Update: 07/14/2021: The annual follow-up of this study provided new data on atezolizumab and bevacizumab for peritoneal mesothelioma.
Most clinical trials experimenting with novel treatments focus on pleural mesothelioma, due to the higher incidence rates and poorer prognosis. Peritoneal mesothelioma often gets little attention.
One study combining two mesothelioma immunotherapy drugs is the anomaly to that truth.
Researchers from the MD Anderson Cancer Center in Houston, Texas, are analyzing the effects of atezolizumab and bevacizumab. Atezolizumab is an anti-PD-L1 drug, and bevacizumab is an anti-VEGF treatment.
Together they are called AtezoBev, and they showed promising results in a recent phase 2 clinical trial.
If you want to learn more about peritoneal mesothelioma treatment options, reach out to our medical staff. Our registered nurse, Karen Ritter, can provide insight into the best methods for treating your individual diagnosis. Email her at firstname.lastname@example.org.
Results of the Peritoneal Mesothelioma Clinical Trial
The standard treatment for peritoneal mesothelioma is cytoreduction with heated intraperitoneal chemotherapy (HIPEC). According to numerous studies, this approach can lead to survival times of between three and five years.
However, mesothelioma recurrence is frequent due to the makeup of the disease. Microscopic tumors fill the peritoneum, which is the small membrane covering the abdominal cavity, along with the abdominal cavity itself. Removing all of them during surgery is challenging.
Additionally, some patients might not be eligible for cytoreduction with HIPEC. Their cancer may resist traditional chemotherapy, which is typical for mesothelioma. Any treatment that may reduce tumor size prior to surgery or extend life for non-surgical patients should be investigated.
The atezolizumab and bevacizumab study included many types of cancers, including both peritoneal mesothelioma and pleural mesothelioma. It involved 160 patients, of which 20 had peritoneal mesothelioma. Patients received both atezolizumab and bevacizumab for 60 minutes once every three weeks, so long as the disease did not progress.
The American Society of Clinical Oncology analyzed the effectiveness of AtezoBev just among those 20 participants with peritoneal mesothelioma. Eight of the 20 (40%) experienced at least a minimal reduction in tumor size, which surpasses the original goal of just 11%.
Long-term follow-ups showed substantial benefits of AtezoBev:
- 80% (16 of 20) patients survived for at least one year.
- 60% (12 of 20) had no disease progression for at least one year.
- The median response time — meaning the length of time the treatment worked — was 12.8 months.
- The median progression-free survival was 17.6 months, which far exceeds the original goal of four months.
How Atezolizumab and Bevacizumab Work for Peritoneal Mesothelioma
Atezolizumab and bevacizumab work in distinctly different ways, but they have the same goal: mesothelioma cell death. This is the main goal of immunotherapy for mesothelioma.
Atezolizumab prevents a connection that helps mesothelioma cells survive. These infected cells have a protein called PD-L1, which can subdue the body’s T-cells. These disease-fighting cells have the protein PD-1. When the two protein receptors link, the T-cells are inhibited from accurately assessing mesothelioma cells as dangerous.
Atezolizumab breaks this link and acts as a wall between the receptors. Its presence allows the T-cells to recognize mesothelioma cells as dangerous.
Bevacizumab, the generic name for the brand drug Avastin, subdues another mesothelioma protein called VEGF (vascular endothelial growth factor). This protein stimulates the creation of new blood vessels, a process called “angiogenesis.”
All cells, even cancerous ones, need to receive oxygen and nutrients to survive. Making new blood vessels is how mesothelioma tumors grow and spread through the body. Bevacizumab blocks this protein and can prevent mesothelioma cells from receiving oxygen and nutrients.
Sources & Author
- A phase II trial of atezolizumab and bevacizumab in patients with relapsed/refractory and unresectable malignant peritoneal mesothelioma. American Journal of Clinical Oncology. Retrieved from:
https://meetinglibrary.asco.org/record/184537/abstract. Accessed: 06/10/2020.
- Atezolizumab and Bevacizumab in Treating Patients With Rare Solid Tumors. Clinicaltrials.gov. Retrieved from:
https://clinicaltrials.gov/ct2/show/NCT03074513. Accessed: 06/10/2020.
Sources & Author