Ho, Thai H.

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.

AbstractObjectivesPrevious studies noted discordance of programmed death‐1 (PD‐1) and one of its ligands (PD‐L1) across patient‐matched primary and metastatic clear cell renal cell carcinoma (ccRCC). There are inconsistencies if the primary or metastatic tumor has higher expression, and whether metastatic tumor expression is associated with patient outcome. Thus, we examined PD‐1 and PD‐L1 in patient‐matched tumors using a large number of ccRCC patients with long follow‐up.Materials and MethodsWe analyzed PD‐1 and PD‐L1 using immunohistochemistry in patient‐matched primary and metastatic tumors from 110 ccRCC patients. Concordance was assessed among longitudinal metastatic tumors, as well as across patient‐matched primary and metastatic tumors. Cox proportional hazards regression was used to evaluate the associations of metastatic tumor expression with cancer‐specific survival.ResultsWe observed inter‐metastatic tumor heterogeneity of PD‐1 in 25 (69%) of the 36 patients and of PD‐L1 in seven (19%) patients. Concordance between patient‐matched primary and metastatic tumors was 73% (Kappa = 0.16, 95% CI: −0.003‐0.32). Similarly, concordance of PD‐L1 between metastatic and patient‐matched primary tumors was 78% (Kappa = 0.27, 95% CI: 0.09‐0.46). Both markers demonstrated higher expression in primary vs metastatic tumors. Metastatic tumor expression of PD‐1 was significantly associated with metastatic location (P < .0001) and ccRCC‐specific survival (HR = 2.15, 95% CI: 1.06‐4.36, P = .035).ConclusionsThe expression of PD‐1 and PD‐L1 is discordant across patient‐matched ccRCC tumors, with higher expression in primary tumors. Higher PD‐1 expression was associated with metastatic location and lower cancer‐specific survival. If validated, these results highlight the importance of evaluating these biomarkers in metastatic tissue specifically.

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.

Abstract Background: The methylthioadenosine phosphorylase (MTAP) gene encodes an essential enzyme for the salvage pathway of adenosine synthesis and is frequently lost in different types of cancer including urothelial bladder carcinoma. Therefore, MTAP-deficient tumors are theoretically very sensitive to anti-folate agents such as pemetrexed that can effectively block the de novo pathway of adenosine synthesis and as a result, create a state of synthetic lethality. We thus hypothesize that tumor MTAP gene deficiency is associated with response to pemetrexed therapy in bladder cancer. Methods: In this study, we investigated MTAP gene deficiency rates in the TCGA database and confirmed MTAP protein loss by immunohistochemistry using a tumor tissue microarray containing bladder tumor tissues from 151 patients. We then performed in vitro and in vivo studies using MTAP-proficient and MTAP-deficient human bladder cancer cell lines. Functional loss of MTAP was verified with mass spectrometry, which detects its substrate methylthioadenosine (MTA) levels. We also correlated these pre-clinical studies with clinical response data on patients with metastatic bladder cancer treated with pemetrexed. Results: We identified that 27.8% bladder cancer patients have MTAP protein deficiency, which is consistent with exome sequencing data from the TCGA database. In vitro data showed MTAP-deficient human bladder cancer cell lines were significantly more sensitive to pemetrexed, with IC50 at least 40 times lower than MTAP-proficient cell lines. Subsequent knockdown of the MTAP gene in MTAP-proficient cell lines increased sensitivities to pemetrexed treatment. Consistent with the in vitro data, pemetrexed significantly inhibited the growth of MTAP-deficient or knockdown xenograft tumors but not MTAP-proficient tumors. Furthermore, 4 of 4 (100%) patients with MTAP-deficient metastatic bladder cancer responded to pemetrexed treatment, whereas only 1 of 11 (9%) patients with MTAP-proficient metastatic bladder cancer responded to pemetrexed. Conclusion: Our data demonstrate that MTAP gene loss in urothelial bladder cancer leads to a metabolic state of synthetic lethality with pemetrexed therapy. Therefore, bladder tumor MTAP loss should be further investigated as a potential biomarker for selection of patients for anti-folate therapy. Citation Format: Jianfeng Chen, Omar Alhalabi, Guangchun Han, Wei-Lien Wang, Xin-Qiao Zhang, Jian H. Song, Lidia P. Lopez, Sumankalai Ramachandran, Anh G. Hoang, Tyrone Garnett, Matthew Campbell, Amishi Y. Shah, Jennifer Wang, Arlene O. Siefker-Radtke, Shi-Ming Tu, Mark Titus, Charles C. Guo, Gary E. Gallick, Eleni Efstathiou, William F. Benedict, Christopher J. Logothetis, Thai H. Ho, Linghua Wang, Jianjun Gao. MTAP gene deficiency creates vulnerability to anti-folate therapy in urothelial bladder carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 385.

