Surrogate End Points for All-Cause Mortality in Men With Localized Unfavorable-Risk Prostate Cancer Treated With Radiation Therapy vs Radiation Therapy Plus Androgen Deprivation Therapy: A Secondary Analysis of a Randomized Clinical Trial

Salvage therapies for biochemical recurrence after definitive local treatment: a systematic review, meta-analysis, and network meta-analysis

PURPOSE

Recent advancements in the management of biochemical recurrence (BCR) following local treatment for prostate cancer (PCa), including the use of androgen receptor signaling inhibitors (ARSIs), have broadened the spectrum of therapeutic options. We aimed to compare salvage therapies in patients with BCR after definitive local treatment for clinically non-metastatic PCa with curative intent.

METHODS

In October 2023, we queried PubMed, Scopus, and Web of Science databases to identify randomized controlled trials (RCTs) and prospective studies reporting data on the efficacy of salvage therapies in PCa patients with BCR after radical prostatectomy (RP) or radiation therapy (RT). The primary endpoint was metastatic-free survival (MFS), and secondary endpoints included progression-free survival (PFS) and overall survival (OS).

RESULTS

We included 19 studies (n = 9117); six trials analyzed RT-based strategies following RP, ten trials analyzed hormone-based strategies following RP ± RT or RT alone, and three trials analyzed other agents. In a pairwise meta-analysis, adding hormone therapy to salvage RT significantly improved MFS (HR: 0.69, 95% CI: 0.57-0.84, p < 0.001) compared to RT alone. Based on treatment ranking analysis, among RT-based strategies, the addition of elective nodal RT and androgen deprivation therapy (ADT) was found to be the most effective in terms of MFS. On the other hand, among hormone-based strategies, enzalutamide + ADT showed the greatest benefit for both MFS and OS.

CONCLUSIONS

The combination of prostate bed RT, elective pelvic irradiation, and ADT is the preferred treatment for eligible patients with post-RP BCR based on our analysis. In remaining patients, or in case of post-RT recurrence, especially for those with high-risk BCR, the combination of ADT and ARSI should be considered.

Cost-Effectiveness Analysis of Triptorelin, Goserelin, and Leuprolide in the Treatment of Patients With Metastatic Prostate Cancer: A Societal Perspective

OBJECTIVES

Metastatic prostate cancer is the most common malignant cancer and the second leading cause of death due to various types of cancer among men after lung cancer. This study aimed to analyze the cost-effectiveness of triptorelin, goserelin, and leuprolide in the treatment of the patients with metastatic prostate cancer from the societal perspective in Iran in 2020.

METHODS

This is a cost-effectiveness study in which a 20-year Markov transition modeling was applied. In this study, local cost and quality-of-life data of each health state were gathered from cohort of patients. The TreeAge pro 2020 and Microsoft Excel 2016 software were used to simulate cost-effectiveness of each treatment in the long term. The one-way and probabilistic sensitivity analyses were also performed to measure robustness of the model outputs.

RESULTS

The findings indicated that the mean costs and utility gained over a 20-year horizon for goserelin, triptorelin, and leuprolide treatments were $ 13 539.13 and 6.365 quality-adjusted life-years (QALY), $ 18 124.75 and 6.658 QALY, and $ 26 006.92 and 6.856 QALY, respectively. Goserelin was considered as a superior treatment option, given the estimated incremental cost-effectiveness ratio. The one-way and probabilistic sensitivity analyses confirmed the robustness of the study outcomes.

CONCLUSIONS

According to the results of the present study, goserelin was the most effective and cost-effective strategy versus 2 other options. It could be recommended to policy makers of the Iran healthcare system to prioritize it in clinical guidelines and reimbursement policies.

Prognostic Impact of Prostate-Specific Antigen at 6 Months After Radiotherapy in Localized Prostate Cancer: An Individual Patient Data Analysis of Randomized Trials

PURPOSE

We sought to evaluate the prognostic impact of prostate-specific antigen (PSA) at 6 months after completion of radiotherapy (RT) in patients treated with RT alone, RT plus short-term (st; 3-6 months), and RT plus long-term (lt; 24-36 months) androgen-deprivation therapy (ADT).

PATIENTS AND METHODS

Individual patient data were obtained from 16 randomized trials evaluating RT ± ADT for localized prostate cancer (PCa) between 1987 and 2011. The lowest PSA recorded within 6 months after RT completion was identified and categorized as < or ≥0.1 ng/mL. The primary outcomes were metastasis-free survival (MFS), PCa-specific mortality (PCSM), and overall survival (OS), from 12 months after random assignment.

RESULTS

Ninety-eight percent (n = 2,339/2,376) of patients allocated to RT alone, 84% (n = 4,756/5,658) allocated to RT + stADT, and 77% (n = 1,258/1,626) allocated to RT + ltADT had PSA ≥0.1 ng/mL within 6 months after completing RT. PSA ≥0.1 ng/mL was associated with lower MFS and OS and higher PCSM among patients allocated to RT ± ADT (RT - MFS: hazard ratio [HR], 2.24 [95% CI, 1.21 to 4.16]; PCSM: subdistribution hazard ratio [sHR], 1.82 [0.51 to 6.49]; OS: HR, 1.72 [0.97 to 3.05]; RT + stADT - MFS: HR, 1.27 [1.12 to 1.44]; PCSM: sHR, 2.10 [1.52 to 2.92]; OS: HR, 1.26 [1.11 to 1.44]; RT + ltADT - MFS: HR, 1.58 [1.27 to 1.96]; PCSM: sHR, 1.97 [1.11 to 3.49]; OS: HR, 1.59 [1.27 to 1.99]). Five-year MFS rates among patients allocated to RT, RT + stADT, and RT + ltADT were 91% versus 79%, 83% versus 76%, and 87% versus 74%, respectively, based on PSA < or ≥0.1 ng/mL.

CONCLUSION

PSA ≥0.1 ng/mL within 6 months after RT completion was prognostic for lt outcomes in patients treated with RT ± ADT for localized PCa. This can be used to counsel patients treated with RT ± ADT and in guiding clinical trial design evaluating novel systemic therapies with RT + ADT as well as (de)intensification strategies.

Prostate-Specific Antigen as an Ultrasensitive Biomarker for Patients with Early Recurrent Prostate Cancer: How Low Shall We Go? A Systematic Review

Serum prostate-specific antigen (PSA) needs to be monitored with ultrasensitive PSA assays (uPSAs) for oncologists to be able to start salvage radiotherapy (SRT) while PSA is <0.5 µg/L for patients with prostate cancer (PCa) relapsing after a radical prostatectomy (RP). Our systematic review (SR) aimed to summarize uPSAs for patients with localized PCa. The SR was registered as InPLASY2023110084. We searched for studies on Google Scholar, PUBMED and reference lists of reviews and studies. We only included studies on uPSAs published in English and excluded studies of women, animals, sarcoidosis and reviews. Of the 115 included studies, 39 reported PSA assay methods and 76 reported clinical findings. Of 67,479 patients, 14,965 developed PSA recurrence (PSAR) and 2663 died. Extremely low PSA nadir and early developments of PSA separated PSAR-prone from non-PSAR-prone patients (cumulative p value 3.7 × 1012). RP patients with the lowest post-surgery PSA nadir and patients who had the lowest PSA at SRT had the fewest deaths. In conclusion, PSA for patients with localized PCa in the pre-PSAR phase of PCa is strongly associated with later PSAR and survival. A rising but still exceedingly low PSA at SRT predicts a good 5-year overall survival.

