High-dose fractionated total-body irradiation, etoposide, and cyclophosphamide followed by autologous stem-cell support in patients with malignant lymphoma

PURPOSE

To evaluate a high-dose treatment regimen of fractionated total-body irradiation (TBI), etoposide, and cyclophosphamide (Cy) followed by autologous stem-cell transplantation (ASCT) in patients with malignant lymphoma.

PATIENTS AND METHODS

Fifty-three patients with non-Hodgkin's lymphoma (NHL; n = 43) or Hodgkin's disease (HD; n = 10) received 12.0 Gy of fractionated TBI, etoposide 60 mg/kg, and Cy 100 mg/kg followed by infusion of autologous hematopoietic stem cells.

RESULTS

Thirty-one of 53 patients are alive a median of 643 (range, 177 to 1,144) days after transplant. The 2 year Kaplan-Meier (K-M) estimates of survival, event-free survival (EFS), and relapse for all 53 patients were 54%, 45%, and 43%, respectively. Sixteen of 24 patients with less advanced disease and 10 of 29 patients with more advanced disease survive free of disease for K-M estimates of EFS of 61% and 31%, respectively (P = .006). The K-M estimates of relapse were 34% for patients with less advanced disease and 53% (P = .05) for patients with more advanced disease. The K-M estimates of dying from causes other than relapse were 8% in patients with less versus 25% in patients with more advanced disease (P = .09).

CONCLUSION

These data indicate that approximately 60% of patients transplanted early after failure of initial therapy for malignant lymphoma are projected to be disease-free more than 2 years after treatment with fractionated TBI, etoposide, and Cy and infusion of autologous hematopoietic stem cells. The transplant-related mortality rate is low and relapse is the main cause of treatment failure in patients with less advanced disease. For patients with more advanced disease, the K-M estimates of both transplant-related deaths (25%) and relapse (53%) remain major problems.

DLA-identical bone marrow grafts after low-dose total body irradiation: the effect of canine recombinant hematopoietic growth factors

Previous studies found that bone marrow (BM) allografts from DLA-identical littermates resulted in survival of two thirds of recipient dogs after otherwise lethal doses of 450 to 600 cGy of total body irradiation (TBI) because of successful allografts or autologous recovery after rejection of the allografts. The current study asked whether survival could be further improved by treating allograft recipients with recombinant canine granulocyte colony-stimulating factor (G-CSF), stem cell factor (SCF), or G-CSF/SCF. Of 21 dogs, 14 (67%) receiving allografts but no growth factors survived, 10 with successful allografts (including 5 mixed chimeras) and 4 with autologous recovery; whereas 7 animals died, 5 from infections during BM aplasia and 2 from acute graft-versus-host disease. By comparison, 30 of 34 dogs (88%) receiving hematopoietic growth factors in addition to the BM graft survived, 17 with successful allografts (including 10 mixed chimeras) and 13 with autologous recovery; whereas 4 died, all with infection related to BM aplasia after rejection of the allograft. Survival was similar for recipients of G-CSF, SCF, or the combination of G-CSF and SCF. Logistic regression analyses, which accounted for possible effects of TBI dose, showed a trend for improved survival in dogs receiving growth factors (P = .09), no change in allogeneic engraftment (P = .74), and a slight increase in autologous recovery (P = .22). In agreement with previous data, we found that grafts of BM from DLA-identical littermates improved survival of recipient dogs exposed to low but otherwise lethal doses of TBI. A further improvement in survival could be achieved by additional treatment with G-CSF, SCF, or G-CSF/SCF. Results suggest that treatment by hematopoietic growth factors along with BM grafts should be considered for victims of radiation accidents.

