Site of extranodal metastasis impacts survival in patients with testicular germ cell tumors

BACKGROUND

Using a large, nationally representative, population-based cancer registry, this study systematically evaluated the impact of the location and burden of extranodal testicular germ cell tumor (TGCT) metastases on survival.

METHODS

Men with stage III TGCTs captured by the Surveillance, Epidemiology, and End Results registry from 2010 to 2015 with distant extranodal metastases were identified. Clinicopathologic information was collected, and patients were subdivided according to the specific organ site or sites of metastatic involvement (lung, liver, bone, and/or brain). Kaplan-Meier analysis and multivariable Cox regression were used to evaluate cancer-specific survival (CSS), and model performance was assessed with Harrell's C statistic.

RESULTS

Nine hundred sixty-nine patients with stage III TGCTs were included with predominantly nonseminomatous histology (84%). Most patients (91%) had pulmonary metastases, whereas 20%, 10%, and 10% had liver, bone, and brain metastases, respectively. Over a median follow-up of 21 months, 19% of these men died of TGCTs. When they were grouped by the primary site of metastasis, patients with more than 1 extrapulmonary metastasis exhibited the worst CSS (hazard ratio [HR] vs isolated pulmonary involvement, 4.27; 95% confidence interval [CI], 2.60-7.00; P < .01). Among patients with isolated extrapulmonary involvement, those with brain metastases had the poorest survival (HR, 3.24; 95% CI, 1.98-5.28; P < .01), and they were followed by patients with liver (HR, 2.29; 95% CI, 1.56-3.35; P < .01) and bone metastases (HR, 1.97; 95% CI, 1.11-3.50; P = .02). Harrell's C statistic (multivariable) was 0.71.

CONCLUSIONS

The site of metastatic involvement affects survival outcomes for patients with TGCTs, and this may reflect both the aggressive biology and the challenging treatment of these tumors. Further incorporation of organotropism into current prognostic models for metastatic TGCTs warrants attention.

Abstract 1397: Quantitative MR imaging measures predict intratumoral molecular heterogeneity in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is primarily driven by mutation in von Hippel-Lindau (VHL) leading to constitutive hypoxia inducible factors (HIFs) upregulation promoting angiogenesis. ccRCC is the most aggressive and common histological subtype of kidney cancer. It is characterized by high pathologic and molecular intra-tumor heterogeneity (ITH), a reflection of the genetic branched evolution during the tumor development. The overall molecular complexity in ccRCC may be underestimated with limited tissue samples in percutaneous biopsies. Non-invasive imaging methods that can provide quantitative spatial information on those varying features in the whole tumor may be a valuable tool for predicting tumor progression and therapy outcome. In this work we aim to understand the predictive value of quantitative Magnetic Resonance Imaging (MRI) measures of tumor vascularity as a noninvasive tool to identify molecular heterogeneity in ccRCC. In this IRB approved, prospective, HIPAA compliant study, 62 ccRCC patients underwent 3T multi-parametric MRI: T2-weighted (T2W), dynamic contrast-enhanced (DCE), and arterial spin labeled (ASL) MRI. All tumors were manually segmented with a region of interest (ROI) drawn on the central slice of the tumor. A grey-level co-occurrence matrix (GLCM) was constructed for each ROI and Haralick texture features were extracted. After surgery, 182 snap frozen samples from 49 tumors were subjected to RNA extraction, library preparation and mRNA sequencing using established protocols (Admerahealth, NJ). Spearman correlation coefficient between first- and second-order MRI statistics, including Haralick texture features, and gene expression levels were calculated. Gene ontology (GO) analysis was performed to identify the biological pathways associated with imaging features. Entropy, a measure of ITH, was correlated with standard deviation of normalized gene expression levels in multiple samples obtained from the same tumor. False discovery rate (FDR), q-values &lt;0.05 were considered statistically significant. GO analysis of the top positively correlated genes with ASL-MRI and DCE-MRI measures of tumor perfusion indicated enrichment of immune system and cellular metabolic processes (q&lt;0.05). ASL-MRI perfusion levels correlated positively with 81 HIF2 specific target genes (p&lt;0.05). Gene set Enrichment Analysis (GSEA, Broad Institute, MA) indicated that correlated HIF2 target genes overlapped with key hallmark Molecular Signature database (MSigDB) gene sets, including G2M checkpoint, MTORC1 signaling, and glycolysis. Entropy of the DCE-MRI images correlated with heterogeneity in both metabolic processes, and expression of HIF1/2 target genes. Our study has set the initial framework for utilizing quantitative radiomics to assess the association of the imaging phenotype in ccRCC with specific molecular signatures.

