Outcomes Of Prechemotherapy (Pcht) Abiraterone (Aa) Or Enzalutamide (E) For Metastatic Castration-Resistant Prostate Cancer (Mcrpc) After Androgen Deprivation Therapy (Adt) Plus Docetaxel (D) Or Adt Alone For Metastatic Hormone Sensitive Prostate Cancer (Mhspc) In A Hospital-Based Registry.

e16515 Background: The E3805: CHAARTED trial noted use of D at time of commencing ADT for mHSPC was associated with an improvement in time to CRPC (PSA rise or clinical progression [CP]) or time to CP and resulted in a prolongation of overall survival (OS). Therefore, we postulated that pCHT AA or E maintained activity after ADT+D. Methods: A cohort of CRPC patients (pts) treated with pCHT AA or E for CRPC between 2010 and 2016 was selected from the Dana-Farber Cancer Institute IRB approved database. Patients were grouped by use of D and whether they had prior localized therapy (PLT) or de novo (DN) metastatic disease, at time of ADT start for mHSPC. The analysis endpoints included OS (time to death from all causes) from ADT start, time to AA/E start from ADT start, OS from AA/E start. Kaplan-Meier method estimated the time to events distribution with median (95% CI). Results: Of the 147 pts selected, 134 (91.2%) had previously received ADT alone, while 13 (8.8%) had ADT+D. Once stratified by PLT or DN, the distributions of the 4 groups are 33.3% (ADT/PLT), 57.8% (ADT/DN), 0.7% (ADT+D/PLT), and 8.2% (ADT+D/DN). In the ADT alone group, the median OS with pCHT AA or E for CRPC was approximately 3 years from the AA/E start, regardless of PLT or DN. In the smaller cohort of pts selected for treatment with ADT+D, both the OS from ADT start and from AA/E start were shorter than the ADT alone cohort. However, even in this group with shorter time to AA/E start, the median OS from AA/E start was still 1.5 years despite prior chemotherapy. Conclusions: Within limitations of a hospital-based registry, small sample size for ADT+D and lack of volume of metastases data, pts selected for ADT+D show poorer outcomes but still have an OS of 1.5 yrs from AA/E start. [Table: see text]