Randomized comparison of cyclophosphamide-total body irradiation versus busulfan-cyclophosphamide conditioning in autologous bone marrow transplantation for acute myeloid leukemia

Idiopathic Pneumonitis Syndrome After Total Body Irradiation in Pediatric Patients Undergoing Myeloablative Hematopoietic Stem Cell Transplantation: A PENTEC Comprehensive Review

PURPOSE

Pulmonary complications, especially idiopathic pneumonitis syndrome (IPS), are potentially life altering or fatal sequelae of hematopoietic cell transplantation (HCT). Total body irradiation (TBI) as part of the conditioning regimen has been implicated in IPS. A comprehensive PENTEC (Pediatric Normal Tissues in the Clinic) review was performed to increase our understanding of the role of TBI in the development of acute, noninfectious IPS.

METHODS AND MATERIALS

A systematic literature search was conducted using the MEDLINE, PubMed, and Cochrane library databases for articles describing pulmonary toxicity in children treated with HCT. Data pertaining to TBI and pulmonary endpoints were extracted. Risk of IPS was analyzed in relation to patient age, TBI dose, fractionation, dose rate, lung shielding, timing, and type of transplant, with the goal to better understand factors associated with this complication in children undergoing HCT. A logistic regression model was developed using a subset of studies with comparable transplant regimens and sufficient TBI data.

RESULTS

Six studies met criteria for modeling of the correlation of TBI parameters with IPS; all consisted of pediatric patients undergoing allogeneic HCT with a cyclophosphamide-based chemotherapy regimen. IPS was variably defined, but all studies that reported IPS were included in this analysis. The mean incidence of post-HCT IPS was 16% (range, 4%-41%). Mortality from IPS, when it occurred, was high (median, 50%; range, 45%-100%). Fractionated TBI prescription doses encompassed a narrow range of 9 to 14 Gy. Many differing TBI methods were reported, and there was an absence of 3-dimensional dose analysis of lung blocking techniques. Thus, a univariate correlation between IPS and total TBI dose, dose fractionation, dose rate, or TBI technique could not be made. However, a model, built from these studies based on prescribed dose using a normalized dose parameter of equivalent dose in 2-Gy fractions (EQD2), adjusted for dose rate, suggested correlation with the development of IPS (P = .0004). The model-predicted odds ratio for IPS was 24.3 Gy-1 (95% confidence interval, 7.0-84.3). Use of TBI lung dose metrics (eg, midlung point dose) could not be successfully modeled, potentially because of dosimetric uncertainties in the actual delivered volumetric lung dose and imperfections in our modeling process.

CONCLUSIONS

This PENTEC report is a comprehensive review of IPS in pediatric patients receiving fractionated TBI regimens for allogenic HCT. IPS was not clearly associated with 1 single TBI factor. Modeling using dose-rate adjusted EQD2 showed a response with IPS for allogeneic HCT using a cyclophosphamide-based chemotherapy regimen. Therefore, this model suggests IPS mitigation strategies can focus on not just the dose and dose per fraction but also the dose rate used in TBI. More data are needed to confirm this model and to determine the influence of chemotherapy regimens and contribution from graft-versus-host disease. The presence of confounding variables (eg, systemic chemotherapies) that affect risk, the narrow range of fractionated TBI doses found in the literature, and limitations of other reported data (eg, lung point dose) may have prevented a more straightforward link between IPS and total dose from being observed.

Global research trends in Total Body Irradiation: a bibliometric analysis

Objectives

This manuscript presents a bibliometric and visualization analysis of Total Body Irradiation (TBI) research, aiming to elucidate trends, gaps, and future directions in the field. This study aims to provide a comprehensive overview of the global research landscape of TBI, highlighting its key contributions, evolving trends, and potential areas for future exploration.

Methods

The data for this study were extracted from the Web of Science Core Collection (WoSCC), encompassing articles published up to May 2023. The analysis included original studies, abstracts, and review articles focusing on TBI-related research. Bibliometric indicators such as total publications (TP), total citations (TC), and citations per publication (C/P) were utilized to assess the research output and impact. Visualization tools such as VOS Viewer were employed for thematic mapping and to illustrate international collaboration networks.

Results

The analysis revealed a substantial body of literature, with 7,315 articles published by 2,650 institutions involving, 13,979 authors. Full-length articles were predominant, highlighting their central role in the dissemination of TBI research. The authorship pattern indicated a diverse range of scholarly influences, with both established and emerging researchers contributing significantly. The USA led in global contributions, with significant international collaborations observed. Recent research trends have focused on refining TBI treatment techniques, investigating long-term patient effects, and advancing dosimetry and biomarker studies for radiation exposure assessments.

Conclusions

TBI research exhibits a dynamic and multifaceted landscape, driven by global collaboration and innovation. It highlights the clinical challenges of TBI, such as its adverse effects and the need for tailored treatments in pediatric cases. Crucially, the study also acknowledges the fundamental science underpinning TBI, including its effects on inflammatory and apoptotic pathways, DNA damage, and the varied sensitivity of cells and tissues. This dual focus enhances our understanding of TBI, guiding future research toward innovative solutions and comprehensive care.

Acute Toxicity of Total Body Irradiation Using Volumetric Arc Therapy With a Focus on the Effect of Lung Dose Rate

Purpose

To report adverse effects of high dose total body irradiation (TBI) delivered using a volumetric arc therapy (VMAT) technique and to assess pulmonary toxicity at dose rates of 40 and 100 monitor units per minute (MU/min).

Methods and Materials

This retrospective study included patients >18 years old who received ≥8 Gy TBI using a VMAT technique. The TBI dose was prescribed to a planning target volume consisting of a 0.5 cm retraction of the body with the lungs subtracted. The objective function specified planning target volume coverage goals of D100% ≥ 90% and Dmax <130%. A lung dose control structure consisting of a 1 cm retraction of the lung volume was limited to Dmean <75%. Treatments were initially delivered with a dose rate of 40 MU/min for the thoracic isocenters and 100 MU/min for the other isocenters. Beginning in January 2021, a dose rate of 100 MU/min was used for all isocenters. All treatments were administered in 2 Gy fractions delivered twice daily. Acute toxicity was assessed for 30 days after TBI.

Results

A total of 29 patients were included in this analysis who received TBI between January 2019 and October 2021. Prescription dose ranged from 8 to 12 Gy. Mean lung dose was 7.9 Gy (SD, 1.4 Gy) for patients treated at 40 MU/min and for patients treated at 100 MU/min 7.1 Gy (SD, 1.3 Gy). Mucositis was the most common grade 3 toxicity and occurred in 10 (34%) patients. Only 1 instance of pneumonitis was observed and occurred in a patient who received a mean lung dose of 10.1 Gy delivered at 40 MU/min.

