Fig. 2: Pathologic responses to neoadjuvant anti-PD-1 in primary tumor specimens of squamous cell NSCLC.

a Pathologic complete response (pCR). Absence of any viable invasive tumor in the whole tumor bed. b Major pathologic response (MPR). Percentage of residual viable tumor (%RVT) is no >10%. c Partial pathologic response (pPR). %RVT is >10%. d–f Tumor-immune histopathologic phenotypes responding (d) or non-responding (e, f) to anti-PD-1 therapy, including d immune-activated: presence of different immune cell types both in the parenchyma of tumors and the surrounding stroma, and partial area (lower left, mainly present at the margin of cancer cell nest with an “outside-in” pattern) shows immune-mediated tumor regression; e immune-excluded: presence of different immune cell types that cannot penetrate the parenchyma of the tumors but instead are contained in the stroma that surrounds the cancer cells; f immune desert: absence of abundant immune cells in either the parenchyma or the stroma of the tumor. g Representative heterogeneous responses of different RVT cancer cell nests in the same tumor bed. Original magnifications: (a, c) ×40, (b, g) ×100, (d–f) ×200.