A groundbreaking multi-institutional study has revealed that repeated tumor sampling can uncover immune system activation in glioblastoma patients undergoing treatment, even when traditional MRI scans suggest disease progression. The research, published in Science Translational Medicine and led by investigators from the Mass General Brigham Cancer Institute, challenges current clinical practice and offers new hope for monitoring the most aggressive form of brain cancer.
Revolutionary Approach to Brain Tumor Monitoring
The study involved over 100 brain tumor scientists and clinicians from multiple hospitals, cancer institutes and universities across the United States, conducted through a collaboration funded by Break Through Cancer. Researchers collected 96 tumor samples over four months from two patients with recurrent glioblastoma in a clinical trial of CAN-3110, an oncolytic virus immunotherapy specially engineered to selectively infect and kill tumor cells.
"Standard practice is to not serially sample a patient's brain tumor as they undergo treatment but instead to take a sample only once before a treatment and then follow a patient's response using MRI," said Dr. E. Antonio Chiocca, executive director of the Center for Tumors of the Nervous System at the Mass General Brigham Cancer Institute. "But this study's findings suggest that this thinking and practice may need to change to revolutionize how patients can monitor their disease."
Multi-Omic Analysis Reveals Hidden Treatment Effects
The research team employed comprehensive multi-omic analysis with data integration supported by Break Through Cancer's Data Science Hub (DASH). They integrated data from multiple sources including genetic material, peptides in and around the tumor, metabolites, immune changes, protein signaling factors, and AI-enabled digital pathology.
The serial samples demonstrated that over time, CAN-3110 changed the environment inside and around the tumor, even though the tumor appeared to be progressing on MRI scans. This phenomenon occurs because immune system activation causes swelling and inflammation, which can appear as new or enlarging areas of contrast on scans even when a tumor hasn't grown—a condition known as pseudoprogression.
Clinical Implications and Patient Outcomes
Of the two patients treated during the study, one showed evidence that the tumor was responding to therapy, while the other's disease remained stable. The molecular analyses revealed immune system activation and microenvironmental remodeling consistent with anti-tumor response, despite imaging suggesting disease progression.
"Getting tissue from GBM patients is difficult because the brain is sensitive, the procedures are risky, and the tumors themselves are complex and change over time," Chiocca explained. "But studying the cancerous tissue itself is also the best way to understand how the tumor reacts to treatment."
Transforming Clinical Trial Design
The findings suggest that if CAN-3110 therapy can reshape the microenvironment and activate the immune system, it may improve patient outcomes. The research team advocates for adopting a new paradigm in glioblastoma drug development that incorporates longitudinal sampling into clinical trials to capture real-time snapshots of tumor response over time.
"The breadth and depth of data we generated from repeated tumor biopsies really underscore the value of this approach for studying how therapies work," said Chiocca, emphasizing the collaborative work of brain specialists from across the country. "These results give us strong reason to adopt a new paradigm in GBM drug development."
Future Applications
Although the study reported results on the first two patients from the trial, researchers are accruing 12 patients total to further solidify their findings. The team plans to adopt this clinical trial platform for two additional and distinct vaccine immunotherapies, expanding the application of serial sampling to other treatment modalities.
This innovative methodology sets new standards for precision oncology in brain cancer, offering the potential to transform how glioblastoma is treated and monitored by providing real-time molecular insights that conventional imaging cannot detect.