Conclusions

In this cohort of patients who received high dose TBI using a VMAT technique, the composite rate of acute toxicity was not unexpectedly high. We did not observe an increase in lung toxicity after increasing the dose rate of the thoracic isocenters from 40 MU/min to 100 MU/min.

Long-Term Survival of Patients with Mantle Cell Lymphoma after Total Body Irradiation, High-Dose Chemotherapy and Stem Cell Transplantation: A Monocenter Study

INTRODUCTION

In patients with mantle cell lymphoma (MCL), long-term remissions can be achieved by stem cell transplantation (SCT). Different conditioning treatment protocols exist with or without total body irradiation (TBI). There are few data published on the role of TBI before autologous stem cell transplantation (autoSCT) or allogenic stem cell transplantation (alloSCT). We report on the long-term survival data of patients treated by TBI prior to autologous or allogenic SCT at our center.

PATIENTS

In a retrospective analysis, the data of patients treated at the University Hospital of Muenster from May 2004 to February 2015 were collected and evaluated. For the analysis, all data of patients who were histopathologically diagnosed with MCL and underwent TBI prior to stem cell transplantation (SCT) were evaluated.

RESULTS

A total of 22 patients (19 men and 3 women) were treated with a TBI-based conditioning prior to SCT. The median age at initial diagnosis was 57.5 years (38-65 years). Seventeen patients had Ann Arbor stage IV, two patients had Ann Arbor stage III, and three patients Ann Arbor stage II disease. AutoSCT was performed in 19 patients and alloSCT was performed in 3 patients. In 18 patients, autoSCT was applied as part of first-line therapy, and in one patient after relapse. Two patients received alloSCT after relapse of MCL, and one patient received alloSCT during first-line therapy after an inadequate treatment response. TBI was performed in 12 patients with 10 Gy and in 6 patients with 12 Gy, these patients subsequently received autoSCT. In the group of four patients who received TBI with four Gy, four patients subsequently received alloSCT and one patient received autoSCT. Median overall survival after autoSCT and previous TBI was 11.4 years (142 months). In total, 11 out of 19 patients treated with autoSCT lived longer than 6.8 years (82-202 months). After alloSCT and previous TBI, the median overall survival was 3.25 years (14-59 months).

CONCLUSIONS

A large proportion of patients with advanced MCL survived remarkably longer than 11.4 years after high-dose chemotherapy, TBI, and SCT. The present results of multimodal treatment support the published reports that TBI-based high-dose therapy followed by autoSCT is highly effective in this prognostically unfavorable disease situation.

Impact of respiratory motion on lung dose during total marrow irradiation

We evaluated the impact of respiratory motion on the lung dose during linac-based intensity-modulated total marrow irradiation (IMTMI) using two different approaches: (1) measurement of doses within the lungs of an anthropomorphic phantom using thermoluminescent detectors (TLDs) and (2) treatment delivery measurements using ArcCHECK where gamma passing rates (GPRs) and the mean lung doses were calculated and compared with and without motion. In the first approach, respiratory motions were simulated using a programmable motion platform by using typical published peak-to-peak motion amplitudes of 5, 8, and 12 mm in the craniocaudal (CC) direction, denoted here as M1, M2, and M3, respectively, with 2 mm in both anteroposterior (AP) and lateral (LAT) directions. TLDs were placed in five selected locations in the lungs of a RANDO phantom. Average TLD measurements obtained with motion were normalized to those obtained with static phantom delivery. The mean dose ratios were 1.01 (0.98–1.03), 1.04 (1.01–1.09), and 1.08 (1.04–1.12) for respiratory motions M1, M2, and M3, respectively. To determine the impact of directional respiratory motion, we repeated the experiment with 5-, 8-, and 12-mm motion in the CC direction only. The differences in average TLD doses were less than 1% when compared with the M1, M2, and M3 motions indicating a minimal impact from CC motion on lung dose during IMTMI. In the second experimental approach, we evaluated extreme respiratory motion 15 mm excursion in only the CC direction. We placed an ArcCHECK device on a commercial motion platform and delivered the clinical IMTMI plans of five patients. We compared, with and without motion, the dose volume histograms (DVHs) and mean lung dose calculated with the ArcCHECK-3DVH tool as well as GPR with 3%, 5%, and 10% dose agreements and a 3-mm constant distance to agreement (DTA). GPR differed by 11.1 ± 2.1%, 3.8 ± 1.5%, and 0.1 ± 0.2% with dose agreement criteria of 3%, 5%, and 10%, respectively. This indicates that respiratory motion impacts dose distribution in small and isolated parts of the lungs. More importantly, the impact of respiratory motion on the mean lung dose, a critical indicator for toxicity in IMTMI, was not statistically significant (p > 0.05) based on the Student’s t-test. We conclude that most patients treated with IMTMI will have negligible dose uncertainty due to respiratory motion. This is particularly reassuring as lung toxicity is the main concern for future IMTMI dose escalation studies.

Total marrow irradiation (TMI): Addressing an unmet need in hematopoietic cell transplantation - a single institution experience review

Purpose

TMI utilizes IMRT to deliver organ sparing targeted radiotherapy in patients undergoing hematopoietic cell transplantation (HCT). TMI addresses an unmet need, specifically patients with refractory or relapsed (R/R) hematologic malignancies who have poor outcomes with standard HCT regimens and where attempts to improve outcomes by adding or dose escalating TBI are not possible due to increased toxicities. Over 500 patients have received TMI at this center. This review summarizes this experience including planning and delivery, clinical results, and future directions.

Methods

Patients were treated on prospective allogeneic HCT trials using helical tomographic or VMAT IMRT delivery. Target structures included the bone/marrow only (TMI), or the addition of lymph nodes, and spleen (total marrow and lymphoid irradiation, TMLI). Total dose ranged from 12 to 20 Gy at 1.5-2.0 Gy fractions twice daily.

Results

Trials demonstrate engraftment in all patients and a low incidence of radiation related toxicities and extramedullary relapses. In R/R acute leukemia TMLI 20 Gy, etoposide, and cyclophosphamide (Cy) results in a 1-year non-relapse mortality (NRM) rate of 6% and 2-year overall survival (OS) of 48%; TMLI 12 Gy added to fludarabine (flu) and melphalan (mel) in older patients (≥ 60 years old) results in a NRM rate of 33% comparable to flu/mel alone, and 5-year OS of 42%; and TMLI 20 Gy/flu/Cy and post-transplant Cy (PTCy) in haplo-identical HCT results in a 2-year NRM rate of 13% and 1-year OS of 83%. In AML in complete remission, TMLI 20 Gy and PTCy results in 2-year NRM, OS, and GVHD free/relapse-free survival (GRFS) rates of 0%, 86·7%, and 59.3%, respectively.

