Radiotherapy and Oncology, Suppl. 1 (1990) 68-81 Elsevier

Total body irradiation for bone marrow transplantation: The Memorial Sloan-Kettering Cancer Center experience Brenda Shank1p2, Richard J. O’Reilly3, Isabel Cunningham3, Nancy Keman3, Joachim Yaholoml, Brochstein3, Hugo Castro-Malaspina 3, G.J. Kutcher‘t, Rahde Mohan4 and Patricia Bonfiglio233

Joel

IRadiation Oncology Department, Memorial Sloan-Kettering Cancer Center; 2Present Address: Radiation Oncology Department, Mount Sinai Medical Center, New York, NY 10029-6547. U.S.A.; 3Marrow TransplantationService, and4Medical Physics Department, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, U.S.A.

Keywords: Total body irradiation; Bone marrOw transplantation; Leukemia; Interstitial pneumonitis; Engraftment; Relapse

Summary In May 1979, Memorial Sloan-Kettering embarked on a programme of hyperfractionated TBI (HFTBI), 1320 cGy in 11 fractions over 4 days with partial lung shielding (1 HVL), followed by cyclophosphamide (60 mg/kg/d x 2d) for cytoreduction prior to allogeneic bone marrow transplantation (BMT). Anterior and posterior chest wall electron “boosts” were given to the areas blocked (600 cGy in 2 fractions) on the last two days of treatment. Since then, we have treated over 600 patients with I-IPTBI, the majority for allogeneic BMT. Several modifications have occurred over the years. We have added a “boost” electron dose of 400 cGy to the testes in all male leukemic patients; this reduced testicular relapses from a rate of 14% (4/28) to 0%. In an attempt to increase engraftment of T-depleted BMTs, we added one additional fraction; since our present dose/fraction was also increased to 125 cGy, we now deliver a total dose of 1500 cGy in 12 fractions over 4 days for allogeneic transplants. Tolerance to HFTBI has been excellent relative to the single dose (SD) regimen utilised prior to May, 1979. The incidence of fatal interstitial pneumonitis (IP) decreased from 50% in the SD regimen to 18% after the introduction of HFTBI. In children, the incidence of IP was only 4% with HFTBI. With the introduction of T-depleted marrows, fatal IP in adults has decreased also, e.g. to < 10% in CML patients. With conventional BMT after I-IFTBI, relapse at 5 years has been exceedingly low (e.g. in children, 13% for ALL, 2nd remission and 0% for AML, 1st remission) and engraftment has been 100%. With matched T-depleted BMT, rejections have occurred in 15% overall; the incidence of graft failure has not been reduced by the higher dose of I-IFTBI. Relapses in this setting are equivalent to relapses with conventional BMT for AML, but appear to be increased for ALL. Radiobiological findings related to HFTBI will also be discussed.

Introduction At Memorial Sloan-Kettering Cancer Center (MSKCC), we have been using a hyperfractionated total body irradiation (HFTBI) regimen [25] as part of our cytoreduction procedure for bone marrow 0167-8140/90/$03.50

0 1990 Elsevier Science Publishers B.V. (Biomedical Division)

69 transplantation since 1979. Over the years, the number of transplant patients at our institution has increased to a level of approximately 100 patients per year. As a result we have treated over 600 patients with such a regimen. This regimen has consisted of small fractions of irradiation three times a day over a 4 day period with the use of partial lung blocks throughout the course of treatment. At the end of the course of treatment, additional chest wall electron “boosts” are used in order to give a homogeneous dose to the rib areas blocked during the photon treatment. In addition, a testicular boost is given to all male leukemia patients. This report will concentrate on the results in leukemia patients although we are using this regimen for autologous transplantation in non-Hodgkin’s lymphoma patients as well. The emphasis will be on the incidence of interstitial pneumonitis, engraftment, and relapse. We will also discuss the radiobiological rationale for this regimen in relation to normal tissue tolerance of lung, leukemia cell kill, and immunosuppression. We will discuss the results in both conventional marrow transplants (CBMT), i.e. transplants with unseparated marrow following which the recipient receives graft-versus-host disease (GVHD) prophylaxis with methotrexate, cyclosporin A, or both, and in “lectin-separated” (T-cell depleted) marrow transplants (LSBMT), i.e. marrow which has undergone the T-cell depletion procedures of soybean agglutinin separation and E-rosetting [2 11.

