Aims Collecting duct carcinoma (CDC) and fumarate hydratase-deficient renal cell carcinoma (FH-deficient RCC) have similar histological morphologies and both show a poor prognosis. Programmed death ligand 1 (PD-L1) inhibitor has been approved for the treatment of RCC. However, tumour-infiltrating neutrophils stimulated by interleukin-8 (IL-8) interfere with PD-L1 inhibitors. Here, we retrospectively analysed PD-L1 and IL-8 expression, and examined its relationship with infiltrating immune cells.
Methods Nine cases of CDC and seven cases of FH-deficient RCC were selected. We defined PD-L1 and IL-8 expression by the Tumour Proportion Score and Combined Positive Score (CPS). We counted the numbers of CD8+, CXCR2+, CD11b+, CD66b+ and CD33+ immune cells located in the tumour components.
Results A number of CXCR2+ (p=0.0058), CD11b+ (p=0.0070) and CD66b+ (p=0.0067) immune cells infiltrating into CDC were significantly higher than those infiltrating into FH-deficient RCC. In CDC, PD-L1 expression was correlated with a high density of CD8+ lymphocytes (p=0.0389), but was not in FH-deficient RCC (p=0.6985). IL-8 CPS was significantly higher in CDC than in FH-deficient RCC (p=0.0069). In addition, among the CDC cases, IL-8 CPS showed significant positive correlations with CXCR2+, CD11b+ and CD66b+ immune cell densities (p=0.0250, p=0.0104 and p=0.0374, respectively), whereas FH-deficient RCC showed no significant correlations between IL-8 CPS and immune cell densities.
Conclusions Our results suggest the difference of each tumour microenvironment between CDC and FH-deficient RCC, and IL-8 is a potential therapeutic target for treating CDC, but not FH-deficient RCC.
Data availability statement
No data are available.
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Handling editor Runjan Chetty.
Contributors DK performed the research and wrote the paper. KK, DT and SU contributed to the research design and slide review. ME, MK, KN, KT, YuO and YK contributed to the sample collection and research design. YoO designed the research and gave final approval of the manuscript. All authors critically reviewed and approved the manuscript. YoO is responsible for the overall content as the guarantor.
Funding This study was supported by a Fukuoka Public Health Promotion Organization Cancer Research Fund.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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