Conclusion

TMI/TMLI shows significant promise, low NRM rates, the ability to offer myeloablative radiation containing regimens to older patients, the ability to dose escalate, and response and survival rates that compare favorably to published results. Collaboration between radiation oncology and hematology is key to successful implementation. TMI/TMLI represents a paradigm shift from TBI towards novel strategies to integrate a safer and more effective target-specific radiation therapy into HCT conditioning beyond what is possible with TBI and will help expand and redefine the role of radiotherapy in HCT.

The impact of different optimization strategies on the agreement between planned and delivered doses during volumetric modulated arc therapy for total marrow irradiation

Aim of the study

To evaluate the agreement between planned and delivered doses and its potential correlation with the plans' complexity subjected to dosimetric verification.

Material and methods

Four isocentre volumetric modulated arc therapy for total marrow irradiation plans optimized simultaneously with (P1) and without (P2) MU reduction were evaluated dosimetrically by γ method performed in a global mode for 4 combinations of γ-index criteria (2%/2 mm, 2%/3 mm, 3%/2 mm, and 3%/3 mm). The evaluation was conducted for 4 regions (head and neck, chest, abdomen and upper pelvis, and lower pelvis and thighs) that were determined geometrically by the isocentres. The Wilcoxon test was used to detect significant differences between γ passing rate (GPR) analysis results for the P1 and P2 plans. The Pearson correlation was used to check the relationship between GPR and the plans' complexity.

Results

Except for the head and neck region, the P2 plans had better GPRs than the P1 plans. Only for hard combinations of γ-index criteria (i.e. 2%/3 mm, 2%/2 mm) were the GPRs differences between P1 and P2 clinically meaningful, and they were detected in the chest, abdomen and upper pelvis, and lower pelvis and thighs regions. The highest correlations between GPR and the indices describing the plans' complexity were found for the chest region. No correlation was found for the head and neck region.

Conclusions

The P2 plans showed better agreement between planned and delivered doses compared to the P1 plans. The GPR and the plans' complexity depend on the anatomy region and are most important for the chest region.

Leaf open time sinogram (LOTS): a novel approach for patient specific quality assurance of total marrow irradiation

There is no ideal detector-phantom combination to perform patient specific quality assurance (PSQA) for Total Marrow (TMI) and Lymphoid (TMLI) Irradiation plan. In this study, 3D dose reconstruction using mega voltage computed tomography detectors measured Leaf Open Time Sinogram (LOTS) was investigated for PSQA of TMI/TMLI patients in helical tomotherapy. The feasibility of this method was first validated for ten non-TMI/TMLI patients, by comparing reconstructed dose with (a) ion-chamber (IC) and helical detector array (ArcCheck) measurement and (b) planned dose distribution using 3Dγ analysis for 3%@3mm and dose to 98% (D_98%) and 2% (D_2%) of PTVs. Same comparison was extended for ten treatment plans from five TMI/TMLI patients. In all non-TMI/TMLI patients, reconstructed absolute dose was within ± 1.80% of planned and IC measurement. The planned dose distribution agreed with reconstructed and ArcCheck measured dose with mean (SD) 3Dγ of 98.70% (1.57%) and 2Dγ of 99.48% (0.81%). The deviation in D_98% and D_2% were within 1.71% and 4.10% respectively. In all 25 measurement locations from TMI/TMLI patients, planned and IC measured absolute dose agreed within ± 1.20%. Although sectorial fluence verification using ArcCHECK measurement for PTVs chest from the five upper body TMI/TMLI plans showed mean ± SD 2Dγ of 97.82% ± 1.27%, the reconstruction method resulted poor mean (SD) 3Dγ of 92.00% (± 5.83%), 64.80% (± 28.28%), 69.20% (± 30.46%), 60.80% (± 19.37%) and 73.2% (± 20.36%) for PTVs brain, chest, torso, limb and upper body respectively. The corresponding deviation in median D_98% and D_2% of all PTVs were < 3.80% and 9.50%. Re-optimization of all upper body TMI/TMLI plans with new pitch and modulation factor of 0.3 and 3 leads significant improvement with 3Dγ of 100% for all PTVs and median D_98% and D_2% < 1.6%. LOTS based PSQA for TMI/TMLI is accurate, robust and efficient. A field width, pitch and modulation factor of 5 cm, 0.3 and 3 for upper body TMI/TMLI plan is suggested for better dosimetric outcome and PSQA results.

Dose-escalated volumetric modulated arc therapy for total marrow irradiation: A feasibility dosimetric study with 4DCT planning and simultaneous integrated boost

PURPOSE

To evaluate the planning feasibility of dose-escalated total marrow irradiation (TMI) with simultaneous integrated boost (SIB) to the active bone marrow (ABM) using volumetric modulated arc therapy (VMAT), and to assess the impact of using planning organs at risk (OAR) volumes (PRV) accounting for breathing motion in the optimization.

METHODS

Five patients underwent whole-body CT and thoraco-abdominal 4DCT. A planning target volume (PTV) including all bones and ABM was contoured on each whole-body CT. PRV of selected OAR (liver, heart, kidneys, lungs, spleen, stomach) were determined with 4DCT. Planning consisted of 9-10 full 6 MV photon VMAT arcs. Four plans were created for each patient with 12 Gy prescribed to the PTV, with or without an additional 4 Gy SIB to the ABM. Planning dose constraints were set on the OAR or on the PRV. Planning objective was a PTV D_mean < 110% of the prescribed dose, a PTV V_110% < 50%, and OAR D_mean ≤ 50-60%.

RESULTS

PTV D_mean < 110% was accomplished for most plans (n = 18/20), while all achieved V_110%<50%. SIB plans succeeded to optimally cover the boost volume (median ABM D_mean = 16.3 Gy) and resulted in similar OAR sparing compared to plans without SIB (median OAR D_mean = 40-54% of the ABM prescribed dose). No statistically significant differences between plans optimized with constraints on OAR or PRV were found.

CONCLUSIONS

Adding a 4 Gy SIB to the ABM for TMI is feasible with VMAT technique, and results in OAR sparing similar to plans without SIB. Setting dose constraints on PRV does not impair PTV dosimetric parameters.

Evaluation of three VMAT-TMI planning methods to find an appropriate balance between plan complexity and the resulting dose distribution

PURPOSE

Evaluation of different planning methods of treatment plan preparation for volumetric modulated arc therapy during total marrow irradiation (VMAT-TMI).

METHOD

Three different planning methods were evaluated to establish the most appropriate VMAT-TMI technique, based on organ at risk (OAR) dose reduction, conformity and plan simplicity. The methods were: (M1) the sub-plan method, (M2) use of eight arcs optimised simultaneously and (M3) M2 with monitor unit reduction. Friedman ANOVA comparison, with Nemenyi's procedures, was used in the statistical analysis of the results.

