Cells shed by tumors into the blood circulation can seed metastases. Their capture and analysis could help clinicians determine how well patients are responding to therapy. But because circulating tumor cells (CTCs) are rare, they can be very hard to study, especially in mice, which have very little blood in their bodies. A team led by Ludwig MIT’s Scott Manalis developed an exchange system that allows blood from a healthy mouse to flow into a tumor-bearing mouse and vice versa, while detecting, isolating and counting CTCs. The researchers used their system to analyze CTC dynamics in real-time in mouse models of three types of cancer: small-cell lung cancer (SCLC), a pancreatic cancer and non-small cell lung cancer (NSCLC). The half-lives of the CTCs for the three cancers, they reported in a September paper in Nature Communications, range from 40 seconds to about 250 seconds. SCLC tumors, which tend to be highly metastatic, shed more than 100,000 cells per hour into the blood, while pancreatic tumors released as few as 60 in that period. Just 1%-2% of CTCs shed by SCLCs in a day could seed large metastases in healthy recipient mice.
This article appeared in the February 2022 issue of Ludwig Link. Click here to download a PDF (1 MB).