Samenvatting
Cancer immunotherapy has noticeably improved patient outcomes, albeit with variable success rates. Immunosuppressive cells such as tumor-associated macrophages (TAMs) likely contribute to immunotherapy’s suboptimal response rate. Indeed, elevated TAM presence correlates with poor prognosis and resistance to therapies, highlighting the need for strategies targeting macrophages in cancer treatment. TAMs exhibit significant heterogeneity based on the tumor microenvironment's signals. More than 10 years ago, the CMIM laboratory distinguished two primary TAM subsets: MHC-IIhigh and MHC-IIlowTAMs. The latter is notably immunosuppressive and pro-angiogenic, with high expression of surface molecules like CD206 (MMR) and CD163, which serve as biomarkers for cancer therapy targeting. Nanobodies, derived from Camelid antibodies, offer an interesting means for targeting TAMs. Due to their small size, Nanobodies can easily be functionalized for different applications in cancer treatment. For example, a previous study linked an anti-CD206 Nanobody to an Imidazoquinoline (IMDQ) variant to repolarize MHC-IIlow TAMs into MHC-IIhigh TAMs. However, CD206 expression on non-macrophage cells in the liver led to an antigenic sink and toxic events, thereby emphasizing the necessity for alternative TAM markers. CD163, a transmembrane protein implicated in hemoglobin uptake and inflammation regulation by binding to TWEAK, is highly expressed on CD206high TAMs. Its macrophage-specific expression and therefore lower peripheral antigenic sink makes it a promising TAM marker. The goal of this project is to use novel, in-house generated CD163-specific Nanobodies to target CD163-expressing macrophages for therapeutic purposes.
The main part of this study encompassed the selection, expression, and characterization of ten lead Nbs against mouse CD163. We first investigated their affinities via surface plasmon resonance (SPR) and flowcytometry and demonstrated that a few lead Nbs displayed a clear calcium dependence for binding. A couple of Nbs also appeared to compete with hemoglobin, one of the natural ligands of CD163. In the second part of this thesis, we converted the lead Nb(23766) into adequate formats to investigate its potential
therapeutic efficacy via two different strategies. First, to repolarize tumor-promoting TAMs, we intend to link CD163-specific Nb(s) to immunomodulatory molecules (IMDQ). Secondly, the effects of depleting CD163-expressing TAMs via ADCC will be explored through the design of bivalent Nb-Fc fusion constructs. To achieve this goal, we concurrently examined CD163 expression on MHC-IIlow TAMs across various tumor models to choose the best model for future experiments.
| Datum prijs | 5 sep 2023 |
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| Originele taal | English |
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| Begeleider | Jolien Van Craenenbroeck (Advisor) & Cecile Vincke (Advisor) |