RESULTS

The dosimetric results obtained for the planning target volume and for most OARs do not differ statistically between methods. The M3 method was characterized by the lowest numbers of monitor units (3259 MU vs. 4450 MU for M1 and 4216 MU for M2) and, in general, the lowest complexity. The variability of the monitor units from control points was almost half for M3 than M1 and M2 (i.e. 0.33 MU vs. 0.61 MU for M1 and 0.58 for M2). Analysing the relationship between the dose distributions obtained for the plans and their complexity, the best result was observed for the M3 method.

CONCLUSION

The use of eight simultaneously optimised arcs with MU reduction allows to obtain VMAT-TMI plans that are characterized by the lowest complexity, with dose distributions comparable to the plans generated by other methods.

Image-guided total-body irradiation with a movable electronic portal imaging device for bone marrow transplant conditioning

INTRODUCTION

To prevent radiation pneumonitis following total body irradiation (TBI) clinicians usually use lung shield blocks. The correct position of these shields relative to the patient's lungs is usually verified via mega-voltage imaging and computed radiographic (CR) films. In order to improve this time-consuming procedure, we developed in our department a dedicated, movable, real-time imaging system for image-guided TBI.

MATERIAL & METHODS

The system consists of an electronic portal imaging device (EPID) mounted on a dedicated support whose motion along a rail can be controlled from the linac console outside the bunker room. Images are acquired online using a stand-alone console. To test the system efficacy we retrospectively analyzed data of lung blocks positioning from two groups of 10 patients imaged with EPID or CR-films, respectively.

RESULTS

The median number of portal images per fraction was 2 (range 1-5) and 1 (range 1-2) for the EPID and the CR-film system, respectively. The minimum time required for an EPID image acquisition, without interpretation and no need of patient position correction in the bunker, was 20seconds against 214seconds for the CR-film. Lung shielding positioning in the right-left and superior-inferior directions was improved using the EPID system (p<0.01).

CONCLUSIONS

Compared to CR-films, our movable real-time imaging EPID system is a simple technical solution able to reduce the minimum imaging time for lung shielding by a factor of 10. With the increased possibility to acquire more images as compared to CR-film system the EPID system has the potential to improve patient alignment, as well as patient's comfort and overall setup time.

Total marrow irradiation for hematopoietic malignancies using volumetric modulated arc therapy: A review of treatment planning studies

Total Marrow Irradiation (TMI) has been introduced in the management of hematopoietic malignancies with the aim of reducing toxicities induced by total body irradiation. TMI is one of the most challenging planning and delivery techniques of radiotherapy, as the whole skeleton should be irradiated, while sparing nearby organs at risk (OARs). Target volumes of 7–10 k cm³ and healthy tissue volumes of 50–90 k cm³ should be considered and inverse treatment planning is needed. This review focused on aspects of TMI delivery using volumetric modulated arc therapy (VMAT). In particular, multiple arcs from isocenters with different positions are required for VMAT-TMI as the cranial-caudal lengths of patients are much larger than the jaw aperture. Therefore, many field junctions between arcs with different isocenters should be managed. This review covered, in particular, feasibility studies for managing multiple isocenters, optimization of plan parameters, plan optimization of the lower extremities, robustness of field junctions and dosimetric plan verification of VMAT-TMI. This review demonstrated the possibility of VMAT in delivering TMI with multi-arcs and multi-isocenters. Care should be paid in the patient repositioning, with particular attention to the cranial-caudal direction.

Energy-dependent OAR sparing and dose conformity for total marrow irradiation of obese patients

Purpose

To investigate the effect on target coverage and organs at risk sparing by using 10 versus 6 MV for VMAT total marrow irradiation of obese patients.

Methods and Materials

Twenty‐six total marrow irradiation, TMI, treatment plans delivered between December 2014 and June 2017 were reviewed and 10 were chosen for replanning based on patient characteristics and plan metrics. Beam geometry and isocenter placement were conserved, energy was changed from 6 to 10 MV and plans were reoptimized. Resulting dose distributions were compared to original plans to evaluate any potential advantage of choosing one energy over the other.

Results

Target coverage and total monitor units were consistent between the 6 and 10 MV plans when averaged over all ten patients. Improvement in the conformity index (−11.0%, P = 0.009) when using 10 MV was statistically significant compared to the 6 MV plans. Volumes of normal tissue receiving 50%, 75%, and 90% Rx all decreased for the 10 MV plans compared to the original 6 MV plans. The mean dose to individual OARs decreased significantly for all investigated structures except for the lenses, oral cavity, and genitalia. The largest decreases in D_mean were found for the rectum (22.4%, P = 0.004) and bladder (18.1%, P = 0.005). The three highest priorities for sparing during plan optimization (lungs, liver, and heart), showed decreases of 7.6%, 16.1%, and 13.0%.

Conclusions

Use of a higher energy 10 MV beam provided similar dose to target while achieving increased OAR and normal tissue sparing for the patients reviewed in this study.

Comparison of target volume and clinical effects of four radiotherapy plans for acute lymphoblastic leukemia prior to hematopoietic stem cell transplantation

The present study aimed to investigate the variations in target volume, clinical reaction and transplantation effects of helical tomotherapy (HT)-total body irradiation (TBI), HT-total marrow and lymphatic irradiation (TMLI), intensity modulated radiotherapy (IMRT)-TBI and IMRT-TMLI within patients with acute lymphoblastic leukemia (ALL). A total of 18 patients with ALL were treated with the four aforementioned radiotherapy plans prior to hematopoietic stem cell transplantation. A planned prescribed dose of 12 Gy/6 Frequency was administered to determine planning target volume (PTV). Dosimetry evaluation indexes in PTV and organs at risk were analyzed. Comparison of clinical untoward effects and the results of transplantation among the four plans were performed. The conformity index of HT plans was significantly increased compared with those in IMRT plans. The mean dose (D) to the lung and volume ratio of target volume occupied by 5 Gy (V₅) in TMLI plans were lower compared with TBI plans. Doses to organs were controlled within the normal range. D_max, D_mean and V₅ of bilateral lungs and D_max and D_mean of bilateral crystalline lens in IMRT plans were significantly higher compared with HT plans. There were no significant differences in untoward effects among the four plans. Subsequent to symptomatic treatments with antiemetic, antidiarrheal and fluid infusion, untoward effects improved, and all patients demonstrated tolerance to these therapies. A total of six patients treated with HT-TBI revealed complete and successful transplantation; however, one patient following transplantation suffered from severe rejection and had succumbed to mortality due to severe infection. Patients treated with HT-TMLI, IMRT-TBI and IMRT-TMLI completed successful transplantation and no rejection responses were observed. Conformity of HT plans are higher than that of IMRT plans. The four radiotherapy plans exhibit similar clinical untoward effects and the same transplantation success rate. HT-TMLI is more feasible in dosimetry compared with HT-TBI, IMRT-TBI and IMRT-TMLI, which require further long-term observation.

