There is some exciting news from the front lines of mesothelioma research this week. California scientists say they have dramatically improved the effectiveness of mesothelioma chemotherapy by pairing it with a an immunotherapy drug made of live bacteria.
The University of California, San Francisco team presented their findings to other lung cancer experts at the international European Lung Cancer Conference in Switzerland earlier this week.
Although most pleural mesothelioma patients will receive chemotherapy, only about three in ten of those patients will get any significant benefit from it. The the new research study appears to be changing those odds.
Origins of Bacteria-based Mesothelioma Treatment
Immunotherapy is a process of turning the body’s own defenses against cancer by making it more difficult for mesothelioma cells to “hide” from the immune system.
Many mesothelioma tumors overexpress a protein called mesothelin. In order to find and unmask mesothelioma cells, researchers programmed a live bacterium called listeria monocytogenes to also express mesothelin. They called the new drug CRS-207.
“In our early studies, CRS-207 induced an anti-mesothelin response and cellular tumour specific immunity in patients with mesothelin expressing tumours,” explains lead researcher and professor Thierry Jahan in a press release.
The Quest for Improved Chemotherapy
The current study of CRS-207 included 38 patients with unresectable malignant pleural mesothelioma. In addition to up to six cycles of standard mesothelioma chemotherapy delivered three weeks apart, patients received two CRS-207 infusions two weeks apart.
After chemotherapy, the mesothelioma patients received two additional doses of CRS-207 three weeks apart. Some also got a maintenance dose of CRS-207 every eight weeks after that.
Patients were then monitored for a median of 9.4 months following the experimental treatment.
Impressive Mesothelioma Survival Results
The results of the CRS-207 + chemotherapy treatment approach have the mesothelioma community excited. “Patients receiving the combination of CRS-207 and chemotherapy had a deep response with more than 90% disease control,” reports Jahan.
Fifty-nine percent of patients experienced a partial response, meaning that their tumor actually shrunk. For 35 percent of patients, mesothelioma tumor growth was stopped in its tracks.
Just as importantly, the median amount of time that it took for tumors to start growing again after the immunotherapy/chemotherapy regimen was 8.5 months and none of the patients experienced serious side effects that couldn’t be managed.
“CRS-207 is an exciting agent for patients with mesothelioma,” concludes Jahan. “Our preliminary results are encouraging suggesting superior clinical activity when added to standard chemotherapy.”
A larger randomized clinical trial is already in the planning stages, the next step to making this new approach available to mesothelioma patients around the world.
“Immunotherapy with Live Bacterium Improves Response Rate in Malignant Pleural Mesothelioma”, April 14, 2016, European Society for Medical Oncology, new release