Early biochemical outcomes following neoadjuvant/adjuvant relugolix with stereotactic body radiation therapy for intermediate to high risk prostate cancer

Introduction

Injectable GnRH receptor agonists have been shown to improve cancer control when combined with radiotherapy. Prostate SBRT offers an abbreviated treatment course with comparable efficacy to conventionally fractionated radiotherapy. Relugolix is a new oral GnRH receptor antagonist which achieves rapid, sustained testosterone suppression. This prospective study sought to evaluate early testosterone suppression and PSA response following relugolix and SBRT for intermediate to high prostate cancer.

Methods

Relugolix was initiated at least 2 months prior to SBRT. Interventions to improve adherence were not utilized. PSA and total testosterone levels were obtained prior to and 1-4 months post SBRT. Profound castration was defined as serum testosterone ≤ 20 ng/dL. Early PSA nadir was defined as the lowest PSA value within 4 months of completion of SBRT. Per prior trials, we examined the percentage of patients who achieved PSA level of ≤ 0.5 ng/mL and ≤ 0.2 ng/mL during the first 4 months post SBRT.

Results

Between July 2021 and January 2023, 52 men were treated at Georgetown with relugolix (4-6 months) and SBRT (36.25-40 Gy in 5 fractions) per an institutional protocol (IRB 12-1775). Median age was 71 years. 26.9% of patients were African American and 28.8% were obese (BMI ≥30 kg/m2). The median pretreatment PSA was 9.1 ng/ml. 67% of patients were ≥ Grade Group 3. 44 patients were intermediate- and 8 were high-risk. Patients initiated relugolix at a median of 3.6 months prior to SBRT with a median duration of 6.2 total months. 92.3% of patients achieved profound castration during relugolix treatment. Poor drug adherence was observed in 2 patients. A third patient chose to discontinue relugolix due to side effects. By post-SBRT month 4, 87.2% and 74.4% of patients achieved PSA levels ≤ 0.5 ng/ml and ≤ 0.2 ng/ml, respectively.

Discussion

Relugolix combined with SBRT allows for high rates of profound castration with low early PSA nadirs. We observed a 96% testosterone suppresion rate without the utilization of scheduled cues/reminders. This finding supports the notion that patients with localized prostate cancer can consistently and successfully follow an oral ADT protocol without daily reminders. Given relugolix's potential benefits over injectable GnRH receptor agonists, its usage may be preferred in specific patient populations (fear of needles, prior cardiovascular events). Future studies should focus on boundaries to adherence in specific underserved populations.

Risk of Short-Term Prostate-Specific Antigen Recurrence and Failure in Patients With Prostate Cancer: A Secondary Analysis of a Randomized Clinical Trial

Importance

A shorter time interval to prostate-specific antigen (PSA) failure is associated with worse clinical outcomes; however, specific factors defining this state remain unknown.

Objective

To evaluate the factors of a short time interval to PSA failure in order to identify patients for treatment escalation randomized clinical trials.

Design, Setting, and Participants

This secondary analysis of a randomized clinical trial was a secondary analysis of the Dana-Farber Cancer Institute 05-043 trial and included 350 patients with nonmetastatic unfavorable risk prostate cancer (PC).

Interventions

Patients were randomized 1:1 to receive androgen deprivation therapy (ADT) and radiation therapy (RT) plus docetaxel vs ADT and RT.

Main Outcomes and Measures

Cumulative incidence rates curves of PSA failure, defined as PSA nadir plus 2 ng/mL or initiation of salvage therapies, and the Fine and Gray competing risks regression was used to assess the prognostic association between these factors and time to PSA failure.

Results

The study included 350 males who primarily had a good performance status (330 [94.3%] with Eastern Cooperative Oncology Group score of 0), median (range) age of 66 (43-86) years, with 167 (46.6%) having Gleason scores of 8 to 10, and 195 (55.2%) presenting with a baseline PSA of more than 10 ng/mL. After a median (IQR) follow-up of 10.2 (8.0-11.4) years, having a PSA level of 10 ng/mL to 20 ng/mL (subdistribution hazard ratio [sHR], 1.98; 95% CI, 1.28-3.07; P = .002) and a Gleason score of 8 to 10 (sHR, 2.55; 95% CI, 1.63-3.99; P < .001) were associated with a shorter time to PSA failure, and older age (sHR, 0.82; 95% CI, 0.72-0.93; P = .002) was associated with reduced risk for PSA failure after adjusting for other baseline clinical factors. The high-risk category, defined by these 3 factors, was associated with a shorter time to PSA failure (sHR, 2.69; 95% CI, 1.84-3.93; P < .001).

Conclusions and Relevance

In this secondary analysis of a randomized clinical trial of males with unfavorable risk PC, young age, PSA of 10 ng/mL or more, and a Gleason score of 8 to 10 estimated a shorter time to PSA failure. A subgroup of males at very high-risk for early PSA failure, as defined by our study, may benefit from treatment escalation with androgen receptor signaling inhibitors or cytotoxic chemotherapy and should be the subject of a prospective randomized clinical trial.

Trial Registration

NCT00116142.

RNA modification writers pattern in relation to tumor microenvironment and prognosis in prostate cancer

Background: RNA modifications are important in the study of epigenetic regulatory mechanisms in immune responses and tumorigenesis. When RNA writers are mutated or disrupted in expression, the genes associated with the pathways they modify are also disrupted and can activate or repress related pathways, affecting tumorigenesis and progression. However, the potential role of RNA writers in prostate cancer is unclear. Methods: Based on data from three datasets, we describe 26 RNA writers that mediate gene expression and genetic mutation in prostate cancer and assess their expression patterns in 948 prostate cancer samples. Using principal component analysis algorithms, the RM Score was developed to quantify the RNA modification patterns of specific tumors. Results: Two different categories were determined by unsupervised clustering methods, and survival analysis showed significant differences in OS prognosis between these two categories. Differentially expressed genes between the different categories were detected and the RNA writers-mediated scoring model RM_Score were constructed based on this. Also, the RM_Score was analyzed in relation to clinical characteristics, immune infiltration level, drug response, and efficacy of chemotherapy and immunotherapy. Those results confirm that multilayer alterations in epitope-modified RNA writers are associated with patient prognosis and with immune cell infiltration characteristics. Finally, we examined differentially expressed mRNA, lncRNA and miRNA between high and low RM_Score groups, based on which a ceRNA regulatory network was constructed. Conclusion: This work is a comprehensive analysis of modified writers in prostate cancer and identified them to have a role in chemotherapy and immunotherapy.

Biochemical Failure Is Not a Surrogate End Point for Overall Survival in Recurrent Prostate Cancer: Analysis of NRG Oncology/RTOG 9601

PURPOSE

Metastasis-free survival (MFS), but not event-free survival, is a validated surrogate end point for overall survival (OS) in men treated for localized prostate cancer. It remains unknown if this holds true in biochemically recurrent disease after radical prostatectomy. Leveraging NRG/RTOG 9601, we aimed to determine the performance of intermediate clinical end points (ICEs) as surrogate end points for OS in recurrent prostate cancer.

MATERIALS AND METHODS

NRG/RTOG 9601 randomly assigned 760 men with recurrence after prostatectomy to salvage radiation therapy with 2 years of placebo versus bicalutamide 150 mg daily. ICEs assessed were biochemical failure (BF) per NRG/RTOG 9601 (prostate-specific antigen nadir + 0.3-0.5 ng/mL or initiation of salvage hormone therapy; [BF1]) and NRG/RTOG 0534 (prostate-specific antigen nadir+2 ng/mL; [BF2]), distant metastasis (DM), and MFS (DM or death). Surrogacy was assessed by the Prentice criteria and a two-stage meta-analytic approach (condition one assessed at the patient level with Kendall's τ and condition two assessed by randomly dividing the entire trial cohort into 10 pseudo trial centers and calculating the average R2 between treatment hazard ratios for ICE and OS).