Total body irradiation in allogeneic bone marrow transplantation conditioning regimens: A review

Hematologic malignancies may require, at one point during their treatment, allogeneic bone marrow transplantation. Total body irradiation combined with chemotherapy or radiomimetic used in allogeneic bone marrow transplantation is known to be very toxic. Total body irradiation (TBI) induces immunosuppression to prevent the rejection of donor marrow. TBI is also used to eradicate malignant cells and is in sanctuary organs that are not reached by chemotherapy drugs. TBI has evolved since its introduction in the late fifties, but acute and late toxicities remain. Helical tomotherapy, which is widely used for some solid tumors, is a path for the improvement of outcomes and toxicities in TBI because of its sparing capacities. In this article, we first review the practical aspects of TBI with patient positioning, radiobiological considerations and total dose and fractionation prescriptions. Second, we review the use of intensity modulated radiation therapy in bone marrow transplantation with a focus on helical tomotherapy TBI, helical tomotherapy total marrow irradiation (TMI) and total marrow and lymphoid irradiation (TMLI) and their dosimetric and clinical outcomes. Finally, we review the perspective of dose escalation and the extension to older patients and patients with comorbidity who do not benefit from a standard bone marrow transplantation conditioning regimen.

Similar survival for patients undergoing reduced-intensity total body irradiation (TBI) versus myeloablative TBI as conditioning for allogeneic transplant in acute leukemia

PURPOSE

Hematopoietic stem cell transplantation (HSCT) is the mainstay of treatment for adults with acute leukemia. Total body irradiation (TBI) remains an important part of the conditioning regimen for HCST. For those patients unable to tolerate myeloablative TBI (mTBI), reduced intensity TBI (riTBI) is commonly used. In this study we compared outcomes of patients undergoing mTBI with those of patients undergoing riTBI in our institution.

METHODS AND MATERIALS

We performed a retrospective review of all patients with acute leukemia who underwent TBI-based conditioning, using a prospectively acquired database of HSCT patients treated at our institution. Patient data including details of the transplantation procedure, disease status, Karnofsky performance status (KPS), response rates, toxicity, survival time, and time to progression were extracted. Patient outcomes for various radiation therapy regimens were examined. Descriptive statistical analysis was performed.

RESULTS

Between June 1985 and July 2012, 226 patients with acute leukemia underwent TBI as conditioning for HSCT. Of those patients, 180 had full radiation therapy data available; 83 had acute lymphoblastic leukemia and 94 had acute myelogenous leukemia; 45 patients received riTBI, and 135 received mTBI. Median overall survival (OS) was 13.7 months. Median relapse-free survival (RFS) for all patients was 10.2 months. Controlling for age, sex, KPS, disease status, and diagnosis, there were no significant differences in OS or RFS between patients who underwent riTBI and those who underwent mTBI (P=.402, P=.499, respectively). Median length of hospital stay was shorter for patients who received riTBI than for those who received mTBI (16 days vs 23 days, respectively; P<.001), and intensive care unit admissions were less frequent following riTBI than mTBI (2.22% vs 12.69%, respectively, P=.043). Nonrelapse survival rates were also similar (P=.186).

CONCLUSIONS

No differences in OS or RFS were seen between all patients undergoing riTBI and those undergoing mTBI, despite older age and potential increased comorbidity of riTBI patients. riTBI regimens were associated with shorter length of hospital stay, fewer intensive care unit admissions, and similar rates of nonrelapse survival, which may reflect reduced toxicity. Prospective trials comparing riTBI and mTBI are warranted.

Suberoylanilide hydroxamic acid induces hypersensitivity to radiation therapy in acute myelogenous leukemia cells expressing constitutively active FLT3 mutants

Histone deacetylase inhibitors (HDIs) have shown promise as candidate radiosensitizer for many types of cancers. However, the mechanisms of action are not well understood, and whether they could have clinical impact on radiotherapy for leukemia is unclear. In this study, we demonstrate that suberoylanilide hydroxamic acid (SAHA) can increase radiosensitivity of acute myeloid leukemia (AML) cells through posttranslational modification of Rad51 protein responses and selective inhibition of the homology-directed repair (HDR) pathway. Our data also showed that AML cells with mutant, constitutively active FMS-like tyrosine kinase-3 (FLT3) were more radiation sensitive, caused by compromised non-homologous end joining (NHEJ) repair. Furthermore, SAHA-induced radiosensitization were enhanced in AML cells with expression of these FLT3 mutants. The results of this study suggest that SAHA, a recently approved HDI in clinical trials, may act as a candidate component for novel conditioning regimens to improve efficacy for AML patients undergoing radiotherapy and chemotherapy.

Late effects of total body irradiation and hematopoietic stem cell transplant in children under 3 years of age

BACKGROUND

Total body irradiation (TBI) is an important component of hematopoietic stem cell transplant (SCT) for pediatric malignancies. With increasing survival rates, late effects of SCT become more important. Younger children may be at particular risk of late effects of radiation and SCT.

METHODS

We retrospectively reviewed outcomes of children less than 3 years of age who received TBI as part of their preparative regimen for SCT at Children's Hospital Colorado. Clinical information including the date of last follow-up, most recent lab values, and physiologic tests were extracted from the medical record.

RESULTS

Of 81 patients who underwent SCT, 19 received TBI and of those, 15 were long-term survivors available for review. Late effects occurring in greater than 50% of the children included abnormalities involving endocrine, metabolic, renal, cataracts, and neurocognitive systems. Other organs involved less commonly included liver, skeletal, and cardiac abnormalities. Solid tumors were a rare finding with only one patient developing a benign osteochondroma and no identified secondary malignancies.

CONCLUSIONS

TBI has been shown to be an important part of the preparative regimen for patients undergoing SCT. Our results, similar to other studies, suggest TBI in patients less than 3 years of age will likely result in multi-organ dysfunction including endocrine, metabolic, renal, eye, and neurocognitive abnormalities. A longitudinal study with standardized testing of these systems would further clarify the late effects concerns in this patient population.

Preclinical assessment of volumetric modulated arc therapy for total marrow irradiation

PURPOSE

A preclinical investigation was undertaken to explore a treatment technique for total marrow irradiation using RapidArc, a volumetric modulated arc technique.

MATERIALS AND METHODS

Computed tomography datasets of 5 patients were included. Plans with eight overlapping coaxial arcs were optimized for 6-MV photon beams. Dose prescription was 12 Gy in 2 Gy per fraction, normalized so that 100% isodose covered 85% of the planning target volume (PTV). The PTV consisted of the whole skeleton (including ribs and sternum), from the top of the skull to the medium distal third of the femurs. Planning objectives for organs at risk (OARs) were constrained to a median dose <6 to 7 Gy. OARs included brain, eyes, oral cavity, parotids, thyroid, lungs, heart, kidneys, liver, spleen, stomach, abdominal cavity, bladder, rectum, and genitals. Pretreatment quality assurance consisted of portal dosimetry comparisons, scoring the delivery to calculation agreement with the gamma agreement index.

