Virtual Library

Start Your Search

Nhu-An Pham



Author of

  • +

    MA18 - Advances in Diagnosis of Common Types of NSCLC (ID 145)

    • Event: WCLC 2019
    • Type: Mini Oral Session
    • Track: Pathology
    • Presentations: 1
    • Now Available
    • +

      MA18.07 - Identification of Neuroendocrine Transformation in Anaplastic Lymphoma Kinase Rearranged (ALK+) Tumors After Tyrosine Kinase Inhibitors (Now Available) (ID 1137)

      11:30 - 13:00  |  Author(s): Nhu-An Pham

      • Abstract
      • Presentation
      • Slides

      Background

      Acquired resistance after ALK tyrosine kinase inhibitors treatment has multiple known mechanisms: new mutations or gene amplifications, bypass signaling and rarely neuroendocrine histological transformation. Here we describe results of a program utilizing routine biopsy post-progression in ALK+ patients for clinical and research purposes.

      Method

      Since 2014, ALK+ lung cancer patients treated at the Princess Margaret Cancer Centre have undergone routine biopsies at disease progression time points upon failure of an ALK-tyrosine kinase inhibitor (TKI) for both clinical purposes and research purposes, in particular to obtain tissue for primary derived xenograft (PDX) engraftment.

      Result

      All 9/9 patients consented for research sampling during clinical biopsy procedures (median 2 extra cores/passes); 2 patients were biopsied more than once; 3 PDX models from 2 patients have engrafted; 3 additional models are too early to assess engraftment. Engraftment occurred in patients with clinically aggressive tumors and poor survival outcomes. In this process, we identified 2 patients with neuroendocrine transformation post-second generation ALK TKI: (a) a 59 yo Asian female, never smoker, diagnosed six years prior with metastatic disease, heavily pretreated with crizotinib (12 months), pemetrexed (16 months), ceritinib (25 months), alectinib (6 months) and brigatinib (3 months); post-alectinib biopsy showed no transformation, while post-brigatinib liver biopsy demonstrated transformation to large cell neuroendocrine carcinoma; (b) a 75 yo Caucasian female, never smoker, diagnosed eight months prior and started on alectinib with a partial response, progressed in a single site; endobronchial biopsy demonstrated high grade neuroendocrine transformation. Both biopsies were positive for neuroendocrine markers (chromogranin and synaptophysin), TTF-1 and diffusely co-expressed ALK on immunohistochemistry. Assessment of PDX engraftment of these models is ongoing.

      Conclusion

      Routine combined clinical and research biopsy of ALK+ patients at time of TKI failure helped to identify these recent cases of neuroendocrine transformation as a possible mode of resistance and provide tissue for model development. This is the first time that ALK+ transformation to large cell neuroendocrine carcinoma is reported in the literature. (PP, AFF, SNMF, LN contributed equally).

      Only 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, select "Add to Cart" and proceed to checkout. If you would like to become a member of IASLC, please click here.

      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.

  • +

    OA08 - Advanced Models and "Omics" for Therapeutic Development (ID 133)

    • Event: WCLC 2019
    • Type: Oral Session
    • Track: Biology
    • Presentations: 1
    • Now Available
    • +

      OA08.01 - Organoid Cultures as Novel Preclinical Models of Non-Small Cell Lung Cancer (Now Available) (ID 2115)

      11:00 - 12:30  |  Author(s): Nhu-An Pham

      • Abstract
      • Presentation
      • Slides

      Background

      There is an unmet need to develop novel clinically relevant models of NSCLC to accelerate identification of drug targets and our understanding of the disease. Organoids, which are cells grown in three-dimensional environments in Matrigel, have emerged as novel preclinical models of cancer. Recently protocols for generating NSCLC organoids have been reported, but the growth, and molecular features of organoids as compared to their matching primary patient tumor or patient-derived xenografts (PDX) remain vague.

      Method

      Thirty surgically resected NSCLC patient tumor and 35 PDX tissue of lung adenocarcinoma and squamous cell carcinoma subtypes were processed for organoid establishment. Organoids and matching tumor tissues were characterized by histology and immunohistochemistry, and molecularly profiled by whole exome and RNA-sequencing. Subcutaneous injection of organoids in vivo was performed to confirm tumorgenicity. Organoids were subjected to drug testing and drug response was verified in the matched PDX.

      Result

      Using a novel culture condition that our laboratory developed, we have collected tumor samples from 16 primary and 13 PDX samples of adenocarcinoma (n=29) and 14 primary and 22 PDX samples of squamous cell carcinoma (n=36). Over 85% (57/65) of our patient and PDX tumor tissues formed organoids that exhibited a wide range of short-term (<3 months) and long-term (>3 months) growth. Specifically, the success rate of establishing short-term and long-term models are 74% (48/65) and 14% (9/65), respectively. The long-term propagable organoids recapitulated the histology of the patient and PDX tumor. They also retained the ability to form xenograft in NOD-SCID mice. The organoids preserved mutation, copy number aberrations and global gene expression profile of the parental tumors. We additionally showed the utility of short-term and long-term organoids for identifying biomarkers of sensitivity to drugs and combinational targeted therapies.

