Docetaxel for hormone-naïve prostate cancer: Results from long-term follow-up of metastatic (M1) patients in the STAMPEDE randomised trial (NCT00268476) and sub-group analysis by metastatic burden

Background STAMPEDE has previously reported that upfront docetaxel (Doc) improved overall survival (OS) for patients (pts) starting long-term androgen deprivation therapy (ADT). We report the long-term outcomes for M1 pts using OS as the primary outcome measure. We also assessed if benefit of Doc depended on metastatic burden, as suggested by previous trials, using the CHAARTED definition of high burden (HB) and low burden (LB) baseline disease. Methods 724 SOC and 362 SOC+Doc pts were recruited with a 2:1 randomised stratified allocation. Analysis used Cox regression models, adjusted for all stratification factors, with emphasis on restricted mean survival time if hazards were non-proportional. Retrospectively-collected imaging data, blinded to trial arm, was used to categorise pts as having LB or HB disease. Results Median follow-up was ∼6.5yr, compared to ∼3.5yr when last reported. There were 494 deaths on SOC (41% increase in deaths compared to previous report), with median OS=43.1 months (m). There was good evidence of benefit of SOC+Doc on OS (median = 59.1m, HR=0.81, 95% CI 0.69-0.95, P=0.009). Metastatic burden was assessable for 830/1086 (76%) pts; subgroups were representative of the full M1 cohort in terms of stratification factors. There was no evidence of heterogeneity of Doc effect between the LB and HB subgroups (interaction P=0.827; LB HR=0.76, 95%CI 0.54-1.07, P=0.107; HB HR=0.81, 95%CI 0.64-1.02, P=0.064). Analysis of other outcomes also found evidence of benefit of SOC+Doc over SOC in failure-free survival (FFS; HR=0.66, 95% CI 0.57-0.76, P Conclusions The clinically significant benefit in survival for upfront Doc persists after longer follow-up, with no evidence that the benefit differed dependent on disease burden. We advocate that upfront Doc is considered for both LB and HB M1 pts. Clinical trial identification NCT00268476. Legal entity responsible for the study University College London. Funding Cancer Research UK; Sanofi; MRC; Astellas; Clovis; Janssen; Novartis; Pfizer. Disclosure N.W. Clarke: Advisory / Consultancy: Janssen. G. Attard: Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses: Astellas; Advisory / Consultancy, Travel / Accommodation / Expenses: Medivation; Advisory / Consultancy: Novartis; Advisory / Consultancy: Millennium Pharmaceuticals; Advisory / Consultancy, Travel / Accommodation / Expenses: Abbott Laboratories; Advisory / Consultancy, Travel / Accommodation / Expenses: Essa Pharmaceuticals; Advisory / Consultancy, Travel / Accommodation / Expenses: Bayer Healthcare Pharmaceuticals; Speaker Bureau / Expert testimony: Takeda; Speaker Bureau / Expert testimony: Sanofi-Aventis; Research grant / Funding (self): AstraZeneca; Research grant / Funding (self): Arno Therapeutics; Research grant / Funding (self): Innocrin Pharma; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self), Travel / Accommodation / Expenses, Non-remunerated activity/ies: Janssen; Advisory / Consultancy: Veridex; Advisory / Consultancy, Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses, Non-remunerated activity/ies: Roche/Ventana; Advisory / Consultancy, Non-remunerated activity/ies: Pfizer; Research grant / Funding (institution), I was an employee of the ICR, where abiraterone acetate was developed, up to 8 January 2018. The Institute of Cancer Research (ICR). S. Chowdhury: Honoraria (self), Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses: Janssen Pharmaceutical. D. Dearnaley: Research grant / Funding (institution), Financial Support for Trial Recruitment: UK National Institute for Health Research Clinical Research Network (NIHR CRN); Research grant / Funding (institution), My employer, The Institute of Cancer Research, receives a royalty income from abiraterone. I receive a share of this income through the ICR's Rewards to Discoverer's Scheme: The Institute of Cancer Research (ICR); Research grant / Funding (self): Cancer Research UK; Honoraria (self), Advisory / Consultancy: Takeda; Honoraria (self), Advisory / Consultancy: Amgen; Advisory / Consultancy, Travel / Accommodation / Expenses: Sandoz; Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution), Travel / Accommodation / Expenses: Janssen. S. Gillessen: Honoraria (institution): Bayer; Honoraria (institution): Curevac; Honoraria (institution), Advisory / Consultancy: Janssen; Honoraria (institution): Astellas; Honoraria (institution), Advisory / Consultancy: Orion; Advisory / Consultancy: MaxiVax SA; Honoraria (institution), Advisory / Consultancy: AAA; Honoraria (institution): Ferring; Honoraria (institution), Advisory / Consultancy: Roche; Honoraria (institution): Innocrin Pharmaceuticals; Honoraria (institution), Advisory / Consultancy: Sanofi; Honoraria (institution): Novartis; Non-remunerated activity/ies: Nectar Therapeutics; Non-remunerated activity/ies: ProteoMedix; Honoraria (institution): Cell Search; Honoraria (institution): Clovis; Honoraria (institution): Bristol-Myers Squibb. R. Jones: Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Non-remunerated activity/ies: Janssen; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self): Astellas; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self): Sanofi; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: Novartis. Z. Malik: Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Janssen; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Sanofi; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Astellas; Travel / Accommodation / Expenses: Bayer. M.D. Mason: Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: Sanofi; Advisory / Consultancy, Speaker Bureau / Expert testimony: Janssen; Advisory / Consultancy, Speaker Bureau / Expert testimony: Bayer. C. Parker: Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self): Bayer; Honoraria (self), Advisory / Consultancy: AAA; Advisory / Consultancy, Speaker Bureau / Expert testimony: Janssen. A.G. Omlin: Advisory / Consultancy, Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses: Astellas; Advisory / Consultancy, Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses: Bayer; Advisory / Consultancy, Travel / Accommodation / Expenses: Sanofi; Advisory / Consultancy: Roche; Advisory / Consultancy: MSD; Advisory / Consultancy: Molecular Partners; Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution), Travel / Accommodation / Expenses: Janssen; Research grant / Funding (institution): Teva. M.R. Sydes: Research grant / Funding (self), Non-remunerated activity/ies, Unrestricted grant to contribute to STAMPEDE overall: Astellas; Research grant / Funding (self), Non-remunerated activity/ies, Unrestricted grant to contribute to STAMPEDE overall: Clovis Oncology; Research grant / Funding (self), Non-remunerated activity/ies, Unrestricted grant to contribute to STAMPEDE overall: Novartis; Research grant / Funding (self), Non-remunerated activity/ies, Unrestricted grant to contribute to STAMPEDE overall: Pfizer; Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses: Eli Lilly; Speaker Bureau / Expert testimony, Research grant / Funding (self), Travel / Accommodation / Expenses, Non-remunerated activity/ies, Unrestricted grant to contribute to STAMPEDE overall: Janssen; Research grant / Funding (self), Non-remunerated activity/ies, Unrestricted grant to contribute to STAMPEDE overall: Sanofi. M.K.B. Parmar: Research grant / Funding (self), Unrestricted grant to contribute to another comparison of STAMPEDE which supports the protocol overall, plus relevant drug and distribution.: Astellas; Research grant / Funding (self), Unrestricted grant to contribute to another comparison of STAMPEDE which supports the protocol overall, plus relevant drug and distribution.: Clovis Oncology; Research grant / Funding (self), Unrestricted grant to contribute to another comparison of STAMPEDE which supports the protocol overall, plus relevant drug and distribution.: Novartis; Research grant / Funding (self), Unrestricted grant to contribute to another comparison of STAMPEDE which supports the protocol overall, plus relevant drug and distribution.: Pfizer; Research grant / Funding (self), Unrestricted grant to contribute to another comparison of STAMPEDE which supports the protocol overall, plus relevant drug and distribution.: Sanofi. N.D. James: Advisory / Consultancy: Sanofi; Advisory / Consultancy: Novartis; Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self), Travel / Accommodation / Expenses, Non-remunerated activity/ies: Janssen. All other authors have declared no conflicts of interest.