Prehabilitation during neoadjuvant chemotherapy results in an enhanced immune response in oesophageal adenocarcinoma tumours.

INTRODUCTION: For patients with locally advanced oesophagogastric cancer, the standard of care in the UK is neoadjuvant chemotherapy (NAC) followed by surgery. Prehabilitation exercise can improve physiological function and fitness. As no studies have assessed tumour infiltrating lymphocyte (TIL) responses in humans during NAC undergoing prehabilitation, we aimed to determine whether prehabilitation increased TILs. METHODS: We enrolled 22 patients with locally advanced oesophageal cancer on a randomised control trial comparing 16 weeks of low-to-moderate intensity twice weekly supervised and thrice weekly home-based exercise (Prehab: N=11) to no prehabilitation (Control: N=11). We analysed peak cardiorespiratory fitness (VO2peak) before NAC, after 8 weeks of NAC (Post-NAC) and following 8 weeks of NAC recovery before surgery (Pre-Surgery). We assessed tumours by high-resolution multispectral immunohistochemistry (mIHC) and NanoString spatial transcriptomics. RESULTS: We observed a main effect of time [F(2,40) = 6.394, p=0.004, n2=.242] and a group x time interaction [F(2,40) = 3.445, p=0.042, n2=.147] for relative VO2peak. This was characterised by a 9.0% +/-10.2% reduction at Post-NAC (p=0.018) for the Controls, while the Prehabilitation group maintained VO2peak at Post-NAC (p=1.000) and increased by 9.4% +/- 7.6% from Post-NAC to Pre-Surgery (p=0.010). Prehabilitation had significantly more CD8+ cells in the tumours (3.2% +/- 3.3% v 1.4% +/- 1.3%, p<0.001) and the stroma (3.2% +/- 2.4% v 1.6% +/- 1.4%, p<0.001) than the Controls. Between Baseline and Post-NAC where the Prehabilitation group maintained VO2peak better than Controls there were significant positive associations with changes in VO2peak and the frequencies of CD8+ TILS (r=.531, p=0.016), PDL1+ cells (r=.566, p=0.009), and GrzB+ TILS (r=.592, p=0.007). When normalised to total numbers of TILs, Prehabilitation was associated with higher levels of CD56+ NK cells (p=0.0274) of which CD56dim NK cells were highest (p=0.0464). Evaluation of the presence and localisation of tumour-associated TLSs in the oesophageal tumours revealed that most TLSs were in the peritumoral regions. Prehabilitation was associated with a higher TLS cell density (p<0.001) and a non-significant smaller, less diffuse surface area (p=0.5134). Additionally, Prehabilitation tumours had more clearly defined germinal centres indicative of mature TLSs. CONCLUSION: We show that exercise training during NAC, which improves cardiorespiratory fitness, is associated with increased frequencies of TILs and maturity of TLS. These data suggest that exercise during NAC enhances the immune system, possibly to be suitable for immunotherapy.