tissues. RESULTS: We detected the ERBB2 kinase domain mutations in 9 of 180 gastric carcinomas (5.0%), in 3 of 104 colorectal carcinomas (2.9%), and in 4 of 94 breast carcinomas (4.3%). All of the detected ERBB2 mutations except for one in-frame deletion mutation were missense mutations. Of the 16 ERBB2 mutations detected, 4 affected Val777 in the exon 20 site, and 3 affected Leu755 in the exon 19 site. We simultaneously analyzed the somatic mutations of EGFR, K-RAS, PIK3CA, and BRAF genes in the 16 samples with ERBB2 mutations, and found that all of the 3 colorectal carcinoma samples with ERBB2 mutations harbored K-RAS mutations. CONCLUSION: This study showed that in addition to lung adenocarcinomas, ERBB2 kinase domain mutation occurs in other common human cancers such as gastric, breast, and colorectal cancers, and suggested that alterations of ERBB2-mediated signaling pathway by ERBB2 mutations alone or together with K-RAS mutations may contribute to the development of human cancers.     

Phosphatidylinositol‐3‐kinase pathway aberrations in gastric and colorectal cancer: Meta‐analysis,co‐occurrence and ethnic variation

Inhibition of the phosphatidylinositol‐3‐kinase (PI3K) signaling pathway is a cancer treatment strategy that has entered into clinical trials. We performed a meta‐analysis on the frequency of prominent genetic (PIK3CA mutation, PIK3CA amplification and PTEN deletion) and protein expression (high PI3K, PTEN loss and high pAkt) aberrations in the PI3K pathway in gastric cancer (GC) and colorectal cancer (CRC). We also performed laboratory analysis to investigate the co‐occurrence of these aberrations. The meta‐analysis indicated that East Asian and Caucasian GC patients differ significantly for the frequencies of PIK3CA Exon 9 and 20 mutations (7% vs. 15%, respectively), PTEN deletion (21% vs. 4%) and PTEN loss (47% vs. 78%), while CRC patients differed for PTEN loss (57% vs. 26%). High study heterogeneity (I² > 80) was observed for all aberrations except PIK3CA mutations. Laboratory analysis of tumors from East Asian patients revealed significant differences between GC (n = 79) and CRC (n = 116) for the frequencies of PIK3CA amplification (46% vs. 4%) and PTEN loss (54% vs. 78%). The incidence of GC cases with 0, 1, 2 and 3 concurrent aberrations was 14%, 52%, 27% and 8%, respectively, while for CRC it was 10%, 60%, 25% and 4%, respectively. Our study consolidates knowledge on the frequency, co‐occurrence and clinical relevance of PI3K pathway aberrations in GC and CRC. Up to 86% of GC and 90% of CRC have at least one aberration in the PI3K pathway, and there are significant differences in the frequencies of these aberrations according to cancer type and ethnicity.     

Survival and prognosis analyses of concurrent PIK3CA mutations in EGFR mutant non-small cell lung cancer treated with EGFR tyrosine kinase inhibitors

In non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation, the prognostic impact of a concurrent Phosphoinositide-3-kinase catalytic alpha polypeptide (PIK3CA) mutation was still unknown. Some studies have shown that EGFR mutant NSCLC patients treated with EGFR tyrosine kinase inhibitors (TKIs) when concurrent PIK3CA mutation have a worse prognosis and shorter survival time. This study conducted a retrospective analysis of NSCLC patients with EGFR mutant or concurrent PIK3CA mutations from January 2015 to October 2019 in the First Affiliated Hospital of Nanchang University. Relative to EGFR alone mutations (Single-Mt), we found that NSCLC patients with EGFR mutations coexisting with PIK3CA mutations (Double-Mt) treated with EGFR-TKIs had a shorter median time to progression (TTP): 7.8 months versus 10.9 months (Double-Mt versus Single-Mt, P = 0.001), and decrease in median overall survival (OS): 20.6 months versus 32.4 months (P < 0.001). The objective response rate (ORR) between Double-Mt and Single-Mt was 36.7% versus 61.9% (P = 0.044), disease control rates (DCR) was 80.1% versus 91.7% (P = 0.179). Obviously, EGFR-TKIs for EGFR mutate NSCLC patients when concurrent PIK3CA mutations have a worse prognosis and shorter survival time.