Looking at your data below, you cant convert an alpha-based string to an integer. It has to be a numeric string only.
Hard to know what your actual data looks like with that small sample, but if you can assume that the non-numeric data will always start with an alpha character, you can do something like this:
Iif(Ascii(Left(@yourColumn,1)) < 58 and Ascii(Left(@yourColumn,1)) > 47, ToInteger(@yourColumn) , -1 )
This checks the first character to see if it is between 0 and 9. If it is then convert the value to an Integer. Otherwise put "-1" in the data.