Validated xenograft models refer to preclinical animal models that are used in cancer research to study the behavior of human tumors in vivo. Xenograft models involve the transplantation of human cancer cells or tissues into immunodeficient mice or other animals, where they grow and develop as tumors.

The validation of xenograft models involves demonstrating that the model accurately recapitulates the biological and molecular characteristics of the human tumors it is intended to represent. This includes validating the tumor histology, genetic and molecular profiles, and response to therapies, among other parameters.

Validation of xenograft models typically involves comparing the model to clinical data from human patients, using various techniques such as genomic profiling, gene expression analysis, and histological examination. This helps to ensure that the xenograft model is a reliable and relevant representation of the human tumor, and can be used to accurately predict the efficacy of potential cancer therapies.

Validated xenograft models are a critical tool in cancer research, as they provide a way to study the complex biology of human tumors in vivo and evaluate the efficacy of potential cancer treatments before they are tested in human clinical trials. However, the use of xenograft models also has limitations, such as the lack of immune system interactions and the potential for genetic drift, which must be taken into account when interpreting the results.