ESTRO 2024 - Abstract Book

S1803

Clinical - Lung

ESTRO 2024

1. Horn L, Mansfield AS, Szczęsna A, Havel L, Krzakowski M, Hochmair MJ, et al. First -Line Atezolizumab plus Chemotherapy in Extensive-Stage Small-Cell Lung Cancer. N Engl J Med [Internet]. New England Journal of Medicine (NEJM/MMS); 2018 Dec 6 [cited 2023 Oct 14];379(23):2220 – 9. Available from: https://www.nejm.org/doi/full/10.1056/nejmoa1809064 2. Paz-Ares L, Dvorkin M, Chen Y, Reinmuth N, Hotta K, Trukhin D, et al. Durvalumab plus platinum – etoposide versus platinum – etoposide in first-line treatment of extensive-stage small-cell lung cancer (CASPIAN): a randomised, controlled, open-label, phase 3 trial. Lancet [Internet]. Lancet Publishing Group; 2019 Nov 23 [cited 2023 Oct 14];394(10212):1929 – 39. Available from: http://www.thelancet.com/article/S0140673619322226/fulltext

3070

Proffered Paper

Sparing blood and immune rich organs improve the immune system during lung SBRT- Trial (NCT04273893)

Krishni Wijesooriya 1,2 , James M Larner 1 , Paul W Read 1 , Timothy N Showalter 1 , Lawrence Lum 3 , Mark R Conaway 4 , Archana Thakur 3 , Cam Nguyen 2 , David W Lain 1 , Kara Romano 1 , Einsley Janowski 1 , Christopher M McLaughlin 1 , Christopher K luminais 1 , Bryant Walker 1 , Damon Sprouts 1 , Donald Muller 1 , Kristin Ward 1 , Sunil Dutta 1 , Jason Sanders 1 , David Cousins 1 , Yhana Chavis 1 , Joe Chen 1 , Ebenezer Asare 1 , Song Wood 1 , Kristin Walker 1 1 University of Virgina, Radiation Oncology, Charlottesville, USA. 2 University of Virgina, Physics, Charlottesville, USA. 3 University of Virgina, Hematology, Charlottesville, USA. 4 University of Virgina, Public Health, Charlottesville, USA

Purpose/Objective:

Radiation Therapy (RT) is known to modulate the immune system and contribute to the generation of anti-tumor T cells stimulating T cell infiltration into tumors. However, this anti-tumor activity is offset by radiation-induced immunosuppression (RIIS). Lymphocytes, (80% are T cells) are highly radiosensitive and RIIS means destroying existing as well as newly created T lymphocytes. Optimizing RT treatment planning by considering circulating blood and lymphatics as a critical organ at risk may mitigate RIIS and lead to the creation and preservation of cytotoxic T lymphocytes converting the tumor from an immunologically cold to a hot environment increasing the efficacy of immunotherapy.

Material/Methods:

We conducted a NCI funded clinical trial for 50 early stage lung cancer patients treated with SBRT alone, from 2020 to 2023, to investigate the ability to reduce RIIS by reducing dose to circulating blood and lymphatics with the aid of a predictive algorithm. Patients with baseline absolute lymphocyte counts (ALC) less than 0.5x109 cells/L were ineligible for the trial. Patients were randomized to two arms: experimental optimization for RIIS (reduce dose to blood and lymphatic rich organs) versus standard SBRT planning. All plans adhered to treatment parameters from national protocols. Peripheral blood samples were collected at baseline, end of Tx, 4 weeks and 6 months post Tx. Data acquired for all blood cell types and lymphocyte sub populations CD3+, CD4+, CD8+, CD19+, CD56+. T, B, and