library( stringr)
x <- c( "PIA+1+TC_5504_00_312010_0050+50103 AB346 type 5334" ,
"PIA+1+TC_3444_00_312010_0133+0140" ,
"PIA+1+DRW/50488665600/01/000:DW" ,
"PIA+1+TC_5635_00_312019_2644+LoremIpsum" ,
"PIA+1+TC_5635_00_312010_0040+63503 AB346 type 5334" ,
"PIA+1+TC_5635_00_312018_0223+DolorSit" ,
"PIA+1+TC_5635_00_312019_2644+DolorSit" )
str_extract( x, "(?<=^PIA\\ +\\ d\\ +)(?!.*(?:LoremIpsum|DolorSit)).*$" )
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