Total body irradiation in bone marrow transplantation: the influence of fractionation and delay of marrow infusion

Bone marrow transplantation (BMT) after total body irradiation (TBI) and cyclophosphamide is being employed increasingly in the therapy of end stage leukemia. Interstitial pneumonitis (IP) represents a major acute toxicity after allogeneic transplantation. A more rapid reconstitution of lymphoid organs and bone marrow post transplant may result in increased immune competence and hence fewer opportunistic pulmonary infections and IP. By delaying the infusion of marrow to 72 hr after TBI (1250 rod at 7.5 rad/min) instead of the customary 24 hr, we can demonstrate an increase in initial repopulation of thymus, spleen and marrow, with syngeneic transplants in Lewis rats.Interstitial pneumonitis may also be caused, in part, by the pulmonary toxicity of large single exposures of TBI. Clinical and laboratory data suggest that fractionated TBI may be less toxic to the lung. When fractionated TBI (625 rad × 2, 7.5 rad/min) is compared to single dose TBI (1250 rad, 7.5 rad/min), an increased initial repopulation of lymphoid organs is observed when fractionated therapy is employed. Delay in marrow infusion and fractionation of TBI exposure may have clinical advantages in patients who receive BMT.     

螺旋断层治疗用于全骨髓照射的初步结果

目的：评估全骨髓照射作为异基因外周血干细胞移植（ Allo－PBSCT）前预处理方式的疗效及安全性。方法2014—2015年6例患者Allo－PBSCT前均采用HT联合环磷酰胺（60 mg／kg1次／d共2 d）的预处理方式。采用HT技术实施。结果6例患者中位年龄18．5岁。处方剂量（12 Gy分3次3 d完成）精确覆盖全部骨骼区域,OAR受量较全身照射降低13％～60％。头颈、胸腹、盆腔部位剂量验证通过率分别为（95．8±1．2）％、（96．2±1．1）％、（98．9±0．8）％。上、下部分的HI和平均治疗时间分别为1．18、1．17和39．2、14．3 min。放疗期间5例患者出现1—2级恶心、呕吐,2例患者出现1—2级疼痛,1例患者出现1级腹泻,1例患者出现2级肠炎。所有患者均未出现3—4级非血液学不良反应,并且成功植入骨髓。结论 HT技术应用于全骨髓照射是可行的,靶区适形度高,剂量均匀性好,安全性高且不良反应较传统TBI明显减低,可作为新的骨髓移植前预处理方式。     

Modified total body irradiation as a planned second high-dose therapy with stem cell infusion for patients with bone-based malignancies

PURPOSE: To estimate the maximum tolerated dose of hyperfractionated total marrow irradiation (TMI) as a second consolidation after high-dose chemotherapy with autologous or syngeneic blood stem cell transfusion for patients with bone/bone marrow-based malignant disease. PATIENTS AND METHODS: Fifty-seven patients aged 3-65 years (median, 45 years), including 21 with multiple myeloma, 24 with breast cancer, 10 with sarcoma, and 2 with lymphoma, were treated with 1.5 Gy administered twice daily to a total dose of 12 Gy (n = 27), 13.5 Gy (n = 12), and 15 Gy (n = 18). Median time between the 2 transplants was 105 days (range, 63-162 days). RESULTS: All patients engrafted neutrophils (median, Day 11; range, Day 9-23) and became platelet independent (median, Day 9; range, Day 7-36). There were 5 cases of Grade 3-4 regimen-related pulmonary toxicity, 1 at 12 Gy, and 4 at 15 Gy. Complete responses, partial responses, and stabilizations were achieved in 33%, 26%, and 41% of patients, respectively. Kaplan-Meier estimates of 5-year progression-free survival and overall survival for 56 evaluable patients are 24% and 36%, respectively. Median time of follow-up among survivors was 96 months (range, 77-136 months). CONCLUSION: Total marrow irradiation as a second myeloablative therapy is feasible. The estimated maximum tolerated dose for TMI in a tandem transplant setting was 13.5 Gy. Because 20% of patients are surviving at 8 years free of disease, further studies of TMI are warranted.     