RESULTS

BF1, BF2, DM, and MFS satisfied the four Prentice criteria. However, with the two-condition meta-analytic approach, there was strong correlation between MFS and OS (τ = 0.86), moderate correlation between DM and OS (τ = 0.66), and weaker correlation between BF1 (τ = 0.25) or BF2 (τ = 0.40) and OS. Similarly, for condition two, the treatment effect of antiandrogen therapy on MFS and OS were correlated (R2 = 0.67), but this was not true for BF1 (R2 = 0.09), BF2 (R2 = 0.12), or DM (R2 = 0.18) and OS.

CONCLUSION

MFS is also a strong surrogate for OS in men receiving salvage radiation therapy for recurrence after prostatectomy. Caution should be used when inferring survival benefit from effects on BF in biochemically recurrent prostate cancer. Lack of comorbidity data did not allow us to assess whether BF in men with no/minimal comorbidity could serve as a surrogate for OS.

Impact of age on treatment response in men with prostate cancer treated with radiotherapy

Objective

To analyse the effect of age at diagnosis on clinical outcomes of localized prostate cancer (PCa) treated with radiation therapy.

Subjects and methods

We identified 12 784 patients with intermediate‐ or high‐risk localized PCa treated with radiation therapy (RT) and neoadjuvant androgen deprivation therapy (ADT) between 2000 and 2015 from nationwide Veterans Affairs data. Patients were grouped into three age categories (≤59, 60–69, and ≥70 years old). Outcomes included immediate PSA response (3‐month post‐RT PSA and 2‐year PSA nadir, grouped into <0.10 ng/ml, 0.10–0.49 ng/ml, and ≥0.50 ng/ml), biochemical recurrence, and PCa‐specific mortality. Multivariable regression models included ordinal logistic regression for short‐term PSA outcomes, Cox regression for biochemical recurrence, and Fine‐Gray competing risks regression for PCa‐specific mortality.

Results

A total of 2136 patients (17%) were ≤59 years old at diagnosis, 6107 (48%) were 60–69 years old, and 4541 (36%) were ≥70 years old. Median follow‐up was 6.3 years. Younger age was associated with greater odds of higher 3‐month PSA group (≤59 vs. ≥70: adjusted odds ratio [aOR] 1.90, 95% CI 1.64–2.20; p < 0.001) and higher 2‐year PSA nadir group (≤59 vs. ≥70: aOR 1.89, 95% CI 1.62–2.19, p < 0.001). Younger age was associated with greater risk of biochemical recurrence (≤59 vs. ≥70: adjusted hazard ratio 1.45, 95% CI 1.26–1.67, p < 0.001) but not PCa‐specific mortality (p = 0.16).

Conclusion

In a large nationwide sample of US veterans treated with ADT and RT for localized PCa, younger age was associated with inferior short‐term PSA response and higher risk of biochemical recurrence.

Evidence-based Urology: Surrogate Endpoints - For

The use of intermediate clinical endpoints and overall survival surrogates can shorten trial duration and related costs. This would potentially allow for an earlier introduction in practice of novel practice changing medications or treatments with a consequent impact on patient prognosis.

Early PSA kinetics for low- and intermediate-risk prostate cancer treated with definitive radiation therapy

PURPOSE

This study uses a patient-specific model to characterize and compare ideal PSA kinetics for low- and intermediate-risk prostate cancer following definitive radiation treatment with conventionally fractionated (CFRT), hypofractionated (HFRT), stereotactic body radiation therapy (SbRT), or brachytherapy, both high-dose-rate (HDR) and low-dose-rate (LDR).

METHODS AND MATERIALS

This retrospective analysis includes low- and intermediate-risk prostate cancer patients treated between 1998 and 2018 at an NCI-designated Comprehensive Cancer Center. Demographics and treatment characteristics were prospectively collected. Patients had at least two PSA measurements within 24-months of treatment and were free from biochemical recurrence. The incidence of, time to, and risk factors for PSA nadir (nPSA) and bounce (bPSA) were analyzed at 24-months following radiotherapy. Ideal PSA kinetics were characterized for each modality and compared.

RESULTS

Of 1,042 patients, 45% had low-risk cancer, 37% favorable intermediate-risk, and 19% unfavorable intermediate-risk. nPSA were higher for ablative modalities, both as absolute nPSA and relative to initial PSA (iPSA). Median time to nPSA ranged from 14.8 to 17.1 months. Over 50% treated with non-ablative therapy (CFRT, HFRT, and LDR) reached an nPSA threshold of ≤0.5 ng/mL compared to 23% of SbRT and 33% of HDR cohorts. The incidence of bPSA was 13.3% and not affected by treatment modality, Gleason Score, or prostate volume. PSA decay rate was faster for ablative therapies in the 6-24 month period.

CONCLUSIONS

Analysis of PSA within 24-months following radiation therapy revealed ablative therapies are associated with a latent PSA response and higher nPSA. Multivariable logistics modeling revealed younger age, iPSA above the median, presence of bPSA, and ablative therapy as predictors for not achieving nPSA ≤0.5 ng/mL. PSA decay rate appears to be faster in ablative therapies following a latent period. Understanding the different PSA kinetic profiles is necessary to assess treatment response and survey for disease recurrence.

Association of Increased Prostate-Specific Antigen Levels After Treatment and Mortality in Men With Locally Advanced vs Localized Prostate Cancer: A Secondary Analysis of 2 Randomized Clinical Trials

IMPORTANCE

Increased prostate-specific antigen (PSA) levels after treatment (PSA failure) may have different associations with outcomes for men with locally advanced vs localized prostate cancer.

OBJECTIVE

To evaluate whether the association between PSA failure and death may be different in locally advanced vs localized prostate cancer.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter cohort study included patients from 2 randomized clinical trials. The Dana-Farber Cancer Institute (DFCI) 95-096 trial randomized 206 men with localized prostate cancer from December 1, 1995, to April 15, 2001, whereas the European Organisation for Research and Treatment of Cancer (EORTC) 22961 trial randomized 970 men with locally advanced prostate cancer from October 30, 1997, to May 1, 2002. Data were analyzed from January 1, 2020, to October 31, 2020.

INTERVENTIONS

The DFCI 95-096 trial randomized men to 0 vs 6 months of androgen deprivation therapy (ADT) with external beam radiotherapy; the EORTC 22961 trial randomized men to 6 vs 36 months of ADT with external beam radiotherapy.

MAIN OUTCOMES AND MEASURES

For each trial, the PSA doubling time (time to doubling of PSA levels) associated with PSA failure was evaluated. The risk of all-cause mortality associated with PSA failure (nadir plus 2 definition) was evaluated after adjustment of baseline covariates and treatment.

RESULTS

This analysis included a total of 1173 men (206 from DFCI 95-096 and 967 with available tumor stage from EORTC 22961; median age, 70.0 [interquartile range (IQR), 65.0-74.0 years). For DFCI 95-096, 161 men died (30 [18.6%] due to prostate cancer) at a median follow-up of 18.2 (IQR, 17.3-18.8) years. Among the 108 men with PSA failure, the median PSA doubling time was 13.0 (IQR, 7.4-31.1) months. For EORTC 22961, 230 men died (75 [32.6%] due to prostate cancer) at a median follow-up of 6.4 (IQR, 6.3-6.6) years. Among 290 men who experienced PSA failure, the median PSA doubling time was 5.0 (IQR, 2.9-8.9) months. Compared with DFCI 95-096, PSA failure was associated with a higher risk of all-cause mortality in EORTC 22961 (adjusted hazard ratios, 3.98 [95% CI, 2.92-5.44]; P < .001 vs 1.51 [95% CI, 1.03-2.23]; P = .04).