Materials and Methods Patients with acute or chronic leukemia are referred to the Radiation Oncology Department by the Marrow Transplantation Service for a consultation, simulation, and height and thickness measurements prior to admission to the hospital for marrow transplantation. In addition to the history and physical examination, the patient is simulated for preparation of 1 HVL lung blocks for total body irradiation (TBI). Anterior and posterior chest films are taken in the standing position similar to that used for TBI. After the lung blocks are designed on the films, a tattoo is placed on the anterior and posterior chest of the patient corresponding to the top of the lung blocks at a point midway between the two blocks for appropriate placement during TBI. The patient also undergoes a CT scan of the chest through a level corresponding to the thickest part of the chest, namely at a distance approximately two-thirds down from the top of the lung blocks. This scan is used for computerised treatment planning, utilising CT density information, for electron boosts to the chest wall to compensate for the partial blocking of the marrow in the ribs by the lung blocks. Patients are treated in the standing position on a special stand constructed for this [ll]. They are immobilised between plates with the lung blocks placed on the plate in front of the chest wall. This stand has evolved and now has incorporated a bicycle seat to use for support although the patient is still kept in the standing position. There are also supports for the hands to grip. A 1 cm lexan screen is placed in front of the patient for electron build-up during treatment. Verification films are taken during the first fractions and any minor changes in positioning or shape of the lung blocks may be corrected for the remaining fractions of treatment. Patients are treated three times a day (Fig. l), over a four day period with twelve 125 cGy fractions 5 h apart for a total dose of 1500 cGy. Cyclophosphamide after TBI (60 mg/kg) for two days was used in most patients. Our current scheme evolved from our original fractionation which was similar in the fraction intervals but consisted of only 120 cGy per fraction for eleven fractions for a total dose of 1320 cGy. During the day, treatments are 5 h apart, however, from the third fraction each day to the first fraction on the next day, 14 h elapse. Chest wall boosts are given on the last two days of treatment (300 cGy per fraction). After the first year, we instituted also an electron boost to the testes of 400 cGy in one fraction. All male leukemic patients now receive this testicular boost.

70

PRE-TBI

SUNDAY -9

MONDAY

TUESDAY

-8

c

SIMULATION CT

WEDNESDAY

-7 T8I 125 cGyx3

-1

Cyclophosphamide 60 mglkg

T8I 125 cGyx3

-4 TBI 125 cGy x 3

Chest Wall Electron Boost Ant: 300 cGy Post: 300 cGy

Testicular Electron Boost 400 cGy

FRIDAY

-5

-6

T8I 125 cGyx3

-2

THURSDAY

Chest Wall Electron Boost Ant: 300 cGy Post: 300 cGy

SATURDAY -3 Cyclophosphamide 60 mglkg

0 Marrow Transplant

Fig. I. Schedule of MSKCC hyperfractionated

Total Dose: Dose/Fraction: Dose Rate: lntewal Between Fractions:

.

1500 cGy 125 cGy 6-19 cGy/min 5h

TBI.

For CBMT, GVHD prophylaxis was done utilising either methotrexate, cyclosporin A, or a combination of both as previously described [3]. For T-depleted transplants, marrow was treated with soybean agglutinin following by an E-rosetting procedure, according to the method of Reisner et al. [21]. The soybean agglutinin positive fraction was irradiated and infused into the patient followed by the soybean agglutinin negative and E-rosette negative fraction (SBA-E-) containing stem cells but not mature T-cells. In some patients with a low yield of marrow, only the soybean agglutination step was done and the SBA- was utilised only. In patients receiving T-depleted marrow, no GVHD prophylaxis was used, although in patients receiving the SBA- fraction which had not been E-rosetted, prophylaxis for GVHD was usually used. Survival and disease free survival analysis was by the Kaplan Meier product limit method. All time intervals are from the time of marrow transplantation. We have treated over 600 patients with the methods described. For the present analysis, we have concentrated on a smaller, more homogeneous subset, 93 adult patients (2 16 yr) with CML; previously published data from our institution [3,23-251 will also be summarised where pertinent.

Results Acute

side ejfects

The regimen has been extremely

well tolerated in comparison

to our original single dose scheme (1000

Table I. Incidence of interstitial pneumonitis in adult CML Incidence Population

Matched LSBMT Mismatched LSBMT CBMT

No.