Eradication of leukaemic marrow and prevention of leukaemia relapse with total body irradiation and bone marrow transplantation

A series of studies was carried out to determine the effect of allogeneic bone marrow transplantation (BMT) on leukaemia. The study aimed at two different, but strictly linked issues: (1) identification of the eradication capability of BMT, and (2) evaluation of the effect of BMT, both in preventing relapse and in producing long-term disease-free survival. Fifty-four patients allografted for leukaemia were evaluated at various intervals, after bone marrow transplantation, for the presence of host haemopoiesis using red-blood-cell and cytogenetic markers. Among 40 patients in remission, 10 showed functional host and donor haemopoiesis (mixed chimerism), while in 30, host haemopoiesis was never detected (complete chimerism). Seven of the 14 evaluable patients who relapsed showed the reappearance of host haemopoiesis at the time of relapse. The records of received doses of TBI indicate that patients who achieved mixed chimerism, either relapsing or not, received significantly lower doses than complete chimeras. However, some patients with complete chimerism received a TBI dose equivalent to the dose received by those with mixed chimerism, suggesting that the TBI dose is not the only factor determining the reappearance of host haemopoiesis. The data on chimerism and relapse suggest that there is heterogeneity in radiosensitivity between normal marrow cells and leukaemic cells, and further, within the different types of leukaemia. The incidence/severity of acute and chronic graft-vs-host disease (GvHD) was significantly higher in complete chimeras than in mixed chimeras suggesting that mixed chimerism may play a role in the development of tolerance; however, it could be the tolerance (i.e. absence of GvHD) which is responsible for the persistence of host haemopoietic cells. One-hundred-and-sixty-eight patients undergoing allogeneic bone marrow transplantation (BMT) for acute myeloid leukaemia (AML) and chronic myeloid leukaemia were analyzed for risk factor associated with relapse. All patients received marrow from an HLA identical sibling after preparation with cyclophosphamide 120mg/kg and total body irradiation (TBI) of 330 cGy on days -3, -2, -1. There was a difference of ±18% between the nominal total dose of 990 cGy and the actual received dose as indicated by dosimetric recordings. While interstitial pneumonitis had minimal impact on survival there was a considerable difference in the incidence of relapses. The incidence of relapse was higher in patients receiving less, than in patients receiving more than 1000 cGy respectively and this had a major impact on survival. However, transplant-related mortality was slightly higher in the group of patients receiving higher doses of TBI. These results suggest that a higher dose of TBI, within this schedule, produced long-term disease-free survival in the majority of acute myeloid leukaemia and chronic myeloid leukaemia with minor radiobiological side-effects which, however, tended to be higher as the TBI dose increased. Moreover, a small reduction of the dose may significantly increase the risk of relapse. In addition, the disease status significantly influences the probability of relapse and this is mainly seen in chronic myeloid leukaemia. Moreover, the prevention of graft-vs-host disease plays a relevant role both in relapse as well as in the transplant-related mortality. It is therefore concluded that fine tuning of the conditioning protocol, and of the therapy for graft-vs-host prevention, is needed to improve the results in allogeneic bone marrow transplant.     

Osteochondroma after Total Body Irradiation in Bone Marrow Transplant Recipients: Report of Two Cases

We present two cases of osteochondroma after total body irradiationin bone marrow recipients, the first in a 6-year-old boy withjuvenile chronic myelogenous leukemia and the second in a 13-year-oldboy with acute myelogenous leukemia. The patients developedmultiple osteochondromas three years and seven years, respectively,after 12 Gy of total body irradiation. Neither had a familyhistory of hereditary multiple osteochondromatosis. A reviewof the English literature revealed only one report describingfive cases of osteochondroma after 12 Gy of total body irradiationin bone marrow transplant recipients. Osteochondroma shouldbe considered as an additional adverse effect of total bodyirradiation.     

Radiobiological considerations in magna-field irradiation

Radiobiological considerations are described for total body irradiation (TBI) as given to patients undergoing bone marrow transplantation (BMT). Although much progress has been made in the use of BMT for refractory leukemias, many patients still die from interstitial pneumonia and relapse. Fractionated TBI has been introduced in order to improve leukemic cell kill, while increasing the degree of normal tissue tolerance. Traditionally, bone marrow stem cells, leukemic cells and immunocytes have been considered as having a limited ability to repair radiation damage while cells of lung tissue and intestinal epithelial cells have a greater capacity. During fractionated radiation therapy or continuous low-dose rate exposure, repair of sublethal damage between fractions allows greater recovery in the cells of lung tissue compared to those in the bone marrow. Clinically, the potential benefit of six fractions over one fraction or low dose-rate TBI has yet to be proved, although there is suggestive evidence for a reduced incidence of interstitial pneumonitis. However, other extraneous factors such as doses to the lung, differences in conditioning regimens, effect of increased delay in BMT for patients receiving fractionated TBI, and the immeasurable differences between institutions make definite conclusions impossible. Despite this, a consensus for dose fractionation has developed and most centers are moving away from the use of large single dose TBI.     

