Periodic Reporting for period 3 - INJURMET (Impact of tissue injury induced by diagnostic biopsies and surgery on cancer metastasis)
Reporting period: 2022-08-01 to 2024-01-31
Objectives: This project aims to analyze whether needle biopsies of suspicious lesions in the breast or prostate and surgical removal of the malignant lesion is accompanied by an increased release of tumor cells into the blood circulation. Moreover, we will characterize the biology of CTCs released into the blood and compare the results with the clinical outcome of the patients. Taken together, the INJURMET project will provide a comprehensive set of data on the clinically relevant question whether biopsies and surgery may have a negative side effect in some patients through the release of metastasis-competent CTCs or not.
Objective 2 - Assess primary tumor biology associated with CTC release: The collection of primary tumor tissue has started in collaboration with the departments of pathology of our clinical partners, and it will be performed in the second funding period depending on the results of the monitoring and characterization of the CTCs. The analyses will include next generation sequencing and inflammation profiling.
Objective 3 - Characterize the biology of CTCs released during biopsy and surgery: We have started to capture individual CTCs and perform a phenotypic and genotypic characterization at the single cell level. This will give novel insights into the biological characteristics of CTCs in early-stage breast and prostate cancer, which is still rare because most CTC characterization studies published in the literature were focused on patients with advanced disease. We have continuously optimized our protocols for single cell CTC analysis based on new technical developments (e.g. investment of a new high-resolution microscope with scanning abilities by internal UKE funds). In view of the low concentration of CTCs in early-stage cancer patients, which poses a significant challenge to analyze in particular early-stage patients, we have discovered new CTC markers encompassing the EMT spectrum (see below, patent applications), and we will increase the volume of blood analyzed in selected patients using novel devices (e.g. nRICH device). Moreover, we have also discovered, for the first time, a new source of blood in prostate cancer which contains several log units more CTCs than the peripheral blood and might – beyond the scope of this project – allow researchers worldwide to gain more comprehensive information on CTC biology
Objective 4 - Decipher the extravasation capacity of CTCs: To assess whether CTCs released by biopsy are able to extravasate and home into the bone marrow as one of the prime metastatic sites (in particular in prostate cancer), we have set up the regulatory and organizational basis for starting receiving the bone marrow aspirates from prostate and breast cancer patients, which has become an even more challenging task during the COVID pandemic but we are optimistic that we can achieve the goal to assess the number of DTCs in the bone marrow of corresponding patients in addition to enumerate CTC counts.
Objective 5 - Develop novel therapeutic strategies to prevent CTC extravasation: CTCs released by biopsies and/or surgery might pose an interesting target for drugs that prevent extravasation. To develop an easy-to-use model for studying CTC release in an experimental model, we developed a novel subcutaneous prostate cancer xenograft mouse model and optimized the protocols for the analysis of CTCs and DTCs. These protocols have become already very valuable for the research community, as documented by several request from international colleagues. To further evaluate CTCs released by tissue injury and to characterize the metastatic potential of these cells, the establishment of a zebrafish xenograft model is ongoing. Recently, we established a CTC-derived, ER-positive breast cancer cell line, CTC-ITB-01 (Fig. 2). NGS analyses showed that CTC-ITB-01 cells mirror the in-situ detected CTCs and CTC-ITB-01 possesses tumorigenic and metastatic capacity in immunodeficient mice. Thus, CTC-ITB-01 will be used as an exciting new CTC model to generate our first zebrafish xenograft model.