I think your revenue figures are ridiculously low.
I forget which think tank -- the one that deals with AD drug revenue projections -- a few years ago estimated an annual patient cost of up to $25K per year for a highly effective AD drug. That price is a bargain compared to the present economic and social costs of the disease.
Although it appears that blarcamesine will not be useful after an AD patient has lost too much mental capacity or is genetically unresponsive, the drug itself, at its peak, will extend the patient population by increasing "time saved" for each new person who develops Alzheimer's. Between the EU and the US (assuming the drug is approved there) we could see up to 10 million patients eligible to benefit from the drug each year. If Anavex gets half the revenues in a partnership and the drug works well, I can see a potential peak market of at least $50B annually.
I could be wrong, of course, but not nearly as wrong as a $1.8B estimate.