Note that while TNF inhibitors like adalimumab (Humira) have a black box cancer warning in the US, this was based on assessing a small number of studies early on. We now have more than 20 years of studies and patient registry data, and later studies, including meta-analyses, have concluded that there is no additional risk of cancer with these TNF inhibitors.
E.g. see:
The best thing is if we could target these drugs to only be activated in areas of active inflammation.
Infection risk is currently the case with all current medications that act on the immune system. In all cases we are merely suppressing some pathway where the end goal is to reduce the immune response.
ThatMs really the best we can do until we actually identify the causes, and can address that rather than "dialing down" our immune systems.