- Hematopoietic stem cell transplantation (HSCT) is a process that involves IV infusion of hematopoietic stem cells from a donor into a recipient, after the administration of chemotherapy with or without radiation. The rationale is to increase tumor cell kill by increasing the dose of chemotherapy. Immune-mediated effects also contribute to the tumor cell kill observed after allogeneic HSCT.
- Hematopoietic stem cells used for transplantation can come from the recipient (autologous) or from a related or unrelated donor (allogeneic). If the related donor is a twin, the transplant is referred to as a syngeneic transplant.
- Human leukocyte antigen (HLA) mismatching of allogeneic donor–recipient pairs at either class I or class II loci increases the risk of graft failure, graft-versus-host disease (GVHD), and worse survival. The ideal donor is one that is matched at HLA-A, -B, -C, and DRB1.
- Hematopoietic stem cells are found in the bone marrow, peripheral blood, and umbilical cord blood. Because of the rarity and similarity to other cells, hematopoietic stem cells are difficult to isolate and measure. These stem cells express the CD34 antigen, and measurement of the number of CD34+ cells is a clinically useful measure of the number of hematopoietic stem cells.
- Because of clinical and economic advantages, peripheral blood has replaced bone marrow as the source of hematopoietic stem cells in the autologous and adult allogeneic HSCT setting.
- The purpose of the preparative (or conditioning) regimen in traditional myeloablative transplants is twofold: (a) maximal tumor cell kill and (b) immunosuppression of the recipient to reduce the risk of graft rejection (allogeneic HSCT only).
- Reduced-intensity conditioning regimens (including those that are nonmyeloablative) have been developed in order to reduce early posttranslant morbidity and mortality while maximizing the GVT effect of the allogeneic graft. The advantage to this approach is that patients who would otherwise not be eligible for allogeneic HSCT can now be offered a potentially curative therapy.
- The transplant-related mortality rate associated with allogeneic HSCT ranges from 10% to 80% depending mostly on age and donor and disease status. Major causes of death include infection, organ toxicity, and GVHD. The most common cause of death after autologous HSCT is disease relapse; the transplant-related mortality rate is usually less than 5%, depending on the conditioning regimen, age, and disease status.
- Patients undergoing allogeneic HSCT are given prophylactic immunosuppressive therapy, which inhibits T-cell activation, proliferation, or both. The most commonly used GVHD prophylaxis regimens are cyclosporine or tacrolimus and methotrexate.
- Initial treatment of both acute and chronic GVHD consists of prednisone, either alone or combined with cyclosporine or tacrolimus. Treatment of patients with steroid-refractory GVHD is unsatisfactory.
On completion of the chapter, the reader will be able to:
Describe the different types of donors used in hematopoietic stem cell transplantation (HSCT).
Describe the rationale of autologous and allogeneic HSCT as a treatment modality for cancer.
Describe the role of human leukocyte antigen typing in identifying matched unrelated donors for allogeneic HSCT.
Describe the advantages and disadvantages ...