Challenges to Recruiting Men on Active Surveillance for Prostate Cancer in Clinical Chemoprevention Trials

Clinical trials play a critical role in evidence-based medicine, when rigorous scientific methodology is utilized to discover and test the effectiveness and safety of new drugs to prevent or cure diseases, including cancer. Participation in clinical trials thus becomes key to successful completion of these trials. Although it is estimated that >70% of Americans are inclined to participate in clinical trials, less than 5% of adult cancer patients participate in clinical trials. There is thus a large gap between those inclined to participate in clinical trials and actual participation in clinical trials. As with trials targeting men with prostate cancer (PCa) on active surveillance (AS), where the target population is mostly over 50 years of age, others have observed several challenges with recruitment and accrual in clinical trials. The participation rate is currently unavailable for men on primary and secondary chemoprevention trials. Additionally, with unanticipated environmental factors such as a pandemic or other natural emergencies that may severely impact the economy, personal property, travel and person-to person contact for study-related procedures, there is a need to continuously identify these challenges and determine solutions to recruitment barriers in chemoprevention trials to ensure timely completion of early phase trials. Recent studies regarding the impact of the pandemic on clinical trial recruitment have shown that cancer prevention trials were relatively more negatively impacted compared to cancer treatment trials. The goal of this manuscript is to review our experience in continuously evaluating the protocol and patient level challenges to recruiting subjects on AS for PCa in this cancer chemoprevention trial conducted at the Comprehensive Cancer Center (CCC) and report the contemporary strategies that we are utilizing to continue to recruit subjects in this trial. We provide data from our current trial as an example while discussing future strategies to improve overall clinical trial recruitment. These strategies can inform future design of contemporary cancer chemoprevention trials and, additionally, better select, focus and invest in strategies that are the most productive and efficient for recruiting target populations.

Effects of Green Tea Catechins on Prostate Cancer Chemoprevention: The Role of the Gut Microbiome

Accumulating evidence supports green tea catechins (GTCs) in chemoprevention for prostate cancer (PCa), a leading cause of cancer morbidity and mortality among men. GTCs include (-)-epigallocatechin-3-gallate, which may modulate the molecular pathways implicated in prostate carcinogenesis. Prior studies of GTCs suggested that they are bioavailable, safe, and effective for modulating clinical and biological markers implicated in prostate carcinogenesis. GTCs may be of particular benefit to those with low-grade PCas typically managed with careful monitoring via active surveillance (AS). Though AS is recommended, it has limitations including potential under-grading, variations in eligibility, and anxiety reported by men while on AS. Secondary chemoprevention of low-grade PCas using GTCs may help address these limitations. When administrated orally, the gut microbiome enzymatically transforms GTC structure, altering its bioavailability, bioactivity, and toxicity. In addition to xenobiotic metabolism, the gut microbiome has multiple other physiological effects potentially involved in PCa progression, including regulating inflammation, hormones, and other known/unknown pathways. Therefore, it is important to consider not only the independent roles of GTCs and the gut microbiome in the context of PCa chemoprevention, but how gut microbes may relate to individual responses to GTCs, which, in turn, can enhance clinical decision-making.

Biorepositories and Databanks for the Development of Novel Biomarkers for Genitourinary Cancer Prevention and Management

CONTEXT

Translational research in uro-oncology depends on the availability of high-quality biospecimens and associated data to advance precision medicine and improve clinical outcomes. Procurement, storage, and annotation of these specimens represent critical steps towards this end.

OBJECTIVE

To review best-practice experiences gained via the McCain GU BioBank, a repository of more than 750 000 biospecimens obtained from more than 16 000 patients attending clinics at the University Health Network in Toronto, Canada.

EVIDENCE ACQUISITION

The review summarizes our experiences at a large single-institution genitourinary oncology biorepository.