CONCLUSIONS AND RELEVANCE

The association of PSA failure with outcomes may differ between locally advanced and localized prostate cancer. This finding supports the study of treatment intensification with the use of novel antiandrogen agents in addition to ADT at the time of PSA failure after treatment for locally advanced disease.

TRIAL REGISTRATION

ClinicalTrials.gov Identifiers: NCT00116220 and NCT00003026.

Surrogate Endpoints in Localized Prostate Cancer

Randomized clinical trials assessing novel therapies in men with localized prostate cancer frequently require large patient numbers and more than a decade of follow-up to demonstrate improvements in overall survival. As the landscape of treatment options for prostate cancer is rapidly changing, clinical trials requiring long follow-up threaten to impede treatment improvements and run the risk of results being obsolete by the time that they are reported in publication. To address these issues, there has been tremendous interest in identifying an intermediate clinical endpoint that can be assessed earlier in the disease course to serve as a robust surrogate for overall survival in men with localized prostate cancer. Herein we review the relevant data for surrogate endpoints in localized prostate cancer, highlighting the work performed by the Intermediate Clinical Endpoints in Cancer of the Prostate Working Group identifying metastasis-free survival as a valid surrogate for men treated for localized prostate cancer.

Prostate-specific antigen nadir and testosterone level at prostate-specific antigen failure following radiation and androgen suppression therapy for unfavorable-risk prostate cancer and the risk of all-cause and prostate cancer-specific mortality

BACKGROUND

Although both PSA nadir (PSAn) and testosterone levels at PSA failure are known prognostic factors in men undergoing radiation therapy (RT) and androgen deprivation therapy (ADT) for unfavorable-risk prostate cancer (PC), it is unclear whether their prognostic significance is independent or overlapping.

METHODS

Seventy-five men treated with RT with or without 6 months of ADT for unfavorable-risk nonmetastatic PC enrolled in 2 prospective clinical trials between 1986 and 2001 formed the study cohort. Competing risks and Cox multivariable regression were used to assess whether low versus normal serum testosterone at the time of PSA failure and higher PSAn after initial therapy were independently associated with the risk of PC-specific (PCSM) and all-cause mortality (ACM) adjusting for PC prognostic factors.

RESULTS

After a median follow-up of 15.34 years (interquartile range, 6.66-16.88 years), there were 53 deaths (73.3%): 30 (56.6%) were from PC. Low testosterone at PSA failure was significantly associated with an increased risk of PCSM (adjusted HR [AHR], 7.77; 95% CI, 1.14-52.99; P = .04) and ACM (AHR, 3.01; 95% CI, 1.01-8.96; P = .05), as was higher PSAn (PCSM AHR, 1.03; 95% CI, 1.01-1.05; P < .01; ACM AHR, 1.04; 95% CI, 1.02-1.07; P < .01), although the prognostic significance of PSAn was only noted in men with a normal testosterone at PSA failure.

CONCLUSIONS

Low testosterone level at PSA failure in high-risk patients with PC treated with RT is associated with increased PCSM and ACM risk. In men with normal testosterone levels at the time of PSA failure, an elevated PSAn was associated with worse PCSM and ACM risk.

LAY SUMMARY

This study investigates whether the prostate-specific antigen (PSA) nadir and normal versus low testosterone at the time of PSA failure provide mutually exclusive or overlapping prognostic information following treatment with radiation and androgen deprivation therapy for unfavorable-risk patients with prostate cancer using data from 2 prospective clinical trials. It was found that both provided prognostic information; however, higher PSA nadir was only found to be of prognostic significance in men with normal testosterone levels at PSA failure.

Combination of Radiation Therapy and Short-Term Androgen Blockade With Abiraterone Acetate Plus Prednisone for Men With High- and Intermediate-Risk Localized Prostate Cancer

PURPOSE

Long-term androgen-deprivation therapy (ADT) is the standard of care in combination with radiation therapy (RT) in high-risk prostate cancer (PC), despite substantial toxicity from the resulting hypogonadism. We hypothesized that a combination of more potent but shorter-term androgen inhibition in men with intermediate- or high-risk localized PC would synergize with definitive RT to provide short-term testosterone recovery and improve disease control.

METHODS AND MATERIALS

This prospective phase 2 single-arm trial enrolled men with low-volume unfavorable intermediate or high-risk localized PC. Treatment included 6 months of ADT concurrent with abiraterone acetate plus prednisone (AAP) once daily and RT to prostate and seminal vesicles. The primary endpoint was the proportion of men with an undetectable prostate-specific antigen (PSA) at 12-months; secondary objectives included biochemical progression-free survival (PFS), testosterone recovery, toxicity, and sexual and hormonal quality of life.

RESULTS

We enrolled 37 men between January 2014 and August 2016, 45% of whom were high risk. All patients had T1-2 disease and PSA < 20 ng/mL. Median follow-up is 37 months (95% confidence interval [CI], 35.7-39.1). Treatment noted 32% grade 3 toxicities related to AAP, predominantly hypertension, with no toxicities ≥G4. The rate of undetectable PSA at 12 months was 55% (95% CI, 36%-72%). With 46 months of median follow-up, 2 of 37 patients developed PSA progression (36-month PFS = 96%; 95% CI, 76%-99%), and 81% of patients recovered testosterone with a median time to recovery of 9.2 months. Hormonal or sexual function declined at 6 months with subsequent improvement by 24 months.

CONCLUSIONS

The combination of RT and 6 months of ADT and AAP demonstrated acceptable toxicity and a high rate of testosterone recovery with restoration of quality of life and excellent disease control in men with low-volume, intermediate- or high-risk localized prostate cancer. Prospective comparative studies are justified.

Comprehensive analysis of m6A regulators prognostic value in prostate cancer

Background: N6-methyladenosine (m6A) is the most prevalent RNA modification. While the role of m6A in prostate cancer remains unknown. We aim to measure the effects of m6A methylation regulatory genes during the development and progression of prostate cancer.

Methods: We collected transcriptome information and gene-level alteration data from The Cancer Genome Atlas datasets. The log-rank test and Cox regression model were used to examine the prognosis value of m6A methylation regulatory genes of prostate cancer.

Results: We discovered that most of m6A methylation regulators were highly expressed in aggressive prostate cancer. Univariable and multivariable Cox regression results showed that the expression of Insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3), Heterogeneous nuclear ribonucleoproteins A2/B1 (HNRNPA2B1) and N6-adenosine-methyltransferase non-catalytic subunit (METTL14) and copy number variant of AlkB Homolog 5 (ALKBH5) were considerably associated with a recurrence-free survival of prostate cancer. Furthermore, a high level of m6A methylation in mRNA promotes the progression of prostate cancer via regulating subcellular protein localization.

Conclusion: Patients with a high level of mRNA methylation resulted from overexpression of reader proteins and methyltransferase complexes had poor survival benefits through influencing protein subcellular location in prostate cancer.

Event-Free Survival, a Prostate-Specific Antigen-Based Composite End Point, Is Not a Surrogate for Overall Survival in Men With Localized Prostate Cancer Treated With Radiation

PURPOSE

Recently, we have shown that metastasis-free survival is a strong surrogate for overall survival (OS) in men with intermediate- and high-risk localized prostate cancer and can accelerate the evaluation of new (neo)adjuvant therapies. Event-free survival (EFS), an earlier prostate-specific antigen (PSA)-based composite end point, may further expedite trial completion.

