Immunotherapy for brain cancer metastases shows clinical benefit (42% response rate with pembrolizumab)

Medical Xpress / Mass General Brigham / Nature Medicine ^ | June 2, 2023 | Brastianos, P.K. et al

[ConservativeMind]

In a phase 2 clinical trial of the immune checkpoint inhibitor pembrolizumab, investigators found that 42 percent of patients with metastatic brain cancer benefited from the therapy, with seven patients in the trial surviving longer than two years.

"There are very few effective treatments for patients with brain metastases. Our overarching objective is to find improved therapies for this patient population," said Priscilla K. Brastianos, MD. "With this trial, we investigated pembrolizumab, which is an immunotherapy for patients with brain metastases. We showed that pembrolizumab was tolerated and showed clinical benefit in the brain in 42 percent of patients, which is promising for this patient population."

The single-arm, open-label, phase 2 trial included nine patients with previously untreated, asymptomatic brain metastases (cohort A) and 48 patients with recurrent and progressive disease after prior therapy (cohort B). Participants were enrolled between Oct. 6, 2016 and Oct. 16, 2018.

The primary endpoint of the study was response rate, including complete response, partial response, or stable disease. Patients in the trial had primary tumor diagnoses that included breast, melanoma, non-small cell lung, small-cell lung, pituitary, and other cancers.

The research team found that 24 of the 57 patients had an intracranial benefit, with five patients experiencing a complete or partial response to treatment. This included three patients in cohort A and 21 in cohort B, meaning the study achieved its primary endpoint.

The team also reported that median overall survival for participants was 8 months. While the study did not have a control arm, previous studies have estimated overall survival for patients with brain metastases to be 4-6 months. Seven patients in the study experienced prolonged overall survival of two or more years, including five patients with primary breast cancer, one patient with primary melanoma and one patient with primary sarcoma.

[ConservativeMind]

This immunotherapy is widely available.

[ConservativeMind]

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