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Therapeutic vaccine boosts survival rate in cervical cancer patients

A therapeutic vaccine against HPV-16 (type 16 human papillomavirus) improves the survival rate in cervical cancer patients. A new study by ISA Pharmaceuticals B.V. (a Leiden-based biotechnology company) and the Leiden University Medical Center (LUMC) shows that this vaccine produces a more robust response if it is combined with chemotherapy. The results of this study have been published in the journal Science Translational Medicine.

Prof. Sjoerd van der Burg, who works at the LUMC and is also an Oncode Investigator, is the last author of this publication. “The vaccine has been tested in 77 patients with advanced-stage cervical cancer, over a period of about five years. The results of this phase 2 CervISA study have revealed a strong correlation between a robust immune response to the vaccine and survival rate”, he explains. 

About 30 percent of those patients who mounted a robust immune response are still alive after three years. In patients with a weak response, that percentage is less than 10 percent. Data on deceased patients confirms that individuals who had developed a robust immune response survived longer than patients with a weaker response. 

Use in combination with chemotherapy

Good timing is essential, if patients are to mount a robust immune response. Instead of administering the vaccine after the first round of chemotherapy, it is given to patients two weeks after the second round. This makes the vaccine much more effective. “We were already aware that chemotherapy can boost the immune response to cancer, we just didn’t understand the mechanism involved. We’ve now found the answer, and we’re putting that knowledge to good use”, says Sjoerd van der Burg.   

Cancer patients have weakened immune systems, so the vaccine is not very effective if it is administered after the first round of chemotherapy. In the body, cancer cells secrete substances that trigger the release of immature myeloid cells from the bone marrow. These immature cells inhibit the action of the immune system. As a result, there is a weaker response to the vaccine. After the first round of chemotherapy, these myeloid cells may return. After the second round, however, they disappear completely, which makes the vaccine much more effective. Dr. Marij Welters (LUMC) and her team also played a major role in the publication, by uncovering these aspects of the immune system in detail. 

Further strengthening the vaccine

Nine hospitals throughout the Netherlands and Belgium participated in the CervISA study, which is published on March 18. ISA Pharmaceuticals B.V. was the study’s main sponsor.   

Researchers from the LUMC’s Department of Medical Oncology have been exploring the use of therapeutic vaccines in cancer for quite some time. Their work is funded by grants over a longer period from the Dutch Cancer Society (KWF Kankerbestrijding). The role of myeloid cells in cancer is part of a new LUMC research funded by Oncode Institute. 

As Prof. Van der Burg points out, “Now that we know how to boost the response to the vaccine, we can start exploring ways of enhancing the vaccine still further. This will enable us to achieve an even better patient survival rate.” 

Would you like to know more? Read the publication at the Science Translational Medicine website.  

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