METHODS

EFS was defined as the time from random assignment to the date of first evidence of disease recurrence, including biochemical failure, local or regional recurrence, distant metastasis, or death from any cause, or was censored at the date of last PSA assessment. Individual patient data from trials within the Intermediate Clinical Endpoints in Cancer of the Prostate-ICECaP-database with evaluable PSA and disease follow-up data were analyzed. We evaluated the surrogacy of EFS for OS using a 2-stage meta-analytic validation model by determining the correlation of EFS with OS (patient level) and the correlation of treatment effects (hazard ratios [HRs]) on both EFS and OS (trial level). A clinically relevant surrogacy was defined a priori as an R² ≥ 0.7.

RESULTS

Data for 10,350 patients were analyzed from 15 radiation therapy-based trials enrolled from 1987 to 2011 with a median follow-up of 10 years. At the patient level, the correlation of EFS with OS was 0.43 (95% CI, 0.42 to 0.44) as measured by Kendall's tau from a copula model. At the trial level, the R² was 0.35 (95% CI, 0.01 to 0.60) from the weighted linear regression of log(HR)-OS on log(HR)-EFS.

CONCLUSION

EFS is a weak surrogate for OS and is not suitable for use as an intermediate clinical end point to substitute for OS to accelerate phase III (neo)adjuvant trials of prostate cancer therapies for primary radiation therapy-based trials.

Defining the Most Informative Intermediate Clinical Endpoints for Patients Treated with Salvage Radiotherapy for Prostate-specific Antigen Rise After Radical Prostatectomy

Intermediate clinical endpoints (ICEs) might aid in trial design and potentially expedite study results. However, little is known about the most informative ICE for patients receiving salvage radiation therapy (sRT) after radical prostatectomy. To investigate the most informative ICE for patients receiving sRT, we used a multi-institutional database encompassing patients treated at eight tertiary centers. Overall, 1301 men with node-negative disease who had not received any form of androgen deprivation therapy were identified. Associations of biochemical (BCR) and clinical recurrence (CR) within 1, 3, 5, and 7yr after surgery with the risk of overall mortality were evaluated using multivariable Cox regression analyses fitted at the landmark points of 1, 3, 5, and 7yr after sRT. The discriminative ability of each model for predicting overall survival (OS) was assessed using Harrell's c index. Median follow-up for survivors was 5.6yr (interquartile range 2.0-8.8). On multivariable analysis, progression to CR within 3yr from sRT (hazard ratio 4.19, 95% confidence interval 1.44-11.2; p= 0.008) was the most informative ICE for predicting OS (c index 0.78) compared to CR within 1, 5, and 7yr (c index 0.72, 0.75, and 0.71). In conclusion, progression to CR within 3yr after sRT, irrespective of the time of surgery, was the most informative ICE for prediction of OS. Our study is hypothesis-generating. If these results are confirmed in future prospective studies and surrogacy is met, this information could be applied for study design and could potentially expedite earlier release of results from ongoing randomized controlled trials. PATIENT SUMMARY: Clinical recurrence of prostate cancer within 3yr after salvage radiation therapy, irrespective of the time of radical prostatectomy, represents the most informative intermediate clinical endpoint for the prediction of overall survival. This information could be applied in the design of future studies and could potentially expedite earlier release of results from ongoing randomized controlled trials.

Neoadjuvant rectal score as individual-level surrogate for disease-free survival in rectal cancer in the CAO/ARO/AIO-04 randomized phase III trial

Background

Surrogate end points in rectal cancer after preoperative chemoradiation are lacking as their statistical validation poses major challenges, including confirmation based on large phase III trials. We examined the prognostic role and individual-level surrogacy of neoadjuvant rectal (NAR) score that incorporates weighted cT, ypT and ypN categories for disease-free survival (DFS) in 1191 patients with rectal carcinoma treated within the CAO/ARO/AIO-04 phase III trial.

Patients and methods

Cox regression models adjusted for treatment arm, resection status, and NAR score were used in multivariable analysis. The four Prentice criteria (PC1-4) were used to assess individual-level surrogacy of NAR for DFS.

Results

After a median follow-up of 50 months, the addition of oxaliplatin to fluorouracil-based chemoradiotherapy (CRT) significantly improved 3-year DFS [75.9% (95% confidence interval [CI] 72.30% to 79.50%) versus 71.3% (95% CI 67.60% to 74.90%); P = 0.034; PC 1) and resulted in a shift toward lower NAR groups (P = 0.034, PC 2) compared with fluorouracil-only CRT. The 3-year DFS was 91.7% (95% CI 88.2% to 95.2%), 81.8% (95% CI 78.4% to 85.1%), and 58.1% (95% CI 52.4% to 63.9%) for low, intermediate, and high NAR score, respectively (P < 0.001; PC 3). NAR score remained an independent prognostic factor for DFS [low versus high NAR: hazard ratio (HR) 4.670; 95% CI 3.106-7.020; P < 0.001; low versus intermediate NAR: HR 1.971; 95% CI 1.303-2.98; P = 0.001] in multivariable analysis. Notwithstanding the inherent methodological difficulty in interpretation of PC 4 to establish surrogacy, the treatment effect on DFS was captured by NAR, supporting satisfaction of individual-level PC 4.

Conclusion

Our study validates the prognostic role and individual-level surrogacy of NAR score for DFS within a large randomized phase III trial. NAR score could help oncologists to speed up response-adapted therapeutic decision, and further large phase III trial data sets should aim to confirm trial-level surrogacy.

Prospective study to define the clinical utility and benefit of Decipher testing in men following prostatectomy

Background

Genomic classifiers (GC) have been shown to improve risk stratification post prostatectomy. However, their clinical benefit has not been prospectively demonstrated. We sought to determine the impact of GC testing on postoperative management in men with prostate cancer post prostatectomy.

Methods

Two prospective registries of prostate cancer patients treated between 2014 and 2019 were included. All men underwent Decipher tumor testing for adverse features post prostatectomy (Decipher Biosciences, San Diego, CA). The clinical utility cohort, which measured the change in treatment decision-making, captured pre- and postgenomic treatment recommendations from urologists across diverse practice settings (n = 3455). The clinical benefit cohort, which examined the difference in outcome, was from a single academic institution whose tumor board predefined “best practices” based on GC results (n = 135).

Results

In the clinical utility cohort, providers’ recommendations pregenomic testing were primarily observation (69%). GC testing changed recommendations for 39% of patients, translating to a number needed to test of 3 to change one treatment decision. In the clinical benefit cohort, 61% of patients had genomic high-risk tumors; those who received the recommended adjuvant radiation therapy (ART) had 2-year PSA recurrence of 3 vs. 25% for those who did not (HR 0.1 [95% CI 0.0–0.6], p = 0.013). For the genomic low/intermediate-risk patients, 93% followed recommendations for observation, with similar 2-year PSA recurrence rates compared with those who received ART (p = 0.93).

Conclusions

The use of GC substantially altered treatment decision-making, with a number needed to test of only 3. Implementing best practices to routinely recommend ART for genomic-high patients led to larger than expected improvements in early biochemical endpoints, without jeopardizing outcomes for genomic-low/intermediate-risk patients.

