I am trying to do some regular expressions with replace in VBA for Excel. But I'm unsure how to enter a match while excluding some characters.

The original string is a URL like this:

//lena/sasweb/cgi-bin/broker?_SERVICE=pool4&_PROGRAM=appsas1.MERCHANT.sas&EMAIL=&_DEBUG=0&FILE=MERCHANT&CIM=&DIV=&CIA=&ENTITY=43&FDEPT=&SUBD=772&FSUB=&BUYER=&FCAT=&SUPPLIER=&LOTSET=&BRAND=&LABEL=9

I'd like to change where it says "ENTITY=43" to "ENTITY=45". All the variable are between "&" symbols. So how do I say in RegEx to replace just this one variable?

Right now I'm using:
&ENTITY=\w+
And while it works it is not optimal. I'd like to match between the "&" symbols (or end of line) but not include them in the replacement.

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Right now I'm using:

Dim reg As New RegExp
PatternStr = "&ENTITY=\w+"
ReplacementStr = "&ENTITY=45
reg.Pattern = PatternStr
reg.IgnoreCase = True
URLStr = reg.Replace(URLStr, ReplacementStr)