Any

Fatal

61 11 15

16% 27% 40%

7% 27% 40%

cGy). Nausea and vomiting generally occur on the first day beginning approximately 2 h after initiation of treatment. This, however, improves considerably by the second day and is usually absent by the third and fourth days of treatment. One rare complication occurs occasionally during standing for treatment, namely an orthostatic hypotension which may result in syncope. This is found to be related to administration of a phenothiazine as an antiemetic or to a low hemoglobin concentration. Patients occasionally experience salivary gland swelling and discomfort which is transient. Nearly all patients experience fatigue by the end of the course of treatment. In contrast, with our original single dose regimen, nausea and vomiting generally began about half way through the course of treatment and was frequently quite debilitating throughout the remainder of the course of treatment. Interstitial pneumonitis With HFTBI (1320 cGy), we observed a dramatic decrease in interstitial pneumonitis (IP) compared with our original single dose (1000 cGy) regimen. The incidence of fatal lP dropped to 18% (14/76) from 50% (10/20) with the single dose regimen for CBMT [24]. A recent analysis [3] of the results in youths < 19 years old (who have a low incidence of GVHD) shows that with conventional marrow transplants at MSKCC for AML or ALL, there was an IP incidence of 4% (4/97) with HFTBI. In adults with CBMT, the incidence is higher, e.g. patients with CML (> 16 years old) have a 40% incidence (6/15) of IP with HFI’BI, in association with a 73% incidence of some GVHD. However, in the 13 autologous transplants which have been performed in our present randomised regimen for patients > 16 years old with AML in first remission, we have observed no IP (Berman, E., personal communication). Looking further at this problem in the adult CML patients described above (Table l), the incidence of any IP in 67 HLA-matched LSBMT patients dropped to 16% (7% fatal IP). In 11 HLA-mismatched LSBMT adult patients with CML the incidence of any IP is 27% (all fatal). However, since most of these patients died within 3 months with sepsis in a setting of non-engraftment, it is impossible to attach any significance to the percentage of IP incidence in this mismatched group. In adult CML patients (Table 2), the leading etiologic agent was cytomegalovirus (CMV). Of the 20 cases of IP, 15 were caused by CMV which was usually fatal. The only survivors were 3 matched LSBMT patients who were given DHPG (gancyclovir) and gamma globulin. There was only one instance of an idiopathic Ip, this was in a recipient of a CBMT. Hepatitis In our transplant regimen, we consistently see an elevation of the alkaline phosphatase, serum glutamic oxalacetic transaminase, and lactic dehydrogenase in concert to levels from two to four times normal, peaking at about three to five weeks from the beginning of the TBI procedure (unpublished data). These

72 Table 2. Causes of IP in adult CML No. fatal IP/no. IP

M-LSBMT MM-LSBMT CBMT

CMV

Adenovirus

P. Carini

Idiopathic

Total no. pts.

4l7 3/3* 515

l/l -

Q/3

-

67 11 1.5

l/l

* Also adenovirus in one patient.

levels gradually decline if no other process intervenes such as viral infection or GVHD. During this transient increase in liver function tests, the bilirubin remains relatively stable. If it does not, some other process should be sought. Engraji’ment With CBMT, engraftment with our regimen has not been a problem. Engraftment (sustained WBC >500 cells/mm3) usually occurs from ten days to three weeks post transplant, with a median of 17 days, with an occasional patient experiencing a late engraftment up to 36 days [23]. Time to engraftment was found to be related to the nucleated cell dose. When > 4 x lo* cells/kg was infused, 97% (37/38) of the patients engrafted within one standard deviation from the mean. In those patients who received a dose of < 4 x lo8 cells/kg, 28% (16/58) engrafted at a time greater than one standard deviation from the mean [23]. In the HLA-matched LSBMT patients, graft failure became a problem. Graft failure was seen in 19% of the 57 CML matched LSBMT patients (median age = 33 y), 17% of the 35 AML patients (median age = 25 y), and 8% of the 23 ALL patients (median age = 13 y). Many variables have been tested for their statistical relationship with graft failure. One variable has stood out as being highly statistically related to both early and late graft failure in our series, i.e. the sex of the donor [lo]. Male donors result in a probability of durable engraftment at 60 days of only 75%, while female donors result in a probability of durable engraftment at 60 days of 97%. other variables tested included patient-related variables such as type of leukemia, sex of the patient, splenectomy in CML patients, time from diagnosis to transplant, and age of the patient. Of these, only the sex of the patient (female) and age of the patient (over 17 years old) show a trend. This was not statistically significant due to the small numbers of patients but it was clear that the group that had the poorest engraftment were female patients who received marrow from a male donor. Graft-related variables were also tested [lo] such as nucleated cells/kg, total nucleated cells infused, CFU-GM, CFU-GM/kg, total T-cells, and T-cells/kg. None of these were statistically associated with graft failure. Various strategies to decrease rejection were tried such as increasing the TBI dose, intensifying the chemotherapy, adding back a defined amount of donor T-cells to the graft, or suppressing host immunity by agents such as ATG, prednisone, or immunotoxins. Increasing the HFTBI dose in patients over the age of 15 y did not result in any increase in engraftment. Failures were 19% (3/16) at 1365 cGy and 18% (1 l/61) at 1500 cGy. The addition of methylprednisolone following transplant or the addition of a defined amount of donor T-cells also did not increase engraftment [l-O].