Early Versus Delayed Initiation of Salvage Androgen Deprivation Therapy and Risk of Prostate Cancer-Specific Mortality

Background: This study sought to ascertain whether there is an association between prostate cancer (PC)-specific mortality (PCSM) and timing of salvage androgen deprivation therapy (ADT) among men with short versus long prostate-specific antigen doubling times (PSA-DTs). Methods: The study cohort was selected from 206 men with localized unfavorable-risk PC randomized to radiation therapy (RT) or RT plus 6 months of ADT between 1995 and 2001. A total of 54 men who received salvage ADT for PSA failure after a median follow-up of 18.72 years following randomization defined the study cohort. The Fine-Gray competing risks regression model was used to analyze whether the timing of salvage ADT was associated with an increased risk of PCSM after adjusting for age, comorbidity, known PC prognostic factors, and previously identified interactions. Results: After a median follow-up of 5.68 years (interquartile range, 3.05-9.56) following salvage ADT, 49 of the 54 men (91%) died, of which 27 from PC (54% of deaths). Increasing PSA-DT as a continuous covariate (per month increase) was associated with a decreasing risk of PCSM (adjusted hazard ratio [HR], 0.33; 95% CI, 0.13-0.82; P=.02). Among men with a long PSA-DT (≥6 months), initiating salvage ADT later (PSA level >12 ng/mL, upper quartile) versus earlier was associated with an increased risk of PCSM (adjusted HR, 8.84; 95% CI, 1.99-39.27; P=.004), whereas for those with a short PSA-DT (<6 months; adjusted HR, 1.16; 95% CI, 0.38-3.54; P=.79) this was not true. Conclusions: Early initiation of salvage ADT for post-RT PSA failure in men with a PSA-DT of ≥6 months may reduce the risk of PCSM.

Comparison of outcome endpoints in intermediate- and high-risk prostate cancer after combined-modality radiotherapy

PURPOSE

To compare a standard radio-oncological and a surgical biochemical failure definition after combined-modality radiation therapy (CRT) in men with intermediate- and high-risk prostate cancer.

METHODS

425 men were treated with external beam radiotherapy (59.4 Gy, 33 fractions) and ¹²⁵J seed-brachytherapy (S-BT, 100 Gy). Biochemical recurrence (BR) was defined either as radio-oncologic (rBR), using a +2 ng/mL prostate-specific antigen (PSA) increase above a nadir value, or as surgical (sBR), using a 2-year posttreatment PSA of ≥0.2 ng/mL. Biochemical recurrence-free, metastasis-free, cancer-specific, and overall survival were calculated at 5 and 10 years using the Kaplan-Meier method. Standard validation tests were used to compare both thresholds.

RESULTS

After a median of 7 years, overall recurrence rates were 10.4% and 31.5% for rBR and sBR definitions, respectively. Both failure definitions proved sensitive for the prediction of metastases and cancer-specific death, whereas the rBR definition was significantly more specific. The accuracies of a correct prediction of metastases and death of prostate cancer were 73.1% vs. 96.2% and 72.2% vs. 92.9% for sBR vs. rBR, respectively. The inferior validity results of the sBR definition were attributable to a PSA-bounce phenomenon occurring in 56% of patients with sBR. Still, using the less suitable sBR definition, the results of CRT compared favorably to BRFS rates of surgical interventions.

CONCLUSION

After CRT, the radio-oncological (aka Phoenix) failure definition is more reliable than a fixed surgical endpoint. Exclusively in high-risk patients, sBR offers a direct comparison across surgical and nonsurgical treatment options at 5 and 10 years.

Multi-Institutional Analysis of Prostate-Specific Antigen Kinetics After Stereotactic Body Radiation Therapy

PURPOSE

Understanding prostate-specific antigen (PSA) kinetics after radiation therapy plays a large role in the management of patients with prostate cancer (PCa). This is particularly true in establishing expectations regarding PSA nadir (nPSA) and PSA bounces, which can be disconcerting. As increasingly more patients are being treated with stereotactic body radiation therapy (SBRT) for low- and intermediate-risk PCa, it is imperative to understand the PSA response to SBRT.

METHODS AND MATERIALS

PSA data from 5 institutions were retrospectively analyzed for patients with localized PCa treated definitively with SBRT alone from 2004 to 2016. Patients received 35 to 40 Gy in 5 fractions, per institutional standards. Patients who had less than 12 months of PSA data or received androgen deprivation therapy were excluded from this study. Linear and logistic multivariable analysis were performed to identify predictors of nPSA, bounce, and biochemical recurrence, and joint latent class models were developed to identify significant predictors of time to biochemical failure.

RESULTS

A total of 1062 patients were included in this study. Median follow-up was 66 months (interquartile range [IQR], 36.4-89.9 months). Biochemical failure per the Phoenix criteria occurred in 4% of patients. Median nPSA was 0.2 ng/mL, median time to nPSA was 40 months, 84% of patients had an nPSA ≤0.5 ng/mL, and 54% of patients had an nPSA ≤0.2 ng/mL. On multivariable analysis, nPSA was a significant predictor of biochemical failure. Benign PSA bounce was noted in 26% of patients. The median magnitude of PSA bounce was 0.52 ng/mL (IQR, 0.3-1.0 ng/mL). Median time to PSA bounce was 18.1 months (IQR, 12.0-31.1 months). On multivariable analysis, age and radiation dose were significantly associated with a lower incidence of bounce. Joint latent class models modeling found that nPSA and radiation dose were significantly associated with longer time to biochemical failure.

CONCLUSIONS

In this multi-institutional cohort of patients with long-term follow-up, we found that SBRT led to low nPSAs. In turn, lower nPSAs are associated with reduced incidence of, and longer time to, biochemical failure. Benign PSA bounces occurred in a quarter of patients, as late as several years after treatment. Further studies are needed to directly compare the PSA response of patients who receive SBRT versus other treatment modalities.

Prognostic Value of Biochemical Recurrence Following Treatment with Curative Intent for Prostate Cancer: A Systematic Review

CONTEXT

In men with prostate cancer (PCa) treated with curative intent, controversy exists regarding the impact of biochemical recurrence (BCR) on oncological outcomes.

OBJECTIVE

To perform a systematic review of the existing literature on BCR after treatment with curative intent for nonmetastatic PCa. Objective 1 is to investigate whether oncological outcomes differ between patients with or without BCR. Objective 2 is to study which clinical factors and tumor features in patients with BCR have an independent prognostic impact on oncological outcomes.

EVIDENCE ACQUISITION

Medline, Medline In-Process, Embase, and the Cochrane Central Register of Controlled Trials were searched. For objective 1, prospective and retrospective studies comparing survival outcomes of patients with or without BCR following radical prostatectomy (RP) or radical radiotherapy (RT) were included. For objective 2, all studies with at least 100 participants and reporting on prognostic patient and tumor characteristics in patients with BCR were included. Risk-of-bias and confounding assessments were performed according to the Quality in Prognosis Studies tool. Both a narrative synthesis and a meta-analysis were undertaken.

EVIDENCE SYNTHESIS

Overall, 77 studies were included for analysis, of which 14 addressed objective 1, recruiting 20 406 patients. Objective 2 was addressed by 71 studies with 29 057, 11 301, and 4272 patients undergoing RP, RT, and a mixed population (mix of patients undergoing RP or RT as primary treatment), respectively. There was a low risk of bias for study participation, confounders, and statistical analysis. For most studies, attrition bias, and prognostic and outcome measurements were not clearly reported. BCR was associated with worse survival rates, mainly in patients with short prostate-specific antigen doubling time (PSA-DT) and a high final Gleason score after RP, or a short interval to biochemical failure (IBF) after RT and a high biopsy Gleason score.

