In seven types of mouse tumor models (B16F10, 4T1, CT26, MC38, Renca, P815, and Sa1N), Kristensen et al. developed zirconium-89 (89Zr)-labeled PET radiotracers for the specific detection and assessment of systemic CD8a + and CD4+ TILs [25]. This evidence concerns the gene CD4 and neoplasm.