Citation Format: Durga Udayakumar, Ze Zhang, Durgesh Dwivedi, Yin Xi, Tao Wang, Ananth Madhuranthakam, Payal Kapur, Asghar Hajibeigi, Allison Joyce, Qurratulain Yousuf, Michael Fulkerson, Alberto Diaz de Leon, Matthew Lewis, Jeffrey Cadeddu, Aditya Bagrodia, Vitali Margulis, James Brugarolas, Ivan Pedrosa. Quantitative MR imaging measures predict intratumoral molecular heterogeneity in clear cell renal cell 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 1397.

Nationwide Patterns of Care for Stage II Nonseminomatous Germ Cell Tumor of the Testicle

BACKGROUND

Management strategies for advanced testicular cancer published from a few, high-volume clinical centers may not be generalizable.

OBJECTIVE

To discern treatment patterns for stage II nonseminomatous germ cell tumor (NSGCT) in a nationwide cancer registry.

DESIGN, SETTING, AND PARTICIPANTS

The National Cancer Database was queried for patients with a stage II NSGCT from 2004 to 2014. Patients were stratified by clinical nodal status: cN1/stage IIA, cN2/stage IIB, and cN3/stage IIIC.

OUTCOMES MEASUREMENTS AND STATISTICAL ANALYSIS

Logistic regression was performed to determine factors independently associated with primary retroperitoneal lymph node dissection (RPLND), primary chemotherapy, and postchemotherapy RPLND (PC-RPLND).

RESULTS AND LIMITATIONS

A total of 2203 patients (stages IIA, n=1060; IIB, n=869; and IIC, n=274) met the inclusion criteria. Overall, 83% of patients underwent primary chemotherapy, while 17% underwent primary RPLND. Stratified by stage, use of primary chemotherapy was 78%, 88%, and 86% for stages IIA, IIB, and IIC, respectively. Overall, 24% of patients underwent PC-RPLND. Factors independently associated with a lower likelihood of undergoing primary RPLND were a more recent diagnosis and a higher clinical nodal stage. Conversely, patients treated at high-volume facilities were more likely to receive primary RPLND. Factors associated with a higher likelihood of undergoing PC-RPLND included a higher clinical nodal stage, treatment at a high-volume center, and a greater distance of patient travel. Associations based on serum tumor markers could not be assessed.

CONCLUSIONS

For clinical stage II NSGCT, nationwide utilization of primary chemotherapy is increasing compared with RPLND and is the preferred therapy for more advanced nodal disease. Primary RPLND may be underutilized in stage IIA disease. Utilization of PC-RPLND is driven by nodal stage as well as accessibility of a high-volume center.

PATIENT SUMMARY

The use of primary retroperitoneal lymph node dissection (RPLND) in early nodal disease is declining, while upfront chemotherapy is increasingly utilized. Primary RPLND may identify patients who are actually pN0 and would not benefit from systemic chemotherapy. Primary RPLND and postchemotherapy RPLND are performed more frequently at centers of excellence.

PD-L1 detection using 89Zr-atezolizumab immuno-PET in renal cell carcinoma tumorgrafts from a patient with favorable nivolumab response

Background

Programmed death-ligand 1 (PD-L1) expression in metastatic renal cell carcinoma (RCC) correlates with a worse prognosis, but whether it also predicts responsiveness to anti-PD-1/PD-L1 therapy remains unclear. Most studies of PD-L1 are limited by evaluation in primary rather than metastatic sites, and in biopsy samples, which may not be representative. These limitations may be overcome with immuno–positron emission tomography (iPET), an emerging tool allowing the detection of cell surface proteins with radiolabeled antibodies. Here, we report iPET studies of PD-L1 in a preclinical tumorgraft model of clear cell RCC (ccRCC) from a patient who had a favorable response to anti-PD-1 therapy.

Case presentation

A 49-year-old man underwent a cytoreductive nephrectomy in 2017 of a right kidney tumor invading into the adrenal gland that was metastatic to the lungs and a rib. Histological analyses revealed a ccRCC of ISUP grade 4 with extensive sarcomatoid features. IMDC risk group was poor. Within two hours of surgery, a tumor sample was implanted orthotopically into NOD/SCID mice. Consistent with an aggressive tumor, a renal mass was detected 18 days post-implantation. Histologically, the tumorgraft showed sarcomatoid differentiation and high levels of PD-L1, similar to the patient’s tumor. PD-L1 was evaluated in subsequently transplanted mice using iPET and the results were compared to control mice implanted with a PD-L1-negative tumor. We labeled atezolizumab, an anti-PD-L1 antibody with a mutant Fc, with zirconium-89. iPET revealed significantly higher ⁸⁹Zr-atezolizumab uptake in index than control tumorgrafts. The patient was treated with high-dose IL2 initially, and subsequently with pazopanib, with rapidly progressive disease, but had a durable response with nivolumab.

