Extended Data Table 1. Metastatic frequency and tissue tropism identified by FACS in each PDX model.

	HCI-001	HCI-002	HCI-010
PATIENT
Marker status	ER−/PR−/Her2−	ER−/PR−/Her2−	ER−/PR−/Her2−
Tumor subtype (PAM50)	Basal	Basal	Basal
Sample source	Breast	Breast	Pleural effusion
Diagnosed metastases	Lymph node	Lymph node	Lung
PDX MICE
Total mice with mets	26/32 (81%)	13/35 (37%)	31/33 (94%)
Peripheral blood	7/31	1/19	3/22
Lymph node	8/31	7/34	17/33
Lung	26/32	7/35	31/33
Bone marrow	3/21	4/25	6/23
Brain	0/15	1/8	1/13