Two noninvasive technologies detected tumor response to therapy weeks earlier than tumor volume changes reflected.

Change in tumor volume is considered the gold standard for evaluating how well a given cancer therapy is working in preclinical studies, but new data suggest that ultrasonic molecular imaging (USMI) and dynamic contrast enhanced–perfusion imaging (DCE–PI) may be able to classify and characterize tumor response at an earlier point, and more robustly.

Tumor size measurements alone may not reflect early changes in tumor physiology that occur as a response to treatment, affirmed Paul A. Dayton, PhD, and colleagues in their report for Technology in Cancer Research & Treatment. Dayton, of the University of North Carolina (UNC) Lineberger Comprehensive Cancer Center in Chapel Hill, North Carolina, and his team explored whether USMI and DCE–PI could be used to characterize response to treatment earlier than could traditional methods. These two noninvasive techniques were already known to provide information prior to the appearance of gross phenotypic changes.

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In USMI, targeted contrast agents are used to bind to specific proteins of cancer cells, enabling a standard ultrasound system to detect otherwise undetectable signals from the cells, according to a statement from UNC Health Care describing the study results. Ultrasound DCE–PI monitors blood flow in tumor microcirculation to provide information on changes in blood vessel structure or density and, ultimately, tumor malignancy.

After administering an investigational kinase inhibitor to the mice, Dayton and his fellow researchers used the two imaging tools to measure the responses of two different tumors. One tumor was known to respond to the drug therapy, and one was known not to respond.

USMI detected molecular signs of tumor response to therapy after just 2 days, and DCE-PI detected changes in tumor blood flow after day 14. Standard tumor volume measurements were unable to detect therapeutic response during the same period. Previous research has suggested that tumor volume measurements don’t become indicative of response until approximately 28 days after treatment initiation.

“Having new noninvasive, inexpensive technologies available to measure response to therapy earlier during the course of treatment would be a significant advance in the ability to tailor a person’s treatment to improve outcomes,” pointed out Dayton in the UNC Health Care statement.