Fox Chase Cancer Center, Philadelphia, PA
Philip Abbosh , Daniel M. Geynisman , Nancy Doll , ADAM Hauben , Sandeep K. Reddy , Sherri Z. Millis , Robert G. Uzzo
Background: Chromophobe renal cell carcinoma (chRCC) is a rare kidney cancer subtype that infrequently metastasizes or recurs after definitive local therapy. Limited biomarker data exists to prognosticate outcome or predict response to therapy. We explored the utility of multiplatform tumor profiling, which uses immunohistochemistry (IHC) and targeted next generation sequencing (tNGS) to identify druggable targets, with the intent of developing targeted therapy protocols in patients with (chRCC). Because of the non-aggressive nature of small chRCCs, we excluded T1a tumors. Methods: Cases were identified from 65,000+ tumors submitted for commercial testing at Caris Life Sciences. All tissues were internally reviewed by a dedicated genitourinary pathologist to confirm diagnosis. Markers were analyzed on tumor tissue removed during partial or radical nephrectomy. IHC was performed on 19 proteins. FISH was performed on EGFR, HER2, and TOP2A. tNGS was performed on 47 genes. Results: Twelve patients with chRCC were profiled. Five patients had metastatic disease. Median age was 54 years old; 50% of patients were male. One patient had a T1b tumor, two patients had T2 tumors, 8 patients had T3 tumors, and one had a T4 tumor. Thymidylate synthase (TS), ribonucleotide reductase M1 (RRM1), and O-6-methylguanine-DNA methyltransferase (MGMT) expression was absent in 12/12, 11/12 and 11/12 tumors, respectively. PTEN expression was absent in 7/12 of tumors. cKIT and PDGFR was expressed in 6/9 and 0/4 tumors, respectively. Lastly, point mutations in APC and TP53 were detected in 1/7 and 3/7 tumors, respectively. No mutations were identified in the other 45 genes tested and no changes in copy number were identified. Conclusions: Biomarker analysis showed that advanced chRCC might be amenable to chemotherapy with 5-fluorouracil, gemcitabine, or temozolamide because of absent TS, RRM1, and MGMT expression, respectively. Such rationale has been used successfully in targeted treatment of other cancers. In addition, sunitinib or imatinib but not sorafenib might be preferred tyrosine kinase inhibitors, as cKIT but not PDGFR was detected.
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