Development of Treatments for Localized Prostate Cancer in Patients Eligible for Active Surveillance: U.S. Food and Drug Administration Oncology Center of Excellence Public Workshop

Comparative Effectiveness of Partial Gland Cryoablation Versus Robotic Radical Prostatectomy for Cancer Control

BACKGROUND AND OBJECTIVE

There is an absence of high-level evidence comparing oncologic endpoints for partial gland ablation, and most series use prostate-specific antigen (PSA) rather than biopsy endpoints. Our aim was to compare oncologic outcomes between partial gland cryoablation (PGC) and radical prostatectomy (RP) for prostate cancer.

METHODS

This was a retrospective, single-center analysis of subjects treated with PGC (n = 98) or RP (n = 536) between January 2017 and December 2022 as primary treatment for intermediate-risk (Gleason grade group [GG] 2-3) prostate cancer. Oncologic endpoints included surveillance biopsies per protocol after PGC in comparison to serial PSA testing after RP. The primary outcome was treatment failure, defined as a need for any salvage treatment or development of metastatic disease. Treatment failure and survival analyses were conducted using Cox proportional-hazard regression and Kaplan Meier survival curves.

KEY FINDINGS AND LIMITATIONS

After applying the inclusion/exclusion criteria, the PGC (n = 75) and RP (n = 298) groups were compared. PGC patients were significantly older (71 vs 64 yr; p < 0.001), but there were no differences in PSA, biopsy GG, or treatment year between the groups. The PGC group had higher rates of treatment failures at 24 mo (33% vs 11%; p < 0.001) and 48 mo (43% vs 14%; p < 0.001). One PGC patient (2.1%) and one RP patient (0.7%) developed metastases by 48-mo follow-up (p = 0.4). On adjusted analysis, PGC was associated with a higher risk of treatment failure (hazard ratio 4.6, 95% confidence interval 2.7-7.9; p < 0.001). Limitations include observational biases associated with the retrospective study design.

CONCLUSIONS

This is the first comparative effectiveness study of cancer control outcomes for PGC versus RP. The results demonstrate an almost fivefold higher risk of treatment failure with PGC during short-term follow-up.

PATIENT SUMMARY

We compared cancer control outcomes for patients with intermediate-risk prostate cancer treated with partial gland cryoablation versus radical prostatectomy. We found that partial gland cryoablation had an almost fivefold higher risk of treatment failure. Men with prostate cancer should be counseled regarding this difference in treatment failure.

Partial-gland Cryoablation Outcomes for Localized Prostate Cancer in Patients with Magnetic Resonance Imaging (MRI)-visible and MRI-invisible Lesions

Background

Expert consensus recommends treatment of magnetic resonance imaging (MRI)-visible prostate cancer (PCa). Outcomes of partial-gland ablation (PGA) for MRI-invisible PCa remain unknown.

Objective

To compare recurrence-free survival, adverse events, and health-related quality of life (HRQoL) outcomes following cryoablation of MRI-visible vs invisible PCa.

Design setting and participants

We analyzed data for 75 men who underwent cryoablation therapy between January 2017 and January 2022. PCa identified on MRI-targeted and/or adjacent systematic biopsy cores was defined as MRI-visible, whereas PCa identified on systematic biopsy beyond the targeted zone was defined as MRI-invisible.

Outcome measurements and statistical analysis

The primary outcome was recurrence at 12 mo after PGA, defined as the presence of clinically significant PCa (grade group [GG] ≥2) on surveillance biopsy. Adverse events were captured using the Clavien-Dindo classification and HRQoL was captured using the Expanded Prostate Cancer Index-Clinical Practice (EPIC-CP) tool.

Results and limitations

Of the 58 men treated for MRI-visible and 17 treated for MRI-invisible lesions, 51 (88%) and 16 (94%), respectively, had at least one surveillance biopsy performed. There were no statistically significant differences in age, race, body mass index, biopsy GG, prostate-specific antigen, prostate volume, or treatment extent between the MRI-visible and MRI-invisible groups. Median follow-up was 44 mo (interquartile range 17-54) and did not significantly differ between the groups. The recurrence rate at 12 mo did not significantly differ between the groups (MRI-visible 39%, MRI-invisible 19%; p = 0.2), and log-rank survival analysis demonstrated no significant difference in recurrence-free survival (p = 0.15). Adverse event rates did not significantly differ (MRI-visible 29%, MRI-invisible 53%; p = 0.092); no man in the MRI-visible group had a Clavien-Dindo grade ≥III complication, while one subject in the MRI-invisible group had a Clavien-Dindo grade III complication. Median EPIC-CP urinary and sexual function scores were similar for the two groups at baseline and at 12 mo after PGA. Study limitations include the retrospective design and small sample size.

