I'm not comparing these to the FDA approvals process, but to your claim that trials use thousands of patients. These three studies are ascertaining the pregnancy safety of a drug, irrespective of whether we understand the disease or what the response rate is.

Cimzia has been well-studied, and we understand why it works on autoimmune diseases like inflammatory arthritis. It has 6 FDA approvals for different indications, so your description of the drug itself is incorrect.