73

Relapse In our initial experience with the HFTBI regimen, 4/28 males relapsed in the testes with or without marrow relapse. After that, we added an electron boost (400 cGy) to the testes in all male leukemia patients. When we analysed in 1983 the first group of patients following such a boost [24], O/14 male patients had relapsed with such a boost. We have had no subsequent testicular relapses in over 300 male patients since this boost was instituted. In our initial HFTBI experience comparing adults and children with ALL in comparable remission status with patients treated by the single dose regimen used in Seattle [24], we reported a relapse-free survival in our patients who had less than 5% blasts similar to that in Seattle, but in patients who are considered in relapse (with over 5% blasts) our relapse-free survival was greater than for those patients treated with single fraction irradiation in Seattle. Our recent analysis of children with ALL [3], demonstrated a 64% disease-free survival at 5 years for patients with ALL in second remission and 42% for those in third remission with CBMT. The cumulative probability of leukemic relapse in children with

SURVIVAL

FlOULT

CtlL

llLSBflT

LAST

FBLLBN

CHMNIC TICK

CKL IIAKK f I 1

I 40 INOICATLS

WK.

/

28

CLN1~KLDl

UP

51 . . . . . , 0.00

9.00

18.00

ttONTHS

27.00

FROtI

SK. 00

Bf4T

45.00

/

s4.00

a/a8

Fig. 2. Overall survival after a matched LSBMT in patients with CML in first chronic phase, who are 216 years old.

74

ALL treated with a CBMT is about 20% for second or third remission. With children given a CBMT for AML, the disease-free survival was 66% at 5 years for first remission patients and 75% for second remission patients. The estimates of relapse in the 5 years after transplantation for children with AML were 0% for first remission and 13% for second remission. For LSBMT, the relapse rate, in our experience, appears comparable to that for CBMT in AML patients, but higher relative to CBMT for ALL patients. ln AML, first remission, the probability of remaining free of disease is 81% in our historical CBMT group compared with 76% in the pilot study LSBMT group at 4 years which is not significantly different. For patients with ALL in second remission, however, the probability of remaining free of disease in the historical CBMT group was 90% at 4 years and 39% in the LSBMT pilot group of only 9 patients. ln the matched LSBMT adult CML group in chronic phase (1 16 years old) overall survival is 63% (Fig. 2). Disease-free survival at 4 years, however, is 41% reflecting the overall probability of remaining in remission at 4 years of 57% in this group (Fig. 3). The chance of remaining in remission is significantly less (p = 0.013) for patients over the age of 32 (39% at 3 years) compared with those < 32 years old (76% at 3 years).

REMISSION

0

DURATION

CNAINICCl4L TICM

IlAM

f , I

ADULT

t 40 INOICRTEI

VS.

CtlL

/

IILSBMT

JO CENtOREO)

LAST FOLLOY UP

Fig. 3. Probability of remaining in remission after an HLA-matched LSBMT in CML patients in first chronic phase, who are 2 16 years old.

75 Radiobiology In cell cytofluorometry studies, we have previously shown that in patients receiving total body irradiation, bone marrow cells were blocked in G2-M while there seemed to be an absence of cells in DNA synthesis [23]. We also showed that immunosuppression as measured by peripheral blood lymphocyte count was constant over a full course of TBI in leukemic patients and was independent of age or remission status [23].

Effect on WBC and Platelets of Single Fraction TBI (125cGy)

1

150

r Pt.m

7.0

TBI-125cGy

/+ ,:: 4

8.

6

9.0

h

I 8.0 ’

Pt.m

7.i

///

180

rl 130

I

58

1 =PlalTransfusion

4

It,,

'1 TBI-125cGy

2

3

I,,

4

5

6

,

7

,

,

,

8

9

10

10

Weeks post-TM Fig. 4. Changes with time in peripheral blood white count (WBC = 0) and platelets (Plat = ?? ) after a single fraction of TBI (125cGy) in 2 patients.

76 We have now had the experience of having two patients who completed only a single fraction (125 cGy) of irradiation, which has allowed us to follow the peripheral blood counts for a period of time following this single dose. One patient’s treatment was stopped because of the concern of an infection and the other patient’s treatment was stopped because of elevated liver function tests. The course of the drop in white blood count and platelets, as well as recovery is shown in Fig. 4. The recovery times were quite different between the two patients which may simply reflect their marrow reserve after differing chemotherapy. Of more interest are the kinetics of the initial decrease with a single dose of irradiation,

Effect of Single Fraction TBI (125cGy) on Absolute Lymphocyte and Granulocyte Concentrations 100 80

-\ \

LYMPHOCYTES

\

6

E g L

GRANULOCYTES loo&--x,A

\A

80-

0

60 -

Q

\

\

A h

40 -

\

0 Pt.#l

'k

A Pt.#2 ! -’

I

TBI '

I 2

I 3

I 4

I 5

I 6

I 7

I

I

8

910

I

Days post-TBI Fig. 5. Changes

in time in peripheral blood lymphocyte and granulocyte concentrations after a single fraction of TBI (125 cGy) in 2 patients (0 = Pt.#l. A = Pt.#2), expressed as a percentage of the pre-TESI concentrations of each.

