Tolerability of Olaparib Combined with Abiraterone in Patients with Metastatic Castration-resistant Prostate Cancer: Further Results from the Phase 3 PROpel Trial

BACKGROUND

The PROpel study (NCT03732820) demonstrated a statistically significant progression-free survival benefit with olaparib plus abiraterone versus placebo plus abiraterone in the first-line metastatic castration-resistant prostate cancer (mCRPC) setting, irrespective of homologous recombination repair mutation status.

OBJECTIVE

We report additional safety analyses from PROpel to increase clinical understanding of the adverse-event (AE) profiles of olaparib plus abiraterone versus placebo plus abiraterone.

DESIGN, SETTING, AND PARTICIPANTS

A randomised (1:1), double-blind, placebo-controlled trial was conducted at 126 centres in 17 countries (October 2018-January 2020). Patients had mCRPC and no prior systemic mCRPC treatment.

INTERVENTION

Olaparib (300 mg bid) or placebo with abiraterone (1000 mg od) plus prednisone/prednisolone (5 mg bid).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The data cut-off date was July 30, 2021. Safety was assessed by AE reporting (Common Terminology Criteria for Adverse Events v4.03) and analysed descriptively.

RESULTS AND LIMITATIONS

The most common AEs (all grades) for olaparib plus abiraterone versus placebo plus abiraterone were anaemia (46.0% vs 16.4%), nausea (28.1% vs 12.6%), and fatigue (27.9% vs 18.9%). Grade ≥3 anaemia occurred in 15.1% versus 3.3% of patients in the olaparib plus abiraterone versus placebo plus abiraterone arm. The incidences of the most common AEs for olaparib plus abiraterone peaked early, within 2 mo, and were managed typically by dose modifications or standard medical practice. Overall, 13.8% versus 7.8% of patients discontinued treatment with olaparib plus abiraterone versus placebo plus abiraterone because of an AE; 3.8% versus 0.8% of patients discontinued because of anaemia. More venous thromboembolism events were observed in the olaparib plus abiraterone arm (any grade, 7.3%; grade ≥3, 6.8%) than in the placebo plus abiraterone arm (any grade, 3.3%; grade ≥3, 2.0%), most commonly pulmonary embolism (6.5% vs 1.8% for olaparib plus abiraterone vs placebo plus abiraterone).

CONCLUSIONS

Olaparib plus abiraterone has a manageable and predictable safety profile.

PATIENT SUMMARY

The PROpel trial showed that in patients who had not received any previous treatment for metastatic castration-resistant prostate cancer, olaparib combined with abiraterone was more effective in delaying progression of the disease than abiraterone alone. Most side effects caused by combining olaparib with abiraterone could be managed with supportive care methods, by pausing olaparib administration for a short period of time and/or by reducing the dose of olaparib.

Abstract OT2-16-02: Open-label, phase 3b/4 study of trastuzumab deruxtecan (T-DXd) in patients with or without baseline brain metastasis with advanced/metastatic human epidermal growth factor receptor 2–positive breast cancer: DESTINY-Breast12

