Diagnostic magnetic resonance imaging in synovial chondromatosis of the temporomandibular joint

The aim of this paper was to investigate the clinical and magnetic resonance imaging (MRI) features of synovial chondromatosis (SC) of the temporomandibular joint (TMJ). Fourteen patients with SC of the TMJ were included in the study. Clinical and MRI features were analysed and divided into three types based on MRI classification: type I with loose bodies, type II with homogeneous masses, and type III with a mixture of loose bodies and homogeneous masses. All SCs occurred in the superior compartment of the TMJ. There were two patients (14%) categorised as type I, five (36%) as type II and seven (50%) as type III. Four patients (29%) had disc perforation, and nine had bone erosion; among those nine, seven (78%) had type III and two (22%) type II. Histological examination showed inflammation and calcification in the synovial membrane and, and cartilage of the hyaline type in all cases. MRI has advantages in the diagnosis of SC.

Tumor-Associated Microbiota in Esophageal Squamous Cell Carcinoma

Important evidence indicates the microbiota plays a key role in esophageal squamous cell carcinoma (ESCC). The esophageal microbiota was prospectively investigated in 18 patients with ESCC and 11 patients with physiological normal (PN) esophagus by 16S rRNA gene profiling, using next-generation sequencing. The microbiota composition in tumor tissues of ESCC patients were significantly different from that of patients with PN tissues. The ESCC microbiota was characterized by reduced microbial diversity, by decreased abundance of Bacteroidetes, Fusobacteria, and Spirochaetes. Employing these taxa into a microbial dysbiosis index demonstrated that dysbiosis microbiota had good capacity to discriminate between ESCC and PN esophagus. Functional analysis characterized that ESCC microbiota had altered nitrate reductase and nitrite reductase functions compared with PN group. These results suggest that specific microbes and the microbiota may drive or mitigate ESCC carcinogenesis, and this study will facilitate assigning causal roles in ESCC development to certain microbes and microbiota.

Abstract PS17-44: Pd-l1 expression among different subtypes of chinese breast cancer patients

Background Immunotherapies such as PD-L1 inhibitors have shown promising efficiency in breast cancer (BC) patients. However, treatment responses for immunotherapies are diverse since the immunogenicity of breast cancer is heterogeneous. Specific subtypes such as hormone receptor (HR)-positive, human EGF receptor 2 (HER2)-positive, and triple-negative breast cancer (TNBC) have shown heterogeneity in immunogenicity. Therefore, precisely identification of patients potentially benefit from immunotherapy is important. Previous studies have proved PD-L1 expression and tumor mutational burden (TMB) as predictive biomarkers for immunotherapy. Here, we report the PD-L1 expression and TMB status in Chinese BC patients with different subtypes. Using comprehensive molecular analysis, we also characterized the genomic features related to these biomarkers.

Methods Tumor samples from 112 Chinese patients with BC were collected and subjected to next-generation sequencing (NGS) and immunohistochemical (IHC) analysis. NGS were performed in a laboratory accredited by College of American Pathologists (CAP) and certified by Clinical Laboratory Improvement Amendments (CLIA) using validated panel targeting 450 cancer genes. Genomic alterations, included including single base substitution, short and long insertions/deletion (Indel), copy number variation, gene fusion, and rearrangement, were assessed. Tumor mutational burden (TMB) was measured by an algorithm developed in-house. Tumor tissues were analyzed for PD-L1 expression by IHC with 22C3 or 28-8 antibodies, respectively. Results The 112 Chinese BC patients consisted of 87 HR+ (77.7%), 19 TNBC (17.0%) and 6 HR-/ HER2 + (5.3%), with a median age of 47.5 years old (range 24-81). Of all patients, 42.0% were positive for PD-L1 expression (CPS≥1), including 30.4% PD-L1 (1≥CPS>10) and 11.6% PD-L1 (CPS≥10). PD-L1 expression were observed in HR+ BCs (41.4%) as well as in TNBC (47.4%) and HR-/ HER2+ (33.3%) subtypes, no significant difference were observed among the three subtypes. 8.9% patients were TMB-High (≥10 muts/Mb) with median TMB of 3.4 muts/Mb (range 0-80.8). TMB was slightly correlated with PD-L1 expression (Kendall tau = 0.241; P =0.01). 17.0% of PD-L1 positive patients and 3.1% of PD-L1 negative patients were TMB-High (p=0.016). Patients with PD-L1 CPS≥10 had significantly higher median TMB (7.1 vs. 3.1 muts/Mb, p<0.001). Moreover, patients with TMB-High were significantly elder than TMB-Low (median age, 57.5 vs. 47, p=0.012). In PD-L1 positive patients, the most frequently mutated genes were TP53 (66%), PIK3CA (36%) and ERBB2 (30%); In TMB-High patients, the most frequently mutated genes was PIK3CA (80%), followed by TP53 (60%) and ERBB2 (40%).

Conclusion Our data shows that the PD-L1 expression has no significant difference among HR+, TNBC and HR-/ HER2+ subtypes. These data provide the hypothesis that PD-L1 expression positive in different subtype breast cancers may benefit from immune treatment, including HER2 and Luminal subtypes. Otherwise, there was a correlation between PD-L1 expression and TMB, High TMB was also observed in PD-L1 negative patients, which may enrich the subgroup of patients who could benefit from immunotherapy. The verification of integrated predictive biomarkers for immunotherapy in BC is further needed.

Citation Format: Ning Liao, Cao Li, Jundong Wu, Bo Chen, Guochun Zhang, Xueri Li, Liping Guo, Guangnan Wei, Jiali Lin, Yingzi Li, Yuchen Zhang, Hsiaopei Mok, Chongyang Ren, Yulei Wang, Kai Li, Cheukfai Li, Lingzhu Wen, Minghan Jia, Tengjiao Lin, Chunyan Cheng. Pd-l1 expression among different subtypes of chinese breast cancer patients [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS17-44.

PIK3CA somatic alterations in invasive breast cancers: different spectrum from Caucasians to Chinese detected by next generation sequencing

Purpose

Somatic alteration of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) is a crucial therapeutic target in breast cancer (BC) and PI3Kα-specific inhibitor Alpelisib has been used in clinics. This study investigates the PIK3CA alterations in Chinese and Caucasians BC patients for the purpose of selecting anti-PI3K therapy.