AbstractThere are currently no effective treatments for advanced‐stage papillary renal cell carcinoma (PRCC). The goal of this study is to define potential DNA methylation‐based markers and treatment targets for advanced‐stage type 2 PRCC. Progressive DNA methylation changes and copy number variation (CNV) from localized to advanced‐stage type 2 PRCC are analyzed by using methylation data generated by TCGA's kidney renal papillary cell carcinoma (TCGA‐KIRP, 450k array) project. Survival analyses are performed for the identified biomarkers and genes with CNV. In addition, expression of the corresponding genes is investigated by RNA‐seq analysis. Progressive methylation changes in several CpGs from localized to advanced‐stage type 2 PRCC are observed. Four CpGs (cg00489401, cg27649239, cg20555674, and cg07196505) in particular are identified as markers for differentiating between localized and advanced‐stage type 2 PRCC. Copy number analysis reveals that copy gain of PTK7 mostly occurs in advanced‐stage type 2 PRCC. Both the four CpG methylation changes and PTK7 copy number gain are associated with patient survival. RNA‐seq analysis demonstrates that PTK7 copy gain leads to higher PTK7 expression relative to tumors without copy number gain. Moreover, PTK7 is significantly upregulated from localized to advanced‐stage type 2 PRCC and is linked to cancer cell invasion. In conclusion, DNA methylation markers that differentiate between localized and advanced‐stage type 2 PRCC may serve as useful markers for disease staging or outcome, while PTK7 copy gain represents a potential treatment target for advanced‐stage type 2 PRCC. Stepwise methylation changes and copy number gain also associate with disease stage in PRCC patients.

Background:Injectable azacitidine (AZA) has been evaluated in a variety of malignancies, including acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), and solid tumors. CC‐486, the oral formulation of AZA, allows extended dosing schedules (>7 days per 28‐day treatment cycle) to increase AZA exposure to malignant cells over the course of the cycle. CC‐486 is under investigation in phase 3 clinical trials as maintenance therapy for patients with AML in first complete remission after induction chemotherapy (NCT01757535) and in lower‐risk MDS with concurrent thrombocytopenia and RBC transfusion dependence (NCT01566695). In these studies, patients receive CC‐486 300 mg QD administered in two 150 mg tablets. A single 300 mg CC‐486 tablet is in development for market approval.Aims:Evaluate the bioequivalence (BE) of a single 300 mg CC‐486 tablet relative to two 150 mg CC‐486 tablets, and the food effect (FE) on the bioavailability of the CC‐486 300 mg tablet.Methods:This was a phase 1, randomized, crossover study (NCT01519011). Adult patients had hematologic malignancies or solid tumors relapsed/refractory to prior therapy for which no standard treatments were available, and ECOG PS scores 0‐2. The BE phase assessed pharmacokinetic (PK) parameters of CC‐486 administered as two 150 mg tablets (formulation A) and as one 300 mg tablet (formulation B). Patients were randomized 1:1 to receive each formulation at least 48 hours apart. In the FE phase, patients were randomized to receive formulation B on each of 2 PK study days under fed (high fat, ∼800‐1000 calories) and fasted conditions. PK parameters, including area under the plasma concentration‐time curve from time 0 extrapolated to infinity (AUC∞), maximum plasma concentration (Cmax), time to Cmax (Tmax), terminal half‐life (t1/2), apparent total clearance (CL/F) and volume of distribution (Vz/F) were analyzed. BE of formulations A and B, and absence of FE on formulation B, were indicated when the 90% CI of the ratios of geometric means (RGM) based on log‐transformed data for AUC∞ and Cmax between formulations A and B, and between fed and fasted conditions, were within 80%>125%.Results:30 patients were enrolled in the BE phase (median age 68.5 yrs, range 46‐86); 3 patients (10%) had hematologic malignancies and 27 (90%) had solid tumors. Formulations A and B were bioequivalent: the Cmax RGM was 101.5% (90% CI 89.9, 114.7) and AUC∞ RGM was 105.7% (95.0, 117.6). Median Tmax was 1.0 hour for both formulations.57 patients enrolled in the FE phase (median age 62 yrs, 31‐88); all had solid tumors. Despite a lower Cmax under fed condition (RGM 78.9% [90%CI 68.6, 90.7]), overall drug exposure was similar (AUC∞ RGM 108.9% [90%CI 98.5, 120.5]) (Figure A). Consistent with an effect of gastric emptying, median Tmax was reached at 2 hrs and 1 hr post‐dose in fed and fasted states, respectively (Figure B) and mean t1/2 was 0.78 and 0.58 hr postdose. CL/F and Vz/F were comparable in fed and fasted states. Moderate to high intersubject variability was observed for all CC‐486 PK parameters (Figure A).Summary/Conclusion:A single oral CC‐486 300 mg tablet is bioequivalent to two 150 mg tablets. The PK profile for the CC‐486 300 mg tablet under fed and fasted conditions was comparable although Cmax occurred later and was decreased in fed vs. fasted condition. Systemic drug exposure (AUC∞) in fed and fasted states was similar and within the bioequivalence limits. Limited differences in other CC‐486 PK parameters between fed and fasted states are not expected to have a clinical impact.image

