The -mab suffix means it's a "monoclonal antibody," or a lab-made protein that specifically targets a certain antigen (for example, an antigen found on a cancer cells).

As per the other commenter, but also they have a 10 year development pipeline and 10 years ago some major rockstars started hitting the market (ipilumimab, traztuzumab ) which are anti cancer ones but many others also). These were essentially the second generation of these drugs, the first gen sort of came out in the late 90s/early 2000s (ie Bevacizumab, infliximab ) and proved so versatile that they’ve spawned whole industries.

The particular advantage is that a drug company can generate an antibody, clonally produce it, and demonstrate efficacy but no one else can claim the same efficacy because any other drug company is going to have an antibody that binds slightly differently and so has a different efficacy. (Ie so a generic here is called a bio similar antibody).

There have even been bio similar that have had the opposite effect to the desired one (by for example acting as a receptor agonist rather than an antagonist)

See here: https://en.m.wikipedia.org/wiki/Nomenclature_of_monoclonal_a...