Marrow transplantation for chronic myeloid leukemia: a randomized study comparing cyclophosphamide and total body irradiation with busulfan and cyclophosphamide

A prospective randomized study was conducted comparing two conditioning regimens for the treatment of patients with chronic myeloid leukemia in chronic phase by marrow transplantation from HLA identical siblings. Sixty-nine patients received 60 mg/kg of cyclophosphamide on each of 2 successive days followed by 6 fractions of total body irradiation each of 2.0 Gy (CY-TBI), and 73 patients received 16 mg/kg of busulfan delivered over 4 days followed by 60 mg/kg CY on each of 2 successive days (BU-CY). There was no significant difference between the CY-TBI and the BU-CY groups in the 3-year probabilities of survival (0.80 for both), relapse (0.13 for both), or event-free survival (CY-TBI, 0.68; BU-CY, 0.71) or in speed of engraftment or incidence of venocclusive disease of the liver. The 4-year probabilities of survival and event-free survival for patients transplanted within 1 year of diagnosis were 0.86 and 0.72, respectively, for each group. Significantly more patients in the CY-TBI group experienced major creatinine elevations. There was significantly more acute graft-versus-host disease in the CY-TBI group. Fever days, positive blood cultures, hospitalizations, and inpatient hospital days were significantly more common in the CY-TBI group than in the BU-CY group. In conclusion, the BU-CY regimen was better tolerated than, and associated with survival and relapse probabilities that compare favorably with, the CY-TBI regimen.

Graft-versus-host disease and the development of late complications

Graft-versus-host disease (GVHD) in both its acute and chronic forms is a severe complication after allogeneic marrow transplantation. GVHD is associated with structural and functional defects in many organs and tissues. Severe immunoincompetence may result in frequent, often severe and at times fatal infections caused by various organisms. Prolonged antibiotic prophylaxis, and possibly immunoglobulin administration are beneficial. Ocular complications, airway and pulmonary damage, and oral or dental problems may cause severe morbidity. Despite aggressive management, a proportion of patients will succumb to these complications. Severe skin disease and joint contractures are currently seen less frequently, mostly due to early treatment of the disease. Psychosocial rehabilitation of patients with chronic GVHD is a demanding and protracted challenge and should be approached by a multidisciplinary team.

Secondary malignancies after marrow transplantation for leukemia or aplastic anemia

We conclude that the most common secondary cancers which develop after marrow transplantation are lympho-proliferative disorders and solid tumors. The consequences of the secondary malignancies are serious, with more than 90% of the patients with non-Hodgkin lymphomas associated with EBV infection and more than 75% of the patients with solid tumors dying despite treatment. Secondary leukemia developing in donor T-s is rare, but was fatal in all cases. EBV infection plays a major role in leading to the non-Hodgkin lymphomas in a setting of immune dysregulation from ATG or anti-T-cell monoclonal antibody treatment of acute GVHD. Other factors are also important for development of non-Hodgkin lymphoma and include T-cell depletion of donor marrow and HLA-mismatching between donor and recipient, known to lead to dysregulation of T-lymphocyte function. These factors set up an environment of proliferative stimuli which cannot be controlled by the recovering immune system, setting the stage for a secondary cancer. The role of irradiation is becoming more prominent in association with solid tumors, particularly in aplastic anemia patients conditioned with irradiation. The final event of tumor expression is most likely the result of a cascade of events, perhaps initiated with the conditioning regimen or with stimuli to proliferation, which, after later signals, leads to malignant transformation. For lymphoproliferative disorders, the time of latency is shorter than for solid tumors, suggesting a different molecular mechanism. The incidence of oncogene expression or mutation in tumor suppressor genes in these solid tumor patients has not been investigated.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of acute graft-versus-host disease with humanized anti-Tac: an antibody that binds to the interleukin-2 receptor