5063 Background: The systemic therapies available to patients with metastatic prostate cancer (mPC) have improved dramatically over the past decade. Prior to 2010, the only agents with a proven survival benefit for patients with metastatic disease were androgen deprivation therapy and docetaxel. Since then, five new agents have been FDA approved and have proven survival benefit in phase III trials. Anecdotal experience suggests that the increased available lines of therapy have changed the profile of mPC to include a higher prevalence of visceral metastases. Methods: A retrospective review of 474 patients with prostate cancer who died in 2009 and in 2016 was performed. Patients with metastatic disease who had imaging within 6 months of death were included. A total of 164 patients were eligible for analysis. Results: Mean age at death overall was 77.4 years (SD 9.5) and did not differ signifiantly by cohort. Overall rates of visceral and distant metastases to include lung, liver, adrenal, brain, renal, spleen, and thyroid, were higher in patients who died in 2016 as compared to those who died in 2009 (40.0% and 26.1%, respectively, p = 0.07). Lung metastases were more prevalent in patients who died in 2016 versus in 2009 at 26.3% and 13.0%, respectively (p = 0.05). Patients who died in 2009 received a median of 3 (range 1-10) systemic treatments versus 4 (range 0-13) in those who died in 2016 (p = 0.005). Forty-four percent of patients who died in 2016 used five or more lines of systemic treatments compared to 26.1% of patients in 2009. Conclusions: The emergence of new systemic therapies for mPC is changing the natural history of the disease. Forty percent of patients now develop visceral metastases compared to 26% in the past. These changes will drive the need for new treatment approaches targeting visceral metastases. [Table: see text]

4521 Background: The MTAP gene encodes an essential enzyme for the salvage pathway of nucleotide synthesis and is frequently deleted in UBC. Anti-folate agents such as pemetrexed can effectively inhibit the de novo pathway of nucleotide synthesis and as a result, create a synthetic lethality in MTAP deficient UBC. We hypothesize that MTAP gene loss correlates with enhanced response to pemetrexed in UBC. Methods: We investigated MTAP gene deletion rates in the TCGA database and determined MTAP protein loss rates by immunohistochemistry (IHC) using a UBC tissue microarray (TMA) from 151 patients (pts). We then performed in vitro and in vivo studies using MTAP proficient and MTAP deficient bladder cancer cell lines. At the clinical level, we performed a retrospective analysis based on MTAP status of pts treated with pemetrexed as 2nd line at our institution between 2014 and 2018. We are now enrolling pts in a single-arm, open-label, phase II clinical trial (NCT02693717) with pemetrexed in pts with MTAP deficient UBC. Results: Per our TCGA and TMA IHC analyses, MTAP deficiency rate was 25.9% and 27.8%, respectively. MTAP deficient UBC cell lines were at least 40 times more sensitive to pemetrexed than MTAP proficient lines. Knockdown of the MTAP gene increased apoptosis rate by pemetrexed from approximately 20% to 60%. Additionally, pemetrexed significantly inhibited the growth of MTAP deficient or knockdown xenograft tumors but not MTAP proficient tumors. Retrospective analysis of 12 pts using RECIST criteria indicated that all 4 MTAP deficient UBC pts responded to pemetrexed whereas only 1 of 8 (12.5%) MTAP proficient UBC pts responded. Of the 6 pts enrolled on the clinical trial, 3 (50%) had complete or partial response, 1 had stable disease, 1 was not evaluable and 1 had disease progression. Combined analysis of the entire experience demonstrates a higher response rate in MTAP deficient UBC (70%) as compared to MTAP proficient UBC (12.5%). Conclusions: Our preclinical and clinical data demonstrate that MTAP loss in UBC leads to a state of synthetic lethality when treated with pemetrexed and should be further investigated as a novel biomarker to predict response to anti-folate agents.