Virtual Library

Start Your Search

P. Amstutz



Author of

  • +

    MINI 02 - Immunotherapy (ID 92)

    • Event: WCLC 2015
    • Type: Mini Oral
    • Track: Biology, Pathology, and Molecular Testing
    • Presentations: 1
    • +

      MINI02.04 - Sequential Assessment of DNA Damage Response and PD-L1 Expression in Circulating Tumor Cells of Lung Cancer Patients during Radiotherapy (ID 2511)

      11:00 - 11:05  |  Author(s): P. Amstutz

      • Abstract
      • Presentation
      • Slides

      Background:
      Recent evidence suggests that PD-L1 expression can be induced with radiotherapy and may be a mechanism for resistance to radiotherapy and immunotherapy. Sequentially assessing PD-L1 expression on cancer associated cells in circulation during treatment regimens may be a way to assess the efficacy of radiotherapy and immunotherapy in clinical trials. For this feasibility study, we evaluated the association of RAD50 induction, and PD-L1 expression, on CTCs and Cancer Associated Macrophage-Like Cells (CAMLs) in lung cancer patients (pts) before and during radiotherapy to determine expression changes of these markers.

      Methods:
      Eleven pts with stage I-IV lung cancer were included in this pilot study. Three pts received Stereotactic Body Radiation Therapy (SBRT) for stage I disease and 8 other pts received chemoradiation for stage II-IV disease. Baseline blood samples (7.5 ml) were drawn prior to the start of radiotherapy (T0) and a second blood sample was drawn at a follow up visit during radiotherapy; or for three pts, after completing SBRT (T1); for a total of 22 samples. Blood was processed using CellSieve™ microfiltration (Creatv Microtech), stained for cytokeratin 8, 18 & 19 and CD45, and imaged. Using the QUAS-R (Quench, Underivatize, Amine-Strip and Restain) technique to remove fluoresce signal, all cells were restained for RAD50-AlexaFluor550 and PD-L1-AlexaFluor 488, along with DAPI nuclear stain. The RAD50 foci numbers within nuclear regions were quantified. PD-L1 pixel intensity was measured by the ZenBlue software and grouped into 4 IHC groups: 0-negative (pixel average 0-215), 1-low (pixel average 216-300), 2-medium (pixel average 301-750), and 3-high (pixel average 751+).

      Results:
      There was at least one cytokeratin positive cell (i.e. CTC or CAMLs) found in each of the samples. Specifically CTCs were found in 82% of T0 and 64% of T1 samples, and CAMLs were found in 91% of T0 and 100% of T1 samples. RAD50 foci ranged from 0-16 per cell, with an average of 0.69 at T0 that increased to 3.46 at T1 (p=0.002) during radiotherapy. Distinctively, there were 6 pts with greater than 2 fold RAD50 foci increase at T1 and 5 pts with ≤ 2 fold induction. PD-L1 expression ranged from 34-2004 pixel intensity, with an average of 170 at T0 and 336 at T1 (p=0.08). Interestingly, 4 pts had no PD-L1 expression at T0 but an increase to 2 to 3+ at T1, 4 pts with low/no PD-L1 expression remained low at T1, and 3 pts had high PD-L1 expression that remained high or decreased at T1. There was no correlation between RAD50 induction and PD-L1 expression.

      Conclusion:
      Both RAD50 foci and PD-L1 expression were quantifiable in both CTCs and CAMLs, and had variable responses to radiotherapy +/- chemotherapy. These data suggest that sequential tracking of CTCs or immune-related cells from the primary lung tumor is feasible using microfiltration and potentially can serve as predictive biomarkers for cancer therapy.

      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.