Humanized anti-Tac is a genetically engineered human IgG1 monoclonal antibody specific for Tac, the alpha subunit of the interleukin-2 (IL-2) receptor, and blocks IL-2-dependent activation of human T lymphocytes. The safety, pharmacokinetics, and immunosuppressive activity of humanized anti-Tac were evaluated in 20 patients who developed acute graft-versus-host disease (GVHD) after allogeneic marrow transplantation. Patients had developed acute GVHD at 5 to 26 (median, 14) days after transplantation and had failed to respond to primary therapy with glucocorticoids. Sequential groups of 4 patients each received a single 1-hour infusion of antibody in escalating doses of 0.5, 1.0, or 1.5 mg/kg; 8 additional patients were then treated with 1.5 mg/kg. A second infusion of antibody was administered after 11 to 48 (median, 16) days in 8 patients who had transient improvement of GVHD after the first infusion. Acute side effects, limited to chills in 1 patient and diaphoresis in another, were observed during or shortly after the antibody infusion. Overall improvement of acute GVHD occurred in 8 patients, 6 of whom were treated with a single antibody infusion and 2 with two infusions. Four responses were complete and 4 were partial. Three additional patients had improvement in one organ but progression in another. Responses occurred in 9 of 16 cases with skin disease, 3 of 15 with liver disease, and 6 of 12 with gastrointestinal disease. Two patients survive at 529 and 645 days after antibody treatment. Two patients died after relapse of leukemia. Sixteen patients died of infection or organ failure between 5 and 211 (median, 55) days. The terminal elimination half-life of the antibody was 44 to 363 hours, with a harmonic mean of 79, 88, and 94 hours, respectively, for the three doses studied. Absolute peripheral blood T-lymphocyte counts remained unchanged during the 56 days after infusion of the antibody. A fraction of circulating T cells expressed the alpha chain of the IL-2 receptor that, in some patients, was bound by antibody in vivo up to 28 days after treatment. No patient developed a measurable antibody response to humanized anti-Tac. Humanized anti-Tac has a long half-life after intravenous injection in humans, superior to any rodent monoclonal antibody specific for human T cells, and does not appear to induce antibody formation in recipients of marrow transplants. Improvement of steroid-refractory GVHD in 40% of patients after only one or two antibody infusions indicates that humanized anti-Tac is immunosuppressive.

Cyclophosphamide combined with antithymocyte globulin in preparation for allogeneic marrow transplants in patients with aplastic anemia

Graft rejection has been a problem after marrow grafts for patients with aplastic anemia who were conditioned with cyclophosphamide (CY). Rejection lessened when patients were given the marrow donor's peripheral blood buffy-coat cells in addition to the marrow, but this result was achieved at the price of more chronic graft-versus-host disease (GVHD). Results with second transplants suggested that CY alternating with antithymocyte globulin (ATG) was more immunosuppressive than CY alone. Therefore, the current study explored CY and ATG without buffy-coat cell transfusions in 39 patients with aplastic anemia given marrow transplants from HLA-identical family members (siblings in 38 cases, father in 1 case). We hoped both to minimize the risks of graft rejection and of chronic GVHD and to improve survival. Patients were 2 to 52 years of age (median, 24.5); 87% had received previous transfusions, and 41% had therapy with immunosuppressive agents before transplant. They were administered four daily doses of CY (total, 200 mg/kg) alternating with three doses of ATG (total, 90 mg/kg) followed by an HLA-identical marrow graft. Methotrexate and cyclosporine were administered to prevent GVHD. Two patients rejected their grafts (5%), and both were successfully retransplanted. Acute (grade 2 or 3) GVHD occurred in 15% and chronic GVHD in 34% of patients. The actuarial survival rate at 3 years was 92%, which compares favorably to the 72% survival rate in 39 historical patients who were matched with current patients for age and risk factors for rejection and GVHD. CY/ATG is a well-tolerated and effective conditioning program for marrow grafting in aplastic anemia that, when combined with GVHD prevention by methotrexate/cyclosporine, results in excellent survival.

Fractionated versus single-dose total body irradiation at low and high dose rates to condition canine littermates for DLA-identical marrow grafts

