Personalized cancer vaccine clinical trial to expand following promising early results

A clinical trial at the University of Arizona Health Sciences designed to study the safety and effectiveness of a personalized cancer vaccine in combination with the immunotherapy drug Pembrolizumab will expand its cohort after promising preliminary data was presented at the annual meeting of the Society for the Immunotherapy of Cancer.

Julie E. Bauman, MD, MPH, deputy director of the University of Arizona Cancer Center and a professor of medicine and chief of the Division of Hematology and Oncology at the UArizona College of Medicine — Tucson, presented preliminary data on the first 10 patients with head and neck cancer, seven of which were treated at Banner — University Medicine, the clinical partner for the UArizona Cancer Center. Five of the 10 patients experienced a clinical response to the personalized cancer vaccine, and two patients had a complete response after the treatment (no detectable disease present).

The preliminary response rate of 50% is notable when compared to patients in clinical trials that receive Pembrolizumab immunotherapy alone without the personalized cancer vaccine. In those studies, the reported response rate is approximately 15%.
The UArizona Cancer Center is one of several sites where patients were recruited to participate in the phase I clinical trial sponsored by Moderna, Inc. The trial is studying the use of a personalized mRNA cancer vaccine in combination with Pembrolizumab for patients with multiple cancer types, including colorectal and head and neck cancers. No clinical responses were noted for the study’s cohort of 17 microsatellite stable (MSS) colorectal patients.
Dr. Bauman says the current study will now expand to 40 patients with head and neck cancer.

“The data are preliminary and the sample size is small, but it is promising,” Dr. Bauman said. “A phase I trial is about safety first and foremost, and we now know this treatment is safe and tolerable. But, we also have a strong signal to point us to further study this in head and neck cancer. That is why we are excited to expand this trial.”

Personalized cancer vaccines are an emerging treatment option that uses a patient’s own cancer cells to develop a vaccine intended to teach their immune system how to recognize and destroy their cancer. Cancer cells have DNA mutations that differ from the DNA in normal, healthy cells. These mutations are different from patient to patient, which is where the concept of a personalized vaccine is developed. Combining the personalized vaccine with Pembrolizumab, an immunotherapy medicine that works with the immune system to fight certain types of cancers, will hopefully allow further benefit to patients than pembrolizumab alone.

To identify the patient-specific mutations of the cancer, mutated DNA from the patient’s tumor is simultaneously sequenced with healthy DNA from the patient’s blood. Computers compare the two DNA samples to identify the unique cancer mutations. The results are used to develop a set of genetic instructions that are loaded onto a single molecule of messenger RNA (mRNA) and made into a vaccine. These instructions teach immune cells such as T-cells — white blood cells that help protect against infection — how to identify and attack the mutated cancer cells.

“Our goal is to understand how we can get better at applying this treatment to more patients to result in more successful outcomes,” Dr. Bauman said. “This preliminary data has generated exciting new hypotheses to investigate.”