Analysis Of PIK3CA Mutation And FGFR Fusion In Chinese Non-Small Cell Lung Cancer

Part I Analysis of PIK3CA Mutation in Chinese Non-small Cell Lung Cancer Lung cancer is one of the most common malignant tumors and is the leading cause of cancer-related mortality worldwide. Despite the development of surgery, platinum-containing chemotherapy and the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors(TKIs) such as gefitinib and erlotinib, the global 5-year survival rate of non-small cell lung cancer(NSCLC), which accounts for 85% of lung cancer, including adenocarcinoma, squamous cell carcinoma and large cell lung cancer, remains low ranging from 10% to 15%. It is now evident that phosphatidylinositol-3-kinase (PI3K) pathway is related to carcinogenesis in a variety of human cancers. Dual PI3K/mTOR kinase inhibitor has been reported to have high antitumor activity in gefitinib-resistant cells. However, few studies constitute a comprehensive picture of the expression of components in PI3K pathway, PIK3CA gene alteration, and their correlation to NSCLC. PIK3CA mutation status and its prognostic value in Chinese NSCLC were still not very clear. Clarifying PIK3CA mutation status will be helpful in selecting patients for individual tyrosine kinase inhibitor.Basing on the issue above, in part one of out study, we consecutively collected 1117 primary tumor samples from NSCLC patients who underwent pulmonary resection at the Department of Thoracic Surgery, Fudan University Shanghai Cancer Centre. Driver mutations testing was performed with cDNA sequencing, including PIK3CA(exon9 and exon 20), EGFR(exons 18-21), KRAS (exons 2-3), HER2(exons 18-21), BRAF (exons 11-15), AKT1 (exons 2-3) mutations and ALK(EML4-ALK, KIF5B-ALK and TFG-ALK) rearrangements in patients with NSCLC. PIK3CA gene copy number was examined by fluorescent in situ hybridization and the expression of PI3K p110 subunit alpha (PI3K P110 a), p-Akt, mTOR, PTEN was determined by immunohistochemistry in PIK3CA mutant cases and patients without PIK3CA mutation(consecutively selected between July 2008 and June 2009 from 1117 patients examined above). In our study, PIK3CA mutation was found in 3.9% of squamous cell carcinoma and 2.7% of adenocarcinoma. Among 34 PIK3CA mutant cases,17 tumors harbored concurrent EGFR mutations and 4 had KRAS mutations. PIK3CA mutation was significantly associated with high expression of PI3K P110a (p=0.0001), p-Akt (p=0.024) and mTOR(p=0.001), but not correlated with PIK3CA amplification (p=0.463). Patients with single PIK3CA mutation had shorter overall survival than those with PIK3CA-EGFR/KRAS co-mutation or wildtype PIK3CA (p=0.004). A significantly worse survival was also found in patients with PIK3CA mutation than those without PIK3CA mutation in the EGFR/KRAS wildtype subgroup (p=0.043).Altogether, in this part, we found that PIK3CA mutations frequently coexisted with EGFR/KRAS mutations. The poor prognosis of patients with single PIK3CA mutation in NSCLC and the prognostic value of PIK3CA mutation in EGFR/KRAS wildtype subgroup suggest that the distinct mutation status of PIK3CA gene should be determined for individual therapeutic strategies in NSCLC. This part of our study provided a clinical reference in targeted therapy screening with non-small cell lung cancer and was helpful for anticipating the prognosis in Chinese NSCLC patients.Part Ⅱ Analysis of FGFR Fusion in Chinese Non-small Cell Lung Cancer Lung cancer is the leading cause of cancer-related death worldwide, accounting for about 18% of all cancer deaths. Non-small cell lung cancer (NSCLC) occupies about 85 %of all lung cancers and most of NSCLC cases are shown as advanced disease and have no sign on radical operations. With the development of research on genetic alterations, targeted drugs that specifically bind to tyrosine kinase domains of driver mutations have led to significantly prolonged progression-free survival (PFS) Moreover, oncogenic fusion genes that involve kinases including RET targeted by vandetanib and cabozantinib as well as ALK and ROS1 which are both sensitive to treatment with crizotinib have also been proved to be effective targets for molecular therapy in lung cancers. Recently, FGFR fusion was shown to play crucial roles in cancer initiation and development. However, even with broad genotyping, there remains 30% of lung adenocarcinoma from smokers and 88% of lung squamous cell carcinoma from East Asian population without any known driver mutations. Few studies report FGFR fusion and its correlation to NSCLC. FGFR mutation status and its prognostic value in Chinese NSCLC were still not very clear. Clarifying FGFR status will be helpful in selecting patients for individual tyrosine kinase inhibitor.In the part two, a retrospective series of 1328 NSCLCs were investigated for FGFRI, FGFR2 and FGFR3 fusion by reverse transcriptase polymerase chain reaction (RT-PCR) followed by direct sequencing. All patients were also analyzed for EGFR, KRAS, HER2, BRAF mutations and ALK, RET,ROS1 gene fusions. Patient characteristics including age, sex, smoking status, stage, subtypes of lung adenocarcinoma, relapse free survival(RFS) and overall survival(OS) were collected. FGFRI, FGFR2, FGFR3 expression were determined by immunohistochemistry in FGFR fusion cases and squamous patients without FGFR fusions(consecutively collected from July 2011 to Dec 2012 from 1328 patients examined above). We found that the FGFRI and FGFR3 fusions were exclusively detected in 17 patients(11 of 312 patients with squamous cell carcinomas and 6 of 1016 adenocarcinomas). Of the 17 patients, fifteen patients had FGFR3-TACC3 and two patients had BAG4-FGFR1 fusion. Compared to the FGFR-negative group, patients with FGFR fusion were more likely to be male(p=0.002) smokers(p<0.001), significantly associated with squamous cell carcinoma(p<0.001), more likely to have large tumor(>3cm) (p<0.001). Moreover, lung adenocarcinoma cases with FGFR fusion were solid predominantly or partly solid in histological subtypes. Significant correlation was also found between FGFR fusion and expression. There were no significant differences in RFS or OS between patients with and without FGFR fusions.In summary, our data in this part demonstrated that FGFR1/3 fusions occurred in 1.3% of patients with NSCLCs and 3.5% of patients with lung squamous cell carcinoma. FGFR fusions identified a distinct subset of NSCLC with a higher prevalence among smokers with squamous cell carcinoma and relative larger tumor (>3cm). This part of our study provided a clinical reference in targeted therapy screening with non-small cell lung cancer and was helpful for anticipating the prognosis in Chinese NSCLC patients.