Methods

The molecular profile of the PIK3CA gene was analyzed in 412 Chinese patients with untreated invasive BC using a 540 gene next-generation sequencing panel. The results were compared with data of the Caucasian BC patients in The Cancer Genome Atlas (TCGA-white).

Results

PIK3CA alterations were frequently found in BC of estrogen receptor (ER) positive (49.3%, p = 0.024), low ki67 proliferation index (58.3%, p = 0.007) and low pathological grade (grade I/II/III 80%, 53.4%, 35.9%, p < 0.001). Compared to TCGA-white, Chinese BC patients had a higher alteration frequency (45.6% vs. 34.7%, p < 0.001) with larger proportion of p.H1047R mutation among three common mutation sites (p.E545K, p.E542K and p.H1047R) (66.1% vs. 43.7%, p = 0.01). Across four molecular subtypes, ER + /human epidermal growth factor receptor 2 positive (HER2 +) tumors harbored the most PIK3CA alterations (51.6%), while ER-/HER2- harbored the least alteration (30.0%) but the most copy number amplification (19.05%).

Conclusion

PIK3CA alterations prevail in Chinese BC patients and have different molecular features compared to that of Caucasians. The results provide precise annotations of PIK3CA genomic alterations of Chinese in the context of application of PIK3CA inhibitor.

Prognostic Role of ABO Blood Type in Operable Esophageal Cancer: Analysis of 2179 Southern Chinese Patients

Background

The prognostic value of ABO blood types is not well clarified for esophageal carcinoma (EC). This study attempted to elucidate the associations between different ABO blood types and disease-free survival (DFS) and overall survival (OS) of EC.

Methods

This study was a retrospective review of the records of 2179 patients with EC who received surgery from December 2000 to December 2008. The prognostic impact of ABO blood group on DFS and OS were estimated using the Kaplan-Meier method and cox proportional hazard models.

Results

Univariate analyses found significant differences in DFS and OS among the four blood types. Multivariate analyses showed ABO blood type independently predicted DFS (P=0.001) and OS (P=0.002). Furthermore, patients with non-B blood types had a significantly shorter DFS (HR=1.22, 95%CI:1.07–1.38, P=0.002) and OS (HR=1.22, 95%CI:1.07–1.38, P=0.003) than patients with blood type B, and patients with non-O blood types had a significantly better DFS (HR=0.86, 95%CI:0.77–0.96, P=0.006) and OS (HR=0.86, 95%CI:0.77–0.96, P=0.007) than patients with blood type O. Subgroup analyses found that blood type B had a better DFS and OS than non-B in patients who were male, younger, early pathological stages and had squamous-cell carcinomas (ESCC). Blood type O had a worse DFS and OS than non-O in patients who were male, younger, and had ESCC (P<0.05).

Conclusions

The results demonstrate that ABO blood group is an independent prognostic factor of survival, and that type B predicts a favorable prognosis, whereas type O predicts an unfavorable prognosis for survival in patients with EC, especially those with ESCC.

Abstract 5912: YTHDF1 amplification associates with clinicopathological featuresand predicts worse survival in breast cancer

N6-methyladenosine (m6A) is a common RNA modification on eukaryotic mRNA and several m6a regulatory proteins, which plays a crucial part in breast cancer. But the copy number variations (CNVs) for m6a regulatory proteins and their role in pathogenesis and progression in breast cancer is still unclear. By analyzing the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) and the cancer genome atlas (TCGA database), we screened CNVs of ten m6A regulatory genes, including YTHDF3, YTHDF1, FTO, YTHDC1, ALKBH5, METTL3, WTAP, METTL14, YTHDF2, YTHDC2. Among them, YTHDF3 and YTHDF1 amplification had higher alteration rates among ten m6A regulatory genes. YTHDF1 and YTHDF3 amplification resulted in higher mRNA expression (P&lt;0.001). We found that YTHDF1 and YTHDF3 amplification presented a high correlation with worse cinlicopathological characteristics and overall survival (OS) in breast cancer patients. COX regression analysis showed YTHDF1 amplification was an independent risk factor for 10-year OS in breast cancer (HR=1.549, 95% CI: 1.408-1.705, P&lt;0.001, Table). Moreover, GSEA analysis revealed the downstream target of YTHDF1 may be related to MYC signaling regulation and T cell differentiation. In conclusion, we illustrated genetic alteration of m6A regulatory genes in breast cancer patients and found significant relationship between YTHDF1 amplification and worse clinical characteristics, indicating it a potential target for breast cancer treatment in epigenetic modification.

Univariate and multivariate Cox proportional hazard analysis for 10-year overall survivalUnivariateUnivariateHR95% CIP valueHR95% CIP valueNode status1.7181.566-1.885&lt;0.0011.5491.408-1.705&lt;0.001Tumor Size1.0161.013-1.019&lt;0.001ER status0.6200.530-0.725&lt;0.0010.5260.440-0.629&lt;0.001PR status0.6120.531-0.707&lt;0.001HER2 status1.7471.445-2.112&lt;0.0011.5171.234-1.866&lt;0.001Age1.0241.018-1.030&lt;0.0011.0331.026-1.039&lt;0.001YTHDF11.8111.419-2.313&lt;0.0011.5491.408-1.705&lt;0.001

Citation Format: Cheukfai Li, Guochun Zhang, Yulei Wang, Bo Chen, Kai Li, Li Cao, Chongyang Ren, Lingzhu Wen, Minghan Jia, Hsiaopei Mok, Jianguo Lai, Weikai Xiao, Xuerui Li, Ning Liao. YTHDF1 amplification associates with clinicopathological featuresand predicts worse survival in breast cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5912.

