Anonymous,
You asked some tough questions. I will attempt to answer them as a patient that did one - certainly not an expert like the Doctors that are nice enough to post in the forums.
"What needs to be done to make an allogeneic SCT as safe as an autologous SCT? When would one likely be able to safely proceed to an allo SCT with the same risks associated to an auto SCT (2 years, 5 years, 7 years from now)?"
IMO the answer to that question is never. Allos and autos really have very little in common. An auto is the use of a high dose of drugs (usually melphalan) and the patients own stem cells are returned to them so they can recover faster. Since a myeloma patients problem originates from their immune system, the auto does not attempt to take care of our real problem. Myeloma patients definitely do not have melphalan or Revlimid deficiencies! The therapy is only the high dose of drugs.
Not all allos use a high dose of drugs. Mine did, but there are many patients that do them without the use of a high dose of drugs. An allo is an attempt to transplant the immune system of a healthy donor into a cancer patient. All real transplants can have complications. I think the Doctors have done a great job of making them a much safer procedure. The average age of a patient with a diagnosis of myeloma is in the late 60's age wise. For them, an allo is likely not appropriate therapy. A younger patient should look at non-relapse mortality statistics for patients with other blood cancers that are in their age group. While there are some small risks associated with allo transplant done in first remission, for me the "opportunity cost" of not doing one in first remission far outweighed the risks.
"How would one know if they are ‘functionally' cured as a result of having an allo SCT?"
As I have mentioned elsewhere, IMO the issue of curability of myeloma in the allo transplant setting is really a testing issue, not a therapy issue. Some patients never relapse after an allo. Unfortunately there is not test that can determine with 100% certainty which patients are going to relapse. If there was such a test, the patients could be treated with more immunotherapy or novel agents to prevent relapse. You may have seen some of us mention Immunophenotypic or Molecular responses. They are much more sensitive tests than what constitutes stringent complete response, but they have the disadvantage of being from a bone marrow sample (one spot from the patient). A good paper on testing issues in myeloma was written by Dr. Guido Tricot in 2007.
http://www.clinicaladvances.com/article_pdfs/ho-article-200702-tricot.pdf "What is the success rate of people achieving a functional cure from an allo transplant?
What factors are involved in an allo SCT being potentially curative for one person, and potentially not curative in another?"
Since allo transplants can be done in many different ways there is no way to know what an individual patients chances of success are. There are so many factors that affect the individual patients chances of success, only an experience allo transplant Doctor could answer that question after analyzing an individual patients case. The allo transplant only has a good chance of success if it is done early in disease course. If a patient has experienced a full blown relapse the chance of an allo providing long term disease control or functional cure is low. Well know allo transplant expert Dr. William Bensinger wrote this in 2007:
"Stem-cell transplantation from allogeneic donors may be curative for 10–20% of patients with chemotherapy-resistant, refractory hematologic malignancies, and for up to 80% of patients who are transplanted in remission. Much of the high response and curative potential of allografts is attributed to a ‘graft-versus-tumor’ effect. In patients with multiple myeloma this effect has been well documented.[3–5] In contrast, stem-cell transplantation from autologous or syngeneic donors provides little or no immunologic effect against the myeloma cell. Thus autologous or syngeneic stem-cell transplants are mainly a form of supportive care and require intensive chemotherapy with or without radiation to accomplish eradication of the disease or alternative strategies designed to duplicate or mimic the graft-versus-myeloma effect. Long-term follow-up of recipients of autologous stem-cell transplants indicate a continuing risk of disease recurrence after 5 years, and arguably few if any patients are cured. In contrast allogeneic stem-cell transplants with long-term follow-up appear to result in durable remissions and a lower risk of recurrence after 5 years."
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3017399/Mark
