Brain metastases are the final, lethal consequence of many aggressive cancers, and researchers are racing to discover ways of preventing these intractable growths from developing.
A new Tel Aviv University study finds a known adjuvant — an ingredient used in some vaccines that helps create a stronger immune response — that contains synthetic DNA material may be an effective means of preventing brain metastases in patients whose primary tumors have been excised.
Research for this study was led jointly by Dr. Amit Benbenishty of TAU's Sagol School of Neuroscience, Dr. Pablo Blinder of TAU's George S. Wise Faculty of Life Sciences, and Prof. Shamgar Ben-Eliyahu of TAU's School of Psychological Sciences, in collaboration with Dr. Lior Mayo of TAU's Sagol School of Neuroscience, Prof. Neta Erez of TAU's Sackler School of Medicine, and Prof. Dritan Agalliu of Columbia University Medical Center. It was published in PLoS Biology.
“Some 20 to 40% of lung, breast and melanoma cancer patients develop brain metastases, and current treatments for brain metastases are ineffective,” Dr. Blinder says. “Surgery for removing primary tumors is usually essential, but the period immediately before and after surgery requires that all chemotherapy and radiotherapy be stopped. This creates a high potential for the initiation and rapid progression of deadly metastases.
“Our study showed that an intravenous injection of CpG-C, an adjuvant of synthetic DNA material, during this specific time frame reduces the development of brain metastases,” Dr. Blinder continues. “When the drug is administered systemically, it crosses the blood-brain barrier and works by activating microglia, the brain's primary immune cells, to kill invading tumor cells.”
The scientists harnessed different mouse models to test the efficacy of the CpG-C drug in reducing brain metastases resulting from different cancers of both mouse and human origin. The research team used a combination of cutting-edge imaging techniques to discover the specific immune cells involved in mediating a protective effect against brain metastases and examine tumor progression in the animal models.
“Currently, patients with small-cell lung carcinoma are given preventative whole-brain radiotherapy to reduce brain metastases, but that has many negative side effects,” Dr. Blinder explains. “Our approach gets the immune troops 'ready for combat,' in both the brain and the rest of the body. It's not tumor specific, and it has a promising safety profile in humans. Prof. Ben-Eliyahu's group at TAU and others have previously shown that this drug is beneficial in fighting primary tumors and metastases in other organs.
“We hope that this drug can be implemented as a preventative treatment for various types of metastasizing tumors with the goal of preventing or reducing brain metastases.”
The new treatment could be administered to cancer patients undergoing surgery to excise a primary tumor several days before the operation and continuing a few weeks after surgery. The group is currently conducting several studies to verify that the systemic CpG-C treatment does not risk the patients' health nor the success of surgery to remove a primary tumor.
“We were able to verify that this treatment does not disrupt tissue healing, which is important in the post-operative period,” Prof. Ben-Eliyahu says. “The treatment does not seem to increase the risk of other common surgery-related complications, such as an exaggerated post-operative inflammatory response.
“We are now testing the potential simultaneous use of anti-stress-inflammatory drugs, which we also found effective in reducing perioperative risks of metastases and may mitigate the deleterious stress-inflammatory responses to surgery and potentially to CpG-C treatment. If these tests are successful, we plan to conduct initial studies in cancer patients.”