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Predictive genomic biomarkers in non-metastatic castration resistant prostate cancer (nmCRPC) treated with androgen receptor pathway inhibitors (ARPi)

Predictive genomic biomarkers in non-metastatic castration resistant prostate cancer (nmCRPC) treated with androgen receptor pathway inhibitors (ARPi)

ABSTRACT ONLY| VOLUME 32, SUPPLEMENT 5S647, SEPTEMBER 01, 2021

Predictive genomic biomarkers in non-metastatic castration resistant prostate cancer (nmCRPC) treated with androgen receptor pathway inhibitors (ARPi)

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Background

Although recent trials have demonstrated overall survival (OS) and metastasis free survival (MFS) benefit with the use of ARPi in high-risk nmCRPC, individual treatment outcomes may vary. This retrospective multicentre analysis explores the association between genomic mutations with ARPi treatment outcomes in nmCRPC patients to identify predictive biomarkers.

Methods

In high-risk nmCRPC patients treated with apalutamide, enzalutamide or darolutamide at APCaRI affiliated cancer centres, median MFS, OS, PSA decline ≥ 50% from baseline (PSA50), and second progression free survival (PFS2) were calculated. Next generation gene sequencing (NGS) was performed on archival tumour tissue examining for genomic alterations in 500 genes, including homologous recombination repair (HRR), mismatch repair, tumour suppressor (TS), and PI3K/AKT oncogene (OG) groups. Analysis was conducted using Cox proportional hazards regression using wildtype cases as the reference group, while adjusting for PSA doubling time and presence of pelvic lymph nodes.

Results

Of 32 nmCRPC patients, 25 (78%) were treated with apalutamide, 5 (16%) with darolutamide and 2 (6%) with enzalutamide. 10 patients (31%) had TS/OG mutations (5 PTEN, 8 TP53, 2 PIK3CA), 3 (9%) had HRR gene mutations (2 ATM, 1 BRCA2) and 1 (3%) had 2 MLH1 mutations (microsatellite instability). All 5 patients who received subsequent therapy received abiraterone. Patients with TS/OG mutations had significantly shorter MFS (16.4 mo; HR 5.2; 95% CI 1.4 – 25.7; p = 0.018), PFS2 (22.1 mo; HR 15.4; 95% CI 1.9 – 126.3; p = 0.011) and OS (24.1 mo; HR 8.3; 95% CI 1.2 – 58.8; p = 0.035). Those with HRR mutations had significantly reduced PFS2 (median not reach [NR]; HR 40.4; 95% CI 1.6 – 1034.2; p = 0.025) and OS (NR; HR 21.7; 95% CI 1.1 – 446.1; p = 0.045). 3 (9%) patients did not achieve PSA50, including a patient with 2 MLH1 mutations.

Conclusions

This analysis demonstrates that nmCRPC patient with TS/OG and HRR gene mutations have poor clinical outcomes and may benefit from close follow-up. Our results underline the need for ongoing trials which examine novel targeted therapies (e.g. PARP Inhibitors, AKT inhibitors) in these molecularly defined nmCRPC subgroups.
Physician in operating room

APCaRI and UofA researchers could help diagnose prostate cancer severity more accurately

Adam Kinnaird is co-leading new research to develop precision diagnostics that could predict which men are at risk of more aggressive prostate cancer, based on mutations in their genes. (Photo: Faculty of Medicine & Dentistry; taken pre-COVID-19)

Folio Magazine, Published April 13, 2021 By Keri Sweetman
Scientists at the University of Alberta are part of a new research project to develop innovative precision diagnostics that could predict which men with prostate cancer are at risk of developing an aggressive form of the disease.
The researchers will use germline sequencing (sequencing of the genes a person is born with) to determine which genetic mutations predispose men to aggressive prostate cancer.

“Even though two men may have localized prostate cancer, their cases can be quite different depending on what genes have mutated,” explained John Lewis, who holds the Frank and Carla Sojonky Chair in Prostate Cancer Research funded by Alberta Cancer Foundation and is one of the project leaders. “The project will look at the contribution of your genetics to your risk of having aggressive prostate cancer.”

Prostate cancer is the most commonly diagnosed internal cancer in men in Canada and worldwide. The Canadian Cancer Society estimates that more than 23,000 men were diagnosed with prostate cancer last year, representing 20 percent of all new cancer cases in men.

The vast majority of men with prostate cancer have a non-aggressive form of the disease, at least at the time of initial diagnosis. But even as recently as 15 years ago, most of these men underwent surgery or radiation, which came with significant side effects such as incontinence, erectile dysfunction, and bowel problems.
Today, most men diagnosed with prostate cancer are placed on “active surveillance,” where they are monitored with yearly prostate-specific antigen (PSA) blood tests and biopsies to ensure their cancer has not progressed. When those yearly tests turn up evidence that the cancer is worsening, the patients are offered surgery, radiation, chemotherapy, or other treatments.

“We know, based on old data, that at least 30 percent of men will progress to worse tumours while we’re watching them,” said project leader Adam Kinnaird, a urologic surgeon, assistant professor in the U of A’s Department of Surgery and a member of the Alberta Prostate Cancer Research Initiative. “Is there a way from the get-go, when you start a man on active surveillance, that you can determine if his cancer is more likely to progress and require treatment?”

That’s the goal of the project, which aims to use new technologies to decide sooner which men are likely to develop more aggressive and potentially deadly prostate cancer.
Some mutations associated with aggressive prostate cancer have already been identified but the team will look for more, using unique germline-sequencing software designed by the University of California, Los Angeles’s Paul Boutros, a world leader in prostate cancer sequencing and a collaborator on this project.

Blood samples from almost 1,500 men who have been diagnosed with prostate cancer—including almost 300 from Edmonton—have been shipped to UCLA for sequencing over the next six months to a year. A seed grant from the U of A’s Precision Health Seed Fund Award will pay for the germline sequencing of the Edmonton samples, “allowing Edmonton to be part of an important multi-center and international project,” said Kinnaird. “This seed funding is critical because it allows us to take the first steps in the project,” he said.

Germline sequencing isn’t the only new precision strategy these scientists plan to use in their research.
In their larger research project, which has not yet been funded, they will focus on targeted biopsy, a new technique using multi-parametric MRI and ultrasound, to do more precise biopsies of hot spots in the prostate that are more likely to contain aggressive tumours. Kinnaird said funding from the University Hospital Foundation was recently used to purchase the first MRI/ultrasound fusion biopsy device for Edmonton.

Lewis said he is confident that once the larger project is funded and work begins on both germline sequencing and targeted biopsy, their research could change standard prostate cancer treatment within two or three years.
Lewis describes this scenario in the future: A man diagnosed with prostate cancer gives a blood sample, which is sequenced to look for germline mutations associated with aggressive cancer. Then, using the more accurate MRI/ultrasound targeted biopsy, doctors will be able to check his prostate for hot spots and predict more accurately whether he is likely to develop more aggressive cancer in the future.

“We want to improve outcomes,” said Lewis. “The goal would be, for men who go on active surveillance in Alberta, we want to have fewer failures.”

Find out more about the innovative precision health research happening at the U of A.

- Perrin Beatty