Glioblastoma is an aggressive primary tumor of the central nervous system. Targeting the immunosuppressive glioblastoma-associated microenvironment is an interesting therapeutic approach. Tumor-associated macrophages represent an abundant population of tumor-infiltrating host cells with tumor-promoting features. The colony stimulating factor-1/ colony stimulating factor-1 receptor (CSF-1/CSF1R) axis plays an important role for macrophage differentiation and survival. We thus aimed at investigating the antiglioma activity of CSF1R inhibition alone or in combination with blockade of programmed death (PD) 1. We investigated combination treatments of anti-CSF1R alone or in combination with anti-PD1 antibodies in an orthotopic syngeneic glioma mouse model, evaluated post-treatment effects and assessed treatment-induced cytotoxicity in a coculture model of patient-derived microtumors (PDM) and autologous tumor-infiltrating lymphocytes (TILs) ex vivo. Anti-CSF1R monotherapy increased the latency until the onset of neurological symptoms. Combinations of anti-CSF1R and anti-PD1 antibodies led to longterm survivors in vivo. Furthermore, we observed treatment-induced cytotoxicity of combined anti-CSF1R and anti-PD1 treatment in the PDM/TILs cocultures ex vivo. Our results identify CSF1R as a promising therapeutic target for glioblastoma, potentially in combination with PD1 inhibition.
Glioblastoma are incurable primary tumors of the central nervous system that frequently harbor molecular alterations in the retinoblastoma pathway with subsequent cell cycle abnormalities. It is aimed to investigate the anti‐glioma activity of the novel cell cycle‐stabilizing compound Argyrin F and its potential treatment‐induced vulnerabilities to exploit possibilities for novel rational combination therapies. Human and murine glioma cells are used, cytotoxicity and clonogenic survival assays, cell cycle analyses, and immunoblots are performed. Residual freshly resected tissue is used for a preclinical glioma model ex vivo, i.e., patient‐derived microtumors (PDMs) for co‐culture experiments with autologous tumor‐infiltrating lymphocytes (TILs). Mass spectrometry‐based immunopeptidomics are performed and the orthotopic syngeneic SMA560/VM/Dk glioma mouse model is used. Argyrin F‐induced cell cycle arrest and reduced clonogenic survival is observed. Argyrin F‐treated experimental glioma in vivo displays 4.6‐fold more glioma‐infiltrating CD8+ T cells. A distinctive treatment‐induced immunopeptidome is discovered. The combination of Argyrin F plus PD‐1 antibody increases cellular toxicity in PDM/TILs co‐cultures ex vivo and prolonged overall survival compared with monotherapies in vivo. Thus, Argyrin F leads to anti‐glioma effects and increases the immunogenicity, paving the way for a novel combination therapy of Argyrin F plus PD‐1 blockade.
In light of the frequent development of therapeutic resistance in cancer treatment, there is a strong need for personalized model systems representing patient tumor heterogeneity, while enabling parallel drug testing and identification of appropriate treatment responses in individual patients. Using ovarian cancer as a prime example of a heterogeneous tumor disease, we developed a 3D preclinical tumor model comprised of patient-derived microtumors (PDM) and autologous tumor-infiltrating lymphocytes (TILs) to identify individual treatment vulnerabilities and validate chemo-, immuno- and targeted therapy efficacies. Enzymatic digestion of primary ovarian cancer tissue and cultivation in defined serum-free media allowed rapid and efficient recovery of PDM, while preserving histopathological features of corresponding patient tumor tissue. Reverse-phase protein array (RPPA)-analyses of >110 total and phospho-proteins enabled the identification of patient-specific sensitivities to standard, platinum-based therapy and thereby the prediction of potential treatment-responders. Co-cultures of PDM and autologous TILs for individual efficacy testing of immune checkpoint inhibitor treatment demonstrated patient-specific enhancement of cytotoxic TIL activity by this therapeutic approach. Combining protein pathway analysis and drug efficacy testing of PDM enables drug mode-of-action analyses and therapeutic sensitivity prediction within a clinically relevant time frame after surgery. Follow-up studies in larger cohorts are currently under way to further evaluate the applicability of this platform to support clinical decision making.
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