We explored in dogs the immunosuppressive properties of 450 cGy total body irradiation (TBI) delivered from two opposing 60Co sources, as assessed by the criterion of successful engraftment of allogeneic genotypically DLA-identical littermate marrow. Two questions were asked in this study. Firstly, does dose rate affect the immunosuppressive effect of TBI when administered in a single dose? Secondly, does fractionation alter the immunosuppression of TBI when delivered at a very fast dose rate? Dose rates studied included 7 and 70 cGy/min, and fractionation involved four fractions of 112.5 cGy each, with 6-hour minimum interfraction intervals. Six of 7 dogs receiving 450 cGy single-dose TBI at 70 cGy/min showed sustained engraftment of the allogeneic marrow, compared with 1 of 7 dogs receiving single-dose TBI at 7 cGy/min (P = .01). Fractionated TBI at 70 cGy/min resulted in sustained allogeneic engraftment in 3 of 10 dogs, a result that was statistically significantly worse than that with single-dose TBI at 70 cGy/min (P = .03) and not statistically different (P = .24) from that with fractionated TBI delivered at 7 cGy/min (0 of 5 dogs engrafted). A single dose of 450 cGy of TBI delivered at a rate of 70 cGy/min is significantly more immunosuppressive than the same total dose delivered at 7 cGy/min. Fractionated TBI at 70 cGy/min is significantly less immunosuppressive than single-dose TBI at 70 cGy/min and not significantly different from fractionated TBI administered at 7 cGy/min. Results are consistent with the notion that significant DNA repair in lymphoid cells is possible during interfraction intervals at the relatively high dose rate of 70 cGy/min.

Hemopoietic stem cells: sources and applications

Classically hemopoietic stem cells to be used for transplantation or autologous reinfusion have been harvested from the bone marrow which has remained the major source of stem cells for allogeneic transplantation. However, pluripotent stem cells also circulate in peripheral blood under physiological conditions and can be "mobilized" to appear in very large numbers in peripheral blood by treatment with cytotoxic chemotherapy, hemopoietic growth factors, or both. These cells are now being used widely for autologous stem cell support. They have the advantage of very rapid hemopoietic reconstitution, thereby shortening the posttransplant period of pancytopenia. Fetal liver cells, another classic source of stem cells, are currently used only infrequently. However, there is a growing interest in the use of umbilical cord blood which is rich in stem cells and easily accessible. Cord blood stem cells have been used successfully for pediatric transplants even across major histocompatibility barriers. Technology has been developed which may permit sufficient in vitro expansion so that these cells can also be used for transplants in adults. Furthermore, there is evidence that these cells may be preferable to marrow or even mobilised peripheral blood stem cells for the purpose of gene transfer.

Etoposide in combination with cyclophosphamide and total body irradiation or busulfan as conditioning for marrow transplantation in adults and children

PURPOSE

In an attempt to intensify conditioning therapy for bone marrow transplantation of hematologic malignancies, a retrospective three center evaluation of escalating doses of etoposide added to cyclophosphamide and either total body irradiation or busulfan was undertaken.

METHODS AND MATERIALS

Seventy-six patients who received etoposide (25-65 mg/kg) added to cyclophosphamide (60-120 mg/kg) and either total body irradiation (12.0-13.2 Gy) or busulfan (12-16 mg/kg) were evaluable for toxicity. Fifty-one of the evaluable patients received allogeneic transplants, while twenty-six received autologous transplants. A comparative analysis of toxicities according to conditioning regimen, donor source and etoposide dose was made.

RESULTS

Similar toxicities were observed among the treatment groups with the exception of more frequent skin (p = 0.003) and life threatening hepatic toxicities (p = 0.01) in the busulfan treated patients. Life threatening or fatal toxicities were not influenced by donor source, either when analyzed by treatment group or etoposide dose. Etoposide at a dose of 60-65 mg/kg in combination with TBI and cyclophosphamide was associated with a significantly increased incidence of life threatening or fatal toxicities compared with a combination using a dose of 25-50 mg/kg (15 of 24 vs. 5 of 20; p = 0.013). The maximally tolerated dose of etoposide in combination with busulfan and cyclophosphamide cannot be definitively established in this analysis in part due to the heterogeneity of the patient population and treatment schemes.

CONCLUSION

Although toxicities with bone marrow transplant preparative regimens containing etoposide in combination with cyclophosphamide and total body irradiation or busulfan were frequently severe, treatment related mortality risk was believed to be acceptably low.

