Detailed results of phase III CONTACT-02 pivotal trial evaluating cabozantinib + atezolizumab in metastatic castration-resistant prostate cancer presented at ASCO GU 2024

The detailed findings are being presented during Oral Abstract Session A: Prostate Cancer at 7:55 a.m. PST on January 25 at the American Society of Clinical Oncology 2024 Genitourinary Cancers Symposium (ASCO GU).

“Patients with metastatic castration-resistant prostate cancer with prior progression on a novel hormone therapy and who have measurable soft tissue metastasis experience the worst outcomes among advanced prostate cancer patients and have limited treatment options,” said Neeraj Agarwal, M.D., FASCO, Senior Director for Clinical Research at Huntsman Cancer Institute at the University of Utah and the global lead investigator of the trial. “CONTACT-02 is the only phase III study evaluating a tyrosine kinase inhibitor and an immune checkpoint inhibitor to show a statistically significant improvement in progression-free survival and a trend for overall survival in these patients. I am encouraged by these results and the potential for cabozantinib plus atezolizumab to be a widely available treatment option for our patients.”

As announced in August 2023, CONTACT-02 met one of its primary endpoints, demonstrating a statistically significant improvement in progression-free survival (PFS) as assessed by a blinded independent radiology committee (BIRC) and per RECIST 1.1. The PFS analysis was conducted in the first 400 randomized patients in the intent-to-treat (PFS ITT) population and per protocol. Similar results were observed for all patients.

Detailed results presented at ASCO GU show that at a median follow-up of 14.3 months for the PFS ITT population, the hazard ratio (HR) was 0.65 (95% confidence interval [CI]: 0.50-0.84; p=0.0007); the median PFS (mPFS) was 6.3 months for cabozantinib in combination with atezolizumab compared with 4.2 months for second NHT. This was nearly identical to the PFS for the ITT population (n=507): HR was 0.64 (95% CI: 0.50-0.81, p=0.0002); mPFS was 6.3 months for cabozantinib in combination with atezolizumab and was 4.2 months for second NHT. At a median follow-up of 12.0 months for the ITT population, the median overall survival (OS) was 16.7 months for cabozantinib in combination with atezolizumab compared with 14.6 months for second NHT (HR: 0.79; 95% CI: 0.58-1.07; p=0.13). While a trend toward OS improvement was observed, the data were immature and did not meet the threshold for statistical significance. The study will continue to the next analysis of OS, anticipated in 2024.

Treatment-emergent adverse events (AEs) occurred in 97% of patients treated with cabozantinib in combination with atezolizumab (n=248) compared with 87% of patients treated with a second NHT (n=253), 48% and 23% of which were grade 3/4, respectively. Grade 5 treatment-emergent AEs occurred in 8% of patients treated with the combination regimen compared with 12% of patients treated with a second NHT; no grade 5 treatment-related AEs occurred in either arm. Treatment-related AEs led to the discontinuation of any treatment component in 13% of patients treated with the combination regimen and 2% of patients treated with a second NHT. For all treatment components, the treatment-related AEs leading to discontinuation were 5% vs. 2%, respectively.

"Given there are limited options after progression on novel hormonal therapy, we recognize the need for a regimen that can delay disease progression, that has an acceptable tolerability profile and that is widely available to patients who may not have the means or desire to travel to specialized centers for other therapies,” said Amy Peterson, M.D., Executive Vice President, Product Development & Medical Affairs, and Chief Medical Officer, Exelixis. “Our decision to conduct CONTACT-02, based upon a signal we observed in COMET-01, underscores our commitment to patients with advanced prostate cancer and to improving their standard of care. We look forward to discussing these important results with the FDA, and to learning more in the next analysis of overall survival, anticipated this year.”