CXCL9 and lung cancer: Together, these data place immune checkpoints at the heart of lung cancer immune dysfunction—where cytokine/chemokine circuits (e.g., IL-1β, IL-6, IL-8, TNF-α; CCL2, CCL5, CXCL9) modulate T-cell responses, myeloid skewing, and PD1/PD-L1 regulation—and illustrate how pandemic-related diagnostic barriers intersected with an already complex immunobiology [45,46,47,48,90,93,94,95,96,97,98,99,100,101,102] (Figure 5).