Rescue from anti-MHC class II antibody-mediated marrow graft failure by c-kit ligand

Dogs given 920 cGy of total body irradiation (TBI) followed by autologous marrow infusion uniformly achieve sustained hematopoietic reconstitution. We have previously shown that administration of the anti-MHC class II monoclonal antibody (MoAb) H81.98.21 (IgG2a) at 0.6 mg/kg/d immediately after transplantation results in delayed graft failure. A second noncrossblocking anti-MHC class II MoAb, B1F6, of the same isotype, at the same dose, did not interfere with sustained engraftment, suggesting that the observed effect was epitope dependent. Although higher concentrations of B1F6 were required, in the present study both MoAbs interfered with the propagation of long-term marrow cultures. When MoAb B1F6 was given in vivo at 1.2 mg/kg/d, ie, twice the dose used previously, dogs so treated also developed delayed marrow graft failure. Marrow failure with either MoAb involved myeloid, erythroid, and megakaryocytic lineages. Administration of recombinant canine c-kit ligand/stem cell factor (SCF) for 7 or 21 days posttransplant resulted in reversal of graft failure. Although the short course did induce a broad transient early peak of granulocytes, the longer course of SCF was accompanied by earlier sustained recovery than the short course. In conclusion, therefore, marrow graft failure induced by anti-MHC class II MoAb does not appear to be epitope dependent, involves all hematopoietic lineages, and is overcome by the administration of c-kit ligand.

Effect of recombinant canine granulocyte-macrophage colony-stimulating factor on hematopoietic recovery after otherwise lethal total body irradiation

Recombinant canine granulocyte-macrophage colony-stimulating factor (rcGM-CSF) was studied in normal dogs and in dogs receiving otherwise lethal total body irradiation (TBI) without marrow transplant. Five normal dogs receiving 25 micrograms/kg of rcGM-CSF by subcutaneous (SC) injection twice daily (BID) for 14 days showed increases in peripheral blood neutrophil counts of three to five times the baseline. Platelet counts decreased during administration of rcGM-CSF to a mean nadir of 52,800. Ten dogs received 400 cGy TBI at 10 cGy/min from two opposing 60Co sources and no marrow graft. Within 2 hours of TBI, rcGM-CSF was begun at a dose of 50 micrograms/kg SC BID for 5 doses and then continued at 25 micrograms/kg SC BID for 21 days. Only 1 of the 10 dogs receiving rcGM-CSF survived with complete and sustained recovery of hematopoiesis. One of 13 historical control dogs survived after 400 cGy with no hematopoietic growth factor or marrow infusion. Results with rcGM-CSF were compared with previous and concurrent data with G-CSF studied in the same model. Of 10 dogs receiving G-CSF, 8 survived with complete and sustained hematopoietic recovery, a significantly better survival than that seen with rcGM-CSF (P = .006). Neutrophil counts were sustained at higher levels after TBI for the first 18 days in the G-CSF group (P < .016) and the neutrophil nadirs were higher. No differences in neutrophil nadirs were noted between the rcGM-CSF and control groups. Dogs treated with rcGM-CSF experienced a more rapid decline of platelet counts than G-CSF-treated or control dogs over the first 18 days (P < .001). The nadir of the platelet count was higher in the control group than in either the G-CSF or rcGM-CSF group and no significant difference was observed between the G-CSF and rcGM-CSF groups. After otherwise lethal TBI (400 cGy) in dogs, rcGM-CSF was not effective in promoting hematopoietic recovery or improving survival.

Retrovirus-mediated gene transduction into canine peripheral blood repopulating cells

Genetically marked peripheral blood progenitor cells were used to investigate their contribution to long-term hematopoietic reconstitution after autologous marrow and peripheral blood cell transplantation. After autologous marrow harvest and cryopreservation, canine peripheral blood progenitor cells were mobilized in three dogs by treatment with recombinant canine stem cell factor for 8 days. Peripheral blood mononuclear cells were collected and enriched for major histocompatibility complex (MHC) class II antigen-positive cells by avidin-biotin immunoadsorption, thereby enriching for repopulating cells. Subsequently, the cells were cocultivated for 24 hours on irradiated vector-producing packaging cells (PA317/LN), followed by an 11-day incubation in a vector containing long-term marrow culture system. On the day of transplantation, the animals were irradiated with 9.2 Gy total body irradiation (TBI), and transduced peripheral blood cells and untransduced cryopreserved marrow cells were infused within 2 hours of TBI. All three dogs engrafted. Two dogs are long-term survivors showing intermittently G418-resistant marrow-derived colony-forming unit granulocyte-macrophage colonies at a median of 1% and 2%, respectively (range, 1% to 10%), for now up to 48 weeks after transplantation. Neo-specific sequences were detected by polymerase chain reaction in peripheral blood granulocytes for now up to 65 weeks and in peripheral blood lymphocytes for up to 75 weeks after transplantation. Peripheral blood samples of the dogs were free of helper virus and no side effects from the transduction were observed. One of the three dogs died from chronic canine distemper sclerosing encephalitis on day 84, whereas the other two dogs are alive at 15 and 17 months. Our data show successful retroviral transduction of canine peripheral blood repopulating cells. Long-term persistence of marked myeloid and lymphoid cells after transplantation suggests that peripheral blood contains repopulating cells that contribute to long-term hematopoietic reconstitution after otherwise lethal TBI.

