https://www.sidley.com/-/media/publications/anatomy-of-a-cvr-a-pr...

https://www.sidley.com/-/media/publications/anatomy-of-a-cvr-a-primer-on-the-key-components-and-trends-of-cvrs-in-life-sciences-public-ma-deals.pdf?la=en&rev=849ca264e438474cb90d2c901a4b357e

Contingent Value Rights are the way it works. At least in the US anyway, I'm not sure if there is an equivalent vehicle in Australia.

"In recent months, the life sciences industry has seen the reemergence of contingent value rights, or CVRs, in public
company acquisitions as a way to bridge a valuation gap between buyers and sellers"

In principle, it ties value to a future event. I don't think a long-term stream of royalties is a realistic potential outcome for RAC. However, if a situation arises where a prospective buyer and RAC shareholders cannot reach agreement on value, a CVR may be a way of bridging that gap.

For example:

When AstraZeneca acquired Clincor, they paid $26 USD per share in cash, plus a non-tradeable CVR of $10 per share held at acquisition payable upon completion of some unspecified regulatory milestone.

In this example, the $26 per share cash payment represented a 121% premium over the closing market price at the time of the offer. When combined, the cash + CVR offer represented a 206% premium over the share price.

So mechanisms for extracting value out of bisantrene post-acquisition exist and can add significant extra value to shareholders.

https://www.investopedia.com/terms/c/cvr.asp#:~:text=A%20contingent%20value%20right%20is,potential%20for%20a%20higher%20value.