Engineered opsonin protein captures circulating tumor cells in the bloodstream with high efficiency.
Cancerous tumors are formidable enemies, recruiting blood vessels to aid their voracious growth, damaging nearby tissues, and deploying numerous strategies to evade the body’s defense systems. But even more malicious are the circulating tumor cells (CTCs) that tumors release, which travel stealthily through the bloodstream and take up residence in other parts of the body, a process known as metastasis. While dangerous, their presence is also a valuable indicator of the stage of a patient’s disease, making CTCs an attractive new approach to cancer diagnostics. Unfortunately, finding the relative handful of CTCs among the trillions of healthy blood cells in the human body is like playing the ultimate game of needle–in–a–haystack: CTCs can make up as few as one in ten thousand of the cells in the blood of a cancer patient. This is made even more difficult by the lack of broad–spectrum CTC capture agents, as the most commonly used antibodies fail to recognize many types of cancer cells.

To address this problem, a group of researchers at the Wyss Institute at Harvard University has adapted an engineered human blood opsonin protein known as FcMBL, which was originally developed as a broad–spectrum pathogen capture agent, to target CTCs instead. Using magnetic beads coated with FcMBL, they were able to capture >90% of seven different types of cancer cells. “We were able to rapidly isolate CTCs both in vitro and from blood, including some which are not bound by today’s standard CTC–targeting technologies,” says Michael Super, PhD, Lead Senior Staff Scientist at the Wyss Institute and co–author of the paper. “This new technique could become useful in cancer diagnostics.”

The technology is described in the journal Advanced Biosystems.