Gamma-irradiation of pretransplant blood transfusions from unrelated donors prevents sensitization to minor histocompatibility antigens on dog leukocyte antigen-identical canine marrow grafts

Pretransplant blood transfusions from a dog leukocyte antigen (DLA)-identical canine littermate marrow donor will sensitize the recipient to non-DLA-linked polymorphic minor histocompatibility antigens, which uniformly results in graft rejection. We observed previously that 2000 cGy gamma-irradiation of marrow donor blood transfusions prevented this sensitization and subsequent marrow graft rejection. The purpose of the present study was to determine whether treatment of unrelated blood transfusions with gamma-irradiation would also prevent sensitization. Conceivably, sensitization to minor histocompatibility antigens might be more efficient or potent and thus more difficult to prevent when those antigens are seen in the context of disparity for DLA antigens. Furthermore, this model, in which sensitization to DLA-identical littermate marrow is caused by unrelated blood transfusions, is directly relevant to the clinical circumstances of human marrow transplantation. We assessed sensitization caused by unrelated blood transfusions by monitoring graft outcome in recipients transplanted with DLA-identical littermate marrow after conditioning with 920 cGy total body irradiation. Two thousand cGy gamma-irradiation of unrelated blood transfusions significantly reduced the incidence of transfusion-induced sensitization of recipients. There was successful marrow engraftment in 15 of 16 (94%, P < 0.003) of these animals in contrast to the previous study in which only 7 of 16 (44%) animals engrafted after they were transfused with unmodified blood on the same schedule. These results suggest that blood transfusions for use in humans, especially for patients with aplastic anemia, should be gamma-irradiated in order to reduce the incidence of marrow graft rejection caused by sensitization to minor histocompatibility antigens.

Marrow transplant experience for children with severe aplastic anemia

PURPOSE

The two major factors associated with lack of survival after allogeneic marrow transplant for severe aplastic anemia have been graft rejection and acute graft versus host disease (GVHD). As a result, survival for patients transplanted in the 1970s was approximately 68%. Improved survival during the 1980s was primarily related to the decrease in the incidence of acute GVHD with the use of combination methotrexate and cyclosporine for GVHD prophylaxis. Although the incidence of graft rejection has not changed, the time to graft rejection has been delayed.

PATIENTS AND METHODS

One hundred forty children < 18 years of age received a marrow transplant for severe aplastic anemia at the Fred Hutchinson Cancer Research Center between May, 1971 and June, 1991. Four recipients of syngeneic marrow received a simple marrow infusion, 119 recipients of HLA-identical family member marrow received cyclophosphamide (CY), 200 mg/kg; most recipients of alternative donor marrow received CY plus 12.0 Gy fractionated total body irradiation. GVHD prophylaxis was MTX only for 91 recipients of HLA-identical family member marrow, and was MTX plus CSP for all other allogeneic marrow patients. Estimates of graft rejection, acute and chronic GVHD, survival and event-free survival (EFS) were determined by the Kaplan-Meier method.

