Thank you.
Now I can tell what happened with this drug. The problem is cost and technology. The candidate drug is a protein. Some proteins are extremely difficult to work with or make, and trying to make them synthetically is impossible. With such a protein, it is possible to study it biochemically, but trying to extract it from tissues or make it using genetically engineered microorganisms is impossible.
In graduate school, I worked with such a protein. I could make it in yeast or monkey cells, but the moment I would start to extract the protein, it would disintegrate.
Another problem is that some proteins are toxic to the microorganisms or cells used to produce them. If this is the case, it may be impossible to ever produce enough to be commercially viable.
It may be possible to use some of the new gene therapy techniques to get patients' bodies to make the ApoA-Milano variant protein. This technology is still being developed.
The bottom line is that making enough of this protein to be able to run a proper clinical trial is not possible with current technology. And the cost would be astronomical.
I recall how frustratingly difficult it was for bacteriologists to culture and identify the bacteria in Legionnaire's Disease. It required a rather complex host of symbiotic environmental factors to grow. Numerous attempts to isolate Legionella resulted in failure to culture the bug.