Leiden University Medical Center (LUMC), Netherlands conducted a lab study and found that a combination of immunotherapy and photodynamic therapy (PDT) helps in eradicating aggressive tumors. The resulting effect is a strong localized destruction of the tumor and a robust systemic immune response against the disease. These findings have been reported online in the medical journal of Clinical Cancer Research.
Dr Ossendorp, who is the principal investigator of this study, is aiming for clinical acceptance in Western Europe by preparing preclinical studies for the same. Dr. Ossendorp spearheaded the study together with doctoral candidate Jan Willem Kleinovink of LUMC’s Department of Immunohematology and Blood Transfusion, in close collaboration with Dr. Clemens Lowik, now based at Erasmus University Medical Center in Rotterdam.
In PDT, a special agent or a photosensitizer is used along with oxygen and light. This induces reactions that make the tumors vulnerable to the immune system and selectively destroying them. This study uses a photosensitizing agent called Bremachlorin which is a non-toxic and a chlorophyll-derived agent. It captures and transmits light energy for therapeutic reasons. The immunotherapy work involved in this study uses a peptide-based vaccine that activates the T-cell system, in specific, against cancer. This combination leads to a broad and effective immune response against established tumors,” says Ossendorp. “We have even observed that distant tumors disappeared in some of the animals.”
The Leiden study used two kinds of tumor models – aggressive lymphoma and aggressive cervical cancer. It was found that use of Bremachlorin-PDT resulted in a significant slow growth of tumor in the test animals. The combination of PDT with the peptide-based vaccine strategy resulted in complete curing of cancer in one-third of the mice which is almost the disappearance of the disease. Further, the test subjects were fully protected from relapses of the same cancer type.
The combination of primary tumors also resulted in consequential eradication of metastases, or distant tumors. But this finding will be further delved as metastases is the most common form of cancer-related deaths. In the report for Clinical Cancer Research, they have duly noted that the strategy of blending Bremachlorin-PDT and immunotherapy offers a feasible novel strategy for curing advanced cancer.
Bremachlorin has been clinically approved for use in Russia since 2006 with a conditional approval in South Korea.