In the realm of cancer research, the pursuit of precision is paramount. As scientists tirelessly work towards tailored therapies, the need for accurate and reliable preclinical models has never been more critical. Patient-Derived Xenograft PDX models have emerged as invaluable tools, mirroring the intricate nuances of human tumors within the controlled environment of a laboratory setting. However, the effectiveness of PDX models hinges on the choice of host organisms, and here, immunodeficient mice take center stage.