Immune response and tumour cell detection in lymph nodes of head and neck cancer

Abstract

Many patients with head and neck squamous cell carcinoma present with regional spread to the cervical lymph nodes. Lymph nodes metastases are today the most important factor influencing both the treatment and outcome for this type of cancer. The developments of new cancer treatments and especially immune oncology with the use of new antibodies have changed the field of cancer medicine. In order to fully benefit from this development we have to improve the select patients for the various treatments that can be offered. The overall goal of this thesis is to study the immune responses in tumour tissue, lymph nodes and blood in patients with head and neck cancer with focus on leukocytes, flow cytometry detection of tumour cells and T cell activity.

Paper I delineates the leukocyte ratios in blood from patients with oropharyngeal cancer in an attempt to correlate this with relevant clinical findings. Patients with oropharyngeal cancer displayed signs of increased systemic inflammation. Generally, large tumours seemed to be associated with a high neutrophil to monocyte ratio whereas patients with metastatic node spread showed a low corresponding value.

Paper II characterizes different neutrophil subsets in head and neck cancer and investigates their role in the disease. A specific neutrophil subset, CD16highCD62Ldim appeared to have anti-tumour properties, with the ability to inhibit cancer cell migration and proliferation and to induce apoptosis. Further, the elastase in the activated neutrophils created neutrophil extracellular traps and a high rate of CD16highCD62Ldim neutrophils corresponded to a better survival.

Paper III is a proof-of-concept study that appraises flow cytometry as a method for detecting lymph node metastases in oral cancer. The results could be presented within 6 hours of the time of biopsy and the data correlated precisely with the clinical histopathologic investigation performed in parallel. In addition, the obtained data indicated that flow cytometry can be a very sensitive tool also for finding micro metastases.

Paper IV was made in order to establish a reliable and clinically useful protocol for sentinel lymph node biopsies in elective neck dissections in patients with oral cancer. Various techniques for identification of sentinel nodes in oral cancer were evaluated in a clinical setting. A combination of techniques was found to constitute a reliable, clinical adaptable work concept. An injection of radioactive technetium Tc99m carried on tilmanocept started the process. The lymph nodes were visualized with SPECT-CT before surgery and with indocyanine green fluorescence dye in combination with a hand-held gamma probe during surgery.

Paper V evaluates the immune response in lymph nodes of oral cancer patients with focus on T lymphocyte activation and linkage to PD-1/PD-L1 expression Lymph node metastses in oral cancer exhibited a higher level of activated T cells than cancer free lymph nodes. CD69, a marker of T cell activity was generally higher in sentinel lymph nodes than in regular nodes. PD-L1 on tumour cells did not correlate to the expression of activation markers on T lymphocytes in the tumour. CD8+ T lymphocytes with high CD71+PD-1 expression were more abundant in the tumours than in the sentinel nodes. Altogether this indicates that immunologic activity of the sentinel node might be used to predict selection for immunological treatment.