The value of plasma hypoxia markers for predicting imaging-based hypoxia in patients with head-and-neck cancers undergoing definitive chemoradiation

Is there a role for [18F]-FMISO PET to guide dose adaptive radiotherapy in head and neck cancer? A review of the literature

Purpose

Hypoxia is a major cause of radioresistance in head and neck cancer (HNC), resulting in treatment failure and disease recurrence. 18F-fluoromisonidazole [18F]FMISO PET has been proposed as a means of localising intratumoural hypoxia in HNC so that radiotherapy can be specifically escalated in hypoxic regions. This concept may not be deliverable in routine clinical practice, however, given that [18F]FMISO PET is costly, time consuming and difficult to access. The aim of this review was to summarise clinical studies involving [18F]FMISO PET to ascertain whether it can be used to guide radiotherapy treatment in HNC.

Methods

A comprehensive literature search was conducted on PubMed and Web of Science databases. Studies investigating [18F]FMISO PET in newly diagnosed HNC patients were considered eligible for review.

Results

We found the following important results from our literature review: 1)Studies have focussed on comparing [18F]FMISO PET to other hypoxia biomarkers, but currently there is no evidence of a strong correlation between [18F]FMISO and these biomarkers.2)The results of [18F]FMISO PET imaging are not necessarily repeatable, and the location of uptake may vary during treatment.3)Tumour recurrences do not always occur within the pretreatment hypoxic volume on [18F]FMISO PET.4)Dose modification studies using [18F]FMISO PET are in a pilot phase and so far, none have demonstrated the efficacy of radiotherapy dose painting according to [18F]FMISO uptake on PET.

Conclusions

Our results suggest it is unlikely [18F]FMISO PET will be suitable for radiotherapy dose adaptation in HNC in a routine clinical setting. Part of the problem is that hypoxia is a dynamic phenomenon, and thus difficult to delineate on a single scan. Currently, it is anticipated that [18F]FMISO PET will remain useful within the research setting only.

Prognostic value of tumor-infiltrating immune cells and immune checkpoints in elderly head-and-neck squamous cell carcinoma patients undergoing definitive (chemo)radiotherapy

Background and purpose

Tumor-infiltrating lymphocytes (TILs) are associated with locoregional control (LRC) in head-and-neck squamous cell carcinoma (HNSCC) patients undergoing (chemo)radiotherapy. As immunosenescence results in reduced immune activity, the role of TILs in elderly HNSCC patients may differ compared to younger patients, providing a rationale to study the prognostic role of TILs and immune checkpoints (ICs) in this population.

Material and methods

Sixty-three HNSCC patients aged ≥ 65 years undergoing definitive (chemo)radiotherapy between 2010 and 2019 with sufficient material from pre-treatment biopsies were included in the analysis. Immunohistochemical stainings of CD3, CD4, CD8, PD-L1, TIM3, LAG3, TIGIT and CD96, and of osteopontin as an immunosenescence-associated protein were performed. Overall survival (OS) and progression-free survival (PFS) were determined using the Kaplan–Meier method, and Fine-Gray's models were used for locoregional failure (LRF) analyses.

Results

While there was no correlation between patient age and IC expression, osteopontin levels correlated with increasing age (r = 0.322, p < 0.05). Two-year OS, PFS, and LRC were 44%, 34%, and 71%, respectively. Increased LAG3 expression, both intraepithelial (SHR = 0.33, p < 0.05) and stromal (SHR = 0.38, p < 0.05), and elevated stromal TIM3 expression (SHR = 0.32, p < 0.05) corresponded with reduced LRFs. Absent tumoral PD-L1 expression (TPS = 0%) was associated with more LRFs (SHR = 0.28, p < 0.05). There was a trend towards improved LRF rates in elderly patients with increased intraepithelial CD3 + (SHR = 0.52, p = 0.07) and CD8 + (SHR = 0.52, p = 0.09) TIL levels.

Conclusion

LAG3, TIM3 and TPS are promising biomarkers in elderly HNSCC patients receiving (chemo)radiotherapy. Considering the frequency of non-cancer related deaths in this population, the prognostic value of these biomarkers primarily relates to LRC.