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.

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.

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

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).

Apalutamide 240 mg was administered for 90 days.

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.

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.

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.

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.

European urology open science. 2022 Feb 10*** epublish ***

Tristan Barrett, Simon Pacey, Kelly Leonard, Jerome Wulff, Ionut-Gabriel Funingana, Vincent Gnanapragasam

Translational Prostate Cancer Group, CRUK Cambridge Cancer Centre, Cambridge, UK., Cambridge Urology Translational Research and Clinical Trials Office, Cambridge Biomedical Campus, Addenbrooke's Hospital, Cambridge, UK., Cambridge Clinical Trials Unit-Cancer Theme, Cambridge, UK., Department of Oncology, University of Cambridge, Cambridge, UK.

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