What is the most effective treatment for arthritis thus far? And are we any closer to finding a cure for auto immune diseases?

Yes. It depends on the type of arthritis. When i was in medical school in the 1970's, about one person in 150 would have their life ruined by autoimmune arthritis. The immunomodulators produced by biotechnology have greatly improved the outlook for severe disease and have proved surprisingly safe. It's still a rough and frustrating disease but progress continues. Stay proactive -- and good luck.
Arthritis. Osteoarthritis is allways going to be a natural progression of aging. Nsaids and steroids are first line therapies, but for those autoimmune diseases as ra, lupus etc out there, there are many new drugs on the horizon and it really takes a specialist to keep track of them.