Virtual Library

Start Your Search

Ruifang Mao



Author of

  • +

    P1.03 - Biology (ID 161)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Biology
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/08/2019, 09:45 - 18:00, Exhibit Hall
    • +

      P1.03-04 - Use Supernatant of Malignant Pleural Effusion to Identify Driver Mutants and Monitor Response to Targeted Therapy (ID 2036)

      09:45 - 18:00  |  Author(s): Ruifang Mao

      • Abstract
      • Slides

      Background

      Malignant pleural effusion (MPE) from patients with non-small cell lung cancer (NSCLC) is useful for genetic testing due to advantages including availability, less-invasiveness, and less-heterogeneity. Generally, cell pellets of MPE are used. This study is to further address whether supernatant of MPE is a suitable source to identify key oncogenic mutants in NSCLC patients and provide evidence for clinical molecular testing.

      Method

      MPE samples from 12 NSCLC patients were centrifuged to obtain supernatants and cell pellets, and DNA were extracted. The DNA samples were analyzed by next generation sequencing (NGS) panels using Illumina HiSeq platform.

      Result

      First, MPE samples with the corresponding cancer tissues were collected from 3 NSCLC patients and analyzed with a 500-gene comprehensive cancer panel. Nine mutants were identified in both the paired MPE and cancer tissue samples. We then analyzed nine more NSCLC patient samples using an 18-gene panel to detect key oncogenic mutants; in total, 8 mutants including EGFR L858R, 19DEL, or T790M were identified in the MPE samples. For all of the 17 mutants from the 12 MPE samples, 10 mutants were observed in both the supernatants and pellets of the matched sample sets, of which more pairs (6 out of 10) had supernatants with higher abundance of mutants than the corresponding cell pellets. Importantly, 7 of the 17 mutants were detected only in the supernatants but not the pellets of the paired MPE samples. These results suggest that supernatant of MPE is a better source to detect key oncogenic mutants of NSCLC. Interestingly, 2 patients had both sensitive and resistant mutants to EGFR tyrosine kinase inhibitor (TKI) detected in supernatants of MPE; both patients had treated with EGFR TKI previously, suggesting the development of TKI resistant mutant and supporting the usage of MPE supernatants in monitoring TKI resistance.

      Conclusion

      This study demonstrates that supernatant of MPE is a suitable source for identifying key oncogenic driver mutants for NSCLC and can also be used to monitor response to targeted therapy. The study provides evidence of using supernatant of MPE as an alternative for molecular testing and thus direct precise targeted therapy and surveillance of the therapy effect.

      Only Active Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login or select "Add to Cart" and proceed to checkout.

  • +

    P2.03 - Biology (ID 162)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Biology
    • Presentations: 2
    • Moderators:
    • Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
    • +

      P2.03-21 - MUC16 Germline Mutations May Associate with Inherited Lung Cancer (ID 2150)

      10:15 - 18:15  |  Author(s): Ruifang Mao

      • Abstract
      • Slides

      Background

      Study of inherited cancer may facilitate the understanding of the molecular mechanism of tumorigenesis. Though sporadic reports have shown that mutations in EGFR or ERBB2 may associate with familial lung cancer, the knowledge of the genetic causes for inherited lung cancer is still limited.

      Method

      Genomic DNA (gDNA) from cancer patients or healthy people were extracted from whole blood samples and analyzed using a 500-gene next generation sequencing (NGS) panel. Variants identified by NGS panel were confirmed by Sanger sequencing.

      Result

      In November 2017, four siblings in a Chinese family were diagnosed with lung adenocarcinomas. Additionally, the 5th sibling in the family had prostate cancer. A questionnaire for the family did not reveal significant environmental or habitual reasons leading to cancer in the family, suggestive of possible genetic causes. NGS analysis for gDNA samples indicated all 4 siblings with lung cancer had 3 heterozygous alleles of SNPs in MUC16, namely rs754254000, rs754856910, and rs746152510. In contrast, the sibling with prostate cancer was wild-type for all of the three alleles (Figure below). The NGS results were then confirmed by Sanger sequencing. The three germline mutations in MUC16 all had very low population minor allele frequency (below 0.1%). We further analyzed the gDNA of the children in the family, and detected the 3 heterozygous SNPs in a child whose parent had lung cancer, whereas both children of the prostate cancer patient were wild-type for the 3 MUC16 alleles. Taken together, these results are consistent with a hypothesis that germline mutation of rs754254000, rs754856910, and rs746152510 may predispose the family members to lung cancer. MUC16, also known as CA125, is a biomarker for ovarian cancer, and also shown to be involved in tumorigenesis and metastasis of lung cancer cells. The child with heterozygous SNPs of MUC16 need be cautious in the future routine check-ups.

      muc16 3 snp.png

      Conclusion

      In this study, we have demonstrated that germline mutations of MUC16 may associate with inherited lung adenocarcinomas, which warrants further mechanistic study of MUC16 gene in lung cancer.

      Only Active Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login or select "Add to Cart" and proceed to checkout.

    • +

      P2.03-28 - A 500-Gene Panel to Detect Tumor Mutation Burden of Tissue and Plasma Samples from Lung Cancer Patients (ID 2157)

      10:15 - 18:15  |  Author(s): Ruifang Mao

      • Abstract
      • Slides

      Background

      Tumor mutation burden (TMB) from cancer tissue is an FDA approved biomarker for selecting appropriate patients for immunotherapy. However, tissue samples are not readily accessible. Though reports have shown correlation between tissue TMB and plasma based TMB (bTMB), no FDA approved bTMB product is available yet. More assay needs to be evaluated for correlation analysis of TMB and bTMB.

      Method

      Matched gDNA, ctDNA, and tumor tissue DNA samples from the same patient with non-small-cell lung cancer (NSCLC) were extracted from blood, plasma, and formalin-fixed paraffin-embedded (FFPE) tissue using Qiagen DNA extraction kits. DNA libraries were prepared using Agilent SureSelectXT HS Reagent Ki and were sequenced by a comprehensive 500-gene NGS cancer panel. After variant calling, non-synonymous variants were included to calculate TMB and bTMB using allele frequency cutoffs at 5% and 0.8%, respectively. An in-house bioinformatics method to get rid of germline mutations were also validated in our dataset.

      Result

      To validate the 500-gene panel for TMB and bTMB analysis, we first retrieved TCGA whole exome sequencing (WES) data including 1144 lung cancer patients and about 15500 pan-cancer patients. We then calculated the correlations between the 500-gene panel and WES data on the two datasets and acquired R-square values of 0.93 and 0.94, respectively. Such data demonstrated that our 500-gene is a suitable panel to substitute WES for TMB analysis. We then used the 500-gene panel to analyze 17 NSCLC patients with matched FFPE, ctDNA, and gDNA samples. Using 5% and 0.8% as the allele frequency cutoffs for the variants called from the tissue DNA and ctDNA samples, we found a 0.84 R-square correlation between TMB and bTMB analysis. These results suggest that the bTMB from plasma samples of cancer patients highly correlates to the TMB of the paired tissues using our 500-gene panel.

      Conclusion

      We have demonstrated in this study that a 500-gene panel is suitable for TMB analysis of cancer tissues. We further show that bTMB analysis using the 500-gene panel is close and highly correlate to the TMB from paired cancer tissues. Upon further clinical studies, the TMB and bTMB analysis using the 500-gene panel may represent a good biomarker for patient selection using either cancer tissue or plasma samples.

      Only Active Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login or select "Add to Cart" and proceed to checkout.