77

for predicting immunosuppression over an entire course of irradiation. When the effect on individual components of the white count was studied further it was found that, because the patients had quite different differential cell counts at the time of the single dose of irradiation, the kinetics of the lymphocyte and granulocyte drop were actually quite similar in the two patients in spite of the different appearance of the overall white count drop. Lymphocytes dropped to a nadir at about 3 days to a level that was 40-50% of the initial level in peripheral blood and gradually recovered slowly. Granulocytes, however, fell extremely slowly and were still falling by day 9 after this initial dose of total body irradiation in both patients (Fig. 5). If one looks at the percent lymphocyte concentration nadir achieved with a single 125 cGy fraction, this translates into a D, of 175 cGy for one patient and 135 cGy for the other. If one then predicts the lymphocyte survival seen with 11 or 12 fractions of hyperfractionated TBI assuming either complete recovery between fractions or no shoulder to the lymphocyte survival curve, and no cell growth between fractions, one would get the curve shown in Fig. 6. The lymphocyte survival actually seen in patient data, however, is in the range somewhat above this shown in Fig. 6. This would

I

N lymphocyte SUWal Actually Seen (HTBI)

0.1 _ 0.08 E 0.06 0.04 -

1

0.02 -

Predicted

0.01 _ 0.008 I 0.006 0.004 0.002 0.061

I

I

I

125

500

1000

I

1

13751500

TBI Dose (cGy) Fig. 6. Schematic of predicted % lymphocyte survival with 11 or 12 fractions of hyperfractionated TBI, based on the lymphocyte nadir achieved with a single 125 cGy fraction of TEU in 2 patients, in comparison to the range of % lymphocyte survivals actually seen with HFTESI (see reference 23).

78 indicate that there may be more than one population of lymphocytes with a relative radioresistance of one of the populations, or potentially this could indicate that there is some cell growth between fractions as well, especially in the 14 h overnight between the fractions given at the end of a day and the next morning.

Discussion Side effects HFIBI has proven to be extremely well tolerated when compared with our original single dose fractionation. With the new TBI stand, the set-up time has improved (approximately 20 minutes for each patient including verification films. Interstitial pneumonitis Many factors contribute to IP, such as radiation dose, dose rate and fractionation, chemotherapy (cyclophosphamide, methotrexate), viral infections, and GVHD. In our experience, IP was reduced with the HPTBI regimen particularly in children (4%) and has not been seen in our autologous transplants. In an analysis of a French cooperative group [5], IP was reduced to 10% with a daily fractionation scheme (1000-1300 cGy) compared to 30% with a single 800-1000 cGy dose. When significant GVHD is present, the incidence of IP is still high, e.g. in CML patients receiving a CBMT [15]. With the introduction of LSBMT, however, GVHD, both acute and chronic, has been nearly abolished in our patients and the incidence of fatal IP has fallen accordingly. CMV has been the principle etiologic agent. With the introduction of DHPG (gancyclovir) and gamma globulin, three patients in the matched LSBMT group have survived their CMV pneumonitis: As this trial continues, it is hoped that this will have a further impact on survival. Engraftment In the LSBMT group, engraftment has been a problem, especially with male donors. In our experience, increasing the TBI dose, adding methylprednisolone or T-cells to the donor graft have not improved engraftment. Trials are proceeding with ATG and immunotoxin to improve engraftment. It should be noted that our dose increase in an attempt to increase engraftment was only one additional fraction of 125 cGy. It is possible that greater dose increases such as those of other authors, of either TBI [4,14,20] or TLI [26,27] may increase engraftment, although several investigators have not seen an improvement with increasing TBI [19] or TLI [l]. Some of the best results (lowest rejection rates) have been seen with single dose irradiation of 750 cGy at 15 cGy/min [7,18], hyperfractionated courses [ 121 as in our regimen, or with added chemotherapy, such as cytosine arabinoside [8]. Relapse We have seen an extremely low relapse rate in children receiving CBMT for ALL or AML. In particular, in ALL our low relapse rate compared to other series may be a reflection of several factors in our regimen. Because of the I-IPTBI schedule, we were able to achieve a high dose of irradiation (1320 1500 cGy). In addition, we added a testicular boost which abrogated any further testicular relapses. Finally, we have given cyclophosphamide after TBI. Many studies have shown in animals that the order

