Addition of Novel Hormonal Agents to Standard Therapy Explored in Node-Positive Prostate Cancer

Ronald Chen, MD, MPH, of the University of Kansas Medical Center

Ronald Chen, MD, MPH

Investigators are examining whether the addition of apalutamide (Erleada), abiraterone acetate (Zytiga), and prednisone to standard hormone therapy and radiation therapy will be more effective than standard treatment alone in patients with node-positive prostate cancer following radical prostatectomy in an ongoing phase 3 trial (NRG-GU008; NCT04134260).^1,2

In the randomized trial, which launched on March 5, 2020, and is currently recruiting patients, men will receive the triplet regimen in combination with salvage radiotherapy and a gonadotropin-releasing hormone (GnRH) agonist or salvage radiotherapy combined with a GnRH regimen alone. The primary objective of the trial is to determine whether either treatment approach will improve metastasis-free survival (MFS).

Although node-positive prostate cancer is a very aggressive disease, it is potentially curable; however, very few clinical trials have evaluated the optimal treatment for this patient population, according to press release issued by NRG Oncology.

"Node-positive prostate cancer is classified as 'stage 4' disease and has been understudied in clinical trials," principal investigator Ronald Chen, MD, MPH, of the University of Kansas Medical Center stated in the press release. "This trial is the only one specifically for patients [with node-positive disease], and will determine if adding novel hormonal agents to standard treatment will improve outcomes."

To be eligible for enrollment on the trial, patients need to have undergone a radical prostatectomy and be found to have node-positive disease on surgical pathology. Patients must also have a detectable prostate-specific antigen (PSA), as they will be stratified by their PSA history following prostatectomy before they are randomized to 1 of the 2 treatment arms.

Patients within Arm 1 of the trial will receive standard-of-care hormone therapy per physician discretion for a duration of 24 months. They will also undergo standard-of-care pelvis and prostate bed radiation therapy 5 days/week over the course of 7 to 8 weeks. The radiation therapy will begin either within 56 days following the first hormone injection, if the injection is not started prior to registration, or within 90 days after the first hormone injection, if the injection is started prior to registration in the absence of disease progression or unacceptable toxicity.

Those in Arm 2 of the trial will receive standard-of-care hormone therapy and radiation therapy, just as those in Arm 1. However, patients in Arm 2 will also receive apalutamide and abiraterone acetate orally once daily, and prednisone orally either once daily or twice daily on days 1 to 90. The cycles will repeat every 90 days for 8 cycles or until either the absence of disease progression or unacceptable toxicity. Once the study treatment is completed, patients will be followed up every 6 months for 3 years. Beyond 3 years, patients will be followed up on an annual basis.

Investigators will also compare the following between treatment arms: health-related quality of life; overall survival, biochemical progression-free survival, time to local-regional progression, time to castrate resistance, and cancer-specific survival; and short-term and long-term treatment-related adverse events.

The study is being done in collaboration with the National Cancer Institute and has an estimated completion date of November 1, 2031.

In February 2018, the FDA approved the use of abiraterone acetate in combination with prednisone for use in patients with high-risk metastatic castration-sensitive prostate cancer (mCSPC). The regulatory decision was based on early data from the phase 3 LATITUDE trial, which showed a 38% reduction in the risk of death with the addition of abiraterone acetate and prednisone to androgen deprivation therapy (ADT) compared with ADT alone (HR, 0.62; 95% CI, 0.51-0.76; P <.001).³

More recently, in September 2019, apalutamide was also granted an approval from the FDA for the treatment of patients with mCSPC based on findings from the phase 3 TITAN trial, which showed that apalutamide plus ADT resulted in a 33% reduction in the risk of death compared with placebo and ADT in this patient population (HR, 0.67; 95% CI, 0.51-0.89; P = .0053).^4,5

References

1. NRG oncology trial explores the addition of novel hormonal therapy agents to the usual treatment for node-positive prostate cancer. News release. NRG Oncology; April 15, 2020. Accessed April 24, 2020. bit.ly/3bMMSIt.
2. Testing the Addition of the Drugs, Apalutamide and Abiraterone Acetate with Prednisone, to the Usual Hormone Therapy and Radiation Therapy After Surgery for Prostate Cancer. www. https://clinicaltrials.gov/ct2/show/NCT04134260. Updated April 20, 2020. Accessed April 24, 2020.
3. Fizazi K, Tran NP, Fein L, et al. Abiraterone plus prednisone in metastatic, castration-sensitive prostate cancer. N Engl J Med. 2017;377(4):352-360. doi:10.1056/NEJMoa1704174
4. Chi KN, Agarwal N, Bjartell A, et al. First results from TITAN: a phase III double-blind, randomized study of apalutamide (APA) versus placebo (PBO) in patients (pts) with metastatic castration-sensitive prostate cancer (mCSPC) receiving androgen deprivation therapy (ADT). J Clin Oncol. 2019;37(suppl 15; abstr 5006). doi:10.1200/JCO.2019.37.15_suppl.5006
5. Chi KN, Agarwal N, Bjartell A, et al. Apalutamide for metastatic, castration-sensitive prostate cancer. N Eng J Med. 2019;381:13-24. doi:10.1056/NEJMoa1903307