Conclusions

To our knowledge, this is the first report of non-invasive detection of PD-L1 in renal cancer using molecular imaging. This study supports clinical evaluation of iPET to identify RCC patients with tumors deploying the PD-L1 checkpoint pathway who may be most likely to benefit from PD-1/PD-L1 disrupting drugs.

Leveraging a robust patient-derived xenograft platform to characterize predictors for engraftment and oncologic outcomes in renal cell carcinoma patients

e16100

Background: Patient-derived xenograft (PDX) models of renal cell carcinoma (RCC) preserve the biological features of patient tumors, providing a platform for biomarker identification and preclinical drug testing. We sought to identify predictors of successful tumor engraftment and evaluate the prognostic value of engraftment in patients with RCC using a robust murine PDX platform. Methods: 1,200 specimens derived from nephrectomy, thrombectomy, metastasectomy, or biopsy were orthotopically (renally) implanted into NOD/SCID mice between 2008-2018. Non-RCC pathology was excluded. Stable engraftment was defined by successful passage of tumor tissue at least twice with histologic confirmation. Clinicopathologic characteristics were stratified by engraftment status, and multivariate (MVA) logistic regression was used to identify predictors of engraftment. Kaplan-Meier and Cox regression analyses were used to assess the prognostic value of engraftment on patient overall (OS) and disease-free (DFS) survival. Results: 1,003 independent PDX lines derived from 770 RCC patients were included. 157 (15.6%) lines successfully engrafted and exhibited higher tumor grade, stage, size, and presence of sarcomatoid or rhabdoid components. 79.3% of all tumors were of clear cell histology, and histologic distribution did not vary by engraftment status. We have completed whole exome sequencing and RNAseq on 197 and 213 PDX lines, respectively, and downstream analyses will be reported. On MVA, sarcomatoid (OR 5.71, p < 0.001), rhabdoid (OR 2.79, p = 0.046), and advanced stage (OR 1.72, p = 0.049) were significant predictors for engraftment, while high grade and metastatic tumor source were significant only on UVA. Engraftment was associated with poor OS (HR 2.11, p < 0.001) and DFS (HR 1.85, p = 0.020) in patients after controlling for sarcomatoid, rhabdoid, grade, stage, and age on MVA. Conclusions: Aggressive RCC biology correlates with successful engraftment in PDX models. Engraftment remains independently predictive of OS and DFS even after controlling for adverse pathologic features. Engraftment in mice may illuminate aspects of tumor biology not captured by clinicopathologic variables and provide insight into novel determinants of tumor aggressiveness and metastasis.

Pathologic response and surgical outcomes in patients undergoing nephrectomy after receipt of immune checkpoint inhibitors for renal cell carcinoma

e16102

Background: With the approval of immune checkpoint inhibitors (ICI) for metastatic renal cell carcinoma (RCC), the role, timing, and safety of surgically excising the primary tumor remain unclear. We sought to evaluate the safety and feasibility of nephrectomy following receipt of ICI for RCC. Methods: We reviewed our experience of RCC patients who underwent nephrectomy from 2016-2018 following exposure to nivolumab or combination ipilimumab/nivolumab. Demographics, IMDC risk score, and pathology were collected. Surgical outcomes including operative time (OT), estimated blood loss (EBL), hospital length of stay (LOS), readmission rates, and 30- and 90-day complication rates were analyzed using descriptive statistics. Results: 11 nephrectomies (10 radical, 1 partial) were performed in 10 patients after ICI with median postoperative follow-up 180 days. 6 patients received 1-4 cycles of ipilimumab/nivolumab, while 5 received 2-12 infusions of nivolumab preoperatively. One patient with non-metastatic, synchronous bilateral renal masses underwent staged left radical nephrectomy and right partial nephrectomy. 5 surgeries were performed laparoscopically, and 4 patients underwent thrombectomy. IMDC score for metastatic patients was intermediate (7/9) or poor (2/9). One patient exhibited complete response (pT0) to ICI, and 3/4 patients who underwent metastasectomy for hepatic, pulmonary, or adrenal lesions exhibited no malignancy in any of the metastases resected. No patients experienced any major intraoperative complications, and all surgical margins were negative. Median OT, EBL, and LOS were 180 minutes, 100 mL, and 4 days, respectively. Four patients experienced any complication, including 3 that were addressed with a single interventional radiology procedure. One patient died of progressive disease > 3 months after surgery, and one patient succumbed to pulmonary embolism complicated by sepsis. No complications or readmissions were noted in 6 patients. Conclusions: Nephrectomy following ICI for RCC is safe and technically feasible with favorable surgical outcomes and pathologic response. As multimodal management in the era of ICI continues to evolve, the utility and timing of nephrectomy combined with ICI in selected patients warrants attention.

