On lymph node based immunotherapy of cancer

Abstract

Cancer Immunotherapy based on one’s own immune system to fight cancer is emerging as an important treatment option for advanced stage diseases. The earliest attempts of cancer therapy based on the provocation of the immune system with infectious agents can be traced back to the 18th century, and the field of immunotherapy has since developed into three main groups: cellular-, antibody- and cytokine-therapies. Recently, especially the treatment with so called checkpoint blocking antibodies has led to a breakthrough in the treatment of some cancers, and at the time of writing this thesis the Nobel Prize in medicine is to be awarded to the discoverers of the two first such checkpoint pathways targeted with successful, approved drugs. These agents however, seems not work if there is not a weak suppressed immune response already in the patient and alternative strategies are needed to help the patients where checkpoint blockade is unsuccessful. One such immunotherapy that has proven successful is adoptive transfer of tumor specific T-cells grown in the lab to the patient.

Previous studies in our research group found that sentinel lymph nodes, which are the lymph nodes first draining the tumor, may be sites of specific T-cell responses to the tumor since antigens from the tumor are presented there by professional antigen presenting cells. Due to the fact that these lymph nodes are also the first ones to be colonized by metastasizing tumor cells from the primary tumor, the histopathological status of these tumor draining lymph nodes is essential for staging and prognosis, and this analysis usually involves destructive processing of the lymph node tissue. As the lymph node T-cells are a potential source for tumor-specific T-cell therapy of cancer, it is essential to find a method of metastasis detection that does not require destruction of the whole lymph node tissue. Thus our lab has developed a method to dissociate the cells of the lymph node for flow cytometric analysis based on markers found on tumor cells and not normal lymph node tissue, sparing a large number of lymphocytes for therapeutic use and at the same time enhancing the sensitivity of metastasis detection. In this thesis, this analysis strategy is extended to the micro-metastasis detection in lymph nodes draining penile cancer. We find that, using pan-cytokeratin staining of tumor cells the single cell preparation from lymph nodes of patients, we are able to identify metastasis in all cases also confirmed by standard pathological examination of other parts of the lymph nodes, and additional we identify metastasis in two patients where no metastasis was found by standard measures. We also present preliminary data from an analysis of the cellular composition of the patient lymph nodes, and data on the possible reactivity of the lymph node T-cells to antigens found in autologous whole tumor lysates. As a large proportion of penile cancers are associated with HPV infection we also tested the reactivity of lymph node T-cells to the Gardasil® vaccine antigen preparation.

The thesis also presents a clinical study extending earlier clinical immunotherapy studies on the expansion of tumor reactive, sentinel lymph node T-cells for the treatment of colorectal cancer. We performed a phase I/II clinical study on 71 colorectal cancer patients. No treatment-related toxicity was observed among the patients who received the T-cell therapy. The 9 patients with stage IV that received the sentinel node T-cell therapy showed an increased 24-month survival rate compared to the control group of 16 patients who received standard therapy and there was a tendency to increased overall survival after conclusion of the 33-month follow up. Our study demonstrates that tumor draining lymph node based T cell immunotherapy is feasible and safe for patients with colorectal cancer.