Mesothelioma patients whose T-cell counts bounce back quickly after a round of chemotherapy have a better chance of survival. They are also most likely to benefit from the addition of immunotherapy.
That’s the conclusion of a British study looking for prognostic indicators in mesothelioma patients undergoing a combination of chemotherapy. Noting that there is increased interest in pairing chemotherapy with immunotherapy, the group was also looking for a method of determining who would benefit most from the combination.
Chemotherapy is the most common first-line treatment for mesothelioma. It involves flooding the body with a drug or combination of drugs designed to destroy cancer cells. Immunotherapy involves “programming” the immune system to recognize cancer cells as foreign invaders and attack them the way they might attack bacteria or viruses.
To devise a prognostic method for mesothelioma patients who might undergo both types of therapies, the scientists looked for longitudinal changes in peripheral T-cell subsets in 40 patients with malignant mesothelioma or advanced non-small cell lung cancer. All of the patients were receiving platinum-based chemotherapy.
The study found that the T-cells of all patients were almost entirely knocked out by the 8th day following chemotherapy, but most bounced back quickly and even passed baseline levels. Regulatory T-cells (Treg) have immunosuppressive properties and are the cells responsible for maintaining order in the immune system. In the study, Treg cells were most profoundly depleted by chemotherapy. Mesothelioma patients whose CD8(+)T-cells bounced back the most after a cycle of chemotherapy had the greatest overall survival. A bigger ratio between CD8(+) T-cell to Treg proliferation was also predictive of better outcomes.
Because the effectiveness of immunotherapy depends on the depletion of Treg cells (because of their immunosuppressive properties) and the strength of the T-cell pool, the researchers theorize that those who showed the most dramatic changes in these two cell types areas are the ones most likely to benefit from a combined chemotherapy/immunotherapy approach.
In an abstract on their findings in the British Journal of Cancer the research team concludes that chemotherapy potentially provides a “favourable environment” in which to implement immunotherapy in mesothelioma patients and that CD8(+) T-cell proliferation was a potentially useful indicator of probable outcomes.