Delayed access to feed affects broiler small intestinal morphology and goblet cell ontogeny

Broilers are often deprived of feed and water for up to 48 h after hatch. This delayed access to feed (DAF) can inhibit small intestine development. The objective of this study was to determine the effects of DAF on small intestinal morphology, mRNA abundance of the goblet cell marker Muc2 and absorptive cell marker PepT1, and the distribution of goblet cells in young broilers. Cobb 500 chicks, hatching within a 12-h window, were randomly allocated into 3 groups: control with no feed delay (ND), 24-h feed delay (DAF24), and 36-h feed delay (DAF36). Morphology, gene expression, and in situ hybridization analyses were conducted on the duodenum, jejunum, and ileum at 0, 24, 36, 72, 120, and 168 h after hatch. Statistical analysis was performed using a t test for ND and DAF24 at 24 h. A 2-way ANOVA and Tukey's HSD test (P < 0.05) were used for ND, DAF24, and DAF36 from 36 h. At 24 to 36 h, DAF decreased the ratio of villus height/crypt depth (VH/CD) in the duodenum but increased VH/CD in the ileum due to changes in CD, whereas at 72 h, DAF decreased VH/CD due to a decrease in VH. The mRNA abundance of PepT1 was upregulated, while Muc2 mRNA was downregulated in DAF chicks. Cells expressing Muc2 mRNA were present along the villi and in the crypts. The ratio of the number of goblet cells found in the upper half to the lower half of the villus was greater in DAF chicks than in ND chicks, suggesting that DAF affected the appearance of new goblet cells. The number of Muc2 mRNA-expressing cells in the crypt, however, was generally not affected by DAF. In conclusion, DAF transiently affected small intestinal morphology, upregulated PepT1 mRNA, downregulated Muc2 mRNA, and changed the distribution of goblet cells in the villi. By 168 h, however, these parameters were not different between ND, DAF24, and DAF36 chicks.

Genetic mutation profile of Chinese HER2-positive breast cancers and genetic predictors of responses to Neoadjuvant anti-HER2 therapy

Purpose

Despite the therapeutic success of existing HER2-targeted therapies, tumors respond quite differently to them. This study aimed at figuring out genetic mutation profile of Chinese HER2-positive patients and investigating predictive factors of neoadjuvant anti-HER2 responses.

Methods

We employed two cohorts. The first cohort was comprised of 181 HER2-positive patients treated at Guangdong Provincial People’s Hospital from 2012 to 2018. The second cohort included 40 patients from the first cohort who underwent HER2-targeted neoadjuvant chemotherapy. Genetic mutations were characterized using next-generation sequencing. We employed the most commonly used definition of pathological complete response (pCR)-eradication of tumor from both breast and lymph nodes (ypT0/is ypN0).

Results

In Chinese HER2-positive breast cancer patients, TP53 (74.6%), CDK12 (64.6%) and PIK3CA (46.4%) have the highest mutation frequencies. In cohort 2, significant differences were found between pCR and non-pCR groups in terms of the initial Ki67 status, TP53 missense mutations, TP53 LOF mutations, PIK3CA mutations and ROS1 mutations (p = 0.028, 0.019, 0.005, 0.013, 0.049, respectively). Furthermore, TP53 LOF mutations and initial Ki67 status (OR 7.086, 95% CI 1.366–36.749, p = 0.020 and OR 6.007, 95% CI 1.120–32.210, p = 0.036, respectively) were found to be predictive of pCR status.

Conclusion

TP53 LOF mutations and initial Ki67 status in HER2-positive breast cancer are predictive of pCR status after HER2-targeted NACT.

Undetectable circulating tumor DNA levels correlate with low risk of recurrence/metastasis in postoperative pathologic stage I lung adenocarcinoma patients

OBJECTIVES

The application of circulating tumor DNA (ctDNA) monitoring after resection in pathologic(p) stage I lung adenocarcinoma (LUAD) patients remains controversial and it is of great clinical interest to decipher the difference of genetic features between ground-glass opacity (GGO) and solid nodules (non-GGO) subgroups. We aim to assess the utility of ctDNA in tracking early recurrence or metastasis following surgery and reveal the genetic differences between GGO and non-GGO.

MATERIALS AND METHODS

Tumor tissues and matched postoperative plasma samples were collected from a total of 82 (p)stage I LUAD patients. Comprehensive genomic profiling was performed using capture-based hybrid next generation sequencing by targeting 422 cancer relevant genes.

RESULTS

EGFR and TP53 represent commonly mutated genes in this cohort of (p)stage I lung adenocarcinoma, followed by alterations in ALK, PIK3CA, STK11 and MYC. For a median follow-up period of 22.83 months after surgery, 65 out of 67 ctDNA-negative patients remained progression-free, while 3 out of 15 ctDNA-positive patients progressed [P = 0.040; positive predictive value = 0.20, 95 % confidence interval (CI), 0.04-0.48; negative predictive value = 0.97, 95 % CI, 0.9-1]. With time-dependent Cox regression analysis, we observed that ctDNA positivity significantly correlated with increased probability of early tumor recurrence or metastasis (P = 0.02, HR=8.5). Further comparison between GGO and non-GGO subgroups indicated the frequency of TP53 mutations in non-GGO was markedly higher than that in GGO (47 % vs 21 %, P < 0.05). Pathway analysis showed the epigenetic regulation pathway was more frequently affected in GGO subgroup, while impaired apoptosis/cell cycle pathway was more enriched in non-GGO LUADs.

CONCLUSIONS

Our longitudinal ctDNA monitoring data showed that undetectable ctDNA may predict low risk of tumor recurrence or metastasis in postoperative (p)stage I LUAD patients, while it requires further investigation on how robust the positive ctDNA results could predict tumor relapse in these patients.

CLINICAL REGISTRATION NUMBER

NCT03172156.

Molecular epidemiology of Pseudomonas aeruginosa isolated from lower respiratory tract of ICU patients

