Recently, immunotherapy and other new approaches have been slowly turning the tide in treatment for mesothelioma, a rare cancer that forms in the lining of internal organs.

A case study published in the journal Cureus on January 22, 2024, saw great results with the use of the immunotherapy drug pembrolizumab (Keytruda®) as a second-line treatment for one peritoneal mesothelioma patient.

Doctors found immunotherapy resulted in a complete response after 2 years of treatment, helping the patient achieve remission and be disease-free for nearly 4 years as of today.

The findings could help pave the way for immunotherapy to become a standard approach for peritoneal mesothelioma, which develops in the abdominal lining.

Learn more about how this patient benefited from pembrolizumab for mesothelioma and what this could mean for you if you’ve been diagnosed.

One Patient’s Success With Pembrolizumab for Peritoneal Mesothelioma

The study followed one particular patient, a 59-year-old man who was diagnosed with peritoneal mesothelioma after experiencing weight loss, abdominal pain, and swelling from fluid buildup.

He completed 6 rounds of chemotherapy without success. The existing tumor didn’t respond to treatment, and a new tumor had begun to develop that was roughly one-third the size of the first. His doctors decided to move forward with pembrolizumab.

After completing only 4 months of immunotherapy, an MRI scan indicated that the disease had stabilized — meaning the cancer was not actively growing or spreading. Seeing a positive response to the treatment, his specialists continued with this immunotherapy regimen.

After one year of immunotherapy, the patient’s tumors showed a partial response, which is defined as at least a 30% reduction in tumor size. After two years, the patient experienced a complete response, meaning all cancer cells were attacked and killed by immunotherapy.

Key Takeaways From the Pembrolizumab Mesothelioma Trial

With immunotherapy, this peritoneal mesothelioma patient experienced:

  • Disease stability after 4 months of immunotherapy
  • A 30% reduction in tumor size after 1 year
  • Total disappearance of tumors after 18 months of treatment
  • No mesothelioma symptoms and a complete response to treatment after 2 years

The patient was cancer-free for 4 years after starting treatment with pembrolizumab. The only side effect he experienced was hypothyroidism (an underactive thyroid gland). Not only was the treatment well tolerated, but the patient enjoyed a higher quality of life.

Top mesothelioma specialists around the nation are constantly working to bring the best treatments to their patients. Use our Free Doctor Match program to connect with a specialist near you and get access to life-extending care.

What This Could Mean for Peritoneal Mesothelioma Patients

Immunotherapy has been a popular mesothelioma treatment option for pleural mesothelioma, the most common type of mesothelioma that affects the lung lining.

However, few clinical research studies have evaluated the benefits of immunotherapy for peritoneal mesothelioma. This is due in part to the rarity of the disease and a lack of targeted clinical trials focusing on this type of mesothelioma.

In spite of this, the mesothelioma doctors involved in the case study were encouraged to explore the off-label use of immunotherapy to treat peritoneal mesothelioma because of the promising findings when using it as a first- and second-line treatment for pleural mesothelioma patients.

The outcome of this case study proves promising for future treatment approaches for peritoneal mesothelioma. It also gives hope to other mesothelioma patients whose cancer has not responded to other treatments and could benefit from immunotherapy.

Get Help Finding Peritoneal Mesothelioma Treatments

Currently, there is no standard of care for immunotherapy for peritoneal mesothelioma, though this case study provides hope that it may soon become a more commonly accepted treatment option.

Immunotherapy may be able to help peritoneal mesothelioma patients:

  • Access life-extending treatment if they’re unable to have surgery
  • Lessen the severity of daily symptoms like abdominal pain and bloating
  • Live longer, fuller lives with fewer treatment-related side effects

The best way to access immunotherapy and other emerging treatment options is by connecting with a top mesothelioma specialist. Find a specialist near you with our Free Doctor Match program or by calling our Patient Advocates at (866) 608-8933 now.

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Laura WrightWritten by:

Lead Editor

Laura Wright is a journalist and content strategist with more than 15 years of professional experience. She attended college at the University of Florida, graduating magna cum laude with a bachelor’s degree in journalism in 2008. Her writing has been featured in The Gainesville Sun and other regional publications throughout Florida.

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  1. Bairos Menezes M, Pedroso de Lima R, Dunões I, et al. (2024, January 22). A Complete Response to Pembrolizumab in Malignant Peritoneal Mesothelioma: A Case Report. Cureus. Retrieved February 5, 2024, from!/

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