Dissection of molecular mechanisms contributing to the susceptibility and resistance of breast cancers towards Natural Killer cell immunosurveillance

• Applicant: Dr. Jiri Eitler, Ph.D.
• Subject Area: Hematology, Oncology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 518768566

Breast cancer is the most common cancer in women and the fifth leading cause of cancer death worldwide. The treatment of patients with aggressive breast cancer subtypes still poses a major clinical challenge, which is why new alternative treatment strategies are warranted. Therapies that aim to engage the patients NK cells, or the adoptive transfer of NK cells, represent a promising strategy in tumors where conventional therapies fail. However, most breast carcinomas are resistant to NK cell-mediated killing. Recently, we could define a new and yet unknown mechanism of resistance employed by breast cancers to escape NK cell surveillance. Analysis of the cytotoxic machinery of NK cells in contact with breast cancer cells revealed a block in granule polarization as main cause of resistance. The activation of NK cells is orchestrated by a balance of activating and inhibitory receptors that interplay at the immunological synapse. However, the exact mechanism underlying the failure in lytic granule polarization remains unknown. Here, we wish to build upon our finding using a unique and standardized model of genetically engineered NK-92 cells representing natural-, ADCC- and CAR-mediated killing. Using these NK-92 variants, we aim to systematically decipher the signals at the immunological synapse of NK/breast cancer cells that contribute to susceptibility and/or resistance. In a multilayered research plan genomic, pharmacological and functional methods will be employed. Specifically, we will use 1) CRISPR-based knock out screening approach to identify yet unknown, pharmacologically targetable, NK-specific checkpoint inhibitors or other molecules that mediate tumor resistance, 2) a candidate approach of selected substances to modulate adhesion molecules, activating and inhibitory ligands to improve NK cell-mediated killing. Results from approach 1) and 2) will be used to test multiple combination therapies for maximal NK cell engagement and cytotoxicity towards breast cancer. The best in class approach will be further validated in 3D spheroids and relevant preclinical in vivo xenograft models, respectively. In addition, a special attention will be put on the immune architecture of the tumor microenvironment, which is known to play a significant role in solid tumors, including breast cancer. The ultimate goal of this application is to identify novel yet unknown NK/breast cancer specific checkpoint inhibitors and receptor interactions, which will open the door for new and effective therapeutic interventions in breast cancer.st cancer.

• DFG Programme: Research Grants