“In vivo, single agent tucatinib showed anti-tumor activity and inhibition of HER2 phosphorylation in mouse xenograft models of HER2 expressing tumor cells.”
✓ VerifiedFDA multi-discipline review, p. 33Source ↗
Why that model
Not stated in public reviews
Not reported in the public reviews. Reviewers summarise selectively, so this usually means it wasn't discussed publicly, not that it wasn't studied.
Reviewer's view of the efficacy data
EMA: in vitro and in vivo proof of concept considered well established
“In vitro and in vivo proof of concept is considered well established.”