Castle, Erik P.

Histone‐lysine N‐methyltransferase SETD2 (SETD2), the sole histone methyltransferase that catalyzes trimethylation of lysine 36 on histone H3 (H3K36me3), is often mutated in clear cell renal cell carcinoma (ccRCC). SETD2 mutation and/or loss of H3K36me3 is linked to metastasis and poor outcome in ccRCC patients. Epithelial‐to‐mesenchymal transition (EMT) is a major pathway that drives invasion and metastasis in various cancer types. Here, using novel kidney epithelial cell lines isogenic for SETD2, we discovered that SETD2 inactivation drives EMT and promotes migration, invasion, and stemness in a transforming growth factor‐beta‐independent manner. This newly identified EMT program is triggered in part through secreted factors, including cytokines and growth factors, and through transcriptional reprogramming. RNA‐seq and assay for transposase‐accessible chromatin sequencing uncovered key transcription factors upregulated upon SETD2 loss, including SOX2, POU2F2 (OCT2), and PRRX1, that could individually drive EMT and stemness phenotypes in SETD2 wild‐type (WT) cells. Public expression data from SETD2 WT/mutant ccRCC support the EMT transcriptional signatures derived from cell line models. In summary, our studies reveal that SETD2 is a key regulator of EMT phenotypes through cell‐intrinsic and cell‐extrinsic mechanisms that help explain the association between SETD2 loss and ccRCC metastasis.

e16065 Background: Estrogens, in addition to androgen may contribute to the progression of prostate cancer.The combination of bicalutamide, a non-steroidal anti-androgen, and raloxifene, a selective estrogen receptor modulator, has a synergistic effect on cell death of prostate cancer cell lines such as DU145 and PC3. We investigated the safety of combined treatment of bicalutamide and raloxifene on quality of life in patients affected by hormone-resistant prostate cancer. Methods: Eligibility requirements included metastatic hormone-resistant prostate cancer, Eastern Cooperative Oncology Group performance status of 0 or 1. Patients received the combination of bicalutamide, 50 mg, and raloxifene, 60 mg, daily in 28 day cycles for a maximum of 6 cycles. The primary endpoint was to describe the adverse event profile of combined treatment with bicalutamide and raloxifene. The secondary endpoint was to describe the quality of life of patients receiving the combination. Adverse events were graded by the investigator using the NCI Common Terminology Criteria for Adverse Events version 4.0 and the quality of life was assessed by the patient using aLinear Analog Scale Assessment (scale of 0-100). Serum levels of estradiol and testosterone were monitored during treatment. Results: Eighteen evaluable patients were included in the statistical analysis after an initial run-in safety cohort of six patients. Two patients completed 6 cycles per protocol, the remaining sixteen patients were taken off protocol after disease progression. Patients completed a median of 2 cycles. There were no grade 4 events and grade 3 adverse events consisted of hypertension (5.6%) and back pain (5.6%). Erectile dysfunction (grade 1) was the most common adverse event (77.8%). Patient assessment of quality of life (mental, physical, social, emotional, spiritual) did not reveal any statistically different changes after 2 cycles of treatment. An analysis of testosterone and estradiol levels will be reported. Conclusions: We conclude that combination of bicalutamide and raloxifene is well-tolerated. The combination of androgen and estrogen receptor blockade warrants further study for efficacy in hormone-resistant prostate cancer. Clinical trial information: NCT01050842.

4567 Background: Trials combining anti-PDL1 and anti-VEGF therapies for clear cell renal cell carcinoma (ccRCC) are underway; however the relationship between the expression of PDL1 and genes in the VEGF pathway is poorly understood. Using the Affymetrix platform, we observed an inverse association between the expression of PDL1 and key genes in the VEGF pathway. Herein, we validate this inverse association using an independent set of 100 primary ccRCC tumors. Methods: From our registry database we sampled 100 ccRCC tumors with varying PDL1 protein expression (0%-100%) determined by immunohistochemistry (IHC). We extracted RNA from FFPE slides and performed RT-PCR to quantify gene expression of PDL1, VEGF, VEGFR1, and VEGFR2. All genes were normalized to the POLR2a gene. We evaluated the association of PDL1 protein expression and VEGF gene expression using Spearman rank correlation. In addition, we employed a linear mixed effects model to compare the fold-change in expression of VEGF genes between PDL1 low (0-5%, n=68) and PDL1 high (>5%, n=32) tumors. Results: As expected, PDL1 protein expression positively correlates with PDL1 geneexpression (corr=0.42, p<0.001). Validating our array data, PDL1 protein expression inversely correlates with expression of key VEGF genes: VEGF (corr=-0.23, p=0.01), VEGFR1 (corr=-0.34, p<0.001), and VEGFR2 (corr=-0.23, p=0.01). In our dichotomized analysis, we noted significantly higher expression of VEGF genes in the PDL1 low compared to the PDL1 high group: VEGF (fold change=1.82, p<0.001), VEGFR1 (FC=2.63, p<0.001), and VEGFR2 (FC=2.13, p=0.001). Conclusions: We independently validate an inverse association between the expression of PDL1 and key genes in the VEGF pathway in primary ccRCC. If validated further in larger studies, the existence of an immune evasive and an angiogenic phenotype within ccRCC could inform current clinical trials targeting these two pathways. Ultimately, whether VEGF signaling affects PDL1 expression, or whether angiogenic or immune evasive phenotypes predict response to anti-PDL1, anti-VEGF, or a combination of the two therapies remains unclear.

