Adverse events

Participants initially received a starting dose of talazoparib 1 mg once daily (QD) in combination with enzalutamide 160 mg QD up until Day 66, then the dose of talazoparib was reduced to 0.5 mg QD based on results from a review of available safety and pharmacokinetic (PK) data (up to a maximum of 231.14 weeks for both talazoparib and enzalutamide as of 16 Aug 2022). All-cause mortality and adverse events are reported for participants who received at least 1 dose of study intervention.

Participants received talazoparib 0.5 mg QD in combination with enzalutamide 160 mg QD (up to a maximum of 180 weeks for talazoparib and 219.29 weeks for enzalutamide as of 16 Aug 2022). All-cause mortality and adverse events are reported for participants who received at least 1 dose of study intervention.

Participants were randomized to receive talazoparib 0.5 mg QD in combination with enzalutamide 160 mg QD (up to a maximum of 186.14 weeks for both talazoparib and enzalutamide as of 16 Aug 2022). All-cause mortality are reported for participants who were randomly assigned to double-blind study treatment in Part 2 regardless of whether or not treatment was administered. Adverse events are reported for participants who received at least 1 dose of study treatment in Part 2 and was based on the actual treatment received.

Participants were randomized to receive placebo QD in combination with enzalutamide 160 mg QD (up to a maximum of 182 weeks for both placebo and enzalutamide as of 16 Aug 2022). All-cause mortality are reported for participants who were randomly assigned to double-blind study treatment in Part 2 regardless of whether or not treatment was administered. Adverse events are reported for participants who received at least 1 dose of study treatment in Part 2 and was based on the actual treatment received.

Participants with DDR deficiencies were randomized to receive talazoparib 0.5 mg QD in combination with enzalutamide 160 mg QD (up to a maximum of 169.86 weeks for both talazoparib and enzalutamide as of 03 Oct 2022). Participants who were DDR-deficient and received talazoparib+enzalutamide in Part 2 Cohort 1 were combined with participants enrolled in Part 2 Cohort 2 and included in the analysis for Part 2 Participants With DDR Deficiencies. All-cause mortality are reported for participants who were randomly assigned to double-blind study treatment in Part 2 regardless of whether or not treatment was administered. Adverse events are reported for participants who received at least 1 dose of study treatment in Part 2 and was based on the actual treatment received.

Participants with DDR deficiencies were randomized to receive placebo QD in combination with enzalutamide 160 mg QD (up to a maximum of 157 weeks for both placebo and enzalutamide as of 03 Oct 2022). Participants who were DDR-deficient and received placebo+enzalutamide in Part 2 Cohort 1 were combined with participants enrolled in Part 2 Cohort 2 and included in the analysis for Part 2 Participants With DDR Deficiencies. All-cause mortality are reported for participants who were randomly assigned to double-blind study treatment in Part 2 regardless of whether or not treatment was administered. Adverse events are reported for participants who received at least 1 dose of study treatment in Part 2 and was based on the actual treatment received.