This study examined how hypoxia shapes tumor microenvironment (TME) evolution and treatment response in metastatic clear cell renal cell carcinoma (ccRCC), comparing VEGFR-TKI, anti-PD-1 (aPD-1), and combined VEGFR-TKI/aPD-1 regimens using a transgenic ccRCC mouse model plus human single-cell RNA sequencing and imaging mass cytometry cohorts.
Hypoxia-responsive SPP1+ tumor-associated macrophages (TAMs) were rare at baseline in pseudohypoxic ccRCC tumors but emerged on-treatment as a marker of successful VEGFR-TKI/aPD-1 response (reflecting treatment-induced hypoxic necrosis); paradoxically, *pre-treatment* hypoxia predicted worse outcomes across VEGFR-TKI/aPD-1 trials and real-world cohorts, and prolonged VEGFR-TKI exposure worsened metastasis in mice.
Mechanistic findings rely partly on a transgenic mouse model, which may not fully recapitulate human ccRCC biology; human cohort sizes for on-treatment single-cell and imaging mass cytometry analyses are not specified in the abstract; causal direction of hypoxia-driven metastasis was shown in mice only, not confirmed in a prospective human study.
In metastatic ccRCC treated with VEGFR-TKI/aPD-1 combinations, pre-existing tumor hypoxia may signal a worse prognosis — clinicians should be aware that this differs from the favorable on-treatment hypoxic necrosis signature. These findings may eventually support hypoxia biomarker stratification when selecting between VEGFR-TKI/aPD-1 vs. dual checkpoint (aPD-1/anti-CTLA-4) regimens.
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