Comparison of 2SC, AKR1B10, and FH Antibodies as Potential Biomarkers for FH-deficient Uterine Leiomyomas

Hereditary leiomyomatosis and renal cell cancer (HLRCC) is a tumor predisposition syndrome caused by germline fumarate hydratase ( FH ) mutations and characterized by uterine and cutaneous leiomyomas and renal cell cancer. Currently, there is no generally approved method to differentiate FH-deficient uterine leiomyomas from other leiomyomas. Here, we analyzed 3 antibodies (S-(2-succino)-cysteine [2SC], aldo-keto reductase family 1, member B10 [AKR1B10], and FH) as potential biomarkers. The study consisted of 2 sample series. The first series included 155 formalin-fixed paraffin-embedded uterine leiomyomas, of which 90 were from HLRCC patients and 65 were sporadic. The second series included 1590 unselected fresh frozen leiomyomas. Twenty-seven tumors were from known HLRCC patients, while the FH status for the remaining 1563 tumors has been determined by copy number analysis and Sanger sequencing revealing 45 tumors with monoallelic (n=33) or biallelic (n=12) FH loss. Altogether 197 samples were included in immunohistochemical analyses: all 155 samples from series 1 and 42 available corresponding formalin-fixed paraffin-embedded samples from series 2 (15 tumors with monoallelic and 7 with biallelic FH loss, 20 with no FH deletion). Results show that 2SC performed best with 100% sensitivity and specificity. Scoring was straightforward with unambiguously positive or negative results. AKR1B10 identified most tumors accurately with 100% sensitivity and 99% specificity. FH was 100% specific but showed slightly reduced 91% sensitivity. Both FH and AKR1B10 displayed also intermediate staining intensities. We suggest that when patient’s medical history and/or histopathologic tumor characteristics indicate potential FH-deficiency, the tumor’s FH status is determined by 2SC staining. When aberrant staining is observed, the patient can be directed to genetic counseling and mutation screening.