There was a study published in the journal Nature that described a promising new combination therapy for the treatment of men with advanced prostate cancers that are non-responsive to chemotherapy. The study is entitled “Immunosuppressive Plasma Cells Impede T-Cell Dependent Immunogenic Chemotherapy.”  The study was conducted at the University of California, San Diego.

Prostate cancers are also non-responsive to an encouraging new type of drugs based on immunotherapy called checkpoint inhibitors, which are drugs often able to trigger a stronger immune response to better fight cancer.

It has been suggested that resistance to treatment of advanced prostate cancer is in part due to the body developing an accumulation of cells that suppress the immune system. These cell types are called immunosuppressive immune B cells. They can negatively control the immune system and interfere with a therapies ability to control the growth of malignant cells, despite treatment.

These cells, Immunosuppressive B cells, are often found in larger prostate cancers in mice and in advanced and metastatic prostate cancers in men.

The study used three distinct rodent models of advanced prostate cancer, all resistant to low doses of oxaliplatin, a chemotherapy drug able to activate cancer-killing immune cells and an effective agent in aggressive prostate cancers.  The researchers found that when immunosuppressive B cells were blocked or entirely removed prior to using low-dose oxaliplatin treatment in mice, prostate cancers were nearly completely eliminated by the immune system. Similar results were obtained when low-dose oxaliplatin was tested together with a checkpoint inhibitor.

This novel combination therapy based on immune cell manipulation and chemotherapy, named chemoimmunotherapy, allowed an almost complete remission of advanced prostate cancer in mouse models. Blocking or removing immunosuppressive B cells together with chemotherapy enables the elimination of prostate tumors.

The study’s senior author Dr. Michael Karin said that “In addition to prostate cancer, similar immunosuppressive B cells can be detected in other human cancers, this indicates that B cell-mediated immunosuppression might be the reason several other cancers are also unresponsive to checkpoint inhibitors, raising the hope that chemoimmunotherapy will have broader applications for many cancer types.”

Here is another example of a potential treatment that is “ON THE HORIZON.”

Joel T. Nowak, M.A., M.S.W.