My daughter is trying Humira for the second time. The first time she was on it, it worked really well for two years and then suddenly stopped working. Her dr think it's because she gave up methotrexate which was stopping her from building up antibodies.
However, two years after that we are back on Humira + sulfasalazine (she was on Remicade and mtx for a while but that stopped working too). We didn't test for antibodies (for Humira) because a different doctor said it could work even if she has antibodies. She's been on it for almost two months - no reactions at all and is beginning to feel better.
Good luck!