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Take Away Points:
- CLL is a cancer of our immune system so our ability to fight cancer is compromised and our cancer clones can stay hidden for years.
- The only “cure” for CLL is based on using cells rather than drugs. Chemotherapy and other newer drugs have not yet proven that they can cure CLL.
- Transplants and experimental CAR-T therapies are possible cellular therapies with curative potential.
Hematology in general and CLL specifically are full of jargon and acronyms that can be both overwhelming and daunting. With time and experience, you’ll become familiar with the terminology and acronyms. We will try to explain each medical term the first time it appears in an article, but we will use the true terminology so that you gain comfort and familiarity with the medical terms that you will see in your lab reports and in medical articles. We will also provide a glossary for your reference.
The only possible cure for CLL is a cell based (cellular) therapy, specifically an allogeneic (cells are sourced from someone else, a matched donor) bone marrow or hematopoietic stem cell transplant (HSCT) that essentially tosses out our old immune system and replaces it with a new one to attack our cancer.
But there are significant risks with importing a new immune system. While the new graft can attack the leukemia (graft versus leukemia), which is good, but it can also attack us, the host (graft versus host) which can be very bad. As a result of this common and potentially fatal complication, plus the significant bone marrow and immune suppression needed to prevent us from rejecting the donor graft that can lead to dangerous infections and other problems, transplants are very high-risk procedures.
The inherent risks associated with transplants has generated much excitement about CAR-T therapy (chimeric antigen receptor- T cell therapy). This experimental treatment is all about using our own T cells that our harvested from our bloodstream, grown outside our body, taught by a virus to attack our cancer, and then re-infused where they proliferate inside us, and then go on to continuously seek and destroy cancer cells. The early clinical trial data is encouraging and impressive in very difficult to treat cases.
Cytoxic T Cells:
CLL is a B cell cancer. B cells are a type of lymphocyte (white blood cell found in the lymphatic system) that is charged, among its many duties, with using antibodies to defend us. There are also T cells, another big family of lymphocytes that are responsible for our cellular response to cancer and infections.
This amazing NIH movie of real cells that follows shows the actions of one particular type of T cell, the cytotoxic T cells or CD8+ cell, the heroes of our little story, seeking and destroying cancer cells.
As CLL is a disease of the immune system and although our cancer is only found in our clonal B cells, it is important to remember that many aspects of our immune response are badly compromised at the time of diagnosis and only get worse with time and most traditional treatments.
Also tiny resistant cancer clones can be very patient, sometimes causing relapse many years after therapy. Hence the appeal of an ongoing treatment that offers constant and lifelong immune surveillance for tiny hidden enemy caches of cancer.
To learn more about CAR-T therapy from Dr. David Porter out of the University of Pennsylvania, please start here.