CUA 2018: Real-World Evidence in Patient-Related Outcomes of Metastatic Castrate-Resistant Prostate Cancer Patients Treated with Abiraterone Acetate Plus Prednisone

Halifax, Nova Scotia ( Abiraterone acetate, given in conjunction with prednisone (AA+P), is an oral androgen biosynthesis inhibitor that targets the androgen axis. It is one of two androgen-receptor axis targeted therapies (the other being enzalutamide) that has dramatically altered the management of advanced prostate cancer. As an oral agent, it is an excellent alternative to chemotherapy (docetaxel) and has become a standard of care for metastatic castration-resistant prostate cancer (mCRPC). Indeed, newer studies have demonstrated benefit in earlier stages of the disease and it may soon be used for hormone-sensitive metastatic prostate cancer. 

However, continued work is looking at the patient-reported outcomes, rather than just oncologic benefit, to these novel agents. The COSMiC study (Canadian Observational Study in Metastatic Cancer of the Prostate; NCT02364531) is one such study and set out to prospectively amass real-world data on mCRPC patients managed with AA+P within Canada. In this presentation, they report the interim analysis. 

At a median follow-up of 39.8 weeks, 264 patients were enrolled from 39 sites. The median age of patients was 77 years. Time from metastasis diagnosis is 16.8 months. Bone metastases predominated (84%) in this population. 47% have Gleason 8-10 disease.

All patients were assessed using the Functional Assessment of Cancer Therapy-Prostate (FACT-P) and Montreal Cognitive Assessment (MoCA) tests at baseline and then again at weeks 12, 24, 48, and 72 after AA+P initiation. A 10-point drop denotes clinically significant degradation in FACT-P and a total MoCA score of ≥26 is considered normal. 

  • In term of available responses, response rates dropped significantly throughout the study trial period
  • Starting at 100% at baseline, response rates dropped to 72% week 24, and 24% at week 72 and 22% at the end of the study
Mean baseline FACT-P total score was 111.2 (19.44). On follow-up, at all time points, there was a <3-point absolute change from baseline, denoting no clinically significant change in functional status over time.

The mean baseline MoCA score was 25.2 (4.50) – lower than normal at baseline. Yet all subsequent assessments after baseline scored above 26 and a mean absolute change from baseline of <1, showing an absence of cognitive decline over time. 

In terms of oncologic outcomes, which was not the primary outcome, prostate-specific antigen (PSA) value was available for 221 patients; 64.3% (142/221) and 34.4% (76/221) achieved a PSA decline of >50% and 90%, respectively. This was in line with COU-AA 302 results. 

Lastly, in terms of tolerability, all-grade treatment-related adverse events were reported in 63 patients, with 11% who have had AA+P discontinuation/interruption. This was less than previously reported.

Ultimately, in this interim analysis of the COSMiC study, AA+P, in a real-world setting, appears to maintain men’s quality of life and cognitive status over the course of treatment.

Presented by: Gotto, Geoffrey, MD, Urologic Oncologist, University of Calgary, Calgary, Canada

Co-Authors: Geoffrey Gotto1, Vincent Fradet2, Darrel Drachenberg3, Robert Sabbagh4, Ricardo Rendon5, Bobby Shayegan6, Brita Danielson7, Richard Casey8, Katherine Chan9, Fernando Camacho10, Anousheh Zardan9, Huong Hew9, Andrew H. Feifer11.
Author Information:
1. Division of Urology, University of Calgary, Calgary, AB, Canada 
2. Department of Surgery, Université Laval, Quebec, QC, Canada 
3. Division of Urology, University of Manitoba, Winnipeg, MB, Canada
4. Department of Surgery, Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
5. Queen Elizabeth II Health Science Centre, Dalhousie University, Halifax, NS, Canada
6. Division of Urology, McMaster University, Hamilton, ON, Canada
7. Division of Radiation Oncology, University of Alberta, Edmonton, AB, Canada
8. The Male Health Centre, Oakville, ON, Canada
9. Medical Affairs - Oncology, Janssen Inc., Toronto, ON, Canada
10. Damos, North York, ON, Canada
11. Department of Surgery, University of Toronto, Toronto, ON, Canada

Written By: Thenappan Chandrasekar, MD, Clinical Fellow, University of Toronto   Twitter: @tchandra_uromd at the 73rd Canadian Urological Association Annual Meeting - June 23 - 26, 2018 - Halifax, Nova Scotia
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