Conclusions

We observed similar cancer control, adverse event, and HRQoL outcomes for MRI-visible versus MRI-invisible PCa in the first comparison of partial-gland cryoablation. Longer follow-up and external validation of our findings are needed to inform patient selection for PGA for MRI-invisible PCa.

Patient summary

Patients with prostate cancer lesions that are not visible on magnetic resonance imaging (MRI) scans who undergo partial gland ablation may have similar treatment outcomes compared to patients with cancer lesions that are visible on MRI.

A Feasibility Study of the Therapeutic Response and Durability of Short-term Androgen-targeted Therapy in Early Prostate Cancer Managed with Surveillance: The Therapeutics in Active Prostate Surveillance (TAPS01) Study

Background

Active surveillance (AS) is a preferred management option for men with prostate cancer with favourable prognosis. However, nearly half of men on AS switch to treatment within 5 years, so therapeutic strategies to prevent or delay disease progression could be considered. The androgen receptor is the pre-eminent oncogenic driver in prostate cancer.

Objective

To explore image-based tumour responses and the patient impact of short-duration androgen-targeted therapy (ATT) to abrogate disease progression during AS.

Design, setting, and participants

Men on AS with Cambridge Prognostic Group 1 & 2 (low and favourable intermediate risk) prostate cancer and lesions visible on magnetic resonance imaging (MRI) were recruited to an open-label, single-centre, phase 2 feasibility study of short-term ATT (the TAPS01 study).

Intervention

Apalutamide 240 mg was administered for 90 days.

Outcome measurements and statistical analysis

MRI-measured tumour volume (TV), gland volume (GV), and the TV/GV ratio were calculated at baseline, at day 90 (end of treatment), and at 6- and 18-month follow-up. Quality of life metrics were measured at day 0, day 90, and 6 weeks after ATT.

Results and limitations

Eleven patients (40% of eligible men approached) agreed to participate, of whom nine completed treatment. At day 90, the median percentage reduction was −38.2% (range −51.8% to −23.5%) for GV, −54.2% (range −74.1% to −13.8%) for TV, and −27.2% (range −61.5% to −7.5%) for TV/GV (all p < 0.0001). At 6 mo, while GV had returned to baseline (p = 0.95) both TV (−31.9%; p = 0.0007) and TV/GV (−28.7%; p = 0.0009) remained significantly reduced. This reduction was sustained at 18 months (TV −18%, TV/GV −23.8%; p = 0.01). European Organization for Research and Treatment of Cancer QoL core 30-item questionnaire scores for global, physical, role, and social functioning decreased during treatment, but all were recovering by 6 weeks. EQ-VAS scores were unchanged compared to baseline.

Conclusions

TAPS01 has demonstrated feasibility and patient tolerability for short-term ATT in men on AS. Our data suggest a selective and durable antitumour effect in the short term and support a larger-scale randomised trial.

Patient summary

We investigated the feasibility of short-term treatment with an androgen inhibitor to prevent or delay disease progression for men on active surveillance for prostate cancer. Results for a small group of patients show that 90-day treatment led to a sustained decrease in tumour volume over 18 months. The findings warrant a larger clinical trial for this approach, which could allow patients to delay or even avoid longer-term active treatments.

Perceptions of partial gland ablation for prostate cancer among men on active surveillance: A qualitative study

OBJECTIVES –

Partial gland ablation (PGA) therapy is an emerging treatment modality that targets specific areas of biopsy proven prostate cancer (PCa) to minimize treatment-related morbidity by sparing benign prostate. This qualitative study aims to explore and characterize perceptions and attitudes toward PGA in men with very-low-risk, low-risk, and favorable intermediate-risk PCa on active surveillance (AS).

DESIGN –

92 men diagnosed with very-low-risk, low-risk, and favorable intermediate-risk PCa on AS were invited to participate in semi-structured telephone interviews on PGA.

SETTING –

Single tertiary care center located in New York City.

PARTICIPANTS –

20 men with very-low-risk, low-risk, and favorable intermediate-risk PCa on AS participated in the interviews.

MAIN OUTCOME MEASURES –

Emerging themes on perceptions and attitudes toward PGA were developed from transcripts inductively coded and analyzed under standardized methodology.

