Publications by authors named "Conrad Oja"

6 Publications

  • Page 1 of 1

Evolution of Castration-Resistant Prostate Cancer in ctDNA during Sequential Androgen Receptor Pathway Inhibition.

Clin Cancer Res 2021 Aug 3;27(16):4610-4623. Epub 2021 Jun 3.

Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, British Columbia, Canada.

Purpose: Cross-resistance renders multiple lines of androgen receptor (AR) signaling inhibitors increasingly futile in metastatic castration-resistant prostate cancer (mCRPC). We sought to determine acquired genomic contributors to cross-resistance.

Experimental Design: We collected 458 serial plasma cell-free DNA samples at baseline and progression timepoints from 202 patients with mCRPC receiving sequential AR signaling inhibitors (abiraterone and enzalutamide) in a randomized phase II clinical trial (NCT02125357). We utilized deep targeted and whole-exome sequencing to compare baseline and posttreatment somatic genomic profiles in circulating tumor DNA (ctDNA).

Results: Patient ctDNA abundance was correlated across plasma collections and independently prognostic for sequential therapy response and overall survival. Most driver alterations in established prostate cancer genes were consistently detected in ctDNA over time. However, shifts in somatic populations after treatment were identified in 53% of patients, particularly after strong treatment responses. Treatment-associated changes converged upon the gene, with an average 50% increase in copy number, changes in mutation frequencies, and a 2.5-fold increase in the proportion of patients carrying AR ligand binding domain truncating rearrangements.

Conclusions: Our data show that the dominant genotype continues to evolve during sequential lines of AR inhibition and drives acquired resistance in patients with mCRPC.
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August 2021

Optimal sequencing of enzalutamide and abiraterone acetate plus prednisone in metastatic castration-resistant prostate cancer: a multicentre, randomised, open-label, phase 2, crossover trial.

Lancet Oncol 2019 12 11;20(12):1730-1739. Epub 2019 Nov 11.

Division of Medical Oncology, BC Cancer, Vancouver, BC, Canada; Vancouver Prostate Centre, Vancouver, BC, Canada. Electronic address:

Background: Abiraterone acetate plus prednisone and enzalutamide are both used for the treatment of metastatic castration-resistant prostate cancer. We aimed to determine the best sequence in which to use both drugs, as well as their second-line efficacy.

Methods: In this multicentre, randomised, open-label, phase 2, crossover trial done in six cancer centres in British Columbia, Canada, we recruited patients aged 18 years or older with newly-diagnosed metastatic castration-resistant prostate cancer without neuroendocrine differentiation and Eastern Cooperative Oncology Group performance status 2 or less. Patients were randomly assigned (1:1) using a computer-generated random number table to receive either abiraterone acetate 1000 mg orally once daily plus prednisone 5 mg orally twice daily until PSA progression followed by crossover to enzalutamide 160 mg orally once daily (group A), or the opposite sequence (group B). Treatment was not masked to investigators or participants. Primary endpoints were time to second PSA progression and PSA response (≥30% decline from baseline) on second-line therapy, analysed by intention-to-treat in all randomly assigned patients and in patients who crossed over, respectively. The trial is registered with, NCT02125357.

Findings: Between Oct 21, 2014, and Dec 13, 2016, 202 patients were enrolled and randomly assigned to either group A (n=101) or group B (n=101). At the time of data cutoff, 73 (72%) patients in group A and 75 (74%) patients in group B had crossed over. Time to second PSA progression was longer in group A than in group B (median 19·3 months [95% CI 16·0-30·5] vs 15·2 months [95% CI 11·9-19·8] months; hazard ratio 0·66, 95% CI 0·45-0·97, p=0·036), at a median follow-up of 22·8 months (IQR 10·3-33·4). PSA responses to second-line therapy were seen in 26 (36%) of 73 patients for enzalutamide and three (4%) of 75 for abiraterone (χ p<0·0001). The most common grade 3-4 adverse events throughout the trial were hypertension (27 [27%] of 101 patients in group A vs 18 [18%] of 101 patients in group B) and fatigue (six [10%] vs four [4%]). Serious adverse events were reported in 15 (15%) of 101 patients in group A and 20 (20%) of 101 patients in group B. There were no treatment-related deaths.