Dynamic contrast-enhanced MRI to predict intratumoral molecular heterogeneity in clear cell renal cell carcinoma

4580

Background: Mutation/inactivation of VHL in clear cell renal cell carcinoma (ccRCC) leads to upregulation of hypoxia inducible factors ( HIFs) and angiogenesis. However, ccRCC is characterized by high intra-tumor heterogeneity (ITH). Random small samples such as those in percutaneous biopsies are likely limited for characterization of molecular alterations in heterogeneous ccRCCs. We hypothesize that whole-tumor dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) is useful to noninvasively identify ITH in ccRCC. Methods: This IRB-approved, prospective, HIPAA-compliant study, included 62 ccRCCs. 3T DCE MRI was obtained prior to nephrectomy. Surgical specimens were sectioned to match MRI acquisition plane. 182 snap frozen samples (49 tumors) and adjacent uninvolved renal parenchyma (URP) were collected. RNA isolations, cDNA library preparation and mRNA sequencing were performed using standard protocols. RNA expression in 81 tumor samples were correlated (Spearman ranked) with % enhancement in a region of interest (ROI) drawn in the same location of the tumor on pre- and 3 different post-contrast DCE MRI phases. Gene function overrepresentation (OR) analyses were done on top positively and negatively correlated genes. False discovery rate (FDR) < 0.1 was considered statistically significant. Results: Principal component analysis of > 20,000 genes indicated distinct gene expression in tumors from URP. Unsupervised clustering showed enrichment of ccA samples (better prognosis) compared to ccB samples (worse prognosis). Importantly, ccA and ccB samples coexisted in 25% of tumors. DCE-MRI % enhancement correlated with expression of > 300 genes (p < 0.003, FDR < 0.1). OR analyses placed angiogenic pathway gene processes and the immune/inflammatory response processes within the top 5 positively- and negatively-correlated gene functions, respectively. HIF2 target genes correlated positively with % enhancement. Conclusions: DCE MRI detects specific molecular signatures and may help overcome the challenges of ITH in ccRCC. Further research is needed to explore the potential role of DCE MRI to assess response to antiangiogenic and immune-based therapies.

Identification of testicular cancer driver genes by a cross-species comparative oncology approach

BACKGROUND

Germ cell tumors arise in the testis, ovary, or extragonadal locations and have a wide range of histopathological and clinical presentations. The relative lack of animal models of germ cell tumors has impeded functional assessment of candidate driver genes. Previously, we described the development of testicular germ cell tumors in zebrafish carrying a mutation in bmpr1bb, a BMP family receptor, and demonstrated that human germ cell tumors have defects in BMP signaling.

OBJECTIVE

To further credential the zebrafish model for studies of human germ cell tumor, and to elucidate conserved genetic programs underlying the development of germ cell tumor.

MATERIALS AND METHODS

We used genetic techniques to ablate the germ cell lineage in developing fish and tested tumors for loss-of-heterozygosity of the wild-type allele of bmpr1bb. We performed comparative gene expression profiling of zebrafish and human germ cell tumors and carried out functional studies of selected genes.

RESULTS

Ablation of germ cells completely prevents testis tumor formation in the fish, definitively establishing the germ cell origin of the tumors. Germ cell tumors in bmpr1bb heterozygous mutants retain the wild-type allele, indicating haploinsufficiency of bmpr1bb as the mechanism of tumor formation. Comparison of RNA-Seq and microarray data from human and zebrafish germ cell tumors revealed a unique overlapping signature shared by the zebrafish tumors with human seminomas, yolk sac tumors, and embryonal carcinomas. The most highly conserved gene set in this cross-species analysis included potential driver genes such as JUP, which we show to be essential for germ cell tumor cell growth.

CONCLUSION

Our findings highlight the value of cross-species comparative oncology for the identification of candidate human cancer genes.