Effects of low dose rate irradiation on plateau phase bone marrow stromal cells in vitro: Demonstration of a new form of non-lethal,physiologic damage to support of hematopoietic stem cells

The clinical use of low dose rate (LDR) (5–25 rad/min) total body irradiation in bone marrow transplantation patients is well established. We have developed an in vitro system for study of the effects of LDR irradiation on bone marrow stromal cells. Purified mouse bone marrow stromal cell cultures in plateau phase with no detectable hematopoiesis were prepared and were then “engrafted” in vitro by addition of purified nonadherent hematopoietic cells from continuous bone marrow cultures. Hematopoietic cells were added in liquid medium or suspended in an overlay of semisolid 0.4% agar-containing medium. Other agar overlays contained Interleukin-3-dependent cloned multipotential hematopoietic stem cell fine B6SUtA. In parallel experiments, a cloned permanent bone marrow stromal cell fine D2XRII was used in place of purified stromal cell cultures. Stromal cultures were irradiated at 5 rad/min, 20 rad/min, or 200 rad/min, 24 hours or 3 weeks prior to “engraftment.” Two classes of irradiation damage were demonstrated following 1000 rad irradiation at 200 rad/min: 1) Decreased clonagenic survival of trypsinized replated marrow stromal cells (lethal effect), and 2) decreased production by marrow stromal cells or D2XRII cells of colony stimulating factors (CSF)s for granulocyte-macrophage progenitor cells and B6SUtA cells (physiologic effect). Holding the cultures in plateau phase for 3 weeks after irradiation was associated with significantly more repair of the lethal effect compared to the physiologic effect. Cultures irradiated at 5 rad/min or 20 rad/min to doses producing significantly less lethal effect showed a complex alteration of production of growth factors. Cumulative cell production by hemopoietic stem cells added in liquid culture was comparably decreased for all three dose rates. These data demonstrate a distinct physiologic expression of irradiation damage to bone marrow stromal cells that affects cell to cell interaction, responds differently to changes in dose rate, and is repaired with kinetics different from those of the lethal effect of irradiation. The present system should prove valuable for investigation of cellular interactions in hematopoietic stem cell engraftment that are altered by total body irradiation.     

Comparative 60Co total body irradiation (220 cm SAD) and 25 MV total body irradiation (370 cm SAD) dosimetry

Adults with acute leukemia and malignant lymphoma in relapse after conventional therapy are treated with cyclophosphamide and total body irradiation (TBI) followed by autologous bone marrow transplants. For cobalt TBI, patients seated in a stand angled 45° above the floor are treated in a single fraction with sequential right and left lateral 87 cm ×87 cm fields at 220 cm source-axis distance (SAD) using a 5000 Ci cobalt unit. Typical lateral diameters, mid-plane dose rates, mid-plane doses, and maximum doses are: Hips, 34 cm, 8 rad/min, 900 rad, and 1050 rad; and shoulders, 38 cm, 7.7 rad/min, 800 rad, 1080 rad. The estimated lung dose is 1000 to 1100 rad. A compensator limits the dose to the head to 1000 rad. Estimated organ doses are: small intestine, liver and kidneys-1100 rad, and heart-1200 rad. Phantom dosimetry and dosimetry on patients treated reveals that these doses are delivered within 5 % accuracy. Patient tolerance of treatment, and some biological considerations of low dose rate therapy are reviewed. Certain dosimetry features of an alternate treatment at 370 cm SAD, using 25 MV photons are also presented.     

Single dose total lymphoid irradiation combined with cyclophosphamide as immunosuppression for human marrow transplantation in aplastic anemia.