RESULTS

The median total body volume in the study was 57 liters (range, 49-81 liters), for an average diameter of 47 cm (range, 46-53 cm) and a total length ranging from 95 to 112 cm. The median PTV volume was 6.8 liters (range, 5.8-10.8 liters). The mean dose to PTV was 109% (range, 107-112%). The global mean of median dose to all OARs was 4.9 Gy (range, 4.5-5.1 Gy over the 5 patients). The individual mean of median doses per organ ranged from 2.3 Gy (oral cavity) to 7.3 Gy (bowels cavity). Preclinical quality assurance resulted in a mean gamma agreement index of 94.3 ± 5.1%. The delivery time measured from quality assurance runs was 13 minutes.

CONCLUSION

Sparing of normal tissues with adequate coverage of skeletal bones was shown to be feasible with RapidArc. Pretreatment quality assurance measurements confirmed the technical agreement between expected and actually delivered dose distributions, suggesting the possibility of incorporating this technique in the treatment options for patients.

[Total body irradiation: present and future]

Total body irradiation (TBI) has an established role as preparative regimen for bone-marrow transplantation in the treatment of hematological malignancies. Many randomized trials demonstrated that the clinical outcomes obtained from the association of TBI and cyclophosphamide are equivalent, or, sometimes, better than those based on chemotherapeutic agents. Despite the therapeutic progress of the last years, and the consequent improvement in the overall survival, this preparative regimen remains always associated with a relatively high rate of acute and late toxicity. In this article, we review the actual indications of TBI in clinical practice, and analyze the technological progress in this domain. We focus on the hypothesis that a selective irradiation of the hematopoietic or lymphoid organs is actually possible with intensity-modulated radiotherapy. Technical limits and preliminary results in terms of acute and late toxicities of intensity-modulated TBI are analyzed. With these new technologies, treatment-related toxicity is not anymore a major limiting factor in the preparative regimens for bone-marrow transplantation, allowing for a larger spectrum of TBI indications, a possible extension to patients older than 50 years, or a dose escalation. Preliminary results warrant, however, further evaluation in clinical trials to better assess the impact of this new approach on disease control and the long-term toxicity.

TBI with lung dose reduction does not improve hematopoietic cell homing to BM during allogeneic transplantation

Purpose

To determine the effects of total body irradiation (TBI) dose, fractionation, and lung shielding on hematopoietic stem cell homing to the bone marrow.

Material and Methods

Bone marrow (BM) cells were extracted from tibiae and femurs of B6-GFP mice and were transplanted into B6 mice. Recipient mice had either: 1) no radiation, 2) single dose TBI at 13.6 Gray (Gy), 3) single dose TBI at 13.6 Gy with reduced lung exposure to 0.4 Gy by shielding, 4) split dose TBI at 12 Gy to twice/day over four days, or 5) split dose TBI at 12 Gy to twice/day over four days with reduced lung exposure to 0.36 Gy by shielding. The last radiation exposure preceded tail vein injection by 4–6 hours. Mice were sacrificed after 18 hours.

Results

Homing of GFP positive, lineage negative cells was not significantly improved in any irradiated group compared to control. Homing of GFP positive, lineage negative, Kit positive cells was significantly worse in all irradiated groups.

Conclusion

TBI does not improve the homing of lineage negative donor BM cells to the recipient marrow. Homing of lineage negative, Kit positive donor BM cells was significantly worse following TBI, with or without lung dose reduction.

Image-guided total-marrow irradiation using helical tomotherapy in patients with multiple myeloma and acute leukemia undergoing hematopoietic cell transplantation

PURPOSE

Total-body irradiation (TBI) has an important role in patients undergoing hematopoietic cell transplantation (HCT), but is associated with significant toxicities. Targeted TBI using helical tomotherapy results in reduced doses to normal organs, which predicts for reduced toxicities compared with standard TBI.

METHODS AND MATERIALS

Thirteen patients with multiple myeloma were treated in an autologous tandem transplantation Phase I trial with high-dose melphalan, followed 6 weeks later by total-marrow irradiation (TMI) to skeletal bone. Dose levels were 10, 12, 14, and 16 Gy at 2 Gy daily/twice daily. In a separate allogeneic HCT trial, 8 patients (5 with acute myelogenous leukemia, 1 with acute lymphoblastic leukemia, 1 with non-Hodgkin's lymphoma, and 1 with multiple myeloma) were treated with TMI plus total lymphoid irradiation plus splenic radiotherapy to 12 Gy (1.5 Gy twice daily) combined with fludarabine/melphalan.

RESULTS

For the 13 patients in the tandem autologous HCT trial, median age was 54 years (range, 42-66 years). Median organ doses were 15-65% that of the gross target volume dose. Primarily Grades 1-2 acute toxicities were observed. Six patients reported no vomiting; 9 patients, no mucositis; 6 patients, no fatigue; and 8 patients, no diarrhea. For the 8 patients in the allogeneic HCT trial, median age was 52 years (range, 24-61 years). Grades 2-3 nausea, vomiting, mucositis, and diarrhea were observed. In both trials, no Grade 4 nonhematologic toxicity was observed, and all patients underwent successful engraftment.

CONCLUSIONS

This study shows that TMI using helical tomotherapy is clinically feasible. The reduced acute toxicities observed compare favorably with those seen with standard TBI. Initial results are encouraging and warrant further evaluation as a method to dose escalate with acceptable toxicity or to offer TBI-containing regimens to patients unable to tolerate standard approaches.

Total body irradiation and pneumonitis risk: a review of outcomes

A review was undertaken of all patients treated at Royal Adelaide Hospital, South Australia with total body irradiation (TBI) for the purpose of assessing the incidence of interstitial pneumonitis (IP) and possible prognostic factors for its development. The aim was also to assess the impact of IP and other prognostic factors on long-term survival outcome following bone marrow transplantation. A total of 84 patients received TBI, with 12 Gy in six fractions delivered using two different instantaneous dose rates of 7.5 and 15 cGy min⁻¹. This series included 26 cases of acute lymphoblastic leukaemia, 26 of multiple myeloma and 15 of acute myelogenous leukaemia. On multivariate analysis, a higher dose rate was independently significant for an increased risk of IP.