Genomic Profile of Urothelial Carcinoma of the Upper Tract from Ureteroscopic Biopsy: Feasibility and Validation Using Matched Radical Nephroureterectomy Specimens

Urothelial carcinoma of the upper tract (UTUC) presents specific challenges regarding accurate staging and tumor sampling. We aimed to assess the feasibility of applying next-generation sequencing to biopsy specimens and gauged the concordance of their genetic profiles with matched radical nephroureterectomy (RNU) specimens. Of the 39 biopsy specimens collected, 36 (92%) had adequate material for sequencing using a hybridization-based exon capture assay (MSK-IMPACT). The most frequently altered genes across the patient cohort were consistent with the urothelial carcinoma-associated alterations identified in a cohort of 130 RNU specimens previously sequenced at our center, including mutations in the TERT promoter (64%), hotspot activating mutations in FGFR3 (64%), and frequent mutations in chromatin remodeling genes. For 12 patients, a matching tumor sample from a subsequent RNU was sequenced. We found a high level of concordance between matched biopsy and RNU specimens, up to 92% for the likely pathogenic alterations. PATIENT SUMMARY: We evaluated the feasibility of genomic characterization of tumor tissue collected at the time of ureteroscopic biopsy and found high concordance with subsequent radical nephroureterectomy specimens. Molecular characterization of urothelial carcinoma of the upper tract biopsies could guide treatment decision-making and identify high-risk patients who could benefit from neoadjuvant chemotherapy and low-risk patients who could benefit from conservative or organ-sparing strategies.

New insights into germ cell tumor genomics

BACKGROUND

Testicular germ cell tumors (GCTs) represent the most common malignancy in young men. While GCTs represent a model for curable solid tumors due to exquisite chemosensitivity, mortality for patients with GCT comprises the most life years lost for non-pediatric malignancies. Given limited options for patients with platinum-resistant disease, improved insight into GCT biology could identify novel therapeutic options for patients with platinum-resistant disease. Recent studies into molecular characteristics of both early stage and advanced germ cell tumors suggest a role for rationally targeted agents and potentially immunotherapy.

RECENT DEVELOPMENTS

Recent GWAS meta-analyses have uncovered additional susceptibility loci for GCT and provide further evidence that GCT risk is polygenic. Chromosome arm level amplifications and reciprocal loss of heterozygosity have been described as significantly enriched in GCT compared to other cancer types. Contemporary analyses confirm ubiquitous gain of isochromosome 12 and mutations in addition to previously described GCT-associated genes such as KIT and KRAS. Alterations within the TP53-MDM2 signal transduction pathway appear to be enriched among patients with platinum-resistant disease. Potentially actionable targets, including alterations in TP53-MDM2, Wnt/β-catenin, PI3K, and MAPK signaling, are present in significant proportions of patients with platinum-resistant disease and may be exploited as therapeutic options. Pre-clinical and early clinical data also suggest a potential role for immunotherapy among patients with GCTs.

CONCLUSION

Molecular characterization of GCT patients may provide biologic rationale for novel treatment options in patients with platinum-resistant disease.

Safety and feasibility of nephrectomy after receipt of immune checkpoint inhibitors for renal cell carcinoma

619

Background: With the approval of immune checkpoint inhibitors (ICI) for metastatic renal cell carcinoma (RCC), the role, timing, and safety of surgically excising the primary tumor remain unclear. We sought to evaluate the safety and feasibility of nephrectomy following receipt of ICI for RCC. Methods: We reviewed our experience of RCC patients who underwent nephrectomy from 2016-2018 following exposure to nivolumab or combination ipilimumab/nivolumab. Demographics, IMDC risk score, and pathology were collected. Surgical outcomes including operative time (OT), estimated blood loss (EBL), hospital length of stay (LOS), readmission rates, and 30- and 90-day complication rates were analyzed using descriptive statistics. Results: 11 nephrectomies (10 radical, 1 partial) were performed in 10 patients after ICI with median postoperative follow-up 98 days. 6 patients received 1-4 cycles of ipilimumab/nivolumab, while 5 received 2-12 infusions of nivolumab preoperatively. One patient with non-metastatic, synchronous bilateral renal masses underwent staged left radical nephrectomy and right partial nephrectomy. 5 surgeries were performed laparoscopically, and 4 patients underwent thrombectomy. IMDC score for metastatic patients was intermediate (7/9) or poor (2/9). One patient exhibited complete response (pT0) to ICI, and 3/4 patients who underwent metastasectomy for hepatic, pulmonary, or adrenal lesions exhibited no malignancy in any of the metastases resected. No patients experienced any major intraoperative complications, and all surgical margins were negative. Median OT, EBL, and LOS were 180 minutes, 100 mL, and 4 days, respectively. One patient died of progressive disease > 3 months after surgery; one patient required thoracentesis and another required paracentesis of a sterile fluid collection in the hepatic resection bed. No complications were noted in the remaining 7 patients, none of whom required readmission. Conclusions: Nephrectomy following ICI for RCC is safe and technically feasible with favorable surgical outcomes and pathologic response. As multimodal management in the era of ICI continues to evolve, use of neoadjuvant ICI for selected patients may warrant attention.

