Charles Dai

Corticosteroids compromise survival in glioblastoma

Glioblastoma is the most common and most aggressive primary brain tumour. Standard of care consists of surgical resection followed by radiotherapy and concomitant and maintenance temozolomide (temozolomide/radiotherapy→temozolomide). Corticosteroids are commonly used perioperatively to control cerebral oedema and are frequently continued throughout subsequent treatment, notably radiotherapy, for amelioration of side effects. The effects of corticosteroids such as dexamethasone on cell growth in glioma models and on patient survival have remained controversial. We performed a retrospective analysis of glioblastoma patient cohorts to determine the prognostic role of steroid administration. A disease-relevant mouse model of glioblastoma was used to characterize the effects of dexamethasone on tumour cell proliferation and death, and to identify gene signatures associated with these effects. A murine anti-VEGFA antibody was used in parallel as an alternative for oedema control. We applied the dexamethasone-induced gene signature to The Cancer Genome Atlas glioblastoma dataset to explore the association of dexamethasone exposure with outcome. Mouse experiments were used to validate the effects of dexamethasone on survival in vivo Retrospective clinical analyses identified corticosteroid use during radiotherapy as an independent indicator of shorter survival in three independent patient cohorts. A dexamethasone-associated gene expression signature correlated with shorter survival in The Cancer Genome Atlas patient dataset. In glioma-bearing mice, dexamethasone pretreatment decreased tumour cell proliferation without affecting tumour cell viability, but reduced survival when combined with radiotherapy. Conversely, anti-VEGFA antibody decreased proliferation and increased tumour cell death, but did not affect survival when combined with radiotherapy. Clinical and mouse experimental data suggest that corticosteroids may decrease the effectiveness of treatment and shorten survival in glioblastoma. Dexamethasone-induced anti-proliferative effects may confer protection from radiotherapy- and chemotherapy-induced genotoxic stress. This study highlights the importance of identifying alternative agents such as vascular endothelial growth factor antagonists for managing oedema in glioblastoma patients. Beyond the established adverse effect profile of protracted corticosteroid use, this analysis substantiates the request for prudent and restricted use of corticosteroids in glioblastoma.

Androgen Signaling in Prostate Cancer

The androgen-signaling axis plays a pivotal role in the pathogenesis of prostate cancer. Since the landmark discovery by Huggins and Hodges, gonadal depletion of androgens has remained a mainstay of therapy for advanced disease. However, progression to castration-resistant prostate cancer (CRPC) typically follows and is largely the result of restored androgen signaling. Efforts to understand the mechanisms behind CRPC have revealed new insights into dysregulated androgen signaling and intratumoral androgen synthesis, which has ultimately led to the development of several novel androgen receptor (AR)-directed therapies for CRPC. However, emergence of resistance to these newer agents has also galvanized new directions in investigations of prereceptor and postreceptor AR regulation. Here, we review our current understanding of AR signaling as it pertains to the biology and natural history of prostate cancer.

Intermediate-Term Outcomes for Men with Very Low/Low and Intermediate/High Risk Prostate Cancer Managed by Active Surveillance

Purpose: We compare intermediate term clinical outcomes among men with favorable risk and intermediate/high risk prostate cancer managed by active surveillance. Materials and Methods: A total of 635 men with localized prostate cancer have been on active surveillance since 2002 at a high volume academic hospital in the United States. Median followup is 50.5 months (IQR 31.1–80.3). Time to event analysis was performed for our clinical end points. Results: Of the cohort 117 men (18.4%) had intermediate/high risk disease. Overall 5 and 10‐year all cause survival was 98% and 94%, respectively. Cumulative metastasis‐free survival at 5 and 10 years was 99% and 98%, respectively. To date no cancer specific deaths had been observed. Overall freedom from intervention was 61% and 49% at 5 and 10 years, respectively. Overall cumulative freedom from failure of active surveillance, defined as metastasis or biochemical failure after local therapy with curative intent, was 97% and 91% at 5 and 10 years, respectively. Of the men 21 (9.9%) experienced biochemical failure after deferred treatment and the 5‐year progression‐free probability was 92%. Compared to men with favorable risk disease those with intermediate/high risk cancer experienced no difference in metastases, surveillance failure or curative intervention. However, patients at higher risk were at significantly increased risk for all cause mortality, likely reflecting patient selection factors. These conclusions may be limited by the small number of events and the duration of our study. Conclusions: Patients with localized prostate cancer who are on active surveillance demonstrated a low rate of active surveillance failure, prostate cancer specific mortality and metastases regardless of baseline risk.

