Not all humanized mice are created with aborted fetal tissue. There are other methods, one uses donated adult tissue and another uses donated umbilical cord blood/tissue and donated thymus tissue from infants who have to have emergency heart surgery as apparently the thymus has to be removed or reduced in size in order to access the heart and so it is saved and donated for research.
So do you have direct evidence that Regeneron uses the fetal tissue system rather than the other two methods?
See post 65