Lower respiratory tract infections (LRTIs) caused by Pseudomonas aeruginosa are the most common infection among hospitalized patients, associated with increased levels of morbidity, mortality and attributable health care costs. Increased resistant Pseudomonas worldwide has been quite meaningful to patients, especially in intensive care unit (ICUs). Different species of Pseudomonas exhibit different genetic profile and varied drug resistance. The present study determines the molecular epidemiology through DNA fingerprinting method and drug resistance of P. aeruginosa isolated from patients with LTRIs admitted in ICU. A total of 79 P. aeruginosa isolated from patients with LRTIs admitted in ICU were characterized by Restriction Fragment Length Polymorphism (RFLP), Random Amplified Polymorphic DNA (RAPD) and Repetitive Extrapalindromic PCR (REP-PCR). Antibiotic resistance was determined by minimum inhibitory concentration (MIC) assay while MDR genes, viz, blaTEM, blaOXA, blaVIM, blaCTX-M-15 were detected by polymerase chain reaction (PCR). Of the 137 Pseudomonas sp isolated from ICU patients, 57.7% of the isolates were reported to be P. aeruginosa. The overall prevalence of P. aeruginosa among the all included patients was 34.5%. The RAPD analysis yielded 45 different patterns with 72 clusters with 57% to 100% similarity level. The RFLP analysis yielded 8 different patterns with 14 clusters with 76% to 100% similarity level. The REP PCR analysis yielded 37 different patterns with 65 clusters with 56% to 100% similarity level. There was no correlation among the different DNA patterns observed between the three different methods. Predominant of the isolates (46.8%) were resistant to amikacin. Of the 79 isolates, 60.8% were positive for blaTEM gene and 39.2% were positive for blaOXA gene. P. aeruginosa was predominantly isolated from patients with LRTIs admitted in ICU. The difference in the similarity level observed between the three DNA fingerprinting methods indicates that there is high inter-strain variability. The high genetic variability and resistance patterns indicates that we should continuously monitor the trend in the prevalence and antibiotic resistance of P. aeruginosa especially in patients with LRTIs admitted in ICU.

Circulating tumor DNA dynamics to predict cancer recurrence/metastasis in Chinese pathologic stage I lung adenocarcinoma

3537

Background: Pathologic(p)stage I lung adenocarcinoma (LUAD) patients exhibit high levels of genetic heterogeneity and the association between the genomic characteristics of (p)stage I LUADs and tumor recurrence remains poorly understood. Circulating tumor DNA (ctDNA) monitoring after resection represents a useful tool to predict response to therapy and tumor recurrence but its application in (p)stage I LUAD patients remains controversial. In addition, it is of great clinical interest to decipher the difference of genetic features between ground-glass opacity (GGO) and solid nodules (non-GGO) subgroups. Methods: Tumor tissues and matched post-operative plasma samples were collected from a total of 86 Chinese (p)stage I LUAD patients who were enrolled in a clinical study (NCT03172156). Comprehensive genomic profiling was performed using capture-based hybrid next generation sequencing by targeting 422 cancer relevant genes. Results: EGFR and TP53 represent commonly mutated genes in this cohort of (p)stage I lung adenocarcinoma, followed by alterations in ALK, PIK3CA, STK11and MYC. For a median follow up period of 21.54 months after surgical resection, we observed that ctDNA positivity significantly correlated with an increased probability of early tumor recurrence or metastasis ( P= 0.03, HR = 7.9), and in particular, the EGFR mutation status of ctDNA samples rather than that of primary tumor samples significantly correlated with shorter disease-free survival (DFS). Further comparison between GGO and non-GGO subgroups indicated that the frequency of TP53 mutations in non-GGO was markedly higher than that in GGO (48% vs 20%, P< 0.05). In addition, pathway analysis showed that the epigenetic regulation pathway was more frequently affected in the GGO subgroup, while impaired apoptosis/cell cycle pathway was more enriched in the non-GGO LUADs. Conclusions: Our data show that ctDNA positivity, including the EGFR mutation status, significantly correlated with early relapse or metastasis after surgery, representing a useful tool to predict treatment response and tumor relapse in (p)stage I LUAD patients. Mutated TP53 was more abundant in non-GGO comparing to GGO (p)stage I LUADs that may act as potential oncogenic driver in LUAD development and/or disease progression. Clinical trial information: NCT03172156 .

Distinct genomic profiles of 589 Chinese early-stage breast cancer

552

Background: Extensive efforts by The Cancer Genome Atlas (TCGA) Network had provided much of our current understanding of the molecular profile of various solid tumors including breast tumors; however, Asian patients were underrepresented in this cohort. In this study, we aimed to elucidate the comprehensive genetic alteration profile of early-stage breast tumors among Chinese patients. Methods: Surgical tissue samples from 589 Chinese women with stage I-III breast cancer with various histology and molecular subtype consecutively diagnosed at Guangdong Provincial People’s Hospital were sequenced using a panel targeting 520 cancer-related genes spanning 1.64Mb of the human genome. Clinical and genomic data from our cohort was compared with publicly-available data from 1,046 stage I-III breast cancer patients from the TCGA dataset. Results: Based on the analysis of the genetic alteration profile from our cohort, at least one genetic alteration was observed from 98% of the tumor samples, with TP53 (47%), PIK3CA (45%), ERBB2 (30%), and CDK12 (18%) as the most commonly altered genes. The most common genetic alteration types were copy number amplification (43.6%) and missense mutations (36.8%). As compared with the TCGA dataset, our cohort is mostly composed of women 50 years and younger (59.1% vs. 30.4%, P< 0.001), with significantly fewer patients with lobular carcinoma histology (2.4% vs. 19.0%, P< 0.001), and significantly more patients with pathologic stage I tumors (23.3% vs. 17.3%, P= 0.012). Consistently, genetic alterations detected from our cohort affected genes involved in PI3K (63% vs. 56%, P= 0.009) and cell cycle (23% vs. 35%, P< 0.001) pathways, with statistically different genetic alteration rates as compared with the TCGA dataset. Comparison of genetic alteration profile between the two cohorts revealed that our cohort had more frequent genetic alterations in genes including PIK3CA ( P< 0.001), TP53, particularly in hotspot mutations Q192* ( P< 0.001) and A307V/del ( P= 0.02), and ERBB2 amplification ( P< 0.001). Conclusions: Our study contributes to the understanding of the key pathways and specific genetic alterations harbored by Chinese patients with early-stage breast cancer that could potentially be developed as markers of treatment response to targeted therapeutics.