Six patients with aplastic anemia underwent bone marrow transplantation following conditioning with high dose cyclophosphamide and single dose total lymphoid irradiation with 750 rad, 26 rad/min at the midplane of the patient. They all received bone marrow from human leukocyte antigens/mixed lymphocyte culture (HLA/MLC) matched siblings. Five of 6 patients were alive without complications at 12, 11, 7, 4 and 4 months respectively. The remaining patient died from sepsis which he had prior to transplantation. There were no graft rejection, graft-vs-Host Disease (GVHD) or interstitial pneumonitis among these patients. The procedure was well tolerated with minimal side effects. The results will be compared with those of groups whose bone marrow was previously transplanted with different immunosuppressive methods.     

Effect of dose-rate on total body irradiation: lethality and pathologic findings

The effect of low dose-rate total body irradation (TBI) on hemopoietic and nonhemopoietic lethality has been studied in BALB/c mice using dose-rates ranging from 25 to 1 cGy/min. Deaths were scored at 10 days, 30 days, and one year after irradiation, and dose-response curves were constructed to determine the dose-rate dependence of deaths from the gastrointestinal syndrome, hemopoietic syndrome, and late lethal syndrome(s), respectively. A plot of the LD50S for each of these lethal syndromes versus dose-rate showed the dose-rate dependence for late lethality to be somewhat greater than that for gut death, but both of these endpoints were markedly more dose-rate dependent than was hemopoietic lethality, particularly at dose rates less than 5 cGy/min. To determine which late responding normal tissues might be critical for low dose-rate TBI, complete necropsies were performed on all mice dying later than 60 days after irradiation and on all mice surviving at one year; all tissues were examined histologically. Morphologic evidence of radiation injury was present in only three tissues, lung (fibrosis and scarring) kidney (tubule depletion), and liver (presence of mitoses). Subjectively, the lung changes were most severe up to 9 months while kidney changes became more prominent after this time, suggesting that late death after low dose-rate TBI may not be entirely attributable to lung injury. However, regardless of which late responding normal tissue is dose-limiting, it is clear that low dose-rate TBI preferentially spares these tissues compared with hemopoietic stem cells.     

Autologous bone marrow transplantation in acute leukemia.

Twenty-one cases of relapsed acute leukemia were treated with high dose piperazindione and total body irradiation followed by infusion of autologous cryopreserved remission bone marrow. Evidence for engraftment was obtained in nineteen. Eleven patients achieved complete remission; of two to fourteen months duration (median 3+). Attempts to decrease leukemic contamination of the remission bone marrow by density separation did not influence the complete remission rate and duration.     

Hyperfractionated total body irradiation for bone marrow transplantation: I. early results in leukemia patients

Bone marrow transplantation following cytoreduction with total body irradiation and cyclopbospbamide has previously been shown to be of value in treating refractory leukemias. Major problems, however, have been fatal interstitial pneumonitis and leukmmac relapse. In an attempt to minimize these problems, we initiated a new hyperfractionsted regimen for total body irradiation, with partial long sparing. From May, 1979 throughJuly, 1980, we treated 48 leukemia patients according to this regimen, varying in age from 1.5 to 42 years old (mead age: 18 y). Analysis in September, 1980, with follow-up from 2–16 mos, showed that we have a significantly reduced incidence of interstitial pneumonitis compared with single dose (1000 rad) irradiation (33 vs 70%), as well as decreased deaths attributable to interstitial pneumonitis (23 vs 50%). This is reflected in the survival curves, with loss of the early drop in survival previously observed with single dose irradiation. One year actuarial survival was 65% for acute lympbocytic leukemia (n - 16) and 72% for acute non-lymphocytic leukemia (n - 29). This compares with only 17% for acute non-lympbocytic leukemia patients (n = 12) on our previous single dose regimen. Age was: also found to be an important parameter for both survival and interstitial pneumonitis.     

