This is in regard to BTG "acquired" licensing rights from BioClonetics back then, AND those licensing rights like any licensing rights, have an expiration date.
BioClonetics would in no way, shape, or form hand over their exclusive Clone 3 Patent to any company for any amount of money. Why would they when they can license it to as many Biotechs as they want and profit from it.
An example of this is the Patent on the widely used HMG CoA Reductase Inhibitor that is the ingredient for the Statin Class of cholesterol lowering drugs manufactured by several Pharmaceutical Companies.
I performed research and discovered Merk holds the Master Patent on HMG Co-A Reductase Inhibitor https://patents.google.com/patent/US4933165A/en and has licensed it out to several BigPharmas.
Here's a short list of the BigPharmas that "acquired" licensing rights from Merk for the HMG Co-A Reductase Inhibitor Patent with the corresponding brand name based on their own manufacturing formulary:
Not only this BTG was acquired by Boston Scientific which means that IF Boston Scientific wanted to acquire that technology they would need to be granted licensing right by BioClonetics. As far as I know licensing rights on a Patent for any technology does not survive an acquisition or buy out of one company by another.