Human kidney injury molecule-1 as a urine biomarker differentiating urothelial and renal cell carcinoma

Introduction

Urine concentration of human kidney injury molecule-1 (KIM-1) is suggested to be increased in patients with renal cell carcinoma (RCC). However, it has never been tested in patients with urothelial tumors, while preoperative differentiation between RCC and upper tract urothelial carcinoma (UTUC) plays an essential role in therapeutic decisions.

The aim of the study was to evaluate the role of urinary KIM-1 expression in preoperative differentiation between RCC and urothelial carcinoma (UC).

Material and methods

Sixty-four participants were enrolled in the study, including 30 patients with RCC and 27 with UC (16 with UTUC and 11 with bladder tumor). Preoperative urinary KIM-1 levels were measured using a commercially available ELISA kit and normalized to urinary creatinine levels.

Results

The median concentration of urinary KIM-1 normalized to urinary creatinine was lower in patients with RCC compared to UC (1.35 vs 1.86 ng/mg creatinine, p = 0.04). The comparison between RCC and UTUC shows even more significant difference (1.33 vs 2.23 ng/mg creatinine, p = 0.02). Urinary KIM-1 concentration did not correlate with tumor stage nor grade in any of the groups. ROC analysis to identify UC revealed AUC of 0.657 with sensitivity 33.3% and specificity 96.7% at the cut-off value of 3.226 ng/mg creatinine. Among patients with eGFR ≥60 mL/min/1.73 m², ROC analysis to detect UC achieved AUC of 0.727 with sensitivity 69.5% and specificity 70.2%.

Conclusions

Urine KIM-1 can potentially differentiate UC from RCC. However, a wide range of observed results and limited sensitivity and specificity requires caution in making clinical decisions before confirmatory studies.

Evaluation of Human Kidney Injury Molecule 1 (hKIM-1) Expression in Tumors From Various Organs by Messenger RNA In Situ Hybridization

OBJECTIVES

Human kidney injury molecule 1 (hKIM-1) is a sensitive and specific marker for detection of clear cell renal cell carcinoma (CRCC), papillary renal cell carcinoma (PRCC), and ovarian clear cell carcinoma (OCCC). Its use was limited to a few surgical pathology laboratories because this specific antibody to hKIM-1 was not commercially available. We investigated the diagnostic utility of RNA in situ hybridization/RNAscope in the detection of hKIM-1 in tumors from various organs.

METHODS

RNAscope for hKIM-1 was performed on 1,252 cases on tissue microarray sections, including CRCC (n = 185), PRCC (n = 59), chromophobe renal cell carcinoma (n = 18), oncocytoma (n = 12), OCCC (n = 27), and metastatic CRCC (n = 46).

RESULTS

Fifty-nine (100%) of 59 PRCCs, 94 (95%) of 99 low-grade CRCCs, 83 (96%) of 86 high-grade CRCCs, and 24 (89%) of 27 OCCCs, and 44 (96%) of 46 metastatic CRCCs were positive for hKIM-1. In contrast, hKIM-1 expression was not seen in normal renal tubules or in most nonrenal tumors. Low-level expression could be seen in a small percentage of urothelial, hepatocellular, and colon carcinomas.

CONCLUSIONS

hKIM-1 is a sensitive and relatively specific marker (1) for diagnosing PRCC, CRCC, and OCCC when working on a tumor of unknown origin and (2) for differentiating CRCC from chromophobe renal cell carcinoma and oncocytoma.