Regex – Strip out commas and spaces from ’empty’ address fields

I am using a third party address lookup service that provides address data in the following format:

'addr line one, , , , city, county, postcode, addr line one, addr line two, , , city, county, postcode, addr line one, , , , city, county, postcode, addr line one, addr line two ,addr line three, addr line four, city, county, postcode'

As you can see from the data, often there are ’empty’ fields that are still delimited by a comma followed by a space.

I am looking to produce the following output:

'addr line one, city, county, postcode, addr line one, addr line two, city, county, postcode, addr line one, city, county, postcode, addr line one, addr line two, addr line three ,addr line four, city, county, postcode'

I have two choices, either a recursive replace function that replaces , , with ,
or use a regex to filter the string.

I would imagine that the regex would be the better solution, but I am at a loss as to how to create a regex that would filter this string correctly.