It can vary from insurance company to insurance company depending on the agreement they have with the people involved in the infusion (such as the drug manufacturer and the office that does the infusion). The best way to find out is to get an EOB (explanation of benefits) from your insurance company to see what they paid for it.
From what I could find online, it looks like the cost is around $1500—$2000 per dose, not counting the fee the office charges for doing the infusion. That isn’t necessarily what your insurance pays though.