i think he needs aggressive treatment. Mouth ulcers and dental abscess
may be showing us the immunocompriomse at this state . the treatment he is receiving , is best for him at this state. The positive point is the biopsy
is not showing any cancer condition means he does not need any cancer treatment at present.the treatment you have mentioned , usually prescribed by hematologist/ medical oncologist
. My advise is to follow what he suggests and be positive.