A phase II study combining immunotherapy drugs atezolizumab (Tecentriq) and bevacizumab (Avastin) showed notable results when published earlier this month. A team of researchers from The University of Texas MD Anderson Cancer Center, led by Doctor Kanwal Raghav, found that treatment with both drugs resulted in a 40 percent objective response rate in patients with advanced peritoneal mesothelioma.
Lack of Available Mesothelioma Treatment Options Concerns Researchers
The multicohort study evaluated the drug combination to treat several rare cancers, including appendiceal and pancreatic cancer and pleural mesothelioma. Researchers have not yet released results from the other cancers.
According to the report, the responses among many of the 20 patients in the study indicated prolongation of survival. The combination also proved to be safe among participants. Similar treatment options approved for patients with peritoneal mesothelioma saw response rates of less than 10 percent.
Malignant peritoneal mesothelioma often occurs in women who may have come into contact with second-hand asbestos exposure. While a peritoneal mesothelioma diagnosis often occurs at an earlier stage, limited treatment options are available.
Doctors typically recommend first-line platinum-pemetrexed chemotherapy for peritoneal mesothelioma. Authors of the study note that there is no recommended or FDA-approved second-line therapy for advanced mesothelioma after the failure of the recommended first-line treatment.
Breaking Down the Mesothelioma Immunotherapy Drugs Atezolizumab and Bevacizumab
Atezolizumab, under the brand name Tecentriq, is an immune checkpoint inhibitor that targets PD-L1. An immune checkpoint inhibitor is a type of drug that blocks proteins made by immune system cells, such as T cells and cancer cells.
The proteins, known as checkpoints, prevent the immune responses from being strong enough to kill cancer cells. When an immune checkpoint inhibitor drug blocks these checkpoints, T cells can kill the cancer cells.
Tecentriq has been approved by the U.S. Food and Drug Administration to treat certain non-small cell lung cancers and bladder cancers. The immunotherapy drug is similar to a common mesothelioma drug, Keytruda.
Bevacizumab, under the brand name Avastin, is a targeted therapy angiogenesis drug. An angiogenesis inhibitor drug blocks the nutrients and oxygen from reaching a tumor, causing it to starve and die.
Doctors administered the atezolizumab at a fixed dose of 1,200mg in combination with 15mg/kg of bevacizumab. Study participants received the doses intravenously every 21 days until the diseases started to progress or treatment was deemed too toxic. The median number of cycles of treatment participants received was 15 cycles.
Atezolizumab side effects can vary between patients. Mild to severe symptoms may occur from taking atezolizumab. Immunotherapy patients with non-small cell lung cancer, small cell lung cancer, and other rare cancers are approved to take it. Common side effects include lung, intestinal, liver, kidney, hormone gland, or skin problems. The drug’s full side effects can be found on Tecentriq’s safety page.
Doctors Hopeful For Future Studies
Researchers were impressed with the effectiveness of treatment on the participants who experience disease progression following standard first-line chemotherapy treatment or surgery. The median duration of response among participants was 12.8 months.
The estimated progression-free survival was 17.5 months. The length of progression-free survival was a significant improvement when comparing standard chemotherapy, which has a median disease progression of 8.3 months. The one-year survival rate among participants was 85 percent, while progression-free survival was an impressive 65 percent.
The study indicated that disease control in patients at 12 weeks was 95 percent, while patients at 18 weeks were 85 percent. After nearly two years, six patients were still receiving the treatment, and 12 discontinued treatment due to disease progression or toxicity. One participant ceased treatment due to death.
Researchers conclude that more patients are needed for evaluation in future clinical trials to validate study results and determine if the combination of drugs is effective as a first-line peritoneal mesothelioma treatment.