79 of cytoreductive agents is important. In particular, when cyclophosphamide has been given prior to TBI in cell or animal studies, marrow suppression has been less than when given after TBI [2,6]. In first remission AML patients receiving an LSBMT, the relapse rate continues to be low, comparable to that seen in CBMT in our historical series. In ALL, however, the relapse rate appears to be higher with LSBMT, but the number of patients who had a LSBMT was very small. A higher relapse rate for T-depleted BMT has been seen in other studies for both acute leukemia and CML [ 1,5,7,17] including two small randomised studies [ 13,161. It is possible that, in the ALL group of patients, failures after more aggressive chemotherapy (in the more recent LSBMT group) are much worse than in the previous set of patients with CBMT when chemotherapy was not quite as aggressive. We are proceeding with a randomised study in AML first and second remission patients and in ALL second remission patients comparing CBMT with LSBMT. Relapse figures for CBMT in our CML patients are not reliable due to the small number of chronic phase CML patients treated with CBMT at our institution. In the Seattle experience [28], first chronic phase CML patients who had a CBMT had a probability of clinical relapse in 5 y of slightly over 20%, about half of our probability of relapse in first chronic phase CML patients receiving a LSBMT. Since age and interval from diagnosis to BMT were very important in determining survival in the Seattle study [28], and age was a statistically significant factor in relapse in our LSBMT data, it would be important to have comparable groups of patients before making any definitive statement regarding relapse rates in any T-cell depleted BMT relative to conventional BMT. Our patients who were I 32 years old experienced only a 24% probability of relapse at 4 years. Strategies to reduce relapse include intensifying antileukemic therapy prior to transplantation, promoting engraftment of donor cells by immunotoxins or growth factors, or promoting the engraftment or development of antileukemic cells by the use of growth factors or LAK cells. At present, in CML patients, we are proceeding with a trial of intensified pretransplant antileukemic therapy using Idarubicin and high dose Ara-C along with our cytoreductive regimen of HFTBI and cyclophosphamide. Radiobiology We initially proposed that HFTBI would potentially increase normal tissue tolerance (lungs) by decreasing the effective dose to lung tissue [22]. The use of partial lung blocks would also add to this lung protection. Our results would suggest that lung effects are lessened by our regimen, although one cannot attribute this protection to the fractionation or the lung shielding since they were both introduced at the same time. In addition, we had postulated that we may have a greater antileukemic effect by giving small doses of irradiation so that we could increase the total dose. Indeed, in our CBMT patients we have seen a decreased relapse rate compared to other series. In addition, we have been able to see an effect on the cell cycle in studies utilising flow cytometry on bone marrow of patients undergoing HFTBI. We have found that there are decreased cells in S phase and a buildup of cells in GZ-M, a phase when cells are more sensitive to radiation. Further work in the laboratory along these lines will pursue this further. The lymphocyte survival actually seen at the end of a course of HFTBI is higher than that predicted from data on lymphocyte survival after only one fraction of irradiation. From this, we predict that there may be more than one population of lymphocytes, one being relatively more radiosensitive than the others, or that there may be some cell regrowth between fractions especially overnight during the 14 h interval between fractions. Other data would indicate that there may be a relatively insensitive NK population which survives the dose of irradiation that one would use for HFTBI [9]. In conclusion, for CBMT, utilising HFI’BI we have seen excellent engraftment, a reduced interstitial pneumonitis and an extremely low relapse rate in ALL and AML patients. In LSBMT, utilising HFTBI,

80 we have seen an even further decrease in IP. The relapse rate for LSBMT appears to be similar to that for CBMT in first remission AML patients, but is increased in ALL sekond remission patients. Graft failure occurs in this group in approximately 1520% of the patients with this regimen and studies are proceeding further to try to minimise this problem.

