CD8A and neoplasm: • Substantial uptake of 89Zr-Df-IAB22M2C was seen in PF-07062119-treated tumors, significantly higher than controls, and response varied with PF-07062119 dose and treatment duration.• A moderate correlation was found between the uptake of radioactivity in tumor tissue and the density of CD8+ cells, underscoring the imaging agent’s utility for non-invasive evaluation of intra-tumoral CD8+ T cells and the mechanism of action of PF-07062119.