Institute of Cancer Research study shows how immuno PET imaging reveals whole body immune response to cancer virotherapy

Institute of Cancer Research study shows how immuno PET imaging reveals whole body immune response to cancer virotherapy

(IN BRIEF) Researchers at the Institute of Cancer Research have demonstrated how immuno-PET imaging can be used to track the immune system’s response to oncolytic virotherapy in real time. Using a modified virus known as RP1 in preclinical models of head and neck cancer, the study revealed that local treatment can trigger a temporary but widespread immune response across the body, particularly in immune organs such as the spleen and lymph nodes. By targeting PD-L1, a key immune checkpoint protein, the imaging technique provided a comprehensive view of immune activity beyond the tumour itself. The findings highlight the potential of immuno-PET as a non-invasive tool to guide treatment strategies and optimise the timing of immunotherapy combinations, with future implications for improving patient outcomes.

(PRESS RELEASE) LONDON, 1-May2026 — /EuropaWire/ — Institute of Cancer Research scientists have demonstrated how an advanced imaging technique can reveal the immune system’s response to cancer treatment in real time, offering new insights that could shape the future of immunotherapy.

In a recent study, researchers used immuno-positron emission tomography, commonly known as immuno-PET, to observe how the immune system reacts following oncolytic virotherapy in preclinical models of head and neck squamous cell carcinoma. This approach enabled the team to monitor changes across the entire body, rather than focusing solely on the tumour site.

Oncolytic virotherapy involves engineering viruses to selectively infect and destroy cancer cells while leaving healthy tissue largely unaffected. As the virus breaks down tumour cells, it can also stimulate the immune system, effectively turning the tumour into a trigger for a broader immune response.

For this research, the team employed an experimental virus known as RP1, derived from the herpes simplex virus, which is designed to both attack cancer cells and activate immune defences. The study focused on head and neck cancers, which are often difficult to treat and can respond unpredictably to immunotherapy.

To overcome the limitations of traditional biopsy-based methods, the researchers turned to immuno-PET, a non-invasive imaging technique that uses specialised tracers to detect specific proteins. In this case, the tracer targeted PD-L1, a key protein that tumours use to evade immune detection. Tracking PD-L1 levels allowed the team to visualise immune activity across different organs.

The findings revealed a notable pattern. Shortly after the virus was introduced into tumours, PD-L1 levels increased significantly in immune-related organs such as the spleen and nearby lymph nodes, rather than within the tumour itself. This surge occurred within three days and subsided by the seventh day, indicating a temporary but widespread immune activation triggered by the local treatment.

These observations suggest that oncolytic virotherapy can stimulate a systemic immune response, even when delivered directly into a tumour. This has important implications for how such therapies are combined with other treatments, particularly immune checkpoint inhibitors that target pathways like PD-1 and PD-L1.

The study highlights the potential of immuno-PET to provide a comprehensive, whole-body view of immune dynamics, something that cannot be achieved through standard diagnostic techniques. By enabling repeated, non-invasive monitoring, the technology could help clinicians better understand how treatments are working and determine the optimal timing for combination therapies.

Julia Höbart, the study’s first author, noted that the technique allows scientists to capture both local and systemic immune responses in a way that was previously not possible. Meanwhile, Gabriela Kramer-Marek, who led the research, highlighted the growing importance of imaging technologies in the evolving field of immuno-oncology.

The findings were published in the Journal of Nuclear Medicine and supported by organisations including Cancer Research UK, Oracle Cancer Trust, and Chellaram Foundation.

While the research was conducted in animal models, it provides valuable insight into how immune responses unfold during treatment. As immuno-PET continues to advance and enters clinical development, similar approaches could eventually help guide treatment decisions and improve outcomes for cancer patients by identifying which therapies are most effective and when they should be administered.

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SOURCE: The Institute of Cancer Research