Nucleotide excision repair deficiency is a targetable therapeutic vulnerability in clear cell renal cell carcinoma.

Due to a demonstrated lack of DNA repair deficiencies, clear cell renal cell carcinoma (ccRCC) has not benefitted from targeted synthetic lethality-based therapies. We investigated whether nucleotide excision repair (NER) deficiency is present in an identifiable subset of ccRCC cases that would render those tumors sensitive to therapy targeting this specific DNA repair pathway aberration. We used functional assays that detect UV-induced 6-4 pyrimidine-pyrimidone photoproducts to quantify NER deficiency in ccRCC cell lines. We also measured sensitivity to irofulven, an experimental cancer therapeutic agent that specifically targets cells with inactivated transcription-coupled nucleotide excision repair (TC-NER). In order to detect NER deficiency in clinical biopsies, we assessed whole exome sequencing data for the presence of an NER deficiency associated mutational signature previously identified in ERCC2 mutant bladder cancer. Functional assays showed NER deficiency in ccRCC cells. Some cell lines showed irofulven sensitivity at a concentration that is well tolerated by patients. Prostaglandin reductase 1 (PTGR1), which activates irofulven, was also associated with this sensitivity. Next generation sequencing data of the cell lines showed NER deficiency-associated mutational signatures. A significant subset of ccRCC patients had the same signature and high PTGR1 expression. ccRCC cell line-based analysis showed that NER deficiency is likely present in this cancer type. Approximately 10% of ccRCC patients in the TCGA cohort showed mutational signatures consistent with ERCC2 inactivation associated NER deficiency and also substantial levels of PTGR1 expression. These patients may be responsive to irofulven, a previously abandoned anticancer agent that has minimal activity in NER-proficient cells.

Genomic Validation of 3-Tiered Clinical Subclassification of High-Risk Prostate Cancer.

PURPOSE: Recent data and National Comprehensive Cancer Network (NCCN) guidelines suggest that high-risk prostate cancer (cT3-4, Gleason score ≥8, or prostate-specific antigen [PSA] >20 ng/mL) is a heterogenous group in terms of long-term patient outcomes. We sought to determine whether subclassification of high-risk prostate cancer based on clinical factors correlates with genomic markers of risk. METHODS AND MATERIALS: We identified 3220 patients with NCCN unfavorable intermediate-risk (n = 2000) or high-risk (n = 1220) prostate cancer from a prospective multi-institutional registry cohort. We defined the following subclassification of high-risk prostate cancer based on previously published data: favorable high risk (cT1c, Gleason 6, and PSA >20 ng/mL or cT1c, Gleason 4 + 4 = 8, PSA <10 ng/mL); very high risk (cT3b-T4 or primary Gleason pattern 5); and standard high risk (all others with cT3a, Gleason score ≥8, or PSA >20 ng/mL). We used a set of 33 previously developed genomic classifiers, including Decipher, to determine whether high-risk genomic features correlate with clinical subclasses of high-risk prostate cancer. RESULTS: Among those with favorable high-risk, standard high-risk, and very high-risk prostate cancer, 50.4%, 64.2%, and 81.6% had a high-risk Decipher score, respectively (P < .001). Among 32 other genomic signatures, 29 had a similar trend of increasing risk scores across the 3 subclasses of high-risk disease (P < .05 after correction for multiple hypothesis testing). Patients in the 3 subclasses of high-risk disease had a median of 4, 6, and 13 high-risk signatures, respectively. In comparison, among those with unfavorable intermediate-risk prostate cancer, 38.2% had a high-risk Decipher score, and the median number of high-risk signatures was 3. CONCLUSIONS: Although NCCN guidelines currently use a 2-tiered system for high-risk prostate cancer, genomic markers of risk correlate with the clinically validated subclassification of high-risk prostate cancer into favorable high-risk, standard high-risk, and very high-risk disease, further confirming the prognostic utility of this 3-tiered stratification.

Use and early mortality outcomes of active surveillance in patients with intermediate-risk prostate cancer.

BACKGROUND: Certain patients with intermediate-risk prostate cancer (PCa) may be appropriate candidates for active surveillance (AS). In the current study, the authors sought to characterize AS use and early mortality outcomes for patients with intermediate-risk PCa in the United States. METHODS: The novel Surveillance, Epidemiology, and End Results Active Surveillance/Watchful Waiting database identified 52,940 men diagnosed with National Comprehensive Cancer Network intermediate-risk PCa (cT2b-c, Gleason score of 7, or a prostate-specific antigen level of 10-20 ng/mL) and actively managed (AS, radiotherapy, or radical prostatectomy) from 2010 through 2015. The Cuzick test assessed AS time trends, and logistic multivariable regression characterized features associated with AS. Fine-Gray and Cox modeling determined PCa-specific mortality (PCSM) and overall survival, respectively. RESULTS: The rate of AS increased from 3.7% in 2010 to 7.3% in 2015, and from 7.2% to 11.7% among men aged ≥70 years. Among men with favorable and unfavorable intermediate-risk disease, the use of AS increased from 7.2% to 14.9% and from 2.2% to 3.8%, respectively (all P value for trend, <.001). The mean age of those patients managed with AS decreased from 69.9 years to 67.9 years (P = .0004). Factors found to be associated with AS included favorable risk disease; black race; higher socioeconomic status; older age; and diagnosis in the West, Northwest, or Midwest regions of the United States. The 5-year PCSM rate was comparable to AS versus treatment among patients with low-risk and favorable intermediate-risk disease, but was worse with AS among those with unfavorable intermediate-risk disease (PCSM, 1.3% vs 0.5%; adjusted hazard ratio, 2.48 [95% CI, 1.11-5.50; P = .026]) and intermediate-risk disease overall (PCSM, 1.1% vs 0.4%; adjusted hazard ratio, 2.34 [95% CI, 1.25-4.37; P = .008]). CONCLUSIONS: The use of AS for patients with intermediate-risk PCa is increasing across the United States, particularly for older men and those with favorable intermediate-risk disease. Early estimates of cancer-specific and overall mortality rates are low with AS, although significantly higher compared with treatment.

