Why do drugs stop working?

When should someone get a second opinion for their chronic lymphocytic leukemia?
What tests are required to be able to have a stem cell transplant? What testing is done to determine if I am eligible for a transplant?
How can immunotherapy be used to treat acute myeloid leukemia, and what are the most common side effects?
When should ASCT be considered? When is the best time to have an ASCT?
What is immunotherapy? What immunotherapy options are currently available for acute myeloid leukemia?