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Judy McConnell



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    MA27 - Novel Drugs and PDX Models (ID 931)

    • Event: WCLC 2018
    • Type: Mini Oral Abstract Session
    • Track: Targeted Therapy
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/26/2018, 13:30 - 15:00, Room 206 BD
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      MA27.01 - Establishment of PDX From Tumors Characterized by EGFR Mutations or ALK Fusion Genes from Resections, Biopsies and Pleural Fluids (ID 12144)

      13:30 - 13:35  |  Author(s): Judy McConnell

      • Abstract
      • Presentation
      • Slides

      Background

      Patient-derived xenograft (PDX) models allow for cancer tissue expansion, providing an effective method to evaluate tumor biology and mechanisms of response or resistance. Our study aims to establish models in patients enriched for lung adenocarcinoma (LUAD) with EGFR mutations or ALK fusion genes which respond initially to oral targeted therapy, but typically develop resistance and disease relapse within 2 years. The PDXs will be evaluated for their potential to model therapy outcomes, to determine resistance mechanisms and to evaluate novel therapy strategies to overcome resistance.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      From August 2015 to January 2018, we collected 109 samples from patients with EGFR- or ALK-driven LUAD and from never-smoker LUAD patients with unknown mutation status. Five samples with low tissue viability (i.e. necrotic) or very low tumor content (<100 malignant cells) were excluded. Adequate samples were implanted into the subcutaneous tissue of NOD-SCID mice. At this time, 16 samples have reached the study endpoint (tumor growth ≥1.5cm3) and 60 showed no tumor-growth following implantation (median follow-up: 8m). Results are currently pending for 18 models.

      4c3880bb027f159e801041b1021e88e8 Result

      Samples were collected from surgical resections (31, 36%), CT-guided biopsies (12, 14%), EBUS (19, 22%) and pleural fluid effusions (24, 28%). Most patients were female (51/86, 59%), never smokers (62/85, 73%), and had stage III or IV cancer (55/79, 70%). Mutations in EGFR and ALK were found in 55/81 (68%) and 12/84 (14%) primary cancers, respectively. Early-passage xenograft engraftment (XG) was observed in only 16 (19%) PDXs, including 9/55 (16%) EGFR- and 1/12 (8%) ALK-mutant cancers. The phenotype and molecular changes (EGFR and ALK) were consistent within the PDX model and its corresponding patient sample. Samples collected from surgical-resection specimens showed a trend towards higher engraftment rates (p=0.084). Conversely, the presence of EGFR or ALK mutations showed a trend towards non-engraftment (noXG, p=0.075). Patient smoking status and tumor stage did not influence engraftment rate. To identify reasons for no tumor-growth, we conducted histological analysis in the subcutaneous fat-pads (nodes in the implant sites) of 28 noXG mice. Interestingly, we identified small non-palpable foci of carcinoma in 8 animals (4 EGFR+ and 2 ALK+).

      8eea62084ca7e541d918e823422bd82e Conclusion

      Environmental or molecular factors may impair engraftment rates of EGFR+ and ALK+ LUAD samples in PDX models. Nevertheless, these models recapitulate the primary disease and could be useful for population-based drug-screening studies.

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