Table 1.

Classes of patient similarity

Similarity Class	Temporality	Object or Action	Examples
Feature	Snapshot	Object	Disease type/status, past medical history, treatments received
Outcome	Snapshot	Object	Adverse event, treatment efficacy
Exposure	Change over time	Action	Prior lines of therapy define a cohort for study and reflect disease status
Mixed-class	Snapshot/change over time	Object/Action	Molecularly and disease-matched patients who exhibit a similar outcome to therapy