Direct Metabolic Interrogation of Dihydrotestosterone Biosynthesis from Adrenal Precursors in Primary Prostatectomy Tissues

Purpose: A major mechanism of castration-resistant prostate cancer (CRPC) involves intratumoral biosynthesis of dihydrotestosterone (DHT) from adrenal precursors. We have previously shown that adrenal-derived androstenedione (AD) is the preferred substrate over testosterone (T) for 5α-reductase expressed in metastatic CRPC, bypassing T as an obligate precursor to DHT. However, the metabolic pathway of adrenal-derived DHT biosynthesis has not been rigorously investigated in the setting of primary disease in the prostate. Experimental Design: Seventeen patients with clinically localized prostate cancer were consented for fresh tissues after radical prostatectomy. Prostate tissues were cultured ex vivo in media spiked with an equimolar mixture of AD and T, and stable isotopic tracing was employed to simultaneously follow the enzymatic conversion of both precursor steroids into nascent metabolites, detected by liquid chromatography-tandem mass spectrometry. CRPC cell line models and xenograft tissues were similarly assayed for comparative analysis. A tritium-labeled steroid radiotracing approach was used to validate our findings. Results: Prostatectomy tissues readily 5α-reduced both T and AD. Furthermore, 5α-reduction of AD was the major directionality of metabolic flux to DHT. However, AD and T were comparably metabolized by 5α-reductase in primary prostate tissues, contrasting the preference exhibited by CRPC in which AD was favored over T. 5α-reductase inhibitors effectively blocked the conversion of AD to DHT. Conclusions: Both AD and T are substrates of 5α-reductase in prostatectomy tissues, resulting in two distinctly nonredundant metabolic pathways to DHT. Furthermore, the transition to CRPC may coincide with a metabolic switch toward AD as the favored substrate. Clin Cancer Res; 23(20); 6351–62. ©2017 AACR.

Prognostic Significance of a Negative Confirmatory Biopsy on Reclassification Among Men on Active Surveillance

OBJECTIVE To examine the association between absence of disease on confirmatory biopsy and risk of pathologic reclassification in men on active surveillance (AS). MATERIALS AND METHODS Men with grade groups 1 and 2 disease on AS between 2002 and 2015 were identified who received a confirmatory biopsy within 1 year of diagnosis and ≥3 biopsies overall. The primary outcomes were pathologic reclassification by grade (any increase in primary Gleason pattern or Gleason score) or volume (>33% of sampled cores involved or increase in the number of cores with >50% involvement). The effect of a negative confirmatory biopsy survival was evaluated using Kaplan-Meier analysis and a Cox proportional hazards modeling. RESULTS Out of 635 men, 224 met inclusion criteria (median follow-up: 55.8 months). A total of 111 men (49.6%) had a negative confirmatory biopsy. Decreased grade reclassification (69.7% vs 83.9%; P = .01) and volume reclassification (66.3% vs 87.4%; P = .004) was seen at 5 years for men with a negative confirmatory biopsy compared with those with a positive biopsy. On adjusted analysis, a negative confirmatory biopsy was associated with a decreased risk of grade reclassification (hazard ratio, 0.51; 95% confidence interval, 0.28-0.94; P = .03) and volume reclassification (hazard ratio, 0.32; 95% confidence interval, 0.17-0.61; P = .0006) at a median of 4.7 years. CONCLUSION Absence of cancer on the confirmatory biopsy is associated with a significant decrease in rate of grade and volume reclassification among men on AS. This information may be used to better counsel men on AS.

Impact of 5α-Reductase Inhibitors on Disease Reclassification among Men on Active Surveillance for Localized Prostate Cancer with Favorable Features

Purpose: We determined the effect of 5&agr;‐reductase inhibitors on disease reclassification in men with prostate cancer optimally selected for active surveillance. Materials and Methods: In this retrospective review we identified 635 patients on active surveillance between 2002 and 2015. Patients with favorable cancer features on repeat biopsy, defined as absent Gleason upgrading, were included in the cohort. Patients were stratified by those who did or did not receive finasteride or dutasteride within 1 year of diagnosis. The primary end point was grade reclassification, defined as any increase in Gleason score or predominant Gleason pattern on subsequent biopsy. This was assessed by multivariable Cox proportional hazards regression analysis. Results: At diagnosis 371 patients met study inclusion criteria, of whom 70 (19%) were started on 5&agr;‐reductase inhibitors within 12 months. Median time on active surveillance was 53 vs 35 months in men on vs not on 5&agr;‐reductase inhibitors (p <0.01). Men on 5&agr;‐reductase inhibitors received them for a median of 23 months (IQR 6–37). On actuarial analysis there was no significant difference in grade reclassification for 5&agr;‐reductase inhibitor use in patients overall or in the very low/low risk subset. The overall percent of patients who experienced grade reclassification was similar at 13% vs 14% (p = 0.75). After adjusting for baseline clinicopathological features 5&agr;‐reductase inhibitors were not significantly associated with grade reclassification (HR 0.80, 95% CI 0.31–1.80, p = 0.62). Furthermore, no difference in adverse features on radical prostatectomy specimens was observed in treated patients (p = 0.36). Conclusions: Among our cohort of men on active surveillance 5&agr;‐reductase inhibitor use was not associated with a significant difference in grade reclassification with time.

