Allogeneic transplant can be curative for patients with lymphoma and is often effective in difficult situations where other treatments have failed. Unfortunately very few of us have suitable sibling donors and in a multi-ethnic society such as the US, finding HLA-identical donors in the transplant registry can also represent a challenge. Several studies presented at the Annual Society of Hematology meeting offer evidence of rapid progress and increased success in the field of mismatched transplantation. Dr. Symons from John’s Hopkins used mismatched related donors ( also called haplo-identical donors i.e relatives who are partially HLA-identical) and with a novel chemotherapy regimen and GVHD prophylaxis reported a low risk for graft vs host disease and excellent outcomes in patients with very high risk disease. Using similar technology even better results were reported by Dr. Bashey from Atlanta. He reported that the outcomes of such haplo-transplant were similar to those of transplants from HLA-identical siblings. We used a slightly different approach and combined a haplo-identical transplant with an umbilical cord blood graft. In this procedure, the umbilical cord blood graft tends to assure long term hematopoiesis and may provide a more robust immune system with very little chronic graft vs host disease. We presented data on 51 patients with hematologic malignancies and the group from NIH used a similar approach to treat 10 pts with aplastic anemia. Both groups showed excellent rates of recovery and a high percentage of patients achieving prolonged remissions. Dr. van Rood showed that the choice of umbilical cord graft may minimize the risk for disease recurrence. It is too early to know which of these approaches, haplo or haplo-cord transplantation will ultimately become widely accepted, but the field is moving rapidly and options for patients who lack a sibling donor are rapidly improving.
Allogeneic transplantation for Hodgkin’s lymphoma
Though most patients with Hodgkin’s Lymphoma (HL) are cured with their initial treatment, a small percentage of them fail to achieve remission or relapse after initial treatment. Such patients usually receive a salvage chemotherapy regimen followed by autologous stem cell transplantation. However, only half of those undergoing autologous transplant are cured, and that percentage is even lower for those with incomplete responses to salvage. Using an innovative approach, Peggs et al used the PET response to decide whether or not to assign patients to allogeneic or autologous transplant. Those with a complete response to salvage (PET negative) underwent autologous transplant and over 85% were cured. Those with a partial response as shown by PET scan, underwent an allogeneic transplant using a related or unrelated donor. The results in this very high risk group were excellent with 84% achieving a durable remission. Because allo transplant was introduced earlier in the course of the disease, it was also better tolerated and treatment related morbidity and mortality were minimal. This type of results indicate that allogeneic transplantation is much safer and more effective when applied earlier in the course of the disease and that it can be effective in case of lymphoma when autologous transplant is unlikely to be effective.