Sorrento Therapeutics Inc (SRNE)

[Scandle34]

It all depends on the method they use to engineer the antibody.

One does not (yet) engineer an antibody. That day is coming and so are designer enzymes... not yet though.

What I know is dated (400-level course from 1990 as part of my PhD on biosensors), so the 'unexplained' part below might be known by now.

B-cells make antibodies. Each B cell can only make a single specific antibody. At that time there was no explanation about how the variability occurred, but it was assumed that the portion of the B cell DNA that coded the proteins in the antibody had a high mutation rate.
When a B-cell, covered in antibodies with their reactive end out, encounters a foreign material that binds with the antibody, the B cell detects this and starts shedding antibodies into the blood stream while continuously making more.

The vast majority of the antibody is the same as every other antibody of that type. They all stay in the blood stream until they bind to something or something else binds to them (e.g. an auto-immune response), or until random enzyme activity digests them.