I sort of understand it.

Humira is a humanised monoclonal antibody which blocks TNF. There are other similar products on the market.

Low levels of TNF can affect levels of a group of enzymes (the CYP450 group) which can affect levels of statins among other targets. Presumably the negative interactions arise from this.

As an aside, I agree with Jo*mar about statins. There are several threads here where they have been discussed in this context.