Outcomes of stereotactic ablative radiotherapy for extra-cranial oligo-metastatic renal cell cancer

599

Background: Stereotactic ablative radiotherapy (SAbR) is a standard of care for treating renal cell cancer (RCC) cranial metastasis. We describe the effect of SAbR on oligometastatic extra-cranial RCC disease course. Methods: We retrospectively reviewed 49 patients with oligometastatic RCC with 68 extra-cranial lesions. Patients were treated with SAbR with a curative intent from 2007 to 2017. We analyzed local control, systemic therapy free survival (mPFS), and overall survival. Results: With a median follow-up of 28 months (IQR: 16.0-40.3), the 1-year and 2-year overall survival after SAbR was 93.4% (95% CI: 81.0-97.8), and 83% (95% CI: 67.4-91.5) respectively. The median overall survival was not reached. The median time to systemic therapy was 13.4 months from the first SAbR(95% CI: 8.8-27.6). Median times from the first SabR course to second and third line systemic therapy (or death) were 31.8 months and 45 months, respectively. Patients in the favorable risk group by the Heng’s criteria (HR = 8.67, p = 0.04), with nometastatic disease at diagnosis (HR = 10.38, p < 0.01) and with clear cell histology (HR = 6.15, p < 0.01) exhibited better survival, as shown by univariate analysis. Patients with no metastatic disease at diagnosis (HR = 2.56, p = 0.02) and only one metastasis treated with SAbR (HR = 2.36, p = 0.03) also exhibited better systemic therapy-free survival. SAbR had an excellent local control rate of 94% at 2 years with no reported grade 3 or higher toxicity. Conclusions: SAbR is an effective and safe treatment for oligometastatic RCC, offering excellent local control with minimal toxicity. SAbR delayed the start of systemic therapy for this RCC cohort, offering quality of life benefits for patients without adversely affecting the progression on subsequent lines of systemic therapy. These findings call for prospective verification.

Leveraging a robust patient-derived xenograft platform to characterize predictors for engraftment and oncologic outcomes in renal cell carcinoma patients

651

Background: Patient-derived xenograft (PDX) models of renal cell carcinoma (RCC) preserve the biological features of patient tumors, providing a platform for biomarker identification and preclinical drug testing. We sought to identify predictors of successful tumor engraftment and evaluate the prognostic value of engraftment in patients with RCC using a robust murine PDX platform. Methods: 1,200 specimens derived from nephrectomy, thrombectomy, metastasectomy, or biopsy were orthotopically (renally) implanted into NOD/SCID mice between 2008-2018. Non-RCC pathology was excluded. Stable engraftment was defined by successful passage of tumor tissue at least twice with histologic confirmation. Clinicopathologic characteristics were stratified by engraftment status, and multivariate (MVA) logistic regression was used to identify predictors of engraftment. Kaplan-Meier and Cox regression analyses were used to assess the prognostic value of engraftment on patient overall (OS) and disease-free (DFS) survival. Results: 1,003 independent PDX lines derived from 770 RCC patients were included. 157 (15.6%) lines successfully engrafted and exhibited higher tumor grade, stage, size, and presence of sarcomatoid or rhabdoid components. Whole exome sequencing was performed on 230 PDX lines. On MVA, sarcomatoid (OR 5.71, p < 0.001), rhabdoid (OR 2.79, p = 0.046), and advanced stage (OR 1.72, p = 0.049) were significant predictors for engraftment, while high grade and metastatic tumor source were significant only on UVA. Engraftment was associated with poor OS (HR 2.11, p < 0.001) and DFS (HR 1.85, p = 0.020) in patients after controlling for sarcomatoid, rhabdoid, grade, stage, and age on MVA. Conclusions: Aggressive RCC biology correlates with successful engraftment in PDX models. Engraftment remains independently predictive of OS and DFS even after controlling for adverse pathologic features. Engraftment in mice may illuminate aspects of tumor biology not captured by clinicopathologic variables and provide insight into novel determinants of tumor aggressiveness and metastasis. Efforts are underway to elucidate genomic drivers of engraftment.

Assessment of intratumor heterogeneity using imaging texture features in clear cell renal cell carcinoma