EVIDENCE SYNTHESIS

Key findings are placed in the context of emerging trends in genitourinary oncology, with a focus on integration of molecular profiling and clinical data with traditional biorepository management. Proposed approaches provide high-quality biospecimens with comprehensive and reliable clinical data that can fuel innovation and discovery in research.

CONCLUSIONS

Biorepositories are vital for improving clinical outcomes and advancing personalized medicine. High-quality biospecimens and their associated clinical data are crucial for validation of biomarkers in oncology. Efforts to procure, store, and annotate clinical specimens represent critical steps in translational research. Elements such as biobank size, biospecimen types, disease cohorts, predetermined collection protocols, broad informed consent, sample handling and storage protocols, and available infrastructure directly influence the effectiveness and capacity of a biobank.

PATIENT SUMMARY

Biorepositories, or biobanks, are facilities that store biospecimens such as blood, urine, or tissue (usually collected from humans) for use in research. Biobanks have become an important resource in medical research, as they provide high-quality specimens to support different types of contemporary research such as genomics, biomarker discovery, and personalized medicine. Clinical management and treatment of genitourinary cancers, such as prostate, kidney, and bladder cancers, are particularly suited for biomarker research. The provision of biospecimens and their associated clinical data have become crucial for validation of biomarkers in these cancers.

Older Age at Diagnosis and Initial Disease Volume Predict Grade Reclassification Risk on Confirmatory Biopsy in Patients Considered for Active Surveillance

OBJECTIVE

To identify which active surveillance candidates benefit most from confirmatory biopsies to exclude grade underclassification.

MATERIALS AND METHODS

This observational study includes 556 men diagnosed between 2002 and 2015 with Gleason 3 + 3 (GG1) disease on initial diagnostic biopsy, of whom 406 received a confirmatory biopsy within 12 months for active surveillance. Multivariable logistic regression analysis was performed to determine clinicopathologic features associated with Gleason 7 or higher (GG2+) on a confirmatory biopsy. Regression tree analysis was employed to stratify patients into select risk groups.

RESULTS

Eighty-five of 406 patients (20.9%) with initially GG1 disease were reclassified to GG2+ on a confirmatory biopsy. On multivariable analysis, increasing age (per year odds ratio 1.07; 95% confidence interval 1.02-1.12; P <.01) and more positive cores at diagnosis (per core, odds ratio 1.37, 95% confidence interval 1.09-1.72; P <.01) were significantly associated with reclassification, independent of prostate volume, clinical stage, initial PSA, or confirmatory biopsy type (including magnetic resonance imaging-targeted approaches or transrectal saturation random sampling). Recursive partitioning demonstrated that age over 73 and 5 or more positive cores were factors associated with the greatest reclassification risk.

CONCLUSION

In our cohort, both advancing age and additional positive cores were associated with increased odds of reclassification to GG2+ on confirmatory biopsy. In men over age 73 or with 5 or more positive cores, a repeat biopsy within 12 months may be particularly beneficial to minimize tumor grade underclassification.

Green tea extract for prevention of prostate cancer progression in patients on active surveillance

Background

Active surveillance (AS) has evolved as a management strategy for men with low grade prostate cancer (PCa). However, these patients report anxiety, doubts about the possible progression of the disease as well as higher decisional conflict regarding selection of active surveillance, and have been reported to ultimately opt for treatment without any major change in tumor characteristics. Currently, there is a paucity of research that systematically examines alternate strategies for this target population.

Methods

We conducted a review the evidence from epidemiological, in vitro, preclinical and early phase trials that have evaluated green tea catechins (GTC) for secondary chemoprevention of prostate cancer, focused on men opting for active surveillanceof low grade PCa.

Results

Results of our review of the in vitro, preclinical and phase I-II trials, demonstrates that green tea catechins (GTC) can modulate several relevant intermediate biological intermediate endpoint biomarkers implicated in prostate carcinogenesis as well as clinical progression of PCa, without major side effects.