Background: Patients (pts) with human epidermal growth factor receptor 2–positive breast cancer (HER2+ BC) have a high incidence (up to 50%) of brain metastasis (BM) despite advances in treatment (Zimmer AS et al. Cancer Rep (Hoboken). 2020;e1274; Hurvitz SA et al. Clin Cancer Res. 2019;25:2433-2441). Although several agents have been studied in pts with HER2+ BC with BM, an unmet medical need remains. In DESTINY-Breast01, T-DXd demonstrated efficacy in the overall population and preliminary efficacy in a pt subgroup with stable BM (n=24), with a confirmed objective response rate (ORR) of 61.4%, an extracranial confirmed ORR by independent central review (ICR) of 58.3%, respectively, and median progression-free survival (PFS) of 19.4 and 18.1 months, respectively (Modi S et al. Cancer Res. 2021. Abst PD3-06; Jerusalem G et al. Ann Oncol. 2020. Abst 138O). T-DXd also demonstrated preliminary efficacy in a subgroup of pts with BM in the DESTINY-Breast03 trial, with an extracranial ORR of 67.4%, intracranial ORR of 63.9%, and median PFS of 15.0 months (Hurvitz S et al. SABCS 2021. Abst GS3-01). However, both trials excluded pts with active/progressive BM. Here we describe a trial evaluating T-DXd in a real-world setting in pts with stable or active BM and pts without BM with previously treated advanced/metastatic HER2+ BC. The data generated by this study will complement previous and ongoing studies, providing a more robust understanding of T-DXd treatment in patients with and without BM. Trial design: DESTINY-Breast12 (NCT04739761) is an open-label, multicenter, international (91 sites in the US, Europe, Australia, Canada, and Japan), phase 3b/4 study assessing the efficacy and safety of T-DXd 5.4 mg/kg every 3 weeks in pts with HER2+ BC ± BM. As part of prescreening, all pts will provide informed consent for tumor tissue samples (archival tumor tissue or fresh biopsy) to be collected and tested for HER2 status. Pts will be enrolled in 1 of 2 cohorts (250 pts each): cohort 1 (no BM at baseline) and cohort 2 (BM at baseline). Pts must have previously treated HER2-positive BC that has progressed on or after ≥1 prior anti-HER2–based regimen (including disease progression ≤6 months after adjuvant treatment with HER2-targeted therapies) and received ≤2 lines of therapy in the metastatic setting (excluding pts with prior tucatinib). Cohort 1 will be limited to include ≤25% third-line pts. Pts with BM must have untreated BM not needing immediate local therapy or previously treated stable or progressing BM. Primary endpoints are ORR in cohort 1 and PFS in cohort 2 (both by Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1 per ICR). Secondary endpoints in both cohorts are overall survival, DOR, time to progression, duration of subsequent therapy, PFS2, safety, and changes in symptoms, functioning, and quality of life. Incidence of new symptomatic central nervous system (CNS) metastasis is a secondary endpoint in cohort 1, and ORR and CNS ORR by RECIST 1.1 per ICR, CNS PFS and DOR, and time to new CNS metastasis are secondary endpoints in cohort 2.

Citation Format: Nancy U. Lin, Eva Ciruelos, Guy Jerusalem, Volkmar Müller, Naoki Niikura, Giuseppe Viale, Emma Oscroft, Shawn Anand, Manoj Prahladan, Nadia Harbeck. Open-label, phase 3b/4 study of trastuzumab deruxtecan (T-DXd) in patients with or without baseline brain metastasis with advanced/metastatic human epidermal growth factor receptor 2–positive breast cancer: DESTINY-Breast12 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT2-16-02.

Abstract OT2-26-01: Open-label, multinational, multicenter, phase 3b/4 study of trastuzumab deruxtecan (T-DXd) in patients with or without baseline brain metastasis with previously treated advanced/metastatic human epidermal growth factor receptor 2-positive breast cancer (HER2+ BC): DESTINY-Breast12

Background: HER2+ BC is associated with a high incidence (up to 50%) of brain metastasis (BM) despite advances in treatment (Zimmer AS et al. Cancer Rep (Hoboken). 2020;e1274; Hurvitz SA et al. Clin Cancer Res. 2019;25:2433-2441). Although several agents have been studied in patients (pts) with HER2+ BC with BM, an unmet medical need remains due to the poor prognosis in this pt population. In DESTINY-Breast01, T-DXd demonstrated efficacy in the overall population and preliminary efficacy in a pt subgroup with stable BM, with a confirmed objective response rate (ORR) of 61.4% and an extracranial confirmed ORR by independent central review (ICR) of 58.3%, respectively, median progression-free survival (PFS) of 19.4 and 18.1 mo, respectively, and median duration of response (DOR) of 20.8 and 16.9 mo, respectively (Modi S et al. Cancer Res. 2021. Abst PD3-06; Jerusalem G et al. Ann Oncol. 2020. Abst 138O). Here we describe a trial evaluating T-DXd in pts ± BM with previously treated advanced/metastatic HER2+ BC. Trial design: DESTINY-Breast12 (NCT04739761) is an open-label, multicenter, international (86 sites in the US, Europe, Australia, and Japan), phase 3b/4 study assessing the efficacy and safety of T-DXd 5.4 mg/kg q3w in pts with HER2+ BC ± BM. Pts will be enrolled in 1 of 2 cohorts (250 pts each): cohort 1 (−BM at baseline) and cohort 2 (+BM at baseline). Pts must have previously treated advanced/metastatic HER2+ BC that has progressed with ≥1 prior anti-HER2-based regimen and received ≤2 lines of therapy in the metastatic setting (excludes pts with prior tucatinib). Pts with BM must have untreated BM not needing immediate local therapy or previously treated stable or progressing BM. Primary endpoints are ORR in cohort 1 and PFS in cohort 2 (both by RECIST version 1.1 per ICR). Secondary endpoints in both cohorts are OS, DOR, time to progression, duration of subsequent therapy, PFS2, safety, and changes in symptoms, functioning, and QOL. Incidence of new symptomatic CNS metastasis (CNSM) is a secondary endpoint in cohort 1, and ORR and CNS ORR by RECIST 1.1 per ICR, CNS PFS and DOR, and time to new CNSM are secondary endpoints in cohort 2.