References 1. Apperley, J.F., Arthur, C., Jones, L., Rombos, Y., Guo, A.P., Rassool, F., Hows, J.M., Hale, G. and Goldman, J. Risk factors for relapse after T cell depleted allogeneic BMT for CML in chronic phase. Bone Marrow Transpl. 2 (Suppl. 1). 140, 1987. 2. Blackett, N.M. and Aguado, M. The enhancement of haemopoietic stem cell recovery in irradiated mice by prior treatment with cyclophosphamide. Cell Tissue Kinet. 12, 291-298, 1979. 3. Brochstein, J.A., Keman, N.A., Groshen, S., Cirrincione, C., Shank, B., Emanuel, D., Laver, J. and O’Reilly, R.J. Allogeneic bone marrow transplantation after hyperfractionated total-body irradiation and cyclosphamide in children with acute leukemia. N. Engl. J. Med., 317, 1618-1624, 1987. 4. Burnett, A.K., Robertson, A.G., Harm. I.M., Alcom, M., Gibson, B.E. and McKinnon, S. In vitro T-depletion of allogeneic bone marrow: Prevention of rejection in HLA-matched transplants by increased TBI. Bone Marrow Transpl., 1 (Suppl. I), 121, 1986. 5. Devergie, A., Gluckman, E., Reiffers, J., Vemant, J.P., Flesh, M., Guyotat, D., Maraninchi, D., Rio, B., Michallet, M., Jouet, J.P. and members of French Coop. Group. Bone marrow transplantation for patients with chronic granulocytic leukaemia in France 1979-1986. Bone Marrow Transpl. (Suppl. 1), 24, 1987. 6. Evans, R.G., Wheatley, C.L. and Nielsen, J.R. Modification of radiation-induced damage to bone marrow stem cells by dose rate, dose fractionation, and prior exposure to cytoxan as judged by the survival of CFUs: Application to bone marrow transplantation (BMT). Int. J. Rad. Oncol. Biol. Phys., 14, 491495, 1988. 7. Ganem, G., Kuentz, M., Beaujean, F., LeBourgeois, J.P., Cordonnier, C. and Vemant, J.P. Additional total lymphoid irradiation (TLI) in preventing graft failure of T cell depleted bone marrow transplantation (BMT) from HLA identical siblings: Results of a prospective randomized study. Bone Marrow Transpl. 2 (Suppl. l), 156, 1987. 8. Hagenbeek, A., Lowenberg, B. Prevention of graft-versus-host disease without take failures after allogeneic bone marrow transplantation. Bone Marrow Transpl. 2 (Suppl. l), 141, 1987. 9. Keever, C.A., Benazzi, E.,Keman, N.A., Welte, K., O’Reilly, R.J. and Bordignon, C. Radiosensitivity of NK lytic activities and NK-mediated hematopoietic colony inhibition: Effect of activation with IL-2 and blocking of the T-200 molecule. Cell. Immunol., 113, 143-157, 1988. 10. Keman, N.A., Bordignon, C., Heller, G., Cunningham, I., Castro-Malaspina, H., Shank, B., Flomenberg, N., Bums, J., Yang, S.Y., Black, P., Collins, N.H. and O’Reilly, R.J. Graft failure after T-cell-depleted human leukocyte antigen identical marrow transplants for leukemia: I. Analysis of risk factors and results of secondary transplants. Blood 74, 2227-2236, 1989. 11. Kutcher, G.J., Bonfiglio, P., Shank, B., Masterson, M.E. Combined photon and electron technique for total body irradiation (Abst.), ESTRO, 1988. 12. Latini, P., Checcaglini, F., Maranzano, E., Aristei, C., Panizza, B.M., Gobbi, G., Raymondi, C., Aversa, F. and Martelli, M.F. Hyperfractionated total body irradiation for T depleted HLA identical bone marrow transplants. Radiother. Oncol. 11, 113-l 18, 1988. 13. Marmont, A., Bacigalupo, A., VanLint, M.T., Frassoni, F., Occhini, D., Pittaluga, P.A., Piaggio, G. and Figari, 0. T cell depletion in allogeneic BMT for leukaemia: The Genoa experience. Bone Marrow Transpl. 2 (Suppl. l), 139, 1987. 14. Martin, P.J., Hansen, J.A., Buckner, C.D., Sanders, J.E., Deeg, H.J., Stewart, P., Appelbaum, F.R., Clift, R., Fefer, A., Witherspoon, R.P., Kennedy, M.S., Sullivan, K.M., Floumoy, N., Storb, R. and Thomas, E.D. Effects of in vitro depletion of T cells in HLA-identical allogeneic marrow grafts. Blood 66, 664-672, 1985. 15. McGlave, P., Arthur, D., Haake, R., Hurd, D., Miller, W., Vercelotti, G., Weisdorf, D., Kim, T., Raysey, N. and Kersey, J. therapy of chronic myelogenous leukemia with allogeneic bone marrow transplantation. J. Clin. Oncol., 5, 1033-1040, 1987. 16. Mitsuyasu, R.T., Champlm, R.E., Gale, R.P., Ho, W.G., Lenarsky, C., Winston, D., Selch, M., Elashoff, R., Giorgi, J.V., Wells, J., Terasaki, P., Billing, R. and Feig, S. Treatment of donor bone marrow with monoclonal anti-T-cell antibody and complement for the prevention of graft-versus-host disease: A prospective, randomised double-blind trial. Ann. Int. Med., 105, 20-26, 1986. 17. Papa, G., Arcese, W., Bianchi, A., Mama, F.R., Pasqualetti, D., DeFelice, L., DeCuia, M.R., Dentamaro, T., Screnci, M., Gasparetto, C., Rosata, V., Adomo, G., Malagnino, F. and Mandelli, F. T cell depleted bone marrow transplantation in Ph+ myeloid leukaemia. Bone Marrow Transpl. 2 (Suppl. l), 39, 1987. 18. Patterson, J., Prentice, H.G., Brenner , M.K., Gilmore, M., Janoussy, G., Ivory, K., Skeggs, D., Morgan, H., Lord, J., Blacklock, H.A., Hoffbrand, A.V., Apperley, J.F., Goldman, J.M., Burnett, A., Gribben, J., Alcom, M., Pearson, C., McVickers, I., Han%

