The information comes from a Regeneron spokeperson Alexandra Bowie
This search links to multiple stories
https://www.google.com/search?q=alexandra+bowie+regeneron&source=lnms&tbm=nws&sa=X
The reference to the HEK line is also contained in this PDF produced by Regeneron
https://science.sciencemag.org/content/sci/suppl/2020/06/15/science.abd0831.DC1/abd0831_Baum_SM.pdf
“ Briefly, HEK293T cells (ATCC CRL-3216) were transfected with the genomic clone... ”
So, what are the AtTCC CRL-3216?
https://www.atcc.org/products/all/crl-3216.aspx
Derivative define : (typically of an artist or work of art) imitative of the work of another person, and usually disapproved of for that reason.
The 293T cell line, originally referred as 293tsA1609neo, is a highly transfectable derivative of human embryonic kidney 293 cells, and contains the SV40 T-antigen.