Study: Pleural Mesothelioma Treatment Effective with Peritoneal Disease

The University of Texas MD Anderson Cancer Center has taken an immunotherapy treatment recently approved by the U.S. Food and Drug Administration for pleural mesothelioma and demonstrated similar effectiveness for patients with vastly different peritoneal disease.

In the absence of available clinical trials, doctors in MD Anderson’s Gastrointestinal Medical Oncology department utilized off-label usage of the drug combination to produce surprisingly impressive results for unresectable peritoneal mesothelioma.

Although the two mesothelioma malignancies are immunologically and molecularly different, the treatment was successful for a cohort of patients who volunteered for the study in Houston.

Jama Network Open published the findings in its August issue.

“The efficacy seems comparable,” wrote lead author and heralded oncologist Dr. Kanwal Raghav, associate professor at the University of Texas MD Anderson Cancer Center. “We observed encouraging clinical activity.”

Raghav was not available to provide additional insight to The Mesothelioma Center at Asbestos.com.

Fewer Treatment Options for Peritoneal Patients

The treatment involved the drug combination of nivolumab and ipilimumab, also known by brand names Opdivo and Yervoy, categorized as immune checkpoint inhibitors.

The FDA approved the combination only for pleural mesothelioma in 2020. It was the first new systemic drug approval for mesothelioma in 16 years. Peritoneal mesothelioma was not part of the studies that led to approval.

“There is a critical unmet need for treatment for patients with this rare disease,” the authors wrote. “Given the lack of prospective data, we aimed to define the clinical efficacy of ICIs in patients with MPeM [malignant peritoneal mesothelioma].”

An estimated 1,000 people are diagnosed annually in the U.S. with peritoneal mesothelioma, a cancer that develops within the thin layer of tissue lining the abdomen and often spreads throughout the abdominal cavity.

By comparison, pleural mesothelioma is a thoracic disease that starts in the lining around the lungs. It is diagnosed in approximately 3,000 patients annually within the U.S.

Both types of mesothelioma are caused typically by exposure to asbestos fibers. Neither has a definitive cure.

Study Numbers Show Efficacy

The groundbreaking study involved 29 patients, although nine of those received only one of the two immunotherapy drugs. The study results did not differentiate between the two groups.

Numbers involving all 29 included:

Authors noted there was little difference in disease control when comparing those who received both drugs and those who received only one. There also was little difference between those who had undergone previous chemotherapy treatment and those who had not.

The immunotherapy treatment also was well tolerated, with only one of the 29 patients stopping because of toxic side effects.

Researchers Say Larger Clinical Trials Needed

Although the median survival and progression-free survival using this treatment were comparable between the two types of mesothelioma, the authors cautioned patients from drawing too much from the data because of the differences in disease.

There is a “critical need for dedicated trials and larger cohorts,” study authors wrote.

Peritoneal mesothelioma patients who qualify for a combination of surgery and hyperthermic intraperitoneal chemotherapy, or HIPEC, survive considerably longer than those with pleural mesothelioma.

Although there is no FDA-approved treatment for unresectable peritoneal mesothelioma beyond chemotherapy, there are other immunotherapies also being studied that show even more impressive results.

In a peritoneal mesothelioma clinical trial also led by Raghav, 20 patients with the disease received the combination of Tecentriq and Avastin, known generically as atezolizumab and bevacizumab, also classified as immune checkpoint inhibitors.

Researchers recorded a median progression-free survival of 17.6 months, a one-year progression-free survival of 61% and a one-year survival rate of 85%. They have not yet reached a median survival.

“We report the first real-world evidence regarding clinical outcomes for a cohort of patients with advanced MPeM receiving ICIs,” the MD Anderson study authors wrote. “Our results provide much-needed data supporting the role of ICIs in patients with this rare disease, who cannot participate in clinical trials and otherwise have no or limited treatment options.”

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