RESULTS

Two recipients of syngeneic marrow achieved engraftment with donor marrow infusion only and two required immunosuppression with CY. Among the 119 recipients of HLA-identical family member marrow the type of GVHD prophylaxis did not influence graft rejection but non-transfused patients had 10% incidence of rejection compared to 22% for transfused patients (p = 0.1). All patients with late graft rejection survive whereas those with early rejection usually do not. The incidence of acute GVHD was 27% and 11% for MTX recipients and MTX plus CSP recipients, respectively (p = 0.11), and the probability of chronic GVHD was 30% and 26%, respectively. Survival is 64% for recipients of MTX and 96% for recipients of MTX plus CSP (p = 0.007), but EFS was 60% and 71%, respectively (p = 0.48). Recipients of partially matched family member or unrelated marrow donor grafts have transplants complicated by infections and GVHD. Growth and development of CY only recipients is normal and several children have been born to these former patients.

CONCLUSIONS

High dose CY is usually an effective preparative regimen for children with severe aplastic anemia and an HLA-identical family member marrow donor. Additional immunosuppression with anti-thymocyte globulin may result in a further decrease in graft rejection and improved EFS. Identification of a group of children who are unlikely to respond to immunosuppressive treatment could permit earlier transplantation for patients without HLA-identical family member donors available. Children who receive CY only have normal growth and development.

Major histocompatibility complex class II molecules, hemopoiesis and the marrow microenvironment

Currently available data indicate that the earliest identifiable hemopoietic progenitor in normal marrow is CD34+ MHC class II-; subsequent expression of MHC class II antigens is maturation and lineage dependent. Studies on embryonal cells suggest that CD34+DR- cells are actually the common precursors for stromal and hemopoietic elements, with the earliest hemopoietic precursor being CD34+DR+. DQ antigens are apparently not expressed in cells of hemopoietic potential and the expression of DQ appears to be regulated differentially from DR and DP. MHC class II antigens are also expressed on some stromal cells, especially those with endothelial and macrophage features. MHC class II molecules are involved in hemopoietic cell/stroma interaction. The presence of anti-MHC class II monoclonal antibodies (MABs) at early stages of stem cell proliferation/differentiation, at least under conditions of marrow stress, induces signals which may result in final, especially granulocytic, differentiation of later precursors. These may interfere with the survival of those cells which are required for long-term hemopoietic reconstitution. Observations in allogeneic marrow transplant recipients support a role of MHC molecules as expected in allogeneic interactions. Results in autologous models point towards a role of MHC class II molecules other than that of a histocompatibility marker insofar as these molecules or signals transmitted by them appear to be involved in the regulation of hemopoiesis.

Autologous bone marrow transplantation for acute lymphoblastic leukemia

Between December 1979 and February 1991, 89 patients with ALL received autologous BMT. Median patient age was 18.4 years. Ten patients were in first remission, 52 were in second or greater remission and 27 were in relapse at the time of transplant. Conditioning regimens utilized chemotherapy alone (5 patients) or in combination with 10-15.75 Gy total body irradiation (84 patients). Disease-free survival at 1 year is 50% for patients transplanted in first remission, 27% for those in > or = second remission and 8% for patients in relapse. Pre- and post-transplant variables were evaluated in univariate and multivariate analyses for their effect on survival and relapse. Factors significantly associated with improved survival were being transplanted in first remission and achieving a self-sustained platelet count > or = 20 x 10(9)/l in a shorter period of time. A decreased relapse rate after transplant was associated with a lower white blood count at diagnosis, being transplanted in first remission and not being transplanted in relapse.

FK-506 and methotrexate prevent graft-versus-host disease in dogs given 9.2 Gy total body irradiation and marrow grafts from unrelated dog leukocyte antigen-nonidentical donors