Interpretation: Enzalutamide showed activity as a second-line novel androgen receptor pathway inhibitor, whereas abiraterone acetate did not, leading to a longer time to second PSA progression for the sequence of abiraterone followed by enzalutamide than with the opposite treatment sequence. Our data suggest that using a sequencing strategy of abiraterone acetate followed by enzalutamide provides the greatest clinical benefit.

Funding: Canadian Cancer Society Research Institute, Prostate Cancer Canada, Movember Foundation, Prostate Cancer Foundation, Terry Fox New Frontiers Program, BC Cancer Foundation, Jane and Aatos Erkko Foundation, Janssen, and Astellas.
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December 2019

Health-related Quality of Life for Abiraterone Plus Prednisone Versus Enzalutamide in Patients with Metastatic Castration-resistant Prostate Cancer: Results from a Phase II Randomized Trial.

Eur Urol 2019 06 24;75(6):940-947. Epub 2018 Dec 24.

Department of Medical Oncology, BC Cancer Vancouver Centre, Vancouver, BC, Canada; Department of Urological Sciences, The Vancouver Prostate Centre, University of British Columbia, Vancouver, BC, Canada. Electronic address:

Background: Abiraterone and enzalutamide are associated with side effects that may impair health-related quality of life (HRQoL).

Objective: To assess patient-reported HRQoL, depression symptoms, and cognitive function for abiraterone versus enzalutamide.

Design, Setting, And Participants: We randomized 202 patients in a phase II study of abiraterone versus enzalutamide for first-line treatment of metastatic castration-resistant prostate cancer ( NCT02125357).

Intervention: Patients completed Functional Assessment of Cancer Therapy-Prostate (FACT-P) and Patient Health Questionnaire-9 (PHQ-9) questionnaires, and Montreal Cognitive Assessment (MoCA) cognitive assessments at baseline and on treatment.

Outcome Measurements And Statistical Analysis: To compare the change in FACT-P scores over time between treatment arms, we used a mixed model for repeated measures (MMRM). For FACT-P domains where there was an interaction between the treatment arm and age, we constructed separate models for patients aged <75 and ≥75yr. We compared the proportion of patients with clinically meaningful change from baseline for FACT-P, and the proportion of patients with an abnormal score and median change from baseline for PHQ-9 and MoCA using Fisher's exact test and Mann-Whitney U test.

Results And Limitations: In the MMRM analysis, there was a positive test for interaction in the treatment arm by age for total FACT-P (p=0.048). FACT-P change from baseline over time was better for abiraterone than for enzalutamide in the ≥75-yr model (p=0.003), with no difference in the <75-yr model (p>0.9). A higher proportion of patients experienced clinically meaningful worsening with enzalutamide for the physical and functional well-being domains (37% vs 21%, p=0.013; 39% vs 23%, p=0.015). The distribution of change in PHQ-9 scores from baseline favored abiraterone at weeks 4, 8, and 12. These analyses were not prespecified, and results should be considered to be hypothesis generating.

Conclusions: Patient-reported outcomes favored abiraterone compared with enzalutamide with differences in FACT-P HRQoL and PHQ-9 depression scores. Differences in the total FACT-P scores were seen only in the elderly patient subgroup.

Patient Summary: In this report, we examined the change in patient-reported quality-of-life scores from the start of treatment over time for patients treated with abiraterone versus enzalutamide for metastatic castration-resistant prostate cancer. We found that elderly patients treated with abiraterone had better quality of life over time, with no difference between treatments for the younger subgroup of patients.
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June 2019

Immune system trickery and deception: Allograft-derived neuroendocrine carcinoma post kidney transplantation.

Urol Case Rep 2018 Nov 14;21:89-91. Epub 2018 Sep 14.

Department of Urologic Sciences, University of British Columbia, Level 6 2775 Laurel Street, Vancouver, BC, V5Z 1M9, Canada.

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November 2018

Circulating Tumor DNA Genomics Correlate with Resistance to Abiraterone and Enzalutamide in Prostate Cancer.

Cancer Discov 2018 04 24;8(4):444-457. Epub 2018 Jan 24.

Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada.

