Marrow transplantation in the treatment of acute leukemia

Effect of split dose TBI on hematopoietic stem-cell survival in combined radiation-drug exposures

Studies were carried out to determine if a priming dose of total body irradiation (TBI) given before the first drug exposure in chemo-radiation protocols similar to those used in marrow transplantation would reduce the survival of hematopoietic stem cells. The cytotoxic drugs employed were cyclophosphamide (CY) and piperazinedione (PIP), both of which are currently used in the clinic for ablation of the host marrow prior to transplantation therapy for leukemia. The effects were evaluated in a normal and a leukemic mouse model using the endogenous colony-former technique. Splitting the TBI to give part of the total dose before the first dose of drug was found to enhance stem cell kill in some instances, but not in others. The optimum proportion of TBI given as the first dose did not appear to exceed 100 rads. When a higher proportion of the total TBI was given as the initial dose there was an indication of a protective effect on the stem cells with the PIP-TBI protocols, but similar protection was not observed with the CY-TBI protocols. When CY and PIP were combined together in the same protocol it was found that a simple inversion of the order of these two drugs could result in a six-fold difference in the extent of stem cell ablation achieved, indicating that with multiple drug protocols the drug sequencing itself could be equally important as the manner in which the radiation is given.

Magna-field irradiation and autologous marrow rescue in the tratment of pediatric solid tumors

Marrow ablative therapy has been given to pediatric patients with a variety of disseminated tumors. Eight patients with advanced neuroblastoma received autologous marrow reinfusion after intensive therapy. Three of eight are in continus complete remission for 7 to 60 months. An additional four patients received allogeneic marrow transplantation and two remain in continuous complete response at 21 and 39 months. Intensive therapy and autologous marrow reinfusion have been applied to Ewing's sarcoma, but only preliminary results are available. Six patients with disseminated rhabdomyosarcoma and extra-osseous Ewing's sarcoma received conventional chemotherapy followed by sequential hemi-body irradiation. Four of six patients received autologous marrow rescue. Their median disease-free survival is 17 months. This preliminary experience demonstrates the feasibility of using marrow ablative therapy with autologous marrow transplantation in the treatment of pediatric solid tumors. Continuing Phase II studies are required to substantiate its efficacy.

Two siblings with acute T-cell lymphocytic leukemia

The only two children of clinically healthy parents both developed an acute lymphocytic leukemia of the T-cell type, one with a mediastinal mass, one without. Extensive laboratory studies revealed a combination of the following unusual circumstances. (1) The injection of leukemic bone marrow into BALB/c-nu/nu mice led to an explosive simultaneous development of disseminated lymphomatous tumors with murine karyotype. (2) HLA typing and MLC testing of all four family members revealed sharing of HLA-A,D and DRw determinants between the parents and pointed to the appearance of suppressor cell activity with the outbreak of the acute leukemia of one sibling. (3) Parental lymphocytes gave a low response to mitogen stimulation, suggesting a subclinical cellular immune defect. It is proposed that the siblings inherited from each parent a defective immune response factor, possibly related to HLA-D/DRw antigens, that predisposed to acute T-cell leukemia. The neoplastic process might have been triggered by a transferable agent.

Antileukemic effect of graft-versus-host disease in human recipients of allogeneic-marrow grafts

To determine whether allogeneic bone-marrow transplantation is associated with a graft-versus-leukemia effect, we examined the relation between relapse of leukemia and graft-versus-host disease in 46 recipients of identical-twin (syngeneic) marrow, 117 recipients of HLA-identical-sibling (allogeneic) marrow with no or minimal graft-versus-host disease, and 79 recipients of allogeneic marrow with moderate to severe or chronic disease. The relative relapse rate was 2.5 times less in allogeneic-marrow recipients with graft-versus-host disease than in recipients without it (P less than 0.01). This apparent antileukemic effect was more marked in patients with lymphoblastic than nonlymphoblastic leukemia, and in those who received transplants during relapse rather than during remission, and was most evident during the first 130 days after transplantation. Survival of all patients was comparable since the lesser probability of recurrent leukemia in patients with graft-versus-host disease was offset by a greater probability of other causes of death.