862PRetrospective evaluation of neutropenic admission events in metastatic or high-risk hormone-sensitive prostate cancer (HSPC) patients having docetaxel chemotherapy upfront or for castrate-resistant prostate cancer (CRPC) in STAMPEDE

Abstract Background Docetaxel (Doc) was initially licenced for CRPC (TAX327) but more recently trials showed Doc at HSPC diagnosis improved survival, shifting patterns of use. Higher neutropenic toxicity rates were reported in the HSPC trials, but it is unclear if this was due to the Doc timing or differences in case-mix. We compared sepsis rates for Doc at HSPC and CRPC using routine NHS data for men randomised in STAMPEDE in England. Methods STAMPEDE patient data were linked to routine NHS data (Hospital Episode Statistics: HES; Systemic Anti-Cancer Therapy: SACT). Patient note review (ref) linked to NHS data assessed admission rates by HSPC & CRPC Doc at 1 site (N = 44) and were used to develop and validate algorithms for detecting sepsis events across the entire data set. Algorithms were restricted to sepsis-only & sepsis + neutropenia (S+N) (N = 3645). Missing HES CRPC Doc regimens were imputed with HES (N = 3645) or enhanced with SACT (N = 1573). Odds ratios (OR) were calculated for risk of sepsis (OR  Results Sepsis rates varied by method; for most, rates at CRPC were higher than in TAX327 but similar to or higher than reported STAMPEDE HSPC data. Table . 862P HSPC Sepsis/Pts CRPC Sepsis/Pts % diff OR, 95% CI N % N % Ref 2/15 13 6/22 27 -14 0.4 (0.1 - 2.1) HES Sepsis 69/834 8 114/1183 10 -2 0.9 (0.6 - 1.2) S+N 134/834 16 148/1183 13 3 1.3 (1.0 - 1.6) Imputed 134/834 16 489/1351 36 -20 0.4 (0.4 - 0.6) + SACT 41/200 21 60/297 20 1 1.0 (0.7 - 1.6) Conclusions This analysis does not support the hypothesis that HSPC Doc has a higher sepsis risk than Doc use in CRPC. Sepsis rates found using routine data were higher than in the TAX327 trial but similar to reported “real world” CRPC data. Rates varied by data-identification method used; for most, CRPC sepsis rates were higher or similar to HSPC rates & overall a little higher than the reported STAMPEDE HSPC rate. These data suggest CRPC Doc has a similar or higher sepsis rate than use in HSPC & this should be factored into discussions for men with newly-diagnosed metastatic HSPC and supports Doc use in this setting. Legal entity responsible for the study The STAMPEDE Trial Group. Funding University of Warwick, Warwick Medical School (HM PhD studentship). Disclosure M.K.B. Parmar: Research grant / Funding (institution): Astellas Pharma; Research grant / Funding (institution): Clovis oncology; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Pfizer; Research grant / Funding (institution): Sanofi; Research grant / Funding (institution), The Unit I am Director of also receives educational grants and other non- financial support from a large number of different companies: Other. P. Patel: Advisory / Consultancy: Roche/Genentech. M.R. Sydes: Honoraria (self): Lilly; Honoraria (self), Research grant / Funding (self): Sanofi; Honoraria (self): Janssen; Research grant / Funding (self): Astellas Pharma; Research grant / Funding (self): Janssen-Cilag; Research grant / Funding (self): Pfizer; Research grant / Funding (self): Novartis; Research grant / Funding (self): Clovis Oncology. N.D. James: Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution), Travel / Accommodation / Expenses: Sanofi; Honoraria (self), Advisory / Consultancy: Bayer; Advisory / Consultancy: Merck; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution): Astellas Pharma; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution): Janssen; Honoraria (self), Speaker Bureau / Expert testimony: Pierre Fabre; Speaker Bureau / Expert testimony: Ferring; Honoraria (self): Oncogenex; Research grant / Funding (institution): Pfizer; Research grant / Funding (institution): Novartis. All other authors have declared no conflicts of interest.