Cell survival kinetics in peripheral blood and bone marrow during total body irradiation for marrow transplantation

Cell survival kinetics in both peripheral blood and in bone marrow have been studied over the time course of hyperfractionated total body irradiation (TBI) for bone marrow transplantation. Our unique TBI regimen allows the study of the in vivo radiation effect uncomplicated by prior cyclophosphamide, since this agent is given after TBI in our cytoreduction scheme. Peripheral blood cell concentrations were monitored with conventional laboratory cell counts and differentials. Absolute bone marrow cell concentrations were monitored by measuring cell concentrations in an aspirate sample and correcting for dilution with blood by a cell cycle kinetic method using cytofluorometry. In the entire group of patients, time to engraftment with donor marrow was found to be 16.6 × 4.4 days and more rapid when a nucleated donor cell dose of ≥4.0 × 10⁸ cells/kg was given. For lymphocytes in peripheral blood in patients in remission, the effective D₀ ranged from 373 rad in 10 children ≤10 y old, to 536 rad in the four patients between 11–17 y old, while n = 1.0 in all groups. There was no trend observed according to age. Granulocytes had a much higher effective D₀, approximately 1000 rad in vivo. Absolute nucleated cell concentration in marrow dropped slowly initially, due to an increased lymphocyte concentration in marrow during a concurrent drop in lymphocyte concentration in peripheral blood, but eventually fell on the last day of TBI ranging from 7–44 % of the initial marrow nucleated cell concentration. Marrow myeloid elements, however, dropped continuously throughout the course of TBI.     

Toxicity and dosimetry of fractionated total body irradiation prior to allogeneic bone marrow transplantation using a straightforward radiotherapy technique

Since 1989, we have used a relatively straightforward technique for giving total body irradiation (TBI), using anterior and posterior parallel opposed fields with the arms and fists acting as compensators. The dosimetry, toxicity and outcome of 48 patients (26 adults, 22 children) treated with TBI using this technique have been audited. A dose of 14.4 Gy in eight fractions over 4 days was prescribed to all patients with an unrelated donor and 12 Gy in six fractions over 3 days to those with a sibling donor. From May 1994, all children received 14.4 Gy because of a recommendation from the United Kingdom Children's Cancer Study Group. The range of lung dosimetry was −6% to +7% when the dose was specified to the lung maximum. The trunk doses were all within ±10% of the prescribed dose. Doses to other regions of the body were less homogeneous but clinically acceptable in that the minimum doses were never less than −10% of the prescribed dose. Mucositis was the most common side effect; its treatment with opioids was more frequent after 14.4 Gy than after 12 Gy (P = 0.0004) and in adults than in children (P = 0.01). No cataracts have yet been seen in these patients. The radiation was not found to be a proven cause of clinical pneumonitis, although there was one death due to interstitial pneumonitis, which was likely to have been caused by cytomegalovirus infection in which radiation pneumonitis could not be excluded. There were no other suspected TBI-related deaths.In conclusion, this straightforward technique achieved acceptable dosimetry and was well tolerated.     

Lung function after bone marrow grafting

Results of a prospective lung function study are presented for 48 patients with acute myeloid leukemia (AML) treated with total body irradiation (TBI) and bone marrow transplantation (BMT) at the Royal Marsden Hospital between 1978 and 1980. Patients with active disease or who were in remission following cytoreductive chemotherapy had mildly impaired gas exchange prior to grafting. After TBI and BMT all patients studied developed progressive deterioration of lung function during the first 100 days, although these changes were subclinical. Infection and graft-versus-host disease (GvHD) were associated with further worsening of restrictive ventilatory defects and diffusing capacity (DLCO). Beyond 100 days, ventilatory ability returned to normal and gas transfer improved, although it failed to reach pre-transplant levels. There was no evidence of progressive pulmonary fibrosis during the first year after grafting.     

The cellular basis of long-term marrow injury after irradiation

Haemopoietic recovery from radiation injury can appear complete when measured by blood cell counts, but this can hide deficiencies in the precursor cell populations because of compensatory mechanisms of increased numbers of divisions in the maturing cell populations and increased cycling of the stem cells. These mechanisms can operate for quite long but finite periods, before they fail which then leads to hypoplasia. Also, while these mechanisms are operating, small further injuries could precipitate marrow failure. Persistent injury in the stem cell population can be induced by quite small doses, and in mice the threshold total dose is probably in the region of 1.5 Gy using fractionated whole-body irradiations. The sensitivity of the environment varies enormously, depending largely on the proliferative stress applied to the cell populations involved in the particular assay technique used. When similar tests of reproductive integrity are applied, stromal progenitor cells are more radioresistant than haemopoietic stem cells. The contribution of environmental injuries to haemopoietic defects is uncertain and difficult to assess.