Next-generation sequencing (NGS) identifies a new breast cancer subtype with HER2 low-amplification status as a candidate for targeted therapy

553

Background: HER2 expression or amplification qualify patients to receive targeted therapeutics against HER2; however, traditional methods of quantifying HER2 amplification using fluorescence in situ hybridization (FISH) do not include a reliable definition for low level amplification. With the promising response rate of patients with low HER2 amplified-metastatic breast cancer to subsequent-line trastuzumab deruxtecan (DS-8201a) therapy, there is a need to improve the existing criteria to accurately identify patients with low HER2. In our study, we investigate whether HER2 amplification quantified by NGS could provide a method to stratify patients into subgroups. Methods: A total of 774 patients diagnosed with breast cancer from Guangdong Provincial People's Hospital (GDPH) who underwent targeted NGS using 520 or 33 cancer-related genes and had their HER2 status evaluated with either FISH or IHC were included in this study. HER2 status were defined as per 2018 ASCO/ACP guidelines. Results: Our results demonstrate that NGS could quantify HER2 amplification with high sensitivity and specificity, with area under the curve of 0.990 [95%CI: 0.982-0.999]. The receiver operating curve indicated an optimal cut-off of 2.62 copy number (CN) for identifying IHC/FISH HER2-negative status with 97.8% specificity. Meanwhile, the cut-off of ≥ 3.62 CN identified patients with IHC/FISH HER2-positive status with 99.8% specificity. Among the 774 patients, 65.8% (n = 509) had HER2 CN of ≤ 2.62 and were classified as HER2 non-amplified, while 25.8% (n = 199) had HER2 CN of ≥ 3.62, classified as HER2-amplified. The remaining 66 patients (8.5%) had HER2 CN between 2.62 and 3.62, and were the patients with heterogeneous IHC/FISH results, classified using NGS as HER2 low-amplified. Patients with low-amplified (49.0% vs. 38.8%, P < 0.001) and amplified (50.3% vs. 38.8%, P < 0.001) HER2 had significantly more number of copy number amplifications in other gene, including CDK12, RARA, and SPOP (P < 0.001, P < 0.001) than patients with HER2 non-amplified, indicating distinct mutation profile. Conclusions: Our results demonstrate that NGS could provide a more accurate stratification of patients based on their HER2 amplification levels. Patients with low levels of HER2 amplification has a distinct mutation profile, suggesting that NGS could serve as a robust tool to identify patients with HER2 amplification, whether high or low, who could benefit treatment with targeted agents designed against heterogeneous HER2 expression.

Somatic and germline mutation profiles of Chinese breast cancer patients younger than 35

554

Background: Limited studies have investigated the molecular underpinnings driving breast cancer development in Chinese younger women. Based from our previous data, more Chinese women are diagnosed with early-onset breast cancer than in the West. In our study, we aim to investigate the comprehensive mutational profile of Chinese women 35 years old and younger (≤35y) diagnosed with breast cancer. Methods: Targeted sequencing was performed on surgically-removed tumor tissues and blood samples collected from 589 women diagnosed with stage I-III breast cancer of various molecular subtypes at the Guangdong Provincial People’s Hospital (GPDH) using a gene panel interrogating 520 cancer-related genes. We compared the data of 53 women aged ≤35y from our cohort to the data from 33 breast cancer patients aged ≤35y included in The Cancer Genome Atlas (TCGA) dataset. Results: Among the women aged ≤35y with early-stage breast cancer from both cohorts, our cohort had more number of hormone receptor-positive (HR+) patients (GPDH, 72% vs. TCGA, 61%, P< 0.001). Analysis revealed an overall mutation detection rate of 98% in our cohort, with mutations affecting genes involved in the PI3K pathway (47%) and cell cycle pathway (23%). TP53 and PIK3CA were the most commonly mutated genes, with mutation rates of 51% and 25% from our cohort. No statistical difference in mutation profile was found between GPDH and TCGA cohorts. Moreover, germline mutations considered as pathogenic and likely pathogenic (P/LP) in breast cancer susceptibility genes including BRCA1 (n = 4), BRCA2 (n = 2), PALB2 (n = 1), PMS2 (n = 1), PTEN (n = 1), and ATM (n = 1) were detected from 18.9% (10/53) of the patients from our cohort. Women aged ≤35y had significantly more germline BRCA1 mutations than patients > 35y from our cohort (7.5%, 4/53 vs. 2.1%, 11/536 P= 0.049). Conclusions: Our study has identified the involvement of PI3K and cell cycle as the two key pathways in the early development of breast tumors in younger women. In addition, our results also support the role of P/LP germline mutations in breast oncogenesis in Chinese patients with early-onset breast cancer, indicating the need to include a more comprehensive germline mutation screening in our population.

[Influencing factors of postoperative acute kidney injury in patients undergoing cardiac surgery]

Objective: To analyze the influencing factors of acute kidney injury (AKI) in patients after cardiac surgery using levosimendan or dobutamine, and explore the effect of positive inotropic drugs on AKI. Methods: The clinical data of 417 patients undergoing cardiac surgery from January to June 2018 in Beijing Anzhen Hospital and treated with levosimendan or dobutamine during perioperative period were retrospectively reviewed and collected. Patients were divided into AKI group and non-AKI group according to whether AKI occurred. Univariate logistic regression analysis was used to analyze the factors related to the occurrence of AKI. The statistically significant factors (P<0.05) were further included in the multivariate logistic regression analysis. Results: Totally, 417 patients were enrolled in the study, with a mean age of (58.2±10.4) years old and a male rate of 65.0% (n=271), and the AKI incidence rate was 25.2% (105/417). Univariate logistic regression analysis showed that male, chronic kidney disease, high serum creatinine level in preoperative period, aortic obstruction time ≥ 120 minutes and extracorporeal circulation time ≥ 120 minutes were risk factors for AKI (all P<0.05). Vasodilator and levosimendan treatment during perioperative period were protective factors (P<0.05). Multivariate logistic regression analysis showed that chronic kidney disease (OR=17.291, 95%CI: 4.335-68.960, P<0.001) and high serum creatinine level (OR=1.097, 95%CI: 1.074-1.121, P<0.001) in preoperative period were independent risk factors for AKI. Perioperative application of levosimendan (OR=0.533, 95%CI: 0.288-0.984, P=0.044) was an independent protective factor. Conclusions: Risk factors for AKI after cardiac surgery include chronic kidney disease and high serum creatinine level in preoperative period. The use of levosimendan during preoperative period has the potential effect to protect against AKI.

