Yes, assuming you're definitely talking about an Avios booking through BA, if you cancel a reward flight (+24hrs prior) then you'll receive back all of your Avios and all of the Cash paid, minus the $55 / £35 - so in your case $125.

Its the only time Avios bookings are good value for longhaul economy - One-Way flights when you may need to cancel. For returns, the fees are normally the same price as a cheap Economy cash fare (certainly Ex-UK anyway, maybe not US)