Discussion

Although clinical trials using GTC have been evaluated in early phase trials in men diagnosed with High-Grade Prostatic Intraepithelial Neoplasia, Atypical Small Acinar Proliferation and in men with localized disease before prostatectomy, the effect of GTC on biological and clinical biomarkers implicated in prostate cancer progression have not been evaluated in this patient population.

Conclusion

Results of these studies promise to provide a strategy for secondary chemoprevention, reduce morbidities due to overtreatment and improve quality of life in men diagnosed with low-grade PCa.

Trends in active surveillance for very low-risk prostate cancer: do guidelines influence modern practice?

As recommended by current NCCN guidelines, patients with very low‐risk prostate cancer may be treated with active surveillance (AS), but this may be underutilized. Using the National Cancer Database (NCDB), we identified men (2010–2013) with biopsy‐proven, very low‐risk prostate cancer that met AS criteria as suggested by Epstein (stage ≤ T1c; Gleason score (GS) ≤ 6; PSA < 10; and ≤2 [or <33%] positive biopsy cores) and aged ≤76, and low comorbidity index (Charlson‐Deyo score = 0). For those patients meeting this criteria, we performed generalized estimation equation (GEE) method with incorporation of correlation in patients clustered within facility to determine the likelihood of undergoing AS. Among the 448 773 patients in the NCDB with low‐risk prostate cancer, 40 839 patients met the inclusion criteria. AS was utilized in 5798 patients (14.2%), while within the very low‐risk patients receiving treatment, up to 52.2% received radical prostatectomy. In univariate analyses, AS utilization was associated with older age, uninsured status (compared to private insurance), farther distance from facility, academic/research institutions and particularly in the New England region (all P < 0.01). After adjustments of other predictors in multivariate analysis, patients preferentially received AS if they were older (all OR's > 1 compared to younger groups), uninsured (vs. any insurance type, OR's > 1); or treated at academic/research center (OR > 1). The overall use of AS increased from 11.6% (2010) to 27.3% (2013). We found a low, but rising rate of AS in a nationally representative group of very low‐risk prostate cancer patients. Disparities in the use of AS may be targeted to improve adherence to national guidelines.

Molecular Analysis of Low Grade Prostate Cancer Using a Genomic Classifier of Metastatic Potential

PURPOSE

We determined how frequently histological Gleason 3 + 3 = 6 tumors have the molecular characteristics of disease with metastatic potential.

MATERIALS AND METHODS

We analyzed prostatectomy tissue from 337 patients with Gleason 3 + 3 disease. All tissue was re-reviewed in blinded fashion by genitourinary pathologists using 2005 ISUP (International Society of Urological Pathology) Gleason grading criteria. A previously validated Decipher® metastasis signature was calculated in each case based on a locked model. To compare patient characteristics across pathological Gleason score categories we used the Fisher exact test or the ANOVA F test. The distribution of Decipher scores among different clinicopathological groups was compared with the Wilcoxon rank sum test. The association of Decipher score with adverse pathology features was examined using logistic regression models. The significance level of all statistical tests was 0.05.

RESULTS

Of men with Gleason 3 + 3 = 6 disease only 269 (80%) had a low Decipher score with intermediate and high scores in 43 (13%) and 25 (7%), respectively. Decipher scores were significantly higher among pathological Gleason 3 + 3 = 6 specimens from cases with adverse pathological features such as extraprostatic extension, seminal vesicle involvement or positive margins (p <0.001). The median Decipher score in patients with margin negative pT2 disease was 0.23 (IQR 0.09-0.42) compared to 0.30 (IQR 0.17-0.42) in patients with pT3 disease or positive margins (p = 0.005).

CONCLUSIONS

Using a robust and validated prognostic signature we found that a small but not insignificant proportion of histological Gleason 6 tumors harbored molecular characteristics of aggressive cancer. Molecular profiling of such tumors at diagnosis may better select patients for active surveillance at diagnosis and trigger appropriate intervention during followup.