Heterogeneity of genomic profile in patients with HER2-positive breast cancer

HER2-positive breast cancer is a biologically and clinically heterogeneous disease. Based on the expression of hormone receptors (HR), breast tumors can be further categorized into HR positive and HR negative. Here, we elucidated the comprehensive somatic mutation profile of HR+ and HR- HER2-positive breast tumors to understand their molecular heterogeneity. In this study, 64 HR+/HER2+ and 43 HR-/HER2+ stage I-III breast cancer patients were included. Capture-based targeted sequencing was performed using a panel consisting of 520 cancer-related genes, spanning 1.64 megabases of the human genome. A total of 1119 mutations were detected among the 107 HER2-positive patients. TP53, CDK12 and PIK3CA were the most frequently mutated, with mutation rates of 76, 61 and 49, respectively. HR+/HER2+ tumors had more gene amplification, splice site and frameshift mutations and a smaller number of missense, nonsense and insertion-deletion mutations than HR-/HER2+ tumors. In KEGG analysis, HR+/HER2+ tumors had more mutations in genes involved in homologous recombination (P = 0.004), TGF-beta (P = 0.007) and WNT (P = 0.002) signaling pathways than HR-/HER2+ tumors. Moreover, comparative analysis of our cohort with datasets from The Cancer Genome Atlas and Molecular Taxonomy of Breast Cancer International Consortium revealed the distinct somatic mutation profile of Chinese HER2-positive breast cancer patients. Our study revealed the heterogeneity of somatic mutations between HR+/HER2+ and HR-/HER2+ in Chinese breast cancer patients. The distinct mutation profile and related pathways are potentially relevant in the development of optimal treatment strategies for this subset of patients.

Comparison of BRCA versus non-BRCA germline mutations and associated somatic mutation profiles in patients with unselected breast cancer

The data on the phenotypes associated with some rare germline mutations in Chinese breast cancer patients are limited. The difference in somatic mutation profiles in breast cancer patients with germline BRCA and non-BRCA mutations remains unexplored. We interrogated the germline and somatic mutational profile of 524 Chinese breast cancer patients with various stages unselected for predisposing factors using a panel consisting of 520 cancer-related genes including 62 cancer susceptibility genes. We divided the patients into three groups according to germline mutations: Germline-BRCA1/2, Germline-others (non-BRCA) and Others (non-carriers). A total of 58 patients (11.1%) carried 76 likely pathogenic or pathogenic (LP/P) germline variants in 15 cancer predisposition genes. Germline BRCA1/2 mutations were detected from 29 (5.53%) patients; with 11 (2.10%) BRCA1 carriers and 18 (3.44%) BRCA2 carriers. In addition, LP/P germline mutations were detected in other genes including MUTYH (n=4), PALB2 (n=4), ATM (n=3), BRIP1 (n=3), CDH1 (n=3), RAD51C (n=3), CHEK2 (n=2), FANCA (n=2), PMS2 (n=2), TP53 (n=2), FANCI (n=1), FANCL (n=1) and PTEN (n=1). At least one variant of uncertain significance (VUS) was identified in 490 (93.5%) patients. Young age (P=0.011), premenopausal status (P=0.013), and breast/ovarian cancer family history (P=0.001) were correlated with germline mutations. Germline-BRCA1/2 group was detected with more missense (P=0.02) and less copy-number amplification (P=0.04) than Germline-others group. Meanwhile, Germline-others group and Others group are very similar (P>0.05). The mutation rates of AKT1, CCND1, FGFR1, and PIK3CA were different among the three groups. By investigating all breast and ovarian cancer-related genes listed in the US genetic guidelines, we identified 15 cancer susceptibility genes frequently mutated in the germline of our population and must be included in cancer predisposition screening. Our study contributed a better understanding of the tumor characteristics of patients with LP/P germline mutations.

Abstract P4-09-11: PIK3CA somatic alterations in 412 chinese invasive breast cancers: Higher frequency of mutant H1047R detected by next generation sequencing compared to breast cancer in caucasians

Purpose: Somatic alterations of PIK3CA gene is an important therapeutic target in breast cancer (BC). The PI3Kα-specific inhibitor alpelisib was remarkably active against PIK3CA-mutated, HR-positive/HER2-negative BC in the SOLAR-1 trial. We hypothesized that PIK3CA alterations in Chinese BC patients across different molecular subtypes might differ from other ethnic groups and this information would be useful for selecting anti-PI3K therapy. Methods: The molecular profile of the PIK3CA gene was analyzed in 412 Chinese untreated invasive BC patients with ER/HER2 molecular subtypes, using a 540 gene next-generation sequencing panel. The results were compared to the molecular profile of Caucasian breast cancer patients in The Cancer Genome Atlas(TCGA-white). Results: Compared to wild type, PIK3CA alterations were more frequent in the ER+ subtype (49.3%, p=0.024), and tumors with low ki67 proliferation (58.3%, p=0.007) and low histological grade (grade I/II/III 80%, 53.4%, 35.9%, p&lt;0.001). Compared to TCGA Caucasian race (TCGA-white), Chinese BC patients had a higher alteration frequency (45.6% vs. 34.7%, p&lt;0.001). The p.H1047R mutation predominantly occurred among three hot spots (p.E545K, p.E542K and p.H1047R) for Chinese BC compared to that of the TCGA-white cohort (66.1% vs 43.7%, p=0.01). Nine novel mutation sites of PIK3CA were observed in the Chinese cohort that was absent among Caucasian BC patients. Among the four ER/HER2 molecular subtypes, ER+/HER2+ tumors harbored the most PIK3CA alterations (51.6%), while ER-/HER2- harbored the least (30.0%). However the latter presented the highest frequency of copy number amplification (19.05%). Conclusion: PIK3CA alterations prevail in nearly half of Chinese BC patients and has some different molecular features compared to that of Caucasian BC patients. The PIK3CA distribution patterns differed among four ER/HER2 subtypes. The results provide more insights for evaluating the results of PIK3CA inhibitors.

Citation Format: Minghan Jia, Ning Liao, Bo Chen, Guochun Zhang, Yulei Wang, Xiaoqing Chen, Liping Guo, Li Cao, Hsiaopei Mok, Chongyang Ren, Kai Li, Cheukfai Li, Lingzhu Wen, Jiali Lin, Guangnan Wei, Zhou Zhang, Charles M Balch. PIK3CA somatic alterations in 412 chinese invasive breast cancers: Higher frequency of mutant H1047R detected by next generation sequencing compared to breast cancer in caucasians [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-09-11.

