oracle – Is it possible to nest CASE-statement into WHERE clause?

I am trying to bring this statement into work

SELECT ATTR3
FROM TABLE
WHERE ATTR1 = TO_NUMBER('1460')
  AND (CASE
           WHEN TO_NUMBER('1460') NOT IN (1460, 1478, 1481) THEN 'ATTR2 IS NULL'
           ELSE ATTR2 = TO_NUMBER('000')
       END);

This SQL query was generated using the sqlalchemy.sql.text in Python as shown here, where I paste two variables var1 and var2 into it

SELECT ATTR3
FROM TABLE
WHERE ATTR1 = TO_NUMBER(:var1)
  AND (CASE
          WHEN TO_NUMBER(:var1) NOT IN (1460, 1478, 1481) THEN 'ATTR2 IS NULL'
          ELSE ATTR2 = TO_NUMBER(:var2)
      END);

However, I am getting the following error:

ORA-00905: missing keyword

So, now I am wondering how can I resolve m issue? As well as if it is possible to nest a CASE-statement into the WHERE clause?

I have seen some related topics, but they were not helpful.