Primary resistance to androgen receptor (AR)-directed therapies in metastatic castration-resistant prostate cancer (mCRPC) is poorly understood. We randomized 202 patients with treatment-naïve mCRPC to abiraterone or enzalutamide and performed whole-exome and deep targeted 72-gene sequencing of plasma cell-free DNA prior to therapy. For these agents, which have never been directly compared, time to progression was similar. Defects in and were strongly associated with poor clinical outcomes independently of clinical prognostic factors and circulating tumor DNA abundance. Somatic alterations in , previously linked to reduced tumor dependency on AR signaling, were also independently associated with rapid resistance. Although detection of amplifications did not outperform standard prognostic biomarkers, gene structural rearrangements truncating the ligand binding domain were identified in several patients with primary resistance. These findings establish genomic drivers of resistance to first-line AR-directed therapy in mCRPC and identify potential minimally invasive biomarkers. Leveraging plasma specimens collected in a large randomized phase II trial, we report the relative impact of common circulating tumor DNA alterations on patient response to the most widely used therapies for advanced prostate cancer. Our findings suggest that liquid biopsy analysis can guide the use of AR-targeted therapy in general practice. .
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April 2018

Effect of metformin vs placebo on and metabolic factors in NCIC CTG MA.32.

J Natl Cancer Inst 2015 Mar 4;107(3). Epub 2015 Mar 4.

Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada (PJG); NCIC Clinical Trials Group, Cancer Research Institute, Queen's University, Kingston, Ontario, Canada (WRP, LES, BEC); NCIC Clinical Trials Group, British Columbia Cancer Agency, University of British Columbia, Vancouver, British Columbia, Canada (KAG); Dana Farber Cancer Institute, Harvard Medical School, Boston, MA (JAL); Columbia University Medical Center, New York, NY (DLH); National Surgical Adjuvant Breast and Bowel Project, University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, PA (PR); Vanderbilt-Ingram Medical Center, Vanderbilt University Medical Center, Nashville, TN (IAM); Mayo Clinic College of Medicine, Rochester, MN (TJH); Centre de recherche du CHU de Québec, Unité de recherche en santé des populations Hôpital du Saint-Sacrement, Quebec, Quebec, Canada (JL); National Cancer Research Institute Breast Clinical Studies Group, London, UK (AMT); Sunnybrook Odette Cancer Center, University of Toronto, Toronto, Ontario, Canada (KIP); Juravinski Cancer Center at Hamilton Health Sciences, McMaster University, Hamilton, Ontario, Canada (TJW, SDM); Allan Blair Cancer Centre, Regina, Saskatchewan, Canada (HIC); British Columbia Cancer Agency, Fraser Valley Center, Surrey, British Columbia, Canada (CDO); University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada (KST); British Columbia Cancer Agency - Vancouver Island Center, University of British Columbia, British Columbia, Canada (VB); Ontario Cancer Institute, University Health Network, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, Canada (VS).

Background: Metformin may improve metabolic factors (insulin, glucose, leptin, highly sensitive C-reactive protein [hs-CRP]) associated with poor breast cancer outcomes. The NCIC Clinical Trials Group (NCIC CTG) MA.32 investigates effects of metformin vs placebo on invasive disease-free survival and other outcomes in early breast cancer. Maintaining blinding of investigators to outcomes, we conducted a planned, Data Safety Monitoring Committee-approved, analysis of the effect of metformin vs placebo on weight and metabolic factors at six months, including examination of interactions with baseline body mass index (BMI) and insulin, in the first 492 patients with paired blood samples.

Methods: Eligible nondiabetic subjects with T1-3, N0-3, M0 breast cancer who had completed surgery and (neo)adjuvant chemotherapy (if given) provided fasting plasma samples at random assignment and at six months. Glucose was measured locally; blood was aliquoted, frozen, and stored at -80°C. Paired plasma aliquots were analyzed for insulin, hs-CRP, and leptin. Spearman correlation coefficients were calculated and comparisons analyzed using Wilcoxon signed rank test. All statistical tests were two-sided.

Results: Mean age was 52.1±9.5 years in the metformin group and 52.6 ± 9.8 years in the placebo group. Arms were balanced for estrogen/progesterone receptor, BMI, prior (neo)adjuvant chemotherapy, and stage. At six months, decreases in weight and blood variables were statistically significantly greater in the metformin arm (vs placebo) in univariate analyses: weight -3.0%, glucose -3.8%, insulin -11.1%, homeostasis model assessment -17.1%, leptin -20.2%, hs-CRP -6.7%; all P values were less than or equal to .03. There was no statistically significant interaction of change in these variables with baseline BMI or insulin.

Conclusions: Metformin statistically significantly improved weight, insulin, glucose, leptin, and CRP at six months. Effects did not vary by baseline BMI or fasting insulin.
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March 2015