Abstract P4-07-03: Comprehensive genomic analysis of Chinese breast cancer and clinical application

Background: Next generation sequencing (NGS) and the according target-based precision therapy has shown promising efficacy in many tumors. Here we report the genomic characteristics of Chinese breast cancer to support the development of more precise treatment strategy. Methods: Formalin fixed, paraffin embedded (FFPE) tumor samples and matched peripheral blood samples of 220 Chinese cancer patients including 218 females and 2 males were collected for NGS-based 450-genes panel assay. Pathological subtypes included 104 HR+/HER2-, 30 HR-/HER2+, 44 HR+/HER2+ and 42 triple negative breast cancers (TNBC). Assessed genomic alterations included single base substitution, short and long insertions/deletion, copy number variation, gene fusion and rearrangement. MSK breast cancer data was obtained from cBioPortal for comparing the difference between Chinese and Western patients. Results: The top mutated genes were TP53 (88.1%), PIK3CA (26.2%) and PTEN (21.4%) in TNBC; ERBB2 (86.7%), TP53 (86.7%), CDK12 (80.0%) and PIK3CA (23.3%) in HR-/HER2+ patients; ERBB2 (75%), TP53 (61.4%), CDK12 (54.5%) and PIK3CA (45.5%) in HR+/HER2+ patients. In HR+/HER2- patients, the most frequently mutated genes was PIK3CA (49.0%), followed by TP53 (30.8%) and GATA3 (27.9%), whereas the frequency of PIK3CA and GATA3 mutation were lower (41.6% and 19%, respectively) in Western patients. Although Alpelisib was approved by FDA in PIK3CA mutated HR+/HER2- patients, we observed PIK3CA mutation frequency had no difference among four subtypes. In this cohort, patients with PIK3CA mutation were significantly elder than patient without PIK3CA mutation (50 vs 47 years old, p=0.006). The hotspot mutations of PIK3CA (E542X, E545X and H1047X) accounted for 79.8% of PIK3CA mutations (71/89). Gene fusion/rearrangement was observed in 26% patients, in which 4 patients had gene fusions. Gene variations in homologous recombination pathway were found in 27.7% of patients. Among the 11.4% of patients with BRCA1/2 mutations, 11 patients harbored germline mutations and 19 patients had somatic mutations. Rearrangement accounted for 35% in somatic BRCA1/2 mutations. In the patients with germline BRCA1/2 mutation, 6 were HR+/HER2- patients who have been approved to use Olaparib. Based on the usage of CDK4/6 inhibitor in HR+/HER2- patients, this 450-genes panel enabled us to find that 41.3% HR+/HER2- patients had genes variations are related to CDK4/6 inhibitor resistance (CCND1, 18.3%; FGFR1 17.3%; NF1, 7.7%; MDM2, 6.7%; ESR1, 6.7% and RB1, 1.9%). The median TMB was 4.3 Muts/Mb in the whole cohort and patients with KMT2C mutations had significantly higher TMB (5.5 vs 3.8 Muts/Mb, p=0.004). In addition, Chinese breast cancer patients had a significantly higher frequency of KMT2C mutations compared to western patients (11.4% vs 1.4%, p&lt;0.001). Conclusions: Our study revealed the genomic variation characteristics in Chinese breast cancer patients and the value of NGS-based panel analysis in identifying potential benefit and resistance mechanisms of precision therapy. Integrating genomic features into the diagnosis and treatment of breast cancer patients is necessary to maximize the clinical benefits for each patient.

Citation Format: Ning Liao, Guochun Zhang, Bo Chen, Yulei Wang, Kai Li, Chongyang Ren, Hsiaopei Mok, Li Cao, Lingzhu Wen, Minghan Jia, Cheukfai Li, Liping Guo, Guangnan Wei, Jiali Lin, Jiangguo Lai, Honglin Guo, Wenjing Wang, Shiyue Zhang, Zhijian Song, Jian Wang, Hui Chen, Jinwei Hu, Weifeng Wang, Weiwei Shi, Kai Wang. Comprehensive genomic analysis of Chinese breast cancer and clinical application [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-07-03.

Abstract P5-08-22: Associations between MYC alterations and clinical pathological characteristics in Chinese patients and TCGA cohort

Background MYC is frequently amplified and its amplification is associated with poor prognosis in breast cancer patients. This study aimed to determine the prevalence of MYC alterations from Chinese patients, the correlations between MYC amplification and clinicopathological characteristics, as well as its impacts on patient outcomes in breast cancer patients.

Methods We analyzed 412 cases of breast cancer specimens in Guangdong Provincial People's Hospital (GDPH) for MYC alterations from June 1, 2017 to September 27, 2018, using next generation sequencing. The associations between MYC amplification and clinicopathological characteristics were determined using chi square. We further compared the our results with those from The Cancer Genome Atlas (TCGA) cohort (n=1079). Kaplan-Meier curves were drawn to determine the impacts of MYC amplification on patient outcomes.

Results MYC was amplified in 12.44% (51/410) in GDPH cohort and the mean copy number of our cohort was 4.42 (2.84-11.27), while the frequency of MYC amplification in TCGA cohort was much higher (21.22%, 229/1079). Except that, we also found two fusions. Among these, one was RTFDC1-MYC fusion (AF=1.62%) and the other was PVT1-MYC fusion (AF=3.33%). The case with PVT1-MYC fusion was also found to have PVT1-MYC co-amplification concurrently. In TCGA cohort, we found MYC amplification to be associated with age (P=0.047), tumor type (P=0.000), ER status (P=0.000), PR status (P=0.000), HER2 status (P=0.008) and molecular subtype (P=0.000). Whereas, except for molecular subtype (P=0.028), we only found MYC amplification to be associated with tumor size (P=0.023) and Ki-67 (P=0.031) in GDPH cohort. According to the survival information from TCGA, patients with MYC amplification had significantly inferior overall survival (OS) in both triple negative breast cancer (TNBC) (P=0.02) and HR+/HER2+ breast cancer patients (P=0.03).

Conclusions This study evaluated the differences of MYC mutations in Chinese and and TCGA cohort breast cancer patients. Except for MYC amplification, we found two rare fusions. Results showed MYC amplified less frequently in Chinese patients and was associated with inferior OS in both TNBC and HR+/HER2+ breast cancer patients. We suggest further research with expand the sample size is necessary to draw the ethnical differences of MYC mutations.