RESULTS –

Four themes were derived from twenty interviews that represent the primary considerations in treatment decision-making: (1) the feeling of psychological safety associated with low-risk disease; (2) preference for minimally invasive treatments; (3) the central role of the physician; (4) and the pursuit of treatment options that align with disease severity. Eleven men (55%) expressed interest in pursuing PGA only if their cancer were to progress, while 9 men (45%) expressed interest at the current moment.

CONCLUSIONS –

Though an emerging treatment modality, patients were broadly accepting of PGA for PCa with men primarily debating the risks versus benefits of proactively treating low-risk disease. Additional research on men's preferences and attitudes toward PGA will further guide counseling and shared decision-making for PGA.

Need for Systematic Magnetic Resonance Imaging Interpretation and Reporting after Partial Prostate Gland Ablation

Interpretation guidelines for prostate multiparametric magnetic resonance imaging findings in the post-ablation setting are not available yet; this poses a significant challenge for accurate risk stratification in this clinical setting. Here we propose the development and implementation of a post-ablation Prostate Imaging-Reporting and Data System that would improve patient surveillance and management after prostate ablation for localized prostate cancer.

Temporal trends in the number of men electing for conservative management for low-risk prostate cancer in the United States

BACKGROUND

Concurrent with the decrease in the number of men diagnosed with prostate cancer (PCa), the proportion of men with low-risk PCa managed conservatively (active surveillance or watchful waiting) has increased in the United States. We aimed to determine whether this increase is a result of more men being managed conservatively or rather a higher proportion of the diminishing number of low-risk PCa managed this way.

METHODS

The SEER "Prostate Watchful Waiting Database" identified men managed initially with conservative management between 2010 and 2016. Men > 40 years old who were diagnosed with low-risk (Gleason score 3 + 3, T1-T2a, PSA level < 10 ng/mL) PCa were included. Age-standardized and age-specific PCa incidence and conservative management rates were calculated per 100,000 man-years. The annual percent change in rates for the entire time period was also calculated.

RESULTS

The incidence of low-risk PCa declined by 11.8% per year (95% confidence interval [CI] -15.4% to -8.0%), whereas the number of men assigned to conservative management for low-risk disease did not increase significantly, rising by +3.7% per year (95% CI -0.7% to 8.4%). In age-specific analysis, the number of men < 60 years and those who were 60-69 years managed conservatively increased by +9.6% per year (95% CI 2.7% to 16.9%) and 4.5% per year (95% CI 0.1% to 9.1%), respectively, whereas the number of men ≥ 70 years electing conservative management remained stable at -4% per year (95% CI -11.2% to 3.7%).

CONCLUSIONS

The number of men electing conservative management has remained largely stable between 2010 and 2016, despite an increase in the proportion of low-risk PCa managed in this manner.

Comparative Healthcare Research Outcomes of Novel Surgery in prostate cancer (IP4-CHRONOS): A prospective, multi-centre therapeutic phase II parallel Randomised Control Trial

INTRODUCTION

Focal therapy (FT) targets individual areas of cancer within the prostate, providing oncological control with minimal side-effects. Early evidence demonstrates encouraging short-medium-term outcomes. With no randomized controlled trials (RCT) comparing FT to radical therapies, Comparative Healthcare Research Outcomes of Novel Surgery in prostate cancer (CHRONOS) will compare the cancer control of these two strategies.

PATIENTS AND METHODS

CHRONOS is a parallel phase II RCT for patients with clinically significant non-metastatic prostate cancer, dependent upon clinician/patient decision, patients will enrol into either CHRONOS-A or CHRONOS-B. CHRONOS-A will randomize patients to either radical treatment or FT. CHRONOS-B is a multi-arm, multistage RCT comparing focal therapy alone to FT with neoadjuvant agents that might improve the current focal therapy outcomes. An internal pilot will determine the feasibility of, and compliance to, randomization. The proposed definitive study plans to recruit and randomize 1190 patients into CHRONOS-A and 1260 patients into CHRONOS-B.

RESULTS

Primary outcome in CHRONOS-A is progression-free survival (transition to salvage local or systemic therapy, development of metastases or prostate-cancer-related mortality) and in CHRONOS-B is failure-free survival (includes the above definition and recurrence of clinically significant prostate cancer after initial FT). Secondary outcomes include adverse events, health economics and functional outcomes measured using validated questionnaires. CHRONOS is powered to assess non-inferiority of FT compared to radical therapy in CHRONOS-A, and superiority of neoadjuvant agents with FT in CHRONOS-B.

CONCLUSION

CHRONOS will assess the oncological outcomes after FT compared to radical therapy and whether neoadjuvant treatments improve cancer control following one FT session.