FK-506 was evaluated either alone or combined with methotrexate (MTX) for prevention of graft-versus-host disease (GVHD) in dogs given 9.2 Gy total body irradiation and dog leukocyte antigen-nonidentical unrelated marrow grafts. Studies with marrow autografts showed gut toxicity and weight loss to be major side effects of FK-506. There was no hematopoietic toxicity with FK-506. In an initial allograft study, 5 dogs were given FK-506 intramuscularly at 0.3 mg/kg/day from days 0 to 8 and then orally at 0.5 mg/kg/day. All 5 died, 3 with intussusception most likely due to FK-506 toxicity, 1 with graft failure, and 1 with GVHD. Subsequently, the FK-506 dose was reduced and these drug schedules were used: FK-506 days 0-8 at 0.15 mg/kg/day i.m. and then orally at 0.5 mg/kg/day until day 90, with or without MTX intravenously at 0.4 mg/kg days 1, 3, 6, and 11. Twenty allografts were done, 10 with FK-506 alone, and 10 with MTX/FK-506. Results were compared with those in concurrent and historical controls given either no immunosuppression (n = 64), MTX (n = 114), CsA (n = 15), or MTX/CsA (n = 17). Five of 20 current dogs died with intussusception, too early to be evaluated for GVHD. The 10 dogs given FK-506 alone survived significantly better than those not given immunosuppression but not differently from those given short-term MTX or CsA alone. Three died from toxicity, 2 with graft failure, and 4 with GVHD. Only 1 dog became a long-term survivor, and this dog inadvertently received a single dose of MTX on day 7. Two of 10 dogs given MTX/FK-506 died from toxicity, 1 died with graft failure, 2 died with GVHD, and 5 became long-term survivors, a result that is significantly better than seen with either drug alone and similar to that seen with MTX/CsA. Four of the 5 survivors had no clinical GVHD. FK-506 blood levels were 15-35 ng/ml between days 8 and 15, when gut toxicity was most severe. Thereafter, levels were approximately 5 ng/ml. In conclusion, FK-506 prolonged survival of recipients of dog leukocyte antigen-nonidentical unrelated marrow grafts. When FK-506 was combined with MTX, graft-host tolerance was induced in 50% of dogs, even though FK-506 was stopped on day 90.

Graft-versus-host disease: host and donor views

Major histocompatibility complex (MHC) antigens, termed HLA in man, provide the major barrier to transplantation. Clinical manifestations of the host-versus-graft reaction are generally referred to as rejection and those of the graft-versus-host (GVH) reaction as graft-versus-host disease (GVHD). GVHD can occur after transplantation of marrow or solid organs or transfusion of blood products. GVHD involves antigen-presenting cells, which are recognized by T lymphocytes via the T-cell receptor. CD4 and CD8 serve as accessory molecules. This interaction results in T-cell activation, expression of interleukin-2 receptors (IL-2R) and the production of IL-2 followed, generally, by clonal proliferation and differentiation associated with lymphokine secretion and dysregulation that may involve interferon-gamma; tumor necrosis factor-alpha; IL-2, -3, -4, -5, -6, and -9; granulocyte macrophage colony-stimulating factor (GM-CSF); and other factors. Effector cells such as cytotoxic T cells, natural killer (NK) cells, and macrophages become activated, mostly by bone marrow-derived lymphohemopoietic cells, and contribute to cell and tissue death. Many of the cytokines also alter vascular endothelium; conceivably these changes also affect homing of cells and allogeneic interactions. Another factor is the administration of in vivo GVHD prophylaxis, which may modify both undesirable (GVHD-inducing) and desirable (tolerance-inducing) mechanisms. Exogenous hematopoietic growth factors and cytokines recently introduced into clinical trials may interfere with endogenous feedback loops in a positive or negative fashion. Adverse reactions have been observed with IL-2 and with interferon. Potentially beneficial effects have been reported with the use of soluble IL-1R or IL-1R-antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term survival and cure after marrow transplantation for congenital hypoplastic anaemia (Diamond-Blackfan syndrome)

Four patients with Diamond-Blackfan syndrome (congenital hypoplastic anaemia) whose disease was resistant to corticosteroid treatment and who were red blood cell transfusion-dependent, were given marrow grafts from allogeneic human-leucocyte-antigen (HLA)-identical siblings. The patients were conditioned with regimens including cyclophosphamide and busulfan. Three of four patients had sustained and complete marrow engraftment. One patient showed early signs of haematopoietic recovery but died on day 35 of pulmonary toxicity. The three surviving patients are well with normal haematopoiesis and Karnofsky performance scores of 100%, 3.0, 7.4 and 10.6 years after transplantation. Congenital hypoplastic anaemia can be treated successfully by allogeneic marrow grafts.