      Conclusion

      NSCLC organoids are novel patient-derived ex-vivo tumor models for anti-cancer drug screening and biomarker discovery, thus could be incorporated into novel drug discovery pipelines. Further efforts are ongoing to increase the success rate of establishing long-term organoid lines.

      Only 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, select "Add to Cart" and proceed to checkout. If you would like to become a member of IASLC, please click here.

      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
    • +

      P2.03-11 - Impact of Ethnicity on Outcome in Never Smokers with EGFR and ALK Wildtype (EGFR/ALK-Wildtype) Lung Adenocarcinomas (ID 2035)

      10:15 - 18:15  |  Author(s): Nhu-An Pham

      • Abstract

      Background

      EGFR-mutations and ALK-rearrangements are frequent in lung adenocarcinoma (LUAD) samples from never smoker patients. Nevertheless, up to a quarter of all LUAD cases in never smokers are EGFR/ALK-wildtype: these patients have limited therapeutic options and few well-established clinical and molecular predictors of outcome. Our main objectives here were to investigate the prognostic impact of ethnicity in never smoker patients with EGFR/ALK-wildtype LUAD and seek for specific somatic events correlated to ethnical background in these patients.

      Method

      We included 85 samples from lifetime never-smoker patients with EGFR/ALK-wildtype LUAD collected from surgical resection with curative intent. Stages 1/2/3 were identified in 56 (66%)/15 (18%)/14 (16%) samples. A subset of those samples (n=46), with similar stage distribution, had snap-frozen tumor and paired-adjacent tissue available and were submitted to paired-end whole-exome sequencing. Fisher’s exact and Chi-squared tests were used to compare specific mutations between Asians vs non-Asians. Recurrence-free-survival (RFS) was calculated based on the Kaplan-Meier method; Cox modeling was used to generate hazard ratios (HR), adjusted for key clinical features.

      Result

      Most patients in the cohort were female (63/85, 74%); the median age was 68 years; median follow-up was 51 months. According to self-reports, 19/85 (22%) and 66/85 (78%) patients identified as Asians and non-Asians, respectively; no major clinical and pathologic differences were identified between these populations. Five-year recurrence free survival was significantly lower for Asians compared to non-Asians (50% vs. 78%, adjusted HR = 2.9; CI = 1.1-7.8, p=0.02), Figure 1. Among somatic events, in-frame deletions in CNPY3 (Toll-like receptor-specific co-chaperone for HSP90B1) were more frequent in Asians (30%) compared to non-Asians (18%). In contrast, DDX11 missense mutations (21% vs 0%; nucleic acid binding protein involved in genome stability), NOTCH2 multi-hits and frame-shift deletions (7% vs 1%), and KRAS missense mutations (7% vs 0%) were more frequently altered in non-Asians than in Asians.

      Conclusion

      In our cohort of never-smoker patients with EGFR/ALK-wildtype LUAD, Asian patients showed higher relapse rates than non-Asians. We identified differentially mutated genes by ethnicity that may partly account for these differences in outcome. (SNMF and AFF contributed equally)

      figure 1.jpg

    • +

      P2.03-37 - Genomic Landscape of EGFR/ALK Wild-Type Lung Adenocarcinomas in Never-Smokers and Importance of Epithelial-Mesenchymal-Transition (ID 1283)

      10:15 - 18:15  |  Author(s): Nhu-An Pham

      • Abstract

      Background

      The molecular landscape of EGFR/ALK wild-type Lung Adenocarcinomas in never-smokers is poorly understood. Never-smokers usually have low PD-L1 expression and low Tumor Mutation Burden, challenging treatment strategies when no known driver-mutations are found. To identify putative driver mutations, we compared whole exome sequencing (WES) results in the EGFR/ALK wild-type Lung Adenocarcinoma in the never smokers Toronto cohort with a corresponding EGFR/ALK wild-type Lung Adenocarcinoma group of smokers from TCGA.

      Method

      For never-smokers with resected EGFR/ALK wild-type Lung Adenocarcinomas, frozen tumor and paired-normal-lung were evaluated by WES at a mean coverage of 238x. The paired-end reads were aligned using BWA and were further processed using the standard GATK pipeline. Somatic mutations and indels were identified using MuTect and VarScan, respectively. We compared mutations from our cohort to the TCGA smokers who had EGFR/ALK wild-type Lung Adenocarcinomas from publicly available data (TCGA) to identify genes at least 10% more frequently mutated in never smokers compared to the TCGA cohort.