New approaches to hematopoietic cell transplantation in oncology

The use of high-dose chemotherapy followed by autologous HCT and the use of allogeneic HCT in children and adolescents with high-risk ALL, AML, and NBL has successfully improved outcomes. For other diseases, however, the role of HCT in treatment remains a subject of further research. The availability of HCT was significantly expanded by developing alternative graft sources that currently include BM, peripheral blood, and UCB from autologous and allogeneic related or unrelated donors. Progress in autologous HCT has been achieved by the identification of more effective and less toxic preparative regimens and by ex vivo purging of stem cell products. In allogeneic HCT, graft-versus-leukemia or graft-versus-tumor effects are being exploited increasingly to lower relapse rates. In addition, immunomodulation to promote tolerance, as well as allogeneic antitumor reactions have been achieved by antibody therapy, cytokine therapy, or cell-based immunotherapy. Future improvements are likely, as evidenced by promising preliminary results in the development of stem cell collection techniques, in vitro stem cell expansion, and purging techniques of stem cell grafts. The development of less intensive or nonmyeloablative preparative regimens may further reduce regimen-related morbidity and mortality Specific immunotherapy may facilitate tolerance induction in mismatched allogeneic HCT and support allogeneic HCT in the setting of donor-host HLA disparity. Ultimately, advances in cytokine therapy, tumor-specific vaccines, and gene therapy may decrease or even eradicate recurrence of the malignant disease after HCT.

Comparison of outcome following allogeneic bone marrow transplantation with cyclophosphamide-total body irradiation versus busulphan-cyclophosphamide conditioning regimens for acute myelogenous leukaemia in first remission

We evaluated transplant-related mortality (TRM), leukaemia relapse, leukaemia-free survival (LFS) and overall survival (OS) in patients receiving busulphan and cyclophosphamide (BuCy) or cyclophosphamide and total body irradiation (CyTBI) prior to allogeneic bone marrow transplantation (BMT) for acute myelogenous leukaemia (AML) in first remission. Outcomes of 381 human leucocyte antigen (HLA)-matched sibling transplants using BuCy were compared with 200 transplants using CyTBI performed between 1988 and 1996. The incidence of hepatic veno-occlusive disease was higher with BuCy (13%) than with CyTBI (6%) (P = 0.009). Risks of acute and chronic GVHD were similar. In multivariate analysis, relapse risk was higher in the BuCy group [relative risk (RR) = 1.72; 95% confidence interval (CI), 1.05-2.81; P = 0.031]. Eleven of 373 evaluable patients in the BuCy group had a central nervous system relapse in contrast to none of 194 evaluable patients in the CyTBI group (P = 0.016). There were no differences in TRM, LFS and OS. CyTBI conditioning may lower relapse risk but produces comparable TRM, LFS and OS to BuCy for HLA-matched sibling transplantation in first remission AML.

Renal toxicity after total body irradiation

PURPOSE

To evaluate the incidence of renal dysfunction after total body irradiation (TBI).

METHODS AND MATERIALS

Between 1990 and 1997, 64 patients (median age 50 years) received TBI as part of the conditioning regimen before bone marrow transplantation (BMT). Five patients with abnormal renal function at the beginning of treatment or with incomplete data were excluded. All patients received a total of 12 Gy (6 fractions twice daily for 3 consecutive days) prescribed to the peak lung dose (corrected for lung transmission) at a dose rate of 7.5 cGy/min. Renal shielding was not used. Renal dysfunction was assessed on the basis of the serum creatinine levels measured at the start and end of TBI and at 6, 12, 18, and 24 months after completion of BMT. Cox proportional hazard analysis was used to evaluate the various factors known to affect renal function.

RESULTS

Only 4 patients had elevated serum creatinine levels at 12 months and subsequently only 2 of the 33 surviving patients had persistent elevated renal serum creatinine levels 24 months after BMT. A fifth patient developed proteinuria and mildly elevated serum creatinine levels at 2.5 years. In 2 patients, the elevation coincided with disease relapse and normalized once remission was achieved. In the third patient, the elevation in serum creatinine levels coincided with relapse of multiple myeloma and the presence of Bence-Jones proteinuria. The fourth patient was the only patient who developed chronic renal failure secondary to radiation nephritis at 2 years. The etiology of the fifth patient's rise in creatinine was unknown, but may have been secondary to radiation nephritis. On univariate analysis, but not on multivariate analysis, a significant correlation was found between TBI-related renal dysfunction and hypertension before and after BMT.

CONCLUSION

A dose of 12 Gy at 2 Gy/fraction resulted in only 1 case of radiation nephritis in the 59 patients studied 24 months after the completion of TBI and BMT.

Allogeneic bone marrow transplantation for chronic myeloid leukemia: a retrospective study of busulfan-cytoxan versus total body irradiation-cytoxan as preparative regimen in Koreans

From January 1990 to December 1997, 53 Korean patients with chronic myeloid leukemia (CML) receiving bone marrow transplantation (BMT) from human leucocyte antigen (HLA)-identical sibling donors conditioned with either busulfan and cyclophosphamide (BU/CY regimen) or total body irradiation and cyclophosphamide (TBI/CY regimen) were compared retrospectively. Transplantation-related mortality was 19% in BU/CY and 12% in TBI/CY, and early death (<100 d) occurred in 3 patients conditioned with BU/CY. Grade II-IV acute graft-versus-host disease (GVHD) was 9% of BU/CY and 52% of TBI/CY patients. Overall incidence of chronic GVHD was 50% of BU/CY and 52% of TBI/CY patients. In patients with chronic phase, 5-yr overall survival was 73% in the BU/CY group compared with 87% in the TBI/CY group (p=NS), and overall disease-free survival was 75% in the BU/CY group and 59% in the TBI/CY group (p=NS). So far, with a median follow-up of 45 months, 11 patients have relapsed; three relapses occurred after BU/CY and 8 after TBI/CY. The actuarial 5-yr relapse rate was 15% after BU/CY, 34% after TBI/CY (p=0.46). For patients transplanted in chronic phase within 1 yr after diagnosis, there was a clear trend for a lower relapse rate in the BU/CY group (5-yr relapse rate 0%) compared with the TBI/CY group (5-yr relapse rate 30%). The BU/CY group had similar BMT-related toxicity and similar overall survival and showed a clear trend of low relapse compared with the TBI/CY group. Therefore, BU/CY is an acceptable alternative for patients with CML during HLA-identical sibling allogeneic BMT.

