There is zero chance it costs $5 per dose because blinatumomab is a bi-specific T cell engager which is a monoclonal antibody made by extracting it from a cloned white blood cell created from recombinant DNA. The yield for this process is extremely low and it's really complicated in the best of times. The cost of the pipette tips and other consumables used by the lab automation alone probably costs more.

The flip side is that it treats a rare form of leukemia so the market isn't very big and since they can't lower the price enough to compete with chemo, they have to actually charge more to get their money back. For example chemo might cost $10k, but their drug costs $10k to make per person so if they charged $50k they might not even get enough customers to break even. So instead they charge $200k to get the most from the patients they can capture like the X% of patients who are allergic to the chemo drugs and have no choice (Just an example, I don't know the specifics for blinatumomab)

The research, development, approval process, and production all absolutely cost money that needs to be recouped from the sale, but we shouldn’t ever forget the reason why the company exists: to make profit.

You also need to pay for all the other research projects that did NOT yield a successful drug.

In other words, no it is not only supply and demand - it’s the desire to maximize profit as far as the market will bear

Or like the other response to your parent comment said, it could cost a ton to make, which lowers the number of people who can get it, driving costs even higher due to low volume.

It’s both. But it’s ultimately the profit motive that drives a business at all.