      Result

      In our cohort with 45 never-smoker patients, 80% were females; median age was 70y; 29% were Asians; Stage I/II/III+ were 71%/15%/13%; after a median follow-up of 69 months, 24% had recurred. Median non-synonymous Tumor Mutation Burden was 1.3mut/Mb in never-smokers. We identified 39 genes that were more frequently mutated in never-smokers vs smokers, including some known tumor suppressor genes. The most prevalent genes included ADAM21 missense mutations (21% vs 1%; adj p=0.003), NOTCH2 frame-shift deletions and multi-hit mutations (40% vs 17%; adj p=0.04), MST1 missense mutations and in-frame deletions (13% vs 0%; adj p=0.008), ZMIZ2 frame-shift insertions (13% vs 0%; adj p=0.008) and FOXD4 missense mutations (10% vs 0%; adj p=0.02). Many of these differentially mutated genes have been previously associated to epithelial-mesenchymal-transition signaling pathways. Conversely and as expected, KRAS, TP53, STK11 and KEAP1 were more frequently mutated in the TCGA smokers EGFR/ALK wild-type Lung Adenocarcinomas cohort.

      oncoprint wes.png

      Conclusion

      We identified multiple genes, particularly involved in the epithelial-mesenchymal-transition signaling pathways that are over-represented in never-smokers with EGFR/ALK wild-type Lung Adenocarcinomas, when compared to smokers with EGFR/ALK wild-type Lung Adenocarcinomas. This is a novel finding with potential clinical importance. Validation studies, analyzing epithelial-mesenchymal-transition signaling activation pathways on the EGFR/ALK wild-type Lung Adenocarcinomas never smokers population are needed to best identify the actual role in carcinogenesis and metastasis, guiding future treatment strategies. (AFF and SNMF contributed equally).

  • +

    P2.14 - Targeted Therapy (ID 183)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Targeted Therapy
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
    • +

      P2.14-40 - Tumor-Stromal Microenvironment Interactions in a PDX Model of EGFR TKI Drug Tolerance (ID 509)

      10:15 - 18:15  |  Author(s): Nhu-An Pham

      • Abstract

      Background

      Sixty to eighty percent of advanced stage lung adenocarcinoma patients with sensitizing epidermal growth factor receptor (EGFR) mutated tumors respond to EGFR tyrosine kinase inhibitors (TKIs). However, the vast majority of patients eventually progress due to acquired resistance. In vitro evidence suggests that minor populations of drug tolerant cells (DTCs) may be important for tumors surviving TKI. These studies cannot investigate changes in non-cancerous cell populations found within tumors. Yet, stromal cells have been implicated in protecting cancer cells from treatment-induced death and early stage lung adenocarcinomas responding to neoadjuvant EGFR TKI exhibited DTCs within large areas of fibrosis (NCT00188617). We hypothesize that molecularly characterizing DTCs in vivo in comparison to an untreated tumor in a patient-derived xenograft (PDX) model may delineate stromal changes that sustain DTCs, and potentially mimic clinical events.

      Method

      DTCs were harvested after one month of chronic erlotinib exposure in a lung adenocarcinoma PDX model harboring an exon 19 deletion; an untreated baseline (BL) tumor was also harvested. Histological characterization and single-cell RNA-sequencing (scRNA-seq) of DTCs and BL tumors were compared. ScRNAseq cell-types were assigned using reference component analysis. RNA expression levels of receptor/ligands were explored in cell populations.

      Result

      Post-erlotinib treatment, cell-type proportions within the tumor shifted dramatically, with substantially fewer cancer cells and more fibroblasts, mesenchymal stem cells (MSCs), and natural killer cells (NKCs). Two antigen presenting cell transcriptomic states (APC1 and APC2) were identified in both DTC and BL tumors: APC1s exhibited translation-related gene expression profiles while APC2s exhibited immune-response profiles. BL tumors contained mostly APC1s, whereas DTC tumors exhibited more equal proportions of both APC types. Expression profiles for some cell-types also shifted after treatment. Fibroblasts and NKCs exhibited shifts toward more inflammatory and immune-responsive expression profiles post-treatment. Fibroblasts and endothelial cells demonstrated gene expression shifts towards decreased angiogenesis and vasculature development. Paired ligand-receptor interactions between cancer-stromal cells were increased or decreased congruently post-treatment. Specifically, fibroblasts exhibited a shift from alpha-SMA+ myofibroblastic to more IL6+ inflammatory phenotypes, by mRNA and equivalent immunohistochemistry, post-treatment. Cancer cells exhibited a reciprocal increase in IL6R receptor expression post-treatment.

      Conclusion

      Using an EGFR mutant PDX model sensitive to EGFR TKIs, we see substantial post-treatment changes after chronic TKI exposure in non-cancerous (stromal) cell population composition involving their proportions, expression profiles, and their inferred communication with cancer cells. Understanding these potentially protective shifts in non-cancerous cell populations post-TKI-treatment may help identify clinically-relevant mechanisms of drug tolerance.