The findings, from a randomized expansion cohort of the COSMIC-021 trial, build on previous research that suggested the combination could improve progression-free survival (PFS) in patients with soft tissue metastases.

The trial enrolled 101 patients with advanced disease and visceral or nodal metastases outside the pelvis. Patients were randomly assigned to receive either Cabozantinib alone or Cabozantinib plus Atezolizumab. Both groups had a median age of 70 years, and approximately 75% had bone metastases, with 20-24% having liver metastases. Some had also received prior docetaxel chemotherapy for earlier stages of the disease.

Results showed that tumor response rates were similar between the two groups, with an objective response rate (ORR) of 20% for Cabozantinib alone and 22% for the combination. However, despite similar median PFS across the groups, at 12 months, 25.8% of patients in the combination therapy group remained progression-free, compared to just 14.0% in the monotherapy group.

A key finding emerged in patients with liver metastases, a subgroup with particularly poor prognosis, where the combination therapy nearly tripled overall survival, extending median survival to 14.7 months compared to just 5.0 months in the Cabozantinib-only group.

The study also found that patients receiving the combination therapy had a longer duration of response, fewer instances of disease progression, and an extended PSA response. Median PSA progression-free survival was significantly prolonged in the combination group, suggesting a stronger and more sustained therapeutic effect.

While further studies are needed to confirm these findings, the results suggest that Cabozantinib plus Atezolizumab could provide a meaningful survival benefit, particularly for patients with liver metastases, a group with limited treatment options.

Source.