Prognostic value of B7-H1, B7-H3 and the stage, size, grade and necrosis (SSIGN) score in metastatic clear cell renal cell carcinoma.

Introduction: We compared the potential prognostic impact of B7-H1 and B7-H3 glycoprotein expressions with the Mayo Clinic Stage, Size, Grade, and Necrosis (SSIGN) score in metastatic clear cell renal cell carcinoma (mccRCC) during a long term follow-up. Material and methods: We investigated 44 mccRCC patients, who underwent radical nephrectomy between 1995 and 2006 at a single tertiary academic center and received interferon therapy (IFNT) for at least three months. The SSIGN score was applied as a validated prediction outcome model. Representative tumor sections were immunostained with anti-B7-H3 and anti-B7-H1 antibodies. Hereafter, positive antigen-antibody reactions were measured using the Positive-Pixel-Count Algorithm of the Aperio-Technology Image Scope software. Results: In total, 48% of patients were treated with cytoreductive nephrectomy and postoperative IFNT due to synchronous mccRCC, whereas 52% received IFNT after developing metachronous mccRCC. The SSIGN score was independently associated with a higher mortality risk. Patients with a SSIGN score ≤9 showed an extended 'nephrectomy to start of INFT'-interval (p = 0.02), less synchronous clinical metastases (p = 0.0002), as well as an increased median overall - (OS) or cancer-specific survival (CSS) (p = 0.01), respectively. Furthermore, B7-H3 expression levels of ≤16% were associated with an improved OS or CSS and correlated with a more frequent pathologic grade 1-2, as well as a longer 'nephrectomy to start of IFNT'-interval, respectively. B7-H1 expression patterns did not correlate with survival. Conclusions: The SSIGN score demonstrated the best prognostic performance. In contrast, B7-H3 expression patterns showed a low association with histopathological parameters, but predicted the cut-off-dependent impaired survival and in the future may define a cut-off to indicate checkpoint-inhibitor treatment.