Citation Format: Nancy U Lin, Eva Ciruelos, Guy Jerusalem, Volkmar Müller, Naoki Niikura, Giuseppe Viale, Emma Oscroft, Shawn Anand, Graham Walker, Nadia Harbeck. Open-label, multinational, multicenter, phase 3b/4 study of trastuzumab deruxtecan (T-DXd) in patients with or without baseline brain metastasis with previously treated advanced/metastatic human epidermal growth factor receptor 2-positive breast cancer (HER2+ BC): DESTINY-Breast12 [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT2-26-01.

CLRM-14. OPEN-LABEL, MULTINATIONAL, MULTICENTER, PHASE 3B/4 STUDY OF TRASTUZUMAB DERUXTECAN (T-DXD) IN PATIENTS WITH OR WITHOUT BASELINE BRAIN METASTASIS (BM) WITH PREVIOUSLY TREATED ADVANCED/METASTATIC HUMAN EPIDERMAL GROWTH FACTOR RECEPTOR 2–POSITIVE BREAST CANCER (HER2+ BC): DESTINY-BREAST12

BACKGROUND

Despite treatment advances, up to 50% of patients with advanced HER2+ BC develop BM (Zimmer. Cancer Rep. 2020). Patients with HER2+ BC with BM have a worse prognosis than patients without BM. In DESTINY-Breast01, T-DXd demonstrated efficacy in the overall population and preliminary efficacy in a subgroup with stable BM, with a confirmed objective response rate (ORR) of 61.4% and an extracranial confirmed ORR by independent central review (ICR) of 58.3%, median progression-free survival (PFS) of 19.4 and 18.1 mo, and median duration of response (DOR) of 20.8 and 16.9 mo (Modi. Cancer Res. 2021; Jerusalem. Ann Oncol. 2020). Here we describe a trial evaluating T-DXd in patients with previously treated advanced/metastatic HER2+ BC ±BM.

DESIGN

DESTINY-Breast12 (NCT04739761) is an open-label, multicenter, international (86 sites in the US, Europe, Australia, and Japan), phase 3b/4 study assessing T-DXd 5.4 mg/kg q3w efficacy and safety in patients with previously treated advanced/metastatic HER2+ BC ±BM that progressed with ≥1 prior anti-HER2–based regimen and received ≤2 lines of therapy in the metastatic setting (excluding patients with prior tucatinib). Patients (n=250/cohort) will be enrolled in cohort 1 (−BM at baseline) or 2 (+BM at baseline). BM must be untreated and not needing immediate local therapy or previously treated and stable or progressing. Primary endpoints are ORR (cohort 1) and PFS (cohort 2) (both by RECIST version 1.1 per ICR). Secondary endpoints are OS, DOR, time to progression, duration of subsequent therapy, PFS2, safety, and changes in symptoms, functioning, and QOL in both cohorts; incidence of new symptomatic CNS metastasis (CNSM) in cohort 1; and ORR and CNS ORR by RECIST 1.1 per ICR, CNS PFS and DOR, and time to new CNSM in cohort 2. This is an encore; the original presentation will be at The European Society for Medical Oncology 2021.