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V. Ludovini



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    ORAL 38 - Liquid Biopsies (ID 147)

    • Event: WCLC 2015
    • Type: Oral Session
    • Track: Biology, Pathology, and Molecular Testing
    • Presentations: 1
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      ORAL38.07 - Quantification of EGFR Mutations in Plasma of NSCLC Patients: An Early Predictor of Clinical Response to Tyrosine Kinase Inhibitors (ID 2242)

      16:45 - 18:15  |  Author(s): V. Ludovini

      • Abstract
      • Presentation
      • Slides

      Background:
      As DNA analytical methods have become more sensitive, attempts to develop accurate clinical tests to assess tumor mutation status by means of patient plasma samples are now being pursued. The potential to accurately quantify EGFR mutations in plasma from non-small cell lung cancer (NSCLC) patients would enable more rapid and more frequent analyses to assess disease status; however, the utility of such analyses for clinical purposes has only recently started to be explored.

      Methods:
      Plasma samples were obtained from 69 NSCLC patients with EGFR-mutated tumors and 21 negative control cases. EGFR mutations in plasma were analyzed by a standardized allele-specific polymerase chain reaction (PCR) test and ultra-deep next generation sequencing (NGS). A semi-quantitative index (SQI) was derived from dilutions of known EGFR mutation copy numbers. Clinical responses were evaluated by RECIST 1.1 criteria and expressed as percent tumor shrinkage.

      Results:
      The sensitivity and specificity of the PCR test and NGS assay in plasma versus tissue were 72% versus 100%, and 74% versus 100%, respectively. Quantitative indices by the PCR test and NGS were significantly correlated (P<0.001). EGFR testing at baseline and serially at 4–60 days during TKI therapy revealed a progressive decrease in SQI , starting from day 4, in 95% of cases. The rate of SQI decrease correlated with percent tumor shrinkage at 2 months (P<0.0001); at 14 days it was more than 50% in 70% of patients (rapid responders) (Fig.1A-B). In 2 patients with slow response (Fig.1B), an early increase in the circulating levels of the T790M mutation was observed. These patients were defined as early resistant (Fig.1C). No early T790M mutations were seen in plasma samples of rapid responders, suggesting that slow responders are more prone to develop early resistance.

      Conclusion:
      Quantification of EGFR mutations from plasma with a standardized PCR test is feasible. To our knowledge, this is the first study showing a strong correlation between the EGFR SQI during therapy and clinical response with relevant implications for patient management. With the strong correlation between EGFR SQI in plasma and clinical outcome, this study opens the way to prospectively design clinical trials to confirm these data and evaluate the diagnostic value of this test. Figure 1



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    P1.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 233)

    • Event: WCLC 2015
    • Type: Poster
    • Track: Biology, Pathology, and Molecular Testing
    • Presentations: 1
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      P1.04-002 - Protein Signaling Analysis of KRAS Mutant Lung Adenocarcionomas Reveals Variable MAPK and mTOR Pathway Activation (ID 2280)

      09:30 - 17:00  |  Author(s): V. Ludovini

      • Abstract

      Background:
      Despite the numerous efforts made to target KRAS directly, this protein is still undruggable. A number of therapeutics that target linked KRAS pathway members have been tested, but their efficacy in KRAS mutant lung adenocarcinoma is still controversial. Understanding the biochemically linked protein signaling network associated with a KRAS mutation may lead to the identification of therapeutic targets to identify patients that may benefit from a therapeutic agent targeting KRAS downstream substrates.

      Methods:
      Thirty-four archived samples from surgically-treated KRAS mutant adenocarcinomas were included in this study. Samples were collected at the H.Lee Moffitt Cancer Center & Research Institute (Tampa, FL) and at the Santa Maria della Misericordia Hospital (Perugia, Italy). Pure cancer epithelial cell subpopulations were isolated using Laser Capture Microdissection. The expression/activation level of 155 proteins was then measured by Reverse Phase Protein Microarray, a high-throughput semi-quantitative platform.

      Results:
      The protein activation level of ERK (as measured by phosphorylation of T202/Y204), a direct downstream substrate of KRAS activity, was highly variable across KRAS mutant samples. While a subgroup of patients showed, as expected, high activation of ERK, approximately 2/3 of the patients had a comparable ERK activation level to the wild-type counterpart previously analyzed. The activation level of the remaining protein signaling analytes was then compared between samples with high and low ERK activation. Tumors with high levels of ERK activation showed a significant increase in the signaling network of: 1) the MAPK proliferative pathway including Ras-GRF1 S916, Mek 1/2 S217/221, MSK1 S360, p38MAPKinase T180/Y182 (p=0.03, p<0.01, p=0.04, p<0.01 respectively), 2) the AKT-mTOR pathway including Akt S473, AMPKα1 S485, ATP Citrate Lyase S454, LKB1 S428, mTOR S2448, p70S6K T389, p70S6K T412, 4E-BP1 S65 (p<0.01, p<0.01, p<0.01, p<0.01, p<0.01, p<0.01, p=0.02, p=0.03 respectively).

      Conclusion:
      This analysis suggests that the signaling network of KRAS mutant lung adenocarcinomas, while manifesting expected ERK activation as a group, is highly variable. In fact a majority of KRAS mutant tumors had the same range of MEK-ERK activation as KRAS WT tumors. Analysis of high and low ERK activation in the KRAS mutant tumors revealed druggable protein signaling activation of a number of important targets. If validated in a larger study set, these data may have important clinical implication for the allocation of patients toward more effective and specific targeted treatments.