Hi ,

     my $string = q{"2","T,E,S,T,B","Lazowsky","Mike's","Teststring"};

     $string =~ s<
                  (,[A-Z])
                 >
                 <
                  (local $a = $1)  =~ tr/,//d;
                  $a
                 >gex;
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This also works for the $string and gives the TESTB without commas