Читать книгу The SAGE Encyclopedia of Stem Cell Research - Группа авторов - Страница 413

There is currently a phase II clinical trial investigating how transplantation of unrelated donor umbilical cord blood combined with reduced intensity of chemotherapy will affect the overall survival of patients with an advanced hematological cancer. The reduced-intensity chemotherapy in this trial will involve a preparative nonmyeloblative regime, which may improve the efficiency of the transplanted stem cells. All forms of transplantation, including cells and stem cells, are often faced with the challenge of host immune response, making the use of preparative regimens very important in suppressing host immune system and subsequent integration of the stem cells. Although the use of myeloblative regimes are typical for less severe cases of hematological cancer, the benefits to more serious cases are largely unknown.

The current study will determine the rate of survival and progression following two years of transplantation. The study will look at the proportion of patients who achieve full donor chimerism after two years. The occurrence of possible clinically significant infections and engraftment of neutrophil and platelets after two years of transplant will be monitored by the study as well. Monitoring the rate of mortality and survival rate six months following nonmyeloablative conditioning is important in this study since the regime is normally not utilized in serious cases of hematological cancers. The incidence of acute or extensive chronic graft-versus-host disease will also be monitored after two years to help establish the effectiveness of the procedure.

Several clinical studies have found that infusion of unrelated donor stem cells that do not match exactly with those of the hematological cancer patient may help their bone marrow in producing stem cells and other types of blood cells. But the effectiveness and safety of such an approach is not fully characterized to allow routine usage in the clinics. With donor-matched stem cells, several risks will be averted, but the availability of these matched donors currently do not meet the demand. Transplanting stem cells that do not match patients has a higher likelihood of increasing the rejection and failure of these cell grafts; therefore, it is important to understand fully how the use of unrelated stem cells will react and work in patients if this method is allowed in the clinics.

Currently a phase II trial is investigating how unrelated umbilical cord blood transplanted to patients with hematological cancers works. To achieve this feat, unrelated donor stem cells will be transplanted to the patients and many indicators of effectiveness will be monitored. This will include overall survival, rate of progression-free survival, and occurrence of clinically relevant infections after two years.

In addition to monitoring neutrophil and platelet engraftment, the incidence of nonrelapse mortality will be monitored for six months, as will the incidence of chronic graft-versus-host disease and several stages of acute graft-versus-host disease. The progression of the cancer and graft rejection or failure will be examined following the transplant.