CONCLUSIONS

BCR has an impact on survival, but this effect appears to be limited to a subgroup of patients with specific clinical risk factors. Short PSA-DT and a high final Gleason score after RP, and a short IBF after RT and a high biopsy Gleason score are the main factors that have a negative impact on survival. These factors may form the basis of new BCR risk stratification (European Association of Urology BCR Risk Groups), which needs to be validated formally.

PATIENT SUMMARY

This review looks at the risk of death in men who shows rising prostate-specific antigen (PSA) in the blood test performed after curative surgery or radiotherapy. For many men, rising PSA does not mean that they are at a high risk of death from prostate cancer in the longer term. Men with PSA that rises shortly after they were treated with radiotherapy or rapidly rising PSA after surgery and a high tumor grade for both treatment modalities are at the highest risk of death. These factors may form the basis of new risk stratification (European Association of Urology biochemical recurrence Risk Groups), which needs to be validated formally.

An investigator's introduction to statistical considerations in clinical trials

The purpose of this paper is to provide an introduction for investigators to many of the statistical considerations for clinical trials that will aid in their collaborations with statisticians for clinical trial research endeavors and when reading the clinical trials literature. The purpose of this paper is not to turn a physician into a statistician, that takes formal training and education, as well as day in and day out immersion in the statistical design and analysis of clinical trials, hence statistician as a profession. Successful clinical trials, not to be confused with only positive clinical trials, are ones that are well designed to answer the trial question, well conducted, and appropriately reported and published, regardless of the results. Physicians and statisticians each play integral roles in the realm of clinical trials and successful clinical trials are the result of collaborations between physicians and statisticians from the beginning of an idea through the manuscript publication.

Time to Prostate-specific Antigen Nadir and the Risk of Death From Prostate Cancer Following Radiation and Androgen Deprivation Therapy

OBJECTIVE

To assess whether the time to prostate-specific antigen (PSA) nadir (TTN) has differential prognostic value in men who reach an undetectable vs detectable PSA nadir.

METHODS

Two hundred and four men from a prospective randomized controlled trial involving radiation therapy with or without 6 months of androgen deprivation therapy in unfavorable risk Prostate cancer (CaP) at academic or community based centers in Massachusetts, enrolled between 1995 and 2001. Adjusted hazard ratios (AHR) of the risk of CaP-specific mortality calculated using Fine and Gray competing risk regression.

RESULTS

After a median follow-up of 18.17years, 160 men died; 30 (18.75%) of CaP. Among men with a PSA nadir ≥ 0.2ng/ml, a TTN < median (12 months) was significantly associated with an increased CaP-specific mortality-risk vs the median or more (AHR 5.07, 95% CI 2.10-12.23, P <.001); whereas this association was not observed among men with a PSA nadir of < 0.2ng/mL, (AHR 9.9, 95% CI 0.23-433.8, P = .23).

CONCLUSION

Men with both a short TTN and detectable PSA nadir could be considered for entry on randomized controlled trials at a novel entry point prior to PSA failure at the time of PSA nadir to completeplanned conventional androgen deprivation therapy vs that plus agent(s) shown to improve outcomes in men with or at high risk of having castrate-resistant CaP.

Time Interval to Biochemical Failure as a Surrogate End Point in Locally Advanced Prostate Cancer: Analysis of Randomized Trial NRG/RTOG 9202

BACKGROUND

In prostate cancer, end points that reliably portend prognosis and treatment benefit (surrogate end points) can accelerate therapy development. Although surrogate end point candidates have been evaluated in the context of radiotherapy and short-term androgen deprivation (AD), potential surrogates under long-term (24 month) AD, a proven therapy in high-risk localized disease, have not been investigated.

MATERIALS AND METHODS

In the NRG/RTOG 9202 randomized trial (N = 1,520) of short-term AD (4 months) versus long-term AD (LTAD; 28 months), the time interval free of biochemical failure (IBF) was evaluated in relation to clinical end points of prostate cancer-specific survival (PCSS) and overall survival (OS). Survival modeling and landmark analysis methods were applied to evaluate LTAD benefit on IBF and clinical end points, association between IBF and clinical end points, and the mediating effect of IBF on LTAD clinical end point benefits.

RESULTS

LTAD was superior to short-term AD for both biochemical failure (BF) and the clinical end points. Men remaining free of BF for 3 years had relative risk reductions of 39% for OS and 73% for PCSS. Accounting for 3-year IBF status reduced the LTAD OS benefit from 12% (hazard ratio [HR], 0.88; 95% CI, 0.79 to 0.98) to 6% (HR, 0.94; 95% CI, 0.83 to 1.07). For PCSS, the LTAD benefit was reduced from 30% (HR, 0.70; 95% CI, 0.52 to 0.82) to 6% (HR, 0.94; 95% CI, 0.72 to 1.22). Among men with BF, by 3 years, 50% of subsequent deaths were attributed to prostate cancer, compared with 19% among men free of BF through 3 years.

CONCLUSION

The IBF satisfied surrogacy criteria and identified the benefit of LTAD on disease-specific survival and OS. The IBF may serve as a valid end point in clinical trials and may also aid in risk monitoring after initial treatment.

Effect of early salvage radiotherapy at PSA < 0.5 ng/ml and impact of post-SRT PSA nadir in post-prostatectomy recurrent prostate cancer

BACKGROUND

For patients with recurrent prostate cancer after radical prostatectomy (RP), salvage radiotherapy (SRT) offers a second chance of cure. European guidelines (EAU) recommend SRT at a PSA < 0.5 ng/ml. We analyze the efficacy of SRT given according to this recommendation and investigate the predictive power of the post-SRT PSA nadir.

METHODS

Between 1998 and 2013, 301 patients of two university hospitals received SRT at a PSA < 0.5 ng/ml (median 0.192 ng/ml, IQR 0.110-0.300). Patients, who previously received androgen deprivation therapy, were excluded. All patients had 3D-conformal RT or intensity-modulated radiotherapy (IMRT, n = 59) (median 66.6 Gy). The median follow-up was 5.9 years. Progression and overall survival were the endpoints.

RESULTS

After SRT, 252 patients re-achieved an undetectable PSA. In univariate analysis, pre-RP PSA ≥ 10 ng/ml, pT3-4, Gleason score (GS) 7-10 or 8-10, negative surgical margins, post-RP PSA ≥ 0.1 ng/ml, pre-SRT PSA ≥ 0.2 ng/ml and post-SRT PSA nadir ≥ 0.1 ng/ml correlated unfavorably with post-SRT progression. In a multivariable Cox model, pT3-4, GS 7-10, negative margins and a pre-SRT PSA ≥ 0.2 ng/ml were significant risk factors. If the post-SRT PSA was added to the analysis, it dominated the outcome (HR = 9.00). Of the patients with a pre-SRT PSA < 0.2 ng/ml, only 9% failed re-achieving an undetectable PSA. Overall survival in these patients was 98% after 5.9 years compared to 91% in patients with higher pre-SRT PSA (Logrank p = 0.004).

CONCLUSIONS

SRT at a PSA < 0.2 ng/ml correlates significantly with achieving a post-SRT undetectable PSA (<0.1 ng/ml) and subsequently with improved freedom from progression. Given these overall favorable outcomes, whether additional androgen deprivation therapy is required for these men requires further study.

