Lymphocyte Infiltration Determines the Hypoxia-Dependent Response to Definitive Chemoradiation in Head-and-Neck Cancer: Results from a Prospective Imaging Trial

Abstract

Tumor hypoxia in head-and-neck squamous cell carcinoma (HNSCC) leads to an immunosuppressive microenvironment and reduces the response to radiotherapy. In this prospective imaging trial, we investigated potential interactions between functional hypoxia imaging and infiltrating lymphocyte levels as a potential predictor for treatment response in HNSCC patients. Methods: In total, 49 patients receiving definitive chemoradiation for locally advanced HNSCCs underwent pretherapeutic biopsies and peritherapeutic hypoxia imaging using ¹⁸F-misonidazole PET at weeks 0, 2, and 5 during chemoradiation. Hematoxylin-eosin and immunohistochemical stainings for tumor-infiltrating lymphocytes, tissue-based hypoxia, and microvascular markers were analyzed and correlated with the longitudinal hypoxia dynamics and patient outcomes. Results: High levels of tumor-infiltrating total lymphocytes correlated with superior locoregional control (LRC) (hazard ratio [HR], 0.279; P = 0.011) and progression-free survival (PFS) (HR, 0.276; P = 0.006). Similarly, early resolution of ¹⁸F-misonidazole PET-detected tumor hypoxia quantified by ¹⁸F-misonidazole dynamics between weeks 0 and 2 of chemoradiation was associated with improved LRC (HR, 0.321; P = 0.015) and PFS (HR, 0.402; P = 0.043). Outcomes in the favorable early hypoxia resolution subgroup significantly depended on infiltrating lymphocyte counts, with patients who showed both an early hypoxia response and high lymphocyte infiltration levels exhibiting significantly improved LRC (HR, 0.259; P = 0.036) and PFS (HR, 0.242; P = 0.017) compared with patients with an early hypoxia response but low lymphocyte counts. These patients exhibited oncologic results comparable to those of patients with no hypoxia response within the first 2 wk of chemoradiation. Conclusion: This analysis established a clinical hypoxia-immune score that predicted treatment responses and outcomes in HNSCC patients undergoing chemoradiation and may help to devise novel concepts for biology-driven personalization of chemoradiation.

Keywords: FMISO PET; chemoradiation; head-and-neck cancer; hypoxia; immune system.

FIGURE 1.

Lymphocyte levels and hypoxia dynamics during chemoradiation. (A) HNSCC patient with hypoxia response and high intratumoral lymphocyte levels. Pretherapeutic CT and MRI show oral cavity carcinoma. Follow-up MRI after 43 mo shows LRC. Pretherapeutic ¹⁸F-FDG PET and ¹⁸F-misonidazole PET at weeks 0 and 2 are representative images of immunohistochemical stainings for CD3, CD4, and CD8. (B) HNSCC patient with hypoxia response but low intratumoral lymphocyte levels. Pretherapeutic CT and MRI scans show oropharyngeal and hypopharyngeal carcinoma. Follow-up MRI demonstrates locoregional relapse after 5 mo. Representative pretherapeutic ¹⁸F-FDG PET and ¹⁸F-misonidazole PET at weeks 0 and 2 are depicted; pretherapeutic immunohistochemical staining for CD3, CD4, and CD8 shows low lymphocyte infiltration levels.

FIGURE 2.

High lymphocyte levels correspond to increased LRC and PFS rates in HNSCC patients. (A and B) LRC (A) and PFS (B) rates stratified by total tissue lymphocyte levels in tumor biopsies. (C and D) LRC (C) and PFS (D) rates divided by high and low levels of CD3-positive lymphocytes.

FIGURE 3.

Early hypoxia resolution during chemoradiation is prognosticator for improved LRC and PFS. (A and B) LRC (A) and PFS (B) in HNSCC patients undergoing chemoradiation stratified by hypoxia resolution assessed by ¹⁸F-misonidazole PET imaging between weeks 0 and 2.

FIGURE 4.

High lymphocyte levels determine response of hypoxia-resolving and -nonresolving HNSCCs to chemoradiation. (A and B) Kaplan–Meier curves showing LRC (A) and PFS (B) depending on early hypoxia resolution and total tumor lymphocyte levels. (C and D) LRC (C) and PFS (D) divided by early hypoxia resolution and CD3-positive lymphocyte levels.