A comparative analysis of overall survival between high-dose-rate and low-dose-rate brachytherapy boosts for unfavorable-risk prostate cancer.

PURPOSE: External beam radiation therapy (EBRT) with low-dose-rate (LDR) brachytherapy boost has been associated with improved biochemical progression-free survival and overall survival (OS) compared with dose-escalated EBRT (DE-EBRT) alone for unfavorable-risk prostate cancer. However, it is not known whether high-dose-rate (HDR) boost provides a similar benefit. We compare HDR boost against LDR boost and DE-EBRT with respect to OS. METHODS: Using the National Cancer Database, we identified 122,896 patients who were diagnosed with National Comprehensive Cancer Network intermediate- or high-risk prostate cancer between 2004 and 2014 and treated with DE-EBRT (75.6-86.4 Gy), LDR boost, or HDR boost. We compared the OS among the three groups using multivariable Cox proportional hazards regression. Inverse probability treatment weighting was used to adjust for covariate imbalance. RESULTS: On multivariable Cox proportional hazards regression, HDR boost was associated with a similar OS to LDR boost (adjusted hazard ratio [AHR] 1.03 [0.96, 1.11]; p = 0.38) but significantly better OS than DE-EBRT (AHR 1.36 [1.29, 1.44]; p < 0.001). Inverse probability treatment weighting analysis yielded similar results. There was no significant difference between LDR and HDR boosts for National Comprehensive Cancer Network intermediate-risk (AHR 1.05 [0.96, 1.15]; p = 0.32) and high-risk (AHR 1.00 [0.89, 1.12]; p = 0.98) subgroups (p-interaction = 0.55). CONCLUSIONS: Our results suggest that HDR brachytherapy boost yields similar OS benefits compared with LDR brachytherapy boost for unfavorable-risk prostate cancer. HDR boost may be a suitable alternative to LDR boost.

Lack of Benefit From the Addition of External Beam Radiation Therapy to Brachytherapy for Intermediate- and High-risk Prostate Cancer.

PURPOSE: A recent randomized controlled trial demonstrated that the addition of external beam radiation therapy (EBRT) to brachytherapy did not improve progression-free survival in select patients with intermediate-risk prostate cancer. We evaluated whether the addition of EBRT to brachytherapy improves prostate cancer-specific mortality (PCSM) for intermediate- and high-risk disease using a large national database. METHODS AND MATERIALS: We identified 5836 patients in the Surveillance, Epidemiology, and End Results-Medicare linked database with a diagnosis of National Comprehensive Cancer Network intermediate-risk (Gleason score 7, prostate-specific antigen 10-20 ng/mL, or stage cT2b-T2c) or high-risk (Gleason score 8-10 or prostate-specific antigen >20 ng/mL and stage ≤cT3a) prostate cancer who had undergone brachytherapy, with or without EBRT and androgen deprivation therapy (ADT). Patients were diagnosed from 2004 through 2009. Intermediate-risk patients with Gleason score ≤3+4 and 1 intermediate-risk factor were considered favorable and all others unfavorable. We used multivariable Fine-Gray competing risks regression to study PCSM while adjusting for sociodemographic and clinical factors and ADT use. RESULTS: Overall, 50.3% of intermediate- and high-risk patients who received brachytherapy and EBRT did not have significantly improved PCSM compared with that of the patients who received brachytherapy alone (adjusted hazard ratio [AHR] 1.46, 95% confidence interval [CI] 0.69-3.11; P=.322; 5-year PCSM 2.4% vs 1.0%). This lack of benefit was seen among favorable intermediate-risk (AHR 2.66, 95% CI 0.93-7.62, P=.069; 5-year PCSM 1.3% vs 0.6%), unfavorable intermediate-risk (AHR 0.68, 95% CI 0.16-2.96, P=.612; 5-year PCSM 1.0% vs 1.2%), and high-risk (AHR 1.82, 95% CI 0.67-4.98, P=.242; 5-year PCSM 5.3% vs 2.1%) subgroups. CONCLUSIONS: These results suggest that certain patients with intermediate- or high-risk prostate cancer treated with brachytherapy might not benefit from the addition of EBRT. A randomized controlled trial of brachytherapy plus ADT with or without EBRT for unfavorable intermediate- and favorable high-risk organ-confined prostate cancer should be undertaken.