Abstract
Abstract Background The immune system is highly responsive and positively adapts to exercise. A single bout of exercise results in the mobilisation of highly functional effector CD8+ T cells and NK-cells into the circulation. Murine cancer models have shown that exercise reduces tumour burden by increasing the frequency of tumour-infiltrating lymphocytes (TILs). There are no studies assessing the impact of an exercise programme on the levels of TILs in patients’ solid tumours in any cancer. Methods We recently completed a 16-week randomised prehabilitation exercise program (NCT02950324) in esophageal cancer patients before esophagogastric cancer resection. Exercise training was a low-to-moderate intensity twice supervised, thrice home-based weekly program. Tumour specimens obtained at the time of resection were formalin fixed paraffin embedded (FFPE) for multispectral immunohistochemical analysis. Tumour tissues were stained with primary antibodies for CD68, CD57, CD8, CD4, FoxP3, Granzyme B, PDL1 and pancytokeratin. Cell populations and spatial relationships were analysed using the Phenoimager HT (Akoya Biosciences) and QuPath. Results Although our exercise program was ~33% of the physical activity guidelines for cancer patients, physical fitness and well-being were maintained rather than significantly reduced in the intervention group compared to the control group. Multispectral analysis observed that 3.2% ± 1.1% of cells in the tumours were CD8+ T cells compared to 1.4% ± 0.5% in the control group (p < 0.001). Furthermore, we observed positive associations between increased frequencies of CD8 + TILs (Fig 1C: r = 0.562, p = 0.016), Granzyme B+/CD8 + TILs (r = 0.637, p = 0.003) and larger increases in exercise induced aerobic capacity. This data suggests that the more exercise can increase aerobic fitness, the greater the likelihood of increasing functional TILs. Conclusion New approaches to improve outcomes following surgery for esophageal adenocarcinoma are required. One such approach is immunotherapy. However, immunotherapy is relatively ineffective in esophageal adenocarcinoma due to the lack of CD8+ T cells and NK cells in the tumours. Increasing TILs through exercise programmes that are designed to focus on maintaining or improving aerobic capacity may improve patients’ response to immunotherapy and positively impact prognosis and survival.