81

19. 20.

21.

22. 23. 24.

25.

26.

27. 28.

I.M., Reid, C., Wardle, D., Gravett, P.J., Bacigalupa, A. and Robertson, A.G. Graft rejection following HLA matched T-lymphocyte depleted bone marrow transplantation. Br. J. Haematol., 63, 221-230, 1986. Poynton, C.H., MacDonald, D., Byrom, N.A. and Barrett, A.J. Rejection after T cell depletion of donor bone marrow. Bone Marrow Transpl. 2 (Suppl. l), 153, 1987. Racadot, E., Herve, P., Beaujean, F., Vemant, J.-P., Flesch, M., Plouvier, E., Andreu, G., Rio, B., Philippe, N., Souillet, G., Pica, J., Bordigoni, P., Ifrah, N., Paitre, M.-L., Lutz, P., Morizet, J. and Bernard, A. Prevention of graft-versus-host disease in HLA-matched bone marrow transplantation for malignant diseases: Multicentric study of 62 patients using 3-pan-T monoclonal antibodies and rabbit complement. J. Clin. Oncol., 5, 426-435, 1987. Reisner, Y., Kapoor, N., Kirkpatrick, D., Pollack, M.S., Dupont, B., Good, R.A. and O’Reilly, R.J. Transplantation for acute leukaemia with HLA-A and B non-identical parental marrow cells fractionated with soybean agglutinin and sheep red blood cells. Lance& 2, 327-331, 1981. Shank, B. Techniques of magna-field irradiation. Intl. J. Rad. Oncol. Biol. Phys., 9, 1925-1931, 1983. Shank, B., Andreeff, M. and Li, D. Cell survival kinetics in peripheral blood and bone marrow during total body irradiation for marrow transplantation. Intl. J. Rad. Oncol. Biol. Phys., 9, 1613-1623, 1983. Shank, B., Chu, F.C.H., Dinsmore, R., Kapoor, N., Kirkpatrick, D., Teitelbaum, H., Reid, A., Bonfiglio, P., Simpson, L. and O’Reilly, R.J. Hyperfractionated total body irradiation for bone marrow transplantation. Results in seventy leukemia patients with allogeneic transplants. Int. J. Rad. Oncol. Biol. Phys., 9, 1607-1611, 1983. Shank, B., Hopfan, S., Kim, J.H., Chu, F.C.H., Grossbard, E., Kapoor, N., Kirkpatrick, D., Dinsmore, R., Simpson, L., Reid, A., Chui, C., Mohan, R., Finegan, D. and O’Reilly, R.J. Hyperfractionated total body irradiation for bone marrow transplantation: I. Early results in leukemia patients. Int. J. Rad. Oncol. Biol. Phys., 7, 1109-1115, 1981. Slavin, S., Or, R., Naparstek, E., Cividalli, G., Weshler, Z., Weiss, L., Mumcuoglu, M., Engelhard, D., Aker, M., Pollack, A., Ben-Yehuda, A., Brautbar, C., Hale, G. and Waldmann, H. New approaches for the prevention of rejection and graft-versus-host disease in clinical bone marrow transplantation. Israel J. Med. Sci., 22, 264-267, 1986. Slavin, S., Or, R., Weshler, Z., Hale, G. and Waldmann, H. The use of total lymphoid irradiation for abrogation of host resistance to T-cell depleted marrow allografts. Bone Marrow Transpl. 1 (Suppl. l), 98, 1986. Thomas, E.D., Clift, R.A., Fefer, A., Appelbaum, F.R., Beatty, P., Bensinger, W.I., Buckner, C.D., Cheever, M.A., Deeg, H.J., Doney, K., Floumoy, N., Greenberg, P., Hansen, J.A., Martin, P., McGuffm, R., Storb, R., Sullivan, K., Weiden, P.L. and Witherspoon, R. Marrow transplantation for the treatment of chronic myelogenous leukemia. Ann. Intern. Med., 104, 155-163. 1986.