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Matsubara N, de Bono J, Olmos D, Procopio G, Kawakami S, Ürün Y, van Alphen R, Flechon A, Carducci MA, Choi YD, Hotte SJ, Korbenfeld E, Kramer G, Agarwal N, Chi KN, Dearden S, Gresty C, Kang J, Poehlein C, Harrington EA, Hussain M. Olaparib Efficacy in Patients with Metastatic Castration-resistant Prostate Cancer and BRCA1, BRCA2, or ATM Alterations Identified by Testing Circulating Tumor DNA. Clin Cancer Res 2023; 29:92-99. [PMID: 36318705 PMCID: PMC9811154 DOI: 10.1158/1078-0432.ccr-21-3577] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 12/17/2021] [Accepted: 10/28/2022] [Indexed: 11/16/2022]
Abstract
PURPOSE The phase III PROfound study (NCT02987543) evaluated olaparib versus abiraterone or enzalutamide (control) in metastatic castration-resistant prostate cancer (mCRPC) with tumor homologous recombination repair (HRR) gene alterations. We present exploratory analyses on the use of circulating tumor DNA (ctDNA) testing as an additional method to identify patients with mCRPC with HRR gene alterations who may be eligible for olaparib treatment. PATIENTS AND METHODS Plasma samples collected during screening in PROfound were retrospectively sequenced using the FoundationOne®Liquid CDx test for BRCA1, BRCA2 (BRCA), and ATM alterations in ctDNA. Only patients from Cohort A (BRCA/ATM alteration positive by tissue testing) were evaluated. We compared clinical outcomes, including radiographic progression-free survival (rPFS) between the ctDNA subgroup and Cohort A. RESULTS Of the 181 (73.9%) Cohort A patients who gave consent for plasma sample ctDNA testing, 139 (76.8%) yielded a result and BRCA/ATM alterations were identified in 111 (79.9%). Of these, 73 patients received olaparib and 38 received control. Patients' baseline demographics and characteristics, and the prevalence of HRR alterations were comparable with the Cohort A intention-to-treat (ITT) population. rPFS was longer in the olaparib group versus control [median 7.4 vs. 3.5 months; hazard ratio (HR), 0.33; 95% confidence interval (CI), 0.21-0.53; nominal P < 0.0001], which is consistent with Cohort A ITT population (HR, 0.34; 95% CI, 0.25-0.47). CONCLUSIONS When tumor tissue testing is not feasible or has failed, ctDNA testing may be a suitable alternative to identify patients with mCRPC carrying BRCA/ATM alterations who may benefit from olaparib treatment.
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Affiliation(s)
- Nobuaki Matsubara
- National Cancer Center Hospital East, Chiba, Japan
- Corresponding Author: Nobuaki Matsubara, National Cancer Center Hospital East, 6-5-1, Kashiwanoha, 104-0045 Kashiwa, Chiba, Japan. Phone: 814-7133-1111; Fax: 814-7134-6922; E-mail:
| | - Johann de Bono
- The Institute of Cancer Research and Royal Marsden, London, United Kingdom
| | - David Olmos
- Spanish National Cancer Research Centre (CNIO), Madrid, Spain
- Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga, Spain
| | - Giuseppe Procopio
- Medical Oncology Dept, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Satoru Kawakami
- Department of Urology, Saitama Medical Center, Saitama Medical University, Saitama, Japan
| | - Yüksel Ürün
- Department of Medical Oncology, Ankara University, Ankara, Turkey
| | - Robbert van Alphen
- Department of Oncology, Elisabeth Tweesteden Hospital, Tilburg, the Netherlands
| | - Aude Flechon
- Cancérologie Médicale, Centre Léon-Bérard, Lyon Cedex, France
| | | | - Young Deuk Choi
- Department of Urology, Yonsei University Severance Hospital, Seoul, Republic of South Korea
| | | | | | | | - Neeraj Agarwal
- Huntsman Cancer Institute, University of Utah (NCI-CCC), Salt Lake City, Utah
| | - Kim N. Chi
- University of British Columbia, Vancouver, Canada
| | | | | | | | | | | | - Maha Hussain
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois
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Exploring the Impact of Treatment Switching on Overall Survival from the PROfound Study in Homologous Recombination Repair (HRR)-Mutated Metastatic Castration-Resistant Prostate Cancer (mCRPC). Target Oncol 2021; 16:613-623. [PMID: 34478046 PMCID: PMC8484203 DOI: 10.1007/s11523-021-00837-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2021] [Indexed: 11/29/2022]
Abstract
Background In oncology trials, treatment switching from the comparator to the experimental regimen is often allowed but may lead to underestimating overall survival (OS) of an experimental therapy. Objective This study evaluates the impact of treatment switching from control to olaparib on OS using the final survival data from the PROfound study and compares validated adjustment methods to estimate the magnitude of OS benefit with olaparib. Patients and methods The primary population from PROfound (Cohort A) was included, alongside two populations approved for treatment with olaparib by the European Medicines Agency and US Food and Drug Administration: BRCAm and Cohort A+B (excluding the PPP2R2A gene). Five methods were explored to adjust for switching: excluding or censoring patients in the control arm who receive subsequent olaparib, Rank Preserving Structural Failure Time Model (RPSFTM), Inverse Probability of Censoring Weights, and Two-Stage Estimation. Results The RPSFTM was considered the most appropriate approach for PROfound as the results were robust to sensitivity analysis testing of the common treatment effect assumption. For Cohort A, the final OS hazard ratio reduced from 0.69 (95% CI 0.5–0.97) to between 0.42 (0.18–0.90) and 0.52 (0.31–1.00) for olaparib versus control, depending on the RPSFTM selected. Median OS reduced from 14.7 months to between 11.73 and 12.63 months for control. Conclusions The magnitude of the statistically significant (P < 0.05) survival benefit of olaparib versus control observed in Cohort A of PROfound is likely to be underestimated if adjustment for treatment switching from control to olaparib is not conducted. The RPSFTM was considered the most plausible method, although further development and validation of robust methods to estimate the magnitude of impact of treatment switching is needed. Supplementary Information The online version contains supplementary material available at 10.1007/s11523-021-00837-y.
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