I know nothing about Doctrine2, but if the origin for the issue has anything to do with the column name [which seems at least somewhat tenuous given the error implies nothing about a column name], then probably the issue is related to the name of the column [at what is presumably an IBM i as the server] having the first character defined using the EBCDIC code-point 0x5B.
While that EBCDIC code-point x'5B' is valid to represent the variant Dollar Sign character in some code pages [a valid but discouraged character, just like the @; see: Using @ on Variable Names], the Pound Sterling Sign character [ASCII code-point 0xA3] sent from an ASCII client may not get translated to the EBCDIC code-point x'5B'. The outcome depends on how the server is configured for the Code Page, and quite likely the character would translate to the EBCDIC code-point 0xB1; a code-point that is unlikely to represent a valid character for an SQL identifier such as a column name.
So if the client can refer to the column name having specified the first character as the $
character instead of as the £
character, then when the expected\proper character conversion from ASCII to EBCDIC occurs, the server will correctly see the column name as the expected name; i.e. will in effect, see the characters $ADRB1 in EBCDIC [hex:5BC1C4D9C2F1] as translated from the ASCII characters $ADRB1 [hex:2441445231] rather than the likely\undesirable outcome instead whereby the server in effect will see the characters £ADRB1 in EBCDIC [hex:B1C1C4D9C2F1] as translated from the ASCII characters £ADRB1 [hex:A341445231].
p.s. The tag DB2i is defined in the wiki as the DB2 for IBM i and the tag DB2 is defined in the wiki as the DB2 family, but the tag ibm-db2 has no definition https://stackoverflow.com/tags/ibm-db2/info, so if the server is IBM i with the DB2 for i as the database, then perhaps the DB2i is a better [or additional] choice for tagging this topic.?