4 Things to Know About Immunotherapy for Peritoneal Mesothelioma

1: Immunotherapies Are Improving Peritoneal Mesothelioma Life Expectancy

For many years, mesothelioma patients had fairly limited treatment options. When patients didn't qualify for surgery, chemotherapy was the only real option. It also wasn't very effective, with average survival of just over a year.

But immunotherapy has changed the outlook for inoperable cases. You can see the study results below.

The authors of the Opdivo+Yervoy study above say the combo seems to have similar success in pleural and peritoneal cases. These results are good news for peritoneal patients because the Food and Drug Administration (FDA) approved the pair in late 2020. The approval is only for treating pleural mesothelioma when surgery is not an option.

But this approval language didn't stop Opdivo+Yervoy from becoming a peritoneal mesothelioma treatment.

2: Immunotherapy Drugs Are Standard Without Specific FDA Approval

The headline is correct. Some drugs have become standard options without FDA approval for treating peritoneal mesothelioma. Official FDA approval of a cancer drug typically requires large studies. But enrolling hundreds of patients with such a rare cancer can be tough, making major clinical trials a bit scarce.

Only a few studies have looked at systemic treatments for peritoneal mesothelioma. Most of those trials evaluated chemotherapy. None resulted in FDA approval of any systemic treatment for peritoneal mesothelioma.

Despite not having approval, medical societies still publish peritoneal mesothelioma treatment guidelines. According to one set, systemic treatments work as well on pleural tumors as they do for peritoneal tumors. So recommended treatments generally come from pleural mesothelioma studies and FDA approvals.

This means some standard treatments are not FDA approved for peritoneal mesothelioma, including:

• Chemotherapy with Keytruda immunotherapy
• Chemotherapy with pemetrexed and cisplatin
• Chemotherapy with pemetrexed, cisplatin and Avastin
• Immunotherapy with Opdivo
• Immunotherapy with Opdivo+Yervoy

Peritoneal mesothelioma patients have 3 immunotherapy-based standard treatment options. In some cases, these options are preferred over chemotherapy because they work better.

3: Immunotherapy Has Led to Peritoneal Mesothelioma Remission

Only a few instances of this scenario have been reported in case studies. But each remission brings doctors a step closer to figuring out how to make it more common.

Immunotherapy Remission Story #1

• Patient: 59-year-old man
• Diagnosis: Epithelioid peritoneal mesothelioma
• Treatment: Chemotherapy, then Keytruda immunotherapy
• Outcome: Long-term remission

This patient initially received chemotherapy, but his cancer progressed during treatment. Doctors then recommended Keytruda. After a year of treatment, imaging showed the patient's tumor shrinking but still present. Just 6 months later, the cancer had disappeared.

At his 4-year follow-up, he still had no signs of cancer, indicating ongoing remission. This case shows immunotherapy can be effective even after other treatments have failed.

Immunotherapy Remission Story #2

• Patient: 63-year-old woman
• Diagnosis: Epithelioid peritoneal mesothelioma
• Treatment: Opdivo+Yervoy immunotherapy, surgery, heated chemotherapy, Opdivo+Yervoy
• Outcome: Long-term remission

Before treatment, a tumor board found this patient potentially eligible for surgery. If she responded well to immunotherapy, surgery could be possible at that time.

After 4 months of Opdivo+Yervoy, the cancer was controlled enough to move on to surgery. She underwent surgery followed by a heated chemotherapy bath in the abdomen (HIPEC). Both procedures went well, but doctors recommended continuing Opdivo+Yervoy.

At last follow-up about 2.5 years after surgery, she had no signs of cancer. This case shows that immunotherapy can be a key component of a successful combination treatment plan.

4: Immunotherapy Research Is Ongoing

Several immunotherapies are already standard for peritoneal mesothelioma. But research continues, and several clinical trials are ongoing. One study will look at chemotherapy with or without immunotherapy. Another is testing immune cells that are programmed to recognize and kill mesothelioma tumors.

Peritoneal patients considering immunotherapy should discuss it with a mesothelioma specialist. Having this discussion with a true mesothelioma expert matters. General oncologists may not know how beneficial many treatments can be for mesothelioma. But specialists with plenty of mesothelioma experience usually do. Specialty care can help ensure the patient has access to the best treatments for their unique case.