PD55-12 OLDER AGE AT DIAGNOSIS AND DISEASE VOLUME PREDICT UPGRADING ON CONFIRMATORY BIOPSY IN PROSTATE CANCER PATIENTS BEING CONSIDERED FOR ACTIVE SURVEILLANCE

RESULTS: 3669 patients underwent RP between 1/1/04 and 12/31/15. Of these, 1454, 251 and 1361 patients fulfilled criteria for very low/low, favorable intermediate, and unfavorable intermediate-risk groups, respectively. Median follow-up was 37 months. Patients in the favorable intermediate group had significantly higher rates of Gleason score upgrading (16% vs 6%; p<0.001) and non organ-confined disease (16% vs 11%; p1⁄40.035) than those in low risk group. Time to biochemical recurrence for the favorable intermediate group did not differ significantly from the low risk group (p1⁄40.057), but was significantly longer than unfavorable intermediates (p1⁄40.003) (Figure 1). CONCLUSIONS: Compared to very low/low risk prostate cancer patients, men with favorable intermediate-risk disease had significantly higher rates of more aggressive, non-organ confined disease at RP, and trended toward worse biochemical progression free survival. However, when compared to unfavorable intermediate risk patients, it appears the magnitude of these differences would not preclude AS as a reasonable option for appropriately selected patients with favorable intermediate risk prostate cancer.

MP15-15 A RETROSPECTIVE REVIEW OF A LARGE ACTIVE SURVEILLANCE COHORT IN PATIENTS WITH PROSTATE CANCER AT THE CLEVELAND CLINIC

Gleason score undergrading. We compared biochemical recurrence rates (BCR) after radical prostatectomy between patients with active surveillance (AS) suitable prostate cancer versus wider defined low risk prostate cancer and the effect of Gleason score upgrading after surgery. METHODS: Two prostatectomy cohorts were combined. Lowrisk PC was defined as T1-2, Gleason 6 prostate cancer and AS-suitable prostate cancer was defined using the ‘PRIAS-criteria’ as T1-2, PSA 1⁄4<10 ng/ml, PSA density <0.2 ng/ml/ml, 1-2 positive biopsies, Gleason 3+31⁄46. Kaplan-Meier curves of patients with and without Gleason score upgrading were compared using the Log-Rank test. We hypothesized that perfect pre-operative biopsy Gleason grading would lead to 0% upgrading after surgery. RESULTS: We included 755 patients of whom 181 (24%) suitable for AS, 324 (44%) had Gleason upgrading after surgery (to 6.5 in non-AS suitable versus 6.3; p1⁄40.005), and 132 (18%) showed BCR a median of 1.0 year after prostatectomy. For the total group, the 5-year BCR rate was 27%. Regarding the entire low risk group of T1-2 Gleason 6 prostate cancer, Gleason upgrading at surgery was significantly associated with unfavorable BCR rates (Figure 1a; p<0.01). Within the selected group of more favorable risk disease suitable for AS, Gleason upgrading at surgery was not associated with BCR rates (Figure 1b; p1⁄40.936). In patients who did not have Gleason upgrading, patients who were not suitable for AS showed similar BCR rates to patients who did fulfill all AS criteria (Figure 1c; p1⁄40.155). A limitation is the retrospective design; prospective validation is needed. CONCLUSIONS: In the selected group of favorable risk patients considered suitable for AS, no unfavorable effect on BCR rates was found of Gleason undergrading. This may question the additional value of reducing biopsy undergrading with new imaging techniques. In patients not fulfilling the strict AS criteria, exclusion of Gleason upgrading resulted however in BCR rates similarly favorable to patients who were suitable for AS. This may suggest that MRI could be used to expand selection criteria for AS if Gleason upgrading could be excluded.

A dual stable isotope method by LC-MS/MS to define patterns of androgen metabolism in localized versus advanced prostate cancer.

40 Background: Prior work has shown that androstenedione (AD) rather than testosterone (T) is the preferred substrate of 5α-reductase for dihydrotestosterone (DHT) synthesis in castration-resistant prostate cancer. However, patterns of metabolism in hormone-naive prostate cancer are still poorly defined. Previously, we reported on the utility of dual radioisotope labeling of steroid precursors to characterize androgen metabolism in localized prostate tissue. We now describe an alternative approach via stable isotope labeling and analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS), which has unique advantages over the former method. Methods: LNCaP cell lines and prostate tissue from patients undergoing radical prostatectomy for localized cancer were incubated in serum-free media, spiked with 13C-labeled AD and 2H-labeled T. Media was collected at 7, 24, and 48 hours of incubation. Steroids were extracted, separated, and then analyzed by way of LC-MS/MS to identify labeled metabolites of A...