Surrogate endpoints in early prostate cancer research

Clinical research into clinically-localized prostate cancer (PC) is a highly challenging environment. The protracted durations and large numbers required to achieve survival endpoints have placed much pressure on validating early surrogate endpoints. Further confounding is the predominance of deaths from causes other than PC. The analysis of multiple randomized clinical trials in early PC has shown MFS to be a robust surrogate for OS, using a contemporary analytic framework that identify patient-level and trial-level associations. This could potentially save around one year of trial follow-up in some therapies. Identification of a similarly robust surrogate at a substantially earlier timepoint remains a major challenge. Multiple biochemical indices based on PSA have been proposed in the literature, but all remain to be validated at the trial-level. Operationally, many of these indices have inherent biases such as immortal-time bias (ITB) and interval censoring that potentially weakens associations and the individual- or trial-level. The complexity of a failure definition can also impact the reliability of the derived outcomes. Confounding issues such as the impact of comorbidities leading to non-cancer deaths have been largely dealt with by their exclusion using cancer-specific endpoints and advanced statistical methods, while issues such as PSA "bounce" and recovery from androgen deprivation therapy remain important to account for in cohorts treated with radiotherapy. Several potential surrogate endpoints based on serum prostate-specific antigen (PSA) levels show promising associations with PC-specific and overall survival (OS) in individual studies. Further large collaborative projects will continue to refine potential indices with these issues in mind, and explore the objective of an early surrogate of OS.

Three-month posttreatment prostate-specific antigen level as a biomarker of treatment response in patients with intermediate-risk or high-risk prostate cancer treated with androgen deprivation therapy and radiotherapy

BACKGROUND

Prostate-specific antigen (PSA) measurement after definitive radiotherapy (RT) and androgen deprivation therapy for localized prostate cancer has been proposed as an early prognostic biomarker. In the current study, the authors investigated the association between 3-month post-RT PSA level and biochemical progression-free survival (bPFS), prostate cancer-specific survival (PCSS), and overall survival (OS).

METHODS

A total of 5783 patients with intermediate-risk or high-risk localized prostate cancer who were diagnosed between 2000 and 2015 and treated with RT and androgen deprivation therapy were identified from Veterans Affairs data. Patients were divided into groups based on 3-month post-RT PSA values: <0.10 ng/mL, 0.10 to 0.49 ng/mL, and ≥0.50 ng/mL. The effect of the 3-month PSA group on bPFS, PCSS, and OS was evaluated in multivariable Cox models adjusting for potential confounders.

RESULTS

There were 2651 patients with intermediate-risk and 3132 with high-risk disease; approximately 11% had a 3-month PSA level of ≥0.50 ng/mL. A higher 3-month PSA level was found to be strongly associated with each outcome; compared with patients in the group with a 3-month PSA value <0.10 ng/mL, the authors noted greater hazards for the patients with a 3-month PSA value ≥0.50 ng/mL (hazard ratio for bPFS: 5.23; PCSS: 3.97; and OS: 1.50 [P<.001 for all]) and the patients with a 3-month PSA value of 0.10 to 0.49 ng/mL (hazard ratio for bPFS: 2.41 [P<.001]; PCSS: 2.29 [P<.001]; and OS: 1.21 [P = .003]). When analyzed separately, the 3-month PSA level was found to be predictive of OS in the high-risk group (P<.001) but not the intermediate-risk group (P = .21).

CONCLUSIONS

The 3-month post-RT PSA level appears to be a strong prognostic biomarker for bPFS, PCSS, and OS in patients with intermediate-risk and high-risk prostate cancer, particularly those with high-risk disease. The 3-month PSA measurement may augment clinical decision making and holds promise as a potential surrogate endpoint in clinical trials. Cancer 2018;124:2939-47. © 2018 American Cancer Society.

Five criteria for using a surrogate endpoint to predict treatment effect based on data from multiple previous trials

A surrogate endpoint in a randomized clinical trial is an endpoint that occurs after randomization and before the true, clinically meaningful, endpoint that yields conclusions about the effect of treatment on true endpoint. A surrogate endpoint can accelerate the evaluation of new treatments but at the risk of misleading conclusions. Therefore, criteria are needed for deciding whether to use a surrogate endpoint in a new trial. For the meta-analytic setting of multiple previous trials, each with the same pair of surrogate and true endpoints, this article formulates 5 criteria for using a surrogate endpoint in a new trial to predict the effect of treatment on the true endpoint in the new trial. The first 2 criteria, which are easily computed from a zero-intercept linear random effects model, involve statistical considerations: an acceptable sample size multiplier and an acceptable prediction separation score. The remaining 3 criteria involve clinical and biological considerations: similarity of biological mechanisms of treatments between the new trial and previous trials, similarity of secondary treatments following the surrogate endpoint between the new trial and previous trials, and a negligible risk of harmful side effects arising after the observation of the surrogate endpoint in the new trial. These 5 criteria constitute an appropriately high bar for using a surrogate endpoint to make a definitive treatment recommendation.

Low testosterone at first prostate-specific antigen failure and assessment of risk of death in men with unfavorable-risk prostate cancer treated on prospective clinical trials

BACKGROUND

Low testosterone at the time of diagnosis of prostate cancer has been associated with a worse prognosis. Whether this is true and how to define the best treatment approach at the time of first prostate-specific antigen (PSA) failure to the authors' knowledge has not been elucidated to date and was studied herein.

METHODS

Between 1995 and 2001, a total of 58 men with unfavorable-risk PC who were treated on clinical trials with radiotherapy and androgen deprivation therapy (ADT) had available testosterone levels at the time of PSA failure. Cox and Fine and Gray regressions were performed to ascertain whether low versus normal testosterone was associated with the risk of PC-specific mortality, other-cause mortality, and all-cause mortality adjusting for age, salvage ADT, and known PC prognostic factors.

RESULTS

After a median follow-up of 6.68 years after PSA failure, 31 men (53.4%) had died; 10 of PC (32.3%), of which 8 of 11 (72.7%) versus 2 of 47 (4.3%) deaths occurred in men with low versus normal testosterone at the time of PSA failure, respectively. A significant increase in the risk of all-cause mortality (adjusted hazard ratio [AHR], 2.54; 95% confidence interval [95% CI], 1.04-6.21 [P = .04]) and PC-specific mortality (AHR, 13.71; 95% CI, 2.4-78.16 [P = .003]), with a reciprocal trend toward a decreased risk of other-cause mortality (AHR, 0.18; 95% CI, 0.02-1.55 [P = .12]) was observed in men with low versus normal testosterone.

CONCLUSIONS

Low, but not necessarily castrate, testosterone levels at the time of PSA failure confer a very poor prognosis. These observations provide evidence to support testosterone testing at the time of PSA failure. Given prolonged survival when abiraterone or docetaxel is added to ADT in men with castrate-sensitive metastatic PC and possibly localized high-risk PC provides a rationale supporting their use with ADT in men with low testosterone in the setting of a phase 2 trial. Cancer 2018;124:1383-90. © 2017 American Cancer Society.

Drug development for noncastrate prostate cancer in a changed therapeutic landscape

The unprecedented progress in the treatment of metastatic castration-resistant prostate cancer is only beginning to be realized in patients with noncastrate disease. This slow progress in part reflects the use of trial objectives focused on time-to-event end points, such as time to metastasis and overall survival, which require long follow-up durations and large sample sizes, and has been further delayed by the use of approved therapies that are effective at the time of progression. Our central hypotheses are that progress can be accelerated, and that outcomes can be improved by shifting trial objectives to response measures occurring early that solely reflect the effects of the treatment. To test these hypotheses, a continuously enrolling multi-arm, multi-stage randomized trial design, analogous to that used in the STAMPEDE trial, has been developed. Eligibility is focused on patients with incurable disease or those with a high risk of death with any form of monotherapy alone. The primary objective is to eliminate all disease using a multimodality treatment strategy. End points include pathological complete response and an undetectable level of serum prostate-specific antigen, with recovery of serum testosterone levels. Both are binary, objective, and provide an early, quantitative indication of efficacy.