antibodies to infliximab

My 20 yo son was diagnosed with moderate UC in 2018, did not respond to mesalamine/steroids so he was started on infliximab and methotrexate. After his 3rd infliximab infusion, he did great, no more pain, bleeding, diarrhea. etc. (he was in pretty bad shape until this point, looking at surgery when he was 17!). He was taken off methotrexate in 2019. He has also done a great job of altering his diet, so while not perfect, he eats pretty healthy, cutting out sugar/junk food/fast food, etc. He also started running/moderate intense cardio exercise & weight training and takes many anti-inflammatory supplements.


In the past month, he began having some problems, slight abdominal pain, diarrhea. Labs were done and shows his infliximab levels are low and he has a low level on antibodies forming (25) to the infliximab. So while we have a "reason" why he is symptomatic, his GI doctor said it is not well understood why some people form antibodies to the infliximab and there isn't a great way to treat. He suggested putting him back on the methotrexate and rechecking levels in a month.


Anyone else form antibodies to infliximab and have advice for us?
Thanks