Try issueFieldMatch in JQL query like in thes example: issueFunction in issueFieldMatch("project = Myproject" , "summary","\[[Tt][Xx][Tt]\].*" )

this will filter all the issues form Myproject with [TXT] prefix (non case sensitive including square brackets) in summary field. issueFieldMatch allows regex to be included as shown in the example, for that E.g. "[TxT] correct typos in description" will be listed