Vienna, Austria

ESTRO 2023

Session Item

May 13
16:45 - 17:45
Lehar 4
Ioannis Koukourakis, Greece;
Kevin Harrington, United Kingdom
Proffered Papers
17:35 - 17:45
Dynamics of T-cell-driven immune responses to radiotherapy in a model of head and neck cancer
Charleen Min Li Chan Wah Hak, United Kingdom


Dynamics of T-cell-driven immune responses to radiotherapy in a model of head and neck cancer

Charleen Min Li Chan Wah Hak1, Holly Baldock2, Elizabeth Appleton3, Jehanne Hassan4, Malin Pedersen3, Masahiro Ono4, Kevin J. Harrington3, Alan Melcher1

1The Institute of Cancer Research, Translational Immunotherapy Team, London, United Kingdom; 2The Institute of Cancer Research, Biological Services Unit, London, United Kingdom; 3The Institute of Cancer Research, Targeted Therapy Team, London, United Kingdom; 4Imperial College London, Faculty of Natural Sciences, Department of Life Sciences, London, United Kingdom

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Purpose or Objective

Combination treatment immunotherapy (IO) and radiotherapy (RT), or immunoradiotherapy, is a promising therapeutic strategy in preclinical cancer models. However, the results of immunoradiotherapy clinical trials in locally-advanced head and neck squamous cell carcinoma (HNSCC) have been disappointing. This warrants re-evaluation of the translation between preclinical and clinical work. Standard-of-care treatment for unresected locally-advanced HNSCC is chemoradiation (CRT); however, there is a paucity of data on optimal scheduling of IO with respect to (C)RT and how combination therapy impacts on the anti-tumour T-cell response.

Material and Methods

The preclinical model of HPV16-positive HNSCC used was subcutaneous mEER (a syngeneic murine cell line harbouring HPV16 E6 and E7) tumours established in the right flank of C57BL/6 mice. Treatment comprised RT 8 Gy × 3 on alternate days, Cisplatin 7 mg/kg intraperitoneally (i.p.) and anti-PD-1 antibody 200 µg delivered i.p. twice weekly for up to 6 doses. We used the Nr4a3-Tocky model, which allows analysis of transcriptional dynamics induced by T-cell receptor (TCR) stimulation, to demonstrate the temporal changes in effector T-cells following antigen recognition. Tumours were collected from Nr4a3-Tocky mice receiving RT alone versus control and analysed ex vivo, at day 7 or day 10 post-RT, using multi-parameter flow cytometry to characterise the dynamics of TCR signalling following engagement with cognate antigen.


Our preliminary data show improved tumour control and survival with combination treatment (CRT, aPD-1 and RT or triple combination of Cisplatin, RT and anti-PD-1) compared to controls. Scheduling of aPD-1 is important and adjuvant aPD-1, delivered 7 days after last fraction of (C)RT, provides superior tumour control compared to anti-PD-1 delivered concurrently with (C)RT. Multi-parameter flow cytometry on tumour samples from mEER-bearing Nr4a3-Tocky mice show dynamic changes between day 7 versus day 10 post-RT. Specifically, conventional CD4+ T-cells showed a significant increase in “new” TCR signalling at day 7 but not day 10 following RT. Tumour-infiltrating CD8+ T-cells expressed at high levels the activation markers, CD44 and CD69, and the immune checkpoints, PD-1 and TIGIT, with significantly increased “persistent-arrested” TCR antigen engagement between days 7 and 10 post-RT.


Our preclinical model supports starting anti-PD-1 therapy in the adjuvant setting with respect to radiotherapy. There may be a therapeutic window to initiate anti-PD-1 treatment, between day 7 and day 10 following RT, at which time there is active CD8+ and conventional CD4+ T-cell antigen engagement. Improved understanding of the fundamental biology underlying the anti-tumour T-cell response may help guide design of future immunoradiotherapy clinical trials.