Extended Data Fig. 1: Intravital imaging reveals micrometastatic progression and regression of DTCs in brain.

Serial intravital imaging revealed several potential fates for eGFP-T4-2 breast cancer DTCs which reached the brain: a) DTCs progress to micrometastatic lesions but regress and die by day 20 post-intracardiac inoculation; b) proliferate then regress by day 23, but continue to persist as a single cell through day 39; and c) steadily progress to form stable micrometastases. These behaviors were also observed in a second model using MDA-MB-231 cells: d) steady progression to form micrometastases by day 14, which continue to grow along vasculature through day 43; e) death/disappearance of micrometastasis by day 29. Representative images of n = 16 cells over 6 mice (T4-2) and n = 17 cells over 5 mice (MDA-MB-231) over the course of 4 to 7 weeks post-injection were tracked for regression (a,b,e) or progression (c,d). Scale bar = 40 µm.