Immunotherapy before and after surgery may open door to better outcomes for mesothelioma patients

Mesothelioma of the left lower lung on X-ray. Image by James Heilman, MD under Creative Commons license on Wikimedia

CANCER DIGEST – Sept. 21, 2025 – People with a rare form of lung cancer called mesothelioma with tumors that can be treated with surgery, may benefit from receiving immunotherapy before and after surgery, according to results  of a small phase II clinical trial.

Mesothelioma is a rare cancer of the tissues that line many organs, including the pleura or lining of lung tissue. It has been linked to asbestos exposure. According to lead author of this trial, Joshua Reuss, MD, a thoracic oncologist at Georgetown University’s Lombardi Comprehensive Cancer Center, mesothelioma is a difficult cancer to treat.

 “Our study demonstrated the feasibility and safety of using immunotherapy before surgery for patients who have tumors that can potentially be removed surgically," Reuss, who began the trial at Johhs Hopkins Kimmel Cancer Center, said in a press release. “Immunotherapy is making substantial contributions to extending the lives of patients with lung cancer and many other solid tumors. This is an important step in identifying mesothelioma patients who could benefit from immunotherapy in the perioperative period, meaning right before or after their surgery, and in choosing patients who are actually candidates for that surgery.”

In the trial conducted at multiple cancer centers, 30 patients with operable mesothelioma who had not started any treatments were allocated to two treatment regimens, 16 in group A received immunotherapy (nivolumab) before surgery and 14 in group B received nivolumab (Opdivo®) before and after surgery. Both groups also received radiotherapy or chemotherapy after surgery. The results were presented to the World Conference on Lung Cancer, Sept. 8, 2025 in Barcelona Spain, ahead of publication in the Sept. 8, 2025 journal Nature Medicine. 

In Group A. progression free survival was 9.6 months and overall survival was 19.3 months for 14 patients who died. In Group B, progression free survival reached 19.8 months and overall survival (median not reached) was 28.6 months with 6 patients dying at the time of this study report.

During the trial the patients' blood was regularly tested for traces of the cancer circulating in the blood. Using ultra-sensitive DNA technology the researchers were able to detect signs of cancer that could not be shown using imaging. 

Reuss said the benefit of the blood analysis is that it gives clinicians another tool for monitoring treatment and predicting which patients are most likely to benefit from treatment or are likely to relapse.

 “Up until now, ctDNA assessments have not been part of the clinical landscape in the management of diffuse pleural mesothelioma, but our analyses suggest this may be nearing a change in the future,” Reuss said.

He further cautioned that this small study does not tell whether adding immunotherapy  before and after surgery will improve outcomes for these patients, but it opens up opportunities for further studies that may lead to better treatment for mesothelioma patients.

Sources: Georgetown University press release, and Sept. 8, 2025 Nature Medicine