Need help with Regular expression

I have different file name pattern as follows.

ABCD_ABCDEFGH_PARB_ALLB_CCYYMMDD-HHMMSS.TXT
SDCD_NKEDHEI_ALLIA_PARTN_CCYYMMDD-HHMMSS.TXT
UN_URKSLJIE_EXTRACT_DATA_ALLT_PART_CCYYMMDD-HHMMSS.TXT

And I was trying to use the following regex expression but it doesn't work all types of file names as above ...

^.*_(ALLB|ALLIA|ALLT|AMERI|BCBS|CCH|EASB|EASTP|EAST|SANDH|SANT|SANB|TRIB|TRILL|TRIT|UHC|VAYAH|VAYT|VAYB|WELLC)(?_PARTN|?_PART)_\d{8}-\d{6}"\.TXT$

Can someone help me with this?