Pfizer announced the deal in March, its largest purchase in
a string of recent acquisitions thanks to a once-in-a-lifetime cash windfall
from its COVID-19 vaccine and treatment.
The European Commission said the deal would not
significantly reduce competition in the 27-country European Union nor would it
have a negative impact on prices.
"The proposed merger would not raise competition
concerns," the EU antitrust watchdog said in a statement.
Washington-based Seagen is a pioneer of antibody-drug
conjugates, which work like "guided missiles" designed to destroy
cancer while sparing healthy cells.