663

Background: Intratumoral heterogeneity (ITH) relates to aggressiveness in clear cell renal cell carcinoma (ccRCC), the most common and aggressive subtype of kidney cancer. Percutaneous biopsies have high diagnostic accuracy. However, ITH lowers their reliability in larger, heterogeneous tumors. Haralick texture features extracted from a gray level co-occurrence matrix (GLCM) is a robust method to assess intrinsic tumor imaging characteristics. Some of these features, including entropy as a measure of ITH, have recently been used in differentiating malignant from benign tumors in various organs. We aim to understand how tumor entropy extracted from magnetic resonance (MR) imaging correlate with tumor grade (aggressiveness) and gene expression heterogeneity in ccRCC. Methods: This IRB-approved, prospective study included T2-weighted (T2W) and arterial spin labeled (ASL) MR images of 62 patients with ccRCC. The GLCM was constructed for regions-of interest (ROI) within the tumor and 13 Haralick texture features were estimated. Correlations between texture features and tumor grade were evaluated by logistic regression and quantified by the area under the receiving operating characteristic (ROC) curve (AUC). RNA sequencing of 182 tumor samples in 49 resected tumors was performed. Entropy was correlated with standard deviation (SD) of normalized gene expression levels in multiple samples from the same tumor. Spearman correlation (rho) was computed for each gene. False discovery rate q values < 0.05 were considered statistically significant. Results: Entropy was higher in high-grade than low-grade tumors (11.28 ± 0.52 vs. 10.95 ± 0.65) on T2W (q = 0.028) and ASL (10.45 ± 1.15 vs. 9.65 ± 1.29) (q = 0.013). Entropy had an AUC of 0.70 (T2) for high-grade prediction and was weakly correlated with tumor size (R2 = 0.2). Higher T2 and ASL entropy correlated with higher SD of gene expression. Gene ontology analysis of top correlated genes revealed strong enrichment of genes in metabolic processes. Conclusions: Higher MRI entropy predicts high tumor grade and correlates with increased heterogeneity in gene expression of metabolic processes.

Clonal Relatedness and Mutational Differences between Upper Tract and Bladder Urothelial Carcinoma

PURPOSE

To investigate genomic differences between urothelial carcinomas of the upper tract (UTUC) and bladder (UCB), with a focus on defining the clonal relatedness of temporally distinct tumors.

EXPERIMENTAL DESIGN

We prospectively sequenced tumors and matched germline DNA using targeted next-generation sequencing methods. The cohort included 195 UTUC patients and 454 UCB patients. For a subgroup of 29 patients with UTUC and a history of a subsequent UCB, both tumors were analyzed to assess their clonal relatedness.

RESULTS

With the progression to higher UTUC clinical state, there were fewer alterations in the RTK/RAS pathway but more alterations in TP53/MDM2. Compared with UCB, TP53, RB1, and ERBB2 were less frequently altered in UTUC (26% vs. 46%, 3% vs. 20%, 8% vs. 19%, respectively; Q < 0.001), whereas FGFR3 and HRAS were more frequently altered (40% vs. 26%, 12% vs. 4%, respectively; Q < 0.001). On the basis of an integrated analysis of tumor mutational burden, MSIsensor score and mutational signature, 7.2% of UTUC tumors were classified as MSI-high/MMR-deficient (MSI-H/dMMR). The risk of bladder recurrence after UTUC was significantly associated with mutations in FGFR3, KDM6A, CCND1, and TP53. Comparison of UCB with corresponding UTUC tumors from the same patient supports their clonal relatedness.

CONCLUSIONS

UTUC and UCB exhibit significant differences in the prevalence of common genomic alterations. In individual patients with a history of both tumors, UCB and UTUC were always clonally related. Genomic characterization of UTUC provides information regarding the risk of bladder recurrence and can identify tumors associated with Lynch syndrome.

Massive Intra-abdominal Germ Cell Tumors: A Case Series and Review of Literature

Intra-abdominal testes are at increased risk of malignant transformation and can manifest as large abdominal masses with a wide variation in presenting symptoms. In the setting of cryptorchid or nonpalpable testes, large abdominal masses are highly suspect for germ cell tumors. Without standard guidelines, management can vary extensively. Surgical management may not be trivial and can entail a major abdominal operation in the context of a multimodal approach. The use of biopsy and serum tumor markers may effectively guide sequence of management based upon expected histology. In advanced cases, neoadjuvant chemotherapy may be pursued, and retroperitoneal lymph node dissection may be accomplished at the time of orchiectomy to minimize morbidity. The development of these massive late stage tumors reaffirms current guidelines on the early correction of cryptorchidism.

Impact of Hospital Case Volume on Outcomes Following Radical Nephrectomy and Inferior Vena Cava Thrombectomy

BACKGROUND

Radical nephrectomy with inferior vena cava thrombectomy (RN-IVCT) is a complicated procedure for which the impact of hospital case volume on overall survival (OS) is unknown.

OBJECTIVE

To assess the degree to which renal cell carcinoma (RCC) with inferior vena cava tumor thrombus (IVC-TT) care is centralized and to evaluate the impact of hospital case volume on outcomes following RN-IVCT.

