Brief Answer:
Needs a LOT more work done.

Detailed Answer:
Ok, first, that is a significant amount of weight loss. This strongly implies some medical illness is going on to cause it. This can occur from mouth problems causing problems eating--that could be the entire answer. And, one would want an exam, blood work, imaging studies to look for cancer. If there is weight loss progressively over a year due to cancer, the cancer cannot be local, it has to be fairly widespread and has to show abnormalities in blood and imaging studies and likely on physical exam!
One can easily distinguish between groups of problems from lack of intake (count daily intake of calories/food) and disorders of too much calorie burning or malabsorption. Ongoing infections, depression, gastrointestinal malabsorption (which would show as abnormal to Very abnormal bowel movements... if not absorbed food has to go somewhere), various medications can all cause weight loss. Cancer weight loss is mostly lack of intake. Infection weight loss is both lack of intake and increased calorie loss (due to fever).

Once a bit more is known, then the treatment does actually become obvious and there is always ways of ameliorating weight loss.
Here are many:
Different foods. Personally and professionally, I find that small and frequent eating works best. Most of the entire packaged food industry is feverishly and fiendishly devoted to increase intake (chips, snacks) so an initial trial of junk food seriously should be considered. Another medical section of somewhat less junk food is available and is less successful in general (ENSURE). My own experiments have shown that if you make nutrient rich foods into the shape and character of junk, they will be eaten without limit like junk (rare cooked brisket slices cut to 3 cm squares, covered with junk seasonings involving ketchup with sugar prominently, then baked at 300F until just barely carmelized makes finger food that can be eaten without any bounds).
Different arrangements. Having food in the shape that is able to be taken is much of the job of dieticians in hospitals and nursing homes. They should be consulted. Having the food readily available is a stimulus for eating it.
And finally medications. The ones you mentioned are NOT approved for this purpose and although they work sometimes, there are more reliable alternatives. If someone is depressed OR ANOREXIA and that is causing loss of appetite, they both anti-depressants (mirtazepine) and mood stabilizing anti-psychotics (abilify) have reason to be taken AND have weight gain as a prominent side effect. If there is NOT depression, then marijuana derivatives such as marinol are approved specifically for this purpose.

Mainly, I don't have the info of what was previously checked and what was previously done.

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