In vivo models are animal-based systems used to study how cancer therapies behave in a living organism, providing insights that cannot be captured in vitro. They allow researchers to evaluate a drug’s efficacy, toxicity, pharmacokinetics, and impact on the tumor microenvironment under physiological conditions. Common in vivo models include cell line–derived xenografts (CDX), patient-derived xenografts (PDX), syngeneic models, and humanized models, each offering distinct advantages depending on the scientific question. These models help predict clinical outcomes by capturing tumor complexity, immune interactions, and mechanisms of resistance. Ultimately, in vivo systems are essential tools for advancing cancer therapies from preclinical testing to successful clinical development.
In patient-derived xenograft (PDX) models, tumor tissue from cancer patients is implanted into immunocompromised mice, allowing the human tumor to grow in vivo. Fragments from primary or metastatic tumors are sectioned into small pieces and transplanted while preserving their original tissue architecture and cellular composition. Read more
Cell line–derived xenograft (CDX) models are established by implanting human cancer cell lines into immunodeficient mice to generate tumors in vivo. Cultured cells are typically introduced subcutaneously, orthotopically, or intravenously into strains such as athymic nude or severe combined immunodeficient (SCID) mice. Once established, tumors exhibit predictable growth kinetics, providing a robust platform for studying key aspects of human cancer biology, including tumor growth, angiogenesis, and metastasis. Read more
Genetically engineered mouse models (GEMMs) are transgenic mice with defined mutations designed to mimic oncogenic activations and/or tumor-suppressor losses observed in specific human cancers. Tumors arising de novo in these models closely mirror human disease at histopathological, molecular, and clinical levels, including the composition of the tumor microenvironment. GEMMs have advanced from single-allele constructs to sophisticated multiallelic designs that better parallel human genomic complexity. Read more
Humanized mouse models are engineered platforms that reconstitute key components of the human immune system (HIS) in an animal host. By incorporating human immune cells, these models better recapitulate the complexity of the human tumor microenvironment (TME). This is dynamic ecosystem where tumor cells interact with immune cells, stromal components like fibroblasts and endothelial cells, and therapeutic agents. Humanized mice are particularly valuable for immuno-oncology research, where understanding immune-tumor interactions is critical for developing and evaluating new therapies. Read more
Syngeneic tumor models involve implanting tumor cells derived from a specific mouse strain into genetically identical, immunocompetent hosts. Because the host immune system remains intact, these models are particularly useful in evaluating immuno-oncology agents and studying de novo anti-tumor immune responses without requiring any adoptive transfer of immune cells. Unlike xenograft models that rely on immunodeficient mice with human tumors, syngeneic models recreate a species-matched, physiologically relevant tumor microenvironment that is well-suited for investigating immune interactions, immune evasion mechanisms, therapeutic resistance, and immunotherapy mechanisms of action. Read more