DESIGN, SETTING, AND PARTICIPANTS

The National Cancer Data Base was queried for patients with pT3b-c RCC treated with RN-IVCT. Hospitals were classified by case volume percentile as low (<75th percentile, <0.67 cases annually), intermediate (75th-95th percentile, 0.67-2.99 cases annually), or high (>95th percentile, >3 cases annually).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary outcome was OS. Secondary outcomes were short-term (30- and 90-d) mortality rates according to hospital case volume. Kaplan-Meier curves and Cox regression model were used to evaluate OS and the effect of covariables.

RESULTS AND LIMITATIONS

There were 2664 cases of RN-IVCT for pT3b-c tumors reported by 573 institutions, of which 435, 108, and 30 were classified as low, intermediate, and high volume, accounting for 28.5%, 34.5%, and 37% of cases, respectively. Treatment at high-volume institutions was associated with better OS: the median OS was 42, 53, and 60 months for low, intermediate and high-volume centers, respectively (p=0.009). After multivariable adjustment, treatment at a high-volume institution was associated with a 24% relative risk reduction for all-cause mortality compared to treatment at a low-volume institution (hazard ratio 0.76, 95% confidence interval 0.65-0.89; p=0.001). There was no significant difference in short-term mortality following RN-IVCT when stratified by hospital case volume.

CONCLUSIONS

Higher hospital case volume was associated with longer OS for patients undergoing RN-IVCT. These findings support efforts to centralize care for cases of advanced RCC.

PATIENT SUMMARY

In this study we looked at the impact of hospital case volume on survival following surgery for renal cell carcinoma and inferior vena cava thrombectomy. Survival was significantly better in high-volume hospitals performing three or more procedures per year.

Genomic Differences Between "Primary" and "Secondary" Muscle-invasive Bladder Cancer as a Basis for Disparate Outcomes to Cisplatin-based Neoadjuvant Chemotherapy

BACKGROUND

Cisplatin-based neoadjuvant chemotherapy (NAC) followed by radical cystectomy (RC) is the standard of care for patients with muscle-invasive bladder cancer (MIBC). It is unknown whether this treatment strategy is appropriate for patients who progress to MIBC after treatment for prior noninvasive disease (secondary MIBC).

OBJECTIVE

To determine whether clinical and genomic differences exist between primary and secondary MIBC treated with NAC and RC.

DESIGN, SETTING, AND PARTICIPANTS

Clinicopathologic outcomes were compared between 245 patients with clinical T2-4aN0M0-stage primary MIBC and 43 with secondary MIBC treated with NAC and RC at Memorial Sloan Kettering Cancer Center (MSKCC) from 2001 to 2015. Genomic differences were assessed in a retrospective cohort of 385 prechemotherapy specimens sequenced by whole-exome or targeted exon capture by the Cancer Genome Atlas or at MSKCC. Findings were confirmed in an independent validation cohort of 94 MIBC patients undergoing prospective targeted exon sequencing at MSKCC.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Pathologic response rates, recurrence-free survival (RFS), bladder cancer-specific survival (CSS), and overall survival (OS) were measured. Differences in somatic genomic alteration rates were compared using Fisher's exact test and the Benjamini-Hochberg false discovery rate method.

RESULTS AND LIMITATIONS

Patients with secondary MIBC had lower pathologic response rates following NAC than those with primary MIBC (univariable: 26% vs 45%, multivariable: odds ratio=0.4 [95% confidence interval=0.18-0.84] p=0.02) and significantly worse RFS, CSS, and OS. Patients with secondary MIBC treated with NAC had worse CSS compared with cystectomy alone (p=0.002). In a separate genomic analysis, we detected significantly more likely deleterious somatic ERCC2 missense mutations in primary MIBC tumors in both the discovery (10.9% [36/330] vs 1.8% [1/55], p=0.04) and the validation (15.7% [12/70] vs 0% [0/24], p=0.03) cohort.

CONCLUSIONS

Patients with secondary MIBC treated with NAC had worse clinical outcomes than similarly treated patients with primary MIBC. ERCC2 mutations predicted to result in increased cisplatin sensitivity were enriched in primary versus secondary MIBC. Prospective validation is still needed, but given the lack of clinical benefit with cisplatin-based NAC in patients with secondary MIBC, upfront RC or enrollment in clinical trials should be considered.

PATIENT SUMMARY

A retrospective cohort study of patients with "primary" and "secondary" muscle-invasive bladder cancer (MIBC) treated with chemotherapy before surgical removal of the bladder identified lower response rates and shorter survival in patients with secondary MIBC. Tumor genetic sequencing of separate discovery and validation cohorts revealed that chemotherapy-sensitizing DNA damage repair gene mutations occur predominantly in primary MIBC tumors and may underlie the greater sensitivity of primary MIBC to chemotherapy. Prospective validation is still needed, but patients with secondary MIBC may derive greater benefit from upfront surgery or enrollment in clinical trials rather than from standard chemotherapy.