Coadministration of Apalutamide and Relugolix in Patients with Localized Prostate Cancer at High Risk for Metastases.

BACKGROUND: The single-arm, open-label, multicenter, phase II Apa-RP study evaluates the biochemical recurrence (confirmed prostate-specific antigen [PSA] > 0.2 ng/mL)-free rate in patients with high-risk localized prostate cancer (HR-LPC) after radical prostatectomy following adjuvant apalutamide and androgen-deprivation therapy. In this substudy, relugolix, an oral gonadotropin-releasing hormone antagonist, was evaluated in combination with apalutamide. OBJECTIVE: The aim of this study was to evaluate whether the approved standard maintenance dose of relugolix in combination with apalutamide sustains castrate testosterone levels (< 50 ng/dL). PATIENTS AND METHODS: Twelve patients with HR-LPC who met all the main study criteria were included in the substudy. Patients received relugolix monotherapy for 2 weeks (loading dose [360 mg] at Day - 14 then 120 mg/day daily until Day - 1), then daily relugolix (120 mg) with apalutamide (240 mg) from Day 1 to Day 28. Endpoints were rate of maintained castration (testosterone < 50 ng/dL) through Day 28 (primary) and safety (secondary). RESULTS: All 12 patients received relugolix and apalutamide and achieved castrate testosterone levels after 2-week relugolix monotherapy (median testosterone 348.5 ng/dL and 8.7 ng/dL at Days - 14 and - 1). All 11 patients who had testosterone measured at Day 28 maintained castrate testosterone (median 10.0 ng/dL) without relugolix dose adjustment. Treatment-emergent adverse events (TEAEs) occurred in nine patients during relugolix monotherapy and in eight patients during relugolix + apalutamide coadministration. Hot flush was the most common TEAE reported, in six and four patients, respectively. CONCLUSIONS: Relugolix administered at approved standard doses concurrently with apalutamide was effective in maintaining castrate testosterone levels in HR-LPC without new safety signals. TRIAL REGISTRATION NUMBER AND DATE: NCT04523207, 21 August 2020.

The Apa-RP study evaluates the combination of apalutamide with drugs that lower male sex hormones for reducing the risk of prostate cancer recurrence. Patients in this study had their prostate gland surgically removed and were at high risk for disease recurrence. Relugolix, a newly approved oral drug for advanced prostate cancer, lowers blood testosterone (the primary male sex hormone) and, in combination with apalutamide, may reduce the risk of prostate cancer recurrence. The Apa-RP substudy goal was to test whether relugolix lowers blood testosterone and maintains these low levels when administered with apalutamide. Researchers looked at the testosterone levels of 12 patients with early prostate cancer who received standard doses of relugolix alone for 2 weeks followed by apalutamide and relugolix for an additional 28 days. Testosterone was measured before and after 2 weeks of relugolix treatment, and then again 28 days after apalutamide was added. All 12 substudy patients achieved low testosterone levels (< 50 ng/dL) after 2 weeks of relugolix treatment. Testosterone was measured at Day 28 of relugolix + apalutamide treatment in 11 patients, all of whom maintained low testosterone without adjustment of their relugolix dose. Adverse effects were consistent with those previously reported for each drug when administered alone. All 12 patients completed the substudy and moved onto the main study, the longer-term results of which will be reported in the future. In summary, relugolix administered at the same time as apalutamide was effective in maintaining low testosterone levels in patients with prostate cancer, without any new safety concerns.

Concomitant use of oral anticoagulants in patients with advanced prostate cancer receiving apalutamide: A post-hoc analysis of TITAN and SPARTAN studies.

Apalutamide, an androgen receptor signaling inhibitor, in combination with androgen-deprivation therapy (ADT), is approved for treatment of patients with nonmetastatic castration-resistant prostate cancer and metastatic castration-sensitive prostate cancer, based on the data from the phase 3 SPARTAN and TITAN studies respectively. Apalutamide is an inducer of cytochrome P450 enzymes and P-glycoprotein, which are involved in the metabolism of oral anticoagulants (OACs) and may thus have potential drug-drug interactions when co-administered with OACs. Concomitant use of certain OACs such as apixaban, rivaroxaban, edoxaban, dabigatran, and warfarin was allowed in the SPARTAN and TITAN studies. A post-hoc analysis was conducted to evaluate the incidence of treatment-emergent thrombotic and embolic adverse events (AEs) in patients receiving concomitant OACs with apalutamide + ADT or placebo + ADT in both the studies. Anticoagulants were identified by WHO Drug Anatomical Therapeutic Chemical level 4 classifications. Thrombotic and embolic AEs were coded using the Medical Dictionary for Regulatory Activities Version 22.1. Data were analyzed from patients receiving concurrent OACs among all treated patients in SPARTAN (apalutamide + ADT: 95/803 [11.8%]; placebo + ADT: 48/398 [12.1%]) and TITAN (apalutamide + ADT: 31/524 [5.9%]; placebo + ADT: 28/527 [5.3%]). No consequential differences were observed in the occurrence of thrombotic and embolic events between apalutamide + ADT and placebo + ADT groups receiving concomitant OACs in SPARTAN (11.6% vs 12.5%) or TITAN (19.4% vs 21.4%). Grade 3/4 thrombotic and embolic AEs observed in patients receiving concomitant OACs with apalutamide + ADT or placebo + ADT were 6 (6.3%) vs 5 (10.4%) in SPARTAN and 3 (9.7%) vs 1 (3.6%) in TITAN. This analysis suggests that when necessary, concomitant OACs can be used with apalutamide with appropriate monitoring.