696 Background: A number of treatments for metastatic renal cell carcinoma (RCC) have been FDA approved since December, 2005. Trials evaluating these agents excluded non-clear cell histologies and therefore the efficacy of these treatments remains unclear in patients (pts) with metastatic non-clear cell RCC (mncRCC). Methods: This is a single arm Phase II study designed to determine the efficacy of pazopanib in mncRCC. Treatment was pazopanib 800 mg by mouth daily until progression or intolerability of treatment. Dose reductions were allowed for toxicity with dose level -1 being 600 mg daily and dose level -2, 400 mg daily. Cycles were every 28 days. Main eligibility criteria included: (1) age ³ 18 years old; (2) histologic confirmation of ncRCC; (3) ECOG Performance Status (PS) 0, 1, or 2; (4) up to one prior treatment for mncRCC (5) measurable or non-measurable metastatic disease per RECIST criteria. The primary endpoint was overall survival rate at 12 months. Secondary endpoints were best tumor response rates after two cycles, PFS, OS and toxicity. Results: 38 pts were enrolled between May 16, 2013 and February 1, 2018. 35 pts were evaluable for primary endpoint. Median age 63 years old and 22/35 (62.9%) were male. Most common histology was papillary RCC, 14/35 (40%), and most common number of metastatic sites was 1. 29/35 (82.9%) had prior nephrectomy and 30/35 (85.7%) had no prior systemic therapy. Median number of cycles was 5. 12-month OS was 65.7% (90% CI, 50.5-78.9%). Best response in first 2 cycles: PR 11%, SD 60%, PD 9%, not evaluated 20%. Median PFS was 7.5 months (90% CI, 5.0-11.0); median OS 18.9 months (90% CI, 13.0-NE). Grade 3 / 4 AEs seen in 25 pts with hypertension, transaminitis and abdominal pain being most common (seen in >10%). Conclusions: There are limited data about the efficacy of available therapies for mncRCC. This study shows that pazopanib has similar efficacy compared to historical data in clinical trials using other TKIs in mncRCC. The safety profile of pazopanib in pts with mncRCC was found to be similar to that found in prior clinical trials studying pazopanib. Our findings warrant further investigation into the utility of pazopanib in metastatic ncRCC. Clinical trial information: NCT01767636.

Introduction: This study aims to describe robot assisted surgery of the inferior vena cava (IVC) by assessing techniques utilized, perioperative outcomes, complications, and long-term patency of the IVC. Methods: A retrospective review was performed on all robotic surgeries involving dissection and repair of the IVC at our institution. Patient characteristics, operative reports, and follow-up visits were analyzed. Preoperative and postoperative imaging was independently reviewed by a single radiologist to determine changes in IVC diameter. Complications were analyzed according to early (<30 days) vs late (>30 days). Results: Thirty-four patients underwent robot assisted surgery of the vena cava from 2008 to 2018. Twenty-six cases were performed for urologic malignancy, four were performed for IVC filter explantation, and four renal vein transpositions were performed for nutcracker syndrome. Twenty-four of the 26 patients with urologic malignancy underwent radical nephrectomy with IVC tumor thrombectomy. Three cases were converted to open. Median length of stay was two nights, and mean estimated blood loss (EBL) was 375 mL. There were five complications, ranging from Clavien-Dindo grade II–IIIa, four of which were early complications. No patients required return to the operating room, and there were no perioperative mortalities. IVC diameter was reduced by 41% on axial diameter, with no patients experiencing compromised venous return. Conclusion: Robot assisted surgery offers the advantage of minimally invasive surgery with the ability to apply open surgical principles. In our series, an experienced multidisciplinary team approach yielded low EBL, short length of stay, and low complication rates.

Abstract Quiescin sulfhydryl oxidase 1 (QSOX1) is an enzyme overexpressed by many different tumor types. QSOX1 catalyzes the formation of disulfide bonds in proteins. Because short hairpin knockdowns (KD) of QSOX1 have been shown to suppress tumor growth and invasion in vitro and in vivo, we hypothesized that chemical compounds inhibiting QSOX1 enzymatic activity would also suppress tumor growth, invasion, and metastasis. High throughput screening using a QSOX1-based enzymatic assay revealed multiple potential QSOX1 inhibitors. One of the inhibitors, known as “SBI-183,” suppresses tumor cell growth in a Matrigel-based spheroid assay and inhibits invasion in a modified Boyden chamber, but does not affect viability of nonmalignant cells. Oral administration of SBI-183 inhibits tumor growth in 2 independent human xenograft mouse models of renal cell carcinoma. We conclude that SBI-183 warrants further exploration as a useful tool for understanding QSOX1 biology and as a potential novel anticancer agent in tumors that overexpress QSOX1.