Citation Format: Li Cao, Guochun Zhang, Yulei Wang, Bo Chen, Chongyang Ren, Lingzhu Wen, Liping Guo, Kai Li, Minghan Jia, Ning Liao. Associations between MYC alterations and clinical pathological characteristics in Chinese patients and TCGA cohort [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-08-22.

Abstract P5-03-05: Comprehensive analysis of the prevalence of germline mutations and their association with somatic mutations in Chinese unselected breast cancer patients

Background: The data on the prevalence of cancer-related germline mutations and the phenotypes associated with some rare mutations in Chinese breast cancer patients are limited. In this study, the mutation profile of a large cohort of unselected Chinese breast cancer patients were elucidated to determine the prevalence of likely pathogenic or pathogenic (LP/P) germline mutations and their association with clinicopathologic features as well as somatic mutations.Methods: To elucidate the genomic and somatic mutation profile of 524 Chinese breast cancer patients with various stages unselected for predisposing factors, targeted sequencing was performed using a panel consisting of 520 cancer-related genes including 62 cancer susceptibility genes for germline profile. To analyze the somatic mutation profile of the germline mutation carriers, the patients were divided into three groups according to germline mutations: BRCA1/2 (Germline-BRCA1/2), non-BRCA1/2 (Germline-others) and germline wild-type (gWT) groups.Results: A total of 58 patients (11.1%) carried 76 LP/P germline variants in 15 cancer predisposition genes. Germline BRCA1/2 mutations were detected in 29 (5.53%) patients; with 11 (2.10%) BRCA1 carriers and 18 (3.44%) BRCA2 carriers. In addition, LP/P germline mutations were detected in other genes including MUTYH (n=4), PALB2 (n=4), ATM (n=3), BRIP1 (n=3), CDH1 (n=3), RAD51C (n=3), CHEK2 (n=2), FANCA (n=2), PMS2 (n=2), TP53 (n=2), FANCI (n=1), FANCL (n=1) and PTEN (n=1). At least one VUS was identified in 490 (93.5%) patients. Young age (P=0.011), premenopausal status (P=0.013), and breast/ovarian cancer family history (P=0.001) were correlated with germline mutations. Furthermore, patients with Germline-BRCA1/2 had significantly more missense mutations (P=0.02) and less copy number amplification (P=0.04) than patients carrying Germline-others. Meanwhile, mutation types were comparable between Germline-others and gWT patients (P&gt;0.05). Furthermore, the somatic mutation rates for AKT1, CCND1, FGFR1 and PIK3CA varied among the three groups. No mutations in AKT1 and CCND1 were detected in the Germline-BRCA1/2 group. FGFR1 mutations were detected in 24% of the Germline-others group, while the Germline-BRCA1/2 and gWT groups had 10% and 9%, respectively. Moreover, PIK3CA mutations was significantly fewer in the Germline-BRCA1/2 group than Germline-Others (P=0.02) and gWT patients (P=0.002).Conclusions: Our study is the largest germline mutation study in unselected breast cancer patients in Southern China interrogating all breast or ovarian cancer-related genes listed in the US genetic guidelines. The inclusion of the 15 most common cancer susceptibility genes in cancer predisposition screening is important in the Chinese population for selecting the subset of breast cancer patients to receive multigene panel testing. Furthermore, our study also revealed the distinct somatic mutations profiles in germline mutation carriers, which contributes for a better understanding of the tumor characteristics of patients with LP/P germline mutations.

Citation Format: Ning Liao, Bo Chen, Guochun Zhang, Chongyang Ren, Yulei Wang, Liping Guo, Li Cao, Lingzhu Wen, Kai Li, Minghan Jia, Cheukfai Li, Hsiaopei Mok, Guangnan Wei, Jiali Lin, Zhou Zhang, Ting Hou, Analyn Lizaso, Jing Liu. Comprehensive analysis of the prevalence of germline mutations and their association with somatic mutations in Chinese unselected breast cancer patients [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-03-05.

[Study on the relationship between EPHX1 gene polymorphism and antioxidant capacity in patients with chronic obstructive pulmonary disease]

Objective: To explore the difference of mRNA, protein expression levels and the indexes of peripheral blood antioxidant capacity in peripheral blood lymphocytes of different EPHX1 genotypes in chronic obstructive pulmonary disease(COPD). Methods: A case-control study was conducted to collect peripheral blood samples of 220 stable chronic COPD patients with smoking history and 230 healthy smokers (control group) from October 2016 to February 2018 in the First Affiliated Hospital of Kunming Medical University, and the genetic testing was carried out according to the operation instructions of BigDye Terminator v1.1 DNA Sequencing Kit. Based on their EPHX1 exon 3 and exon 4 polymorphism status, the EPHX1 was classified into 4 groups, i. e., normal activity, slow activity, extremely slow activity and fast activity. Then COPD patients were allocated to either a slow activity group (slow and very slow activity) or a fast activity group (normal and fast activity) according to EPHX1 genotype and gene activity. The expression of EPHX1 mRNA and protein in peripheral blood lymphocytes were detected by qRT-PCR and Western blot, and indexes of serum antioxidant capacity was detected by corresponding kits. Results: (1)The 2(-ΔΔCt) of the control group was 1.000, and the 2(-ΔΔCt) of the COPD group was 1.052±0.023. There was no significant difference in the level of EPHX1 mRNA expression between the two groups (t=1.992 P=0.865). The level of EPHX1 mRNA expression in the slow activity group was not different significantly compared to that in the fast-active group (1.053±0.023 vs 1.048±0.021, t=1.133, P=0.260). (2)The level of EPHX1 protein expression by Western blot analysis showed that the EHPX1/GAPDH gray ratio was not different significantly between the COPD group and the control group (0.613±0.089 vs 0.602±0.075, t=0.805, P=0.422). The level of EPHX1 protein expression in the slow activity group was not significantly different compared to that in the fast activity group (0.606±0.088 vs 0.622±0.092, t=-0.786 P=0.434). (3)There were significant differences in indexes of antioxidant capacity between the control group and the COPD group (P<0.05). There were significant differences in indexes of antioxidant capacity between the slow activity group and the fast activity group of COPD patients (P<0.05). Conclusions: The different antioxidant capacity of COPD patients with different EPHX1 genotypes may be related to the polymorphism of EPHX1 gene affecting the activity of microsomal epoxidase, but not to the level of EPHX1 mRNA and protein expression.