Combinatorial approach with Cytokine-Induced Killer (CIK) cells and immunotools to fight HER2-positive breast cancer. Culture optimization of CIK cell expansion and function.

Targeting HER2 molecules for HER2+ breast cancer has become the standard care for both early and advanced-stage disease, on the other hand the treatment of metastatic HER+ tumors that develop resistance and lead to a disease progression, remained a barrier. In these recent years, the Adoptive Cell Therapy (ACT), that achieved dramatic results against hematologic malignancies, has been studied as an adjuvant therapy to cure breast cancer patients even if remains challenging to treat solid tumors. In this thesis work we focus on ACT using Cytokine-Induced Killer (CIK) cells together with several immunotools, to better target HER2-positive breast cancer. CIK cells are known for the relatively easy expansion protocol, minimal side effects upon injection to patients, and for the efficacy, demonstrated both in pre-clinical and clinical studies. Moreover, recent studies showed that the combination of CIK cells with monoclonal antibodies led to an enhancement in cytotoxic function via Antibody-Dependent Cellular Cytotoxicity (ADCC), due to the expression of CD16. Here, we combined CIK cells with different HER2-targeting immunotools against several HER2-positive breast cancer cell lines. CIK cells were easily expanded, reaching clinically relevant numbers, from PBMC of both healthy or breast cancer patients using serum-free culture medium and gas-permeable culture devices, as occur in GMP cell factory when CIK cells are used in clinic. The combination of CIK cells with HER2-targeting immunotools significantly improved the cytotoxic function, compared to CIK only or CIK combined with an isotype control. CIK cell’s GMP-expansion protocol was optimized first on the Gas-permeable Rapid Expansion (G-Rex) 24-well plates and moreover, by adding, at different time points during the culture period, the IL-12, IL-15, and IL-18 cytokines. The combination of all the cytokines showed higher expansion and cytotoxicity against breast cancer cell lines and an increase of CD25 (IL-2Rα) expression in a donor-dependent manner compared to CIK cultured with the standard protocol with only IL-2 as stimulated cytokine.