A non-invasive imaging approach reveals the subtle vascular effects of combining radiotherapy with anti-VEGF therapy in a mouse model of lung cancer.
Study Overview
A study on C57BL/6 mice implanted with Lewis Lung Carcinoma (LLC) investigated how tumor blood vessels respond to radiotherapy (RT) combined with anti-VEGF therapy. Mice received a total of 40 Gy (10 Gy daily for four days) alongside anti-VEGF injections (100 µg every three days). Tumor vasculature was assessed non-invasively using power Doppler sonography and contrast-enhanced imaging with microbubbles (USphere Prime) at multiple time points before and after treatment.
Key Findings
- Increased Perfusion Across All Groups: Power Doppler and contrast imaging consistently showed increased tumor perfusion over time, regardless of the treatment group.
- Limited Impact of Anti-VEGF: The addition of anti-VEGF therapy did not produce a statistically significant difference in perfusion compared to the control group or radiotherapy alone.
- Longitudinal Power of Imaging: Contrast imaging enabled non-invasive, repeated assessment of the same tumors over time. This longitudinal capability reduced the number of mice needed while significantly increasing the statistical power of the study.
Methods in Brief
- Animal Model: 6-week-old C57BL/6 mice were implanted subcutaneously with 2 × 10⁵ LLC cells.
- Treatment Schedule: Nine days after implantation, mice began a course of 10 Gy irradiation daily for 4 days. Anti-VEGF (100 µg) was administered via intraperitoneal injection every 3 days for a total of 4 doses.
- Imaging Timeline: Vascular imaging was performed before radiotherapy and then at days 0, 3, 6, and 9 following the completion of RT.
Implications for Research
This approach provides direct, real-time insight into the efficacy of anti-VEGF therapy as a non-invasive measure in a longitudinal model. Such dynamic vascular data cannot be obtained through endpoint histology alone, making this imaging method a powerful tool for evaluating combination therapies in preclinical cancer research.