In vitro tumor-pulsed or in vivo Flt3 ligand-generated dendritic cells provide protection against acute myelogenous leukemia in nontransplanted or syngeneic bone marrow-transplanted mice

To determine whether immune stimulation could reduce acute myelogenous leukemia (AML) lethality, dendritic cells (DCs) were pulsed with AML antigens and used as vaccines or generated in vivo by Flt3 ligand (Flt3L), a potent stimulator of DC and natural killer (NK) cell generation. Mice were then challenged with AML cells. The total number of splenic anti-AML cytotoxic T-lymphocyte precursors (CTLPs) present at the time of challenge was increased 1.9-fold and 16.4-fold by Flt3L or DC tumor vaccines, respectively. As compared with the 0% survival of controls, 63% or more of recipients of pulsed DCs or Flt3L survived long term. Mice given AML cells prior to DC vaccines or Flt3L had only a slight survival advantage versus non-treated controls. NK cells or NK cells and T cells were found to be involved in the antitumor responses of Flt3L or DCs, respectively. DC vaccines lead to long-term memory responses but Flt3L does not. Syngeneic bone marrow transplantation (BMT) recipients were analyzed beginning 2 months post-BMT. In contrast to the uniform lethality in BMT controls given AML cells, recipients of either Flt3L or DC vaccines had a significant increase in survival. The total number of splenic anti-AML CTLPs at the time of AML challenge in BMT controls was 40% of concurrently analyzed non-BMT controls. Flt3L or DC vaccines increased the total anti-AML CTLPs 1.4-fold and 6.8-fold, respectively. Neither approach was successful when initiated after AML challenge. It was concluded that DC vaccines and Flt3L administration can enhance an AML response in non-transplanted or syngeneic BMT mice but only when initiated prior to AML progression.

Idiopathic pneumonia syndrome following myeloablative chemotherapy and autologous transplantation

OBJECTIVE

To report the outcome as well as the clinical, radiographic, and pathologic features of idiopathic pneumonia syndrome (IPS) following autologous peripheral blood stem cell transplantation (aPBSCT).

CLINICAL FINDINGS

A total of 271 patients with a variety of underlying malignancies received busulfan-containing myeloablative chemotherapy prior to aPBSCT; none of these patients received total body irradiation. Ten individuals developed IPS, with a median time of onset of 102 days after stem cell infusion. The major clinical and radiographic findings included an acute or subacute onset of dyspnea, cough, hypoxemia, and bilateral or unilateral infiltrates with or without pleural effusion. Pathologic findings consisted mainly of diffuse interstitial pneumonitis, organizing alveolitis, and cellular atypia. Nine patients diagnosed with IPS were treated with high doses of glucocorticoids parenterally. Despite heroic measures, eight patients died of IPS. The two remaining individuals recovered without experiencing significant long-term pulmonary sequelae.

DISCUSSION

Chronic low-dose busulfan therapy results in lung injury in 4-6% of patients after several years of treatment and once the cumulative dosage begins to approach 3g. High-dose, short-course busulfan (16 mg/kg)-containing conditioning chemotherapy prior to aPBSCT can also be complicated by IPS. IPS differs from lung damage due to chronic busulfan therapy by its earlier onset, an acute or subacute rather than indolent presentation, characteristic clinical and radiographic features, and lack of multinucleated giant cells on pathologic review. The pathophysiology of IPS secondary to high-dose busulfan-containing myeloablative regimens is not known, but cell-mediated immune reactions and release of cytokines may contribute to the lung injury. Mortality is high (80%) despite the use of heroic measures, including mechanical ventilation. Some patients, however, can respond to high doses of parenteral corticosteroid therapy.

CONCLUSIONS

IPS following high-dose, short-course busulfan-containing regimens exhibits unique clinical, radiographic, and pathologic features that differ from lung damage characteristic of chronic, low-dose busulfan therapy. Mortality from this complication is 80%, but some patients survive without long-term pulmonary sequelae following early treatment with glucocorticoids.

Is there a best transplant conditioning regimen for acute myeloid leukemia?

The outcome of marrow transplantation is largely determined by the effectiveness of the transplant preparative regimen. Nonetheless, there have been startlingly few randomized trials attempting to identify optimal regimens for specific conditions and, at present, no single approach has emerged as superior for the treatment of acute myeloid leukemia (AML) in the few trials that have been performed. Newer approaches that appear encouraging in phase II studies include substituting etoposide for cyclophosphamide, adding thiotepa to the traditional cyclophosphamide plus total body irradiation combination in the setting of T cell depletion, and using antibody-based targeted radiotherapy as part of the transplant regimen. The ability to obtain allogeneic engraftment with nonablative regimens may open the door to additional innovative approaches, combining very specific antileukemia therapy with relatively nontoxic measures to ensure engraftment.

Comparison of preparative regimens in transplants for children with acute lymphoblastic leukemia

PURPOSE

Preparative regimens involving total-body irradiation (TBI) produce significant late toxicities in some children who receive bone marrow transplants, including impaired growth and intellectual development. Busulfan is often used as an alternative to TBI, but there are few data regarding its relative efficacy.

PATIENTS AND METHODS

We compared outcomes of HLA-identical sibling transplants for acute lymphoblastic leukemia (ALL) in children (< 20 years of age) who received cyclophosphamide plus TBI (CY/TBI) (n = 451) versus those who received busulfan plus cyclophosphamide (Bu/CY) (n = 176) for pretransplant conditioning. Patients received transplants between 1988 and 1995 and their results were reported to the International Bone Marrow Transplant Registry by 144 participating institutions. The CY/TBI and Bu/CY groups did not differ in gender, immune phenotype, leukocyte count at the time of diagnosis, chromosome abnormalities, remission status, or length of initial remission. T-cell depletion was used more frequently in the CY/TBI group; the Bu/CY group included a higher proportion of children who were less than 5 years of age. The median follow-up period was 37 months.

RESULTS

The 3-year probabilities of survival were 55% (95% confidence interval [CI], 50% to 60%) with TBI/CY and 40% (95% CI, 32% to 48%) with Bu/CY (univariate P =.003). The 3-year probabilities of leukemia-free survival were 50% (95% CI, 45% to 55%) and 35% (95% CI, 28% to 43%), respectively (univariate P =.005). In a multivariate analysis, the risks of relapse were similar in the two groups (relative risk [RR], 1.30 for Bu/CY v CY/TBI; P =.1). Treatment-related mortality was higher in the Bu/CY group (RR, 1.68; P =.012). Death and treatment failure (relapse or death, inverse of leukemia-free survival) were more frequent in the Bu/CY group (RR, 1. 39; P =.017 for death; RR, 1.42; P =.006 for treatment failure).

CONCLUSION

These data indicate superior survival with CY/TBI conditioning, compared with Bu/CY conditioning, for HLA-identical sibling bone marrow transplants in children with ALL.

Cataract incidence after total-body irradiation

PURPOSE

The aim of this retrospective study was to evaluate cataract incidence in a homogeneously-treated group of patients after total-body irradiation (TBI) followed by autologous bone marrow transplantation or peripheral blood stem cell transplantation.

METHODS AND MATERIALS

Between 1982 and 1994, a total of 260 patients received either autologous bone marrow or blood stem cell transplantation for hematological malignancy at the University of Heidelberg. Two hundred nine of these patients received TBI in our hospital. Radiotherapy was applied as hyperfractionated TBI, with a median dose of 14.4 Gy in 12 fractions over 4 days. Minimum time between fractions was 4 h. Photons with an energy of 23 MeV were used with a dose rate of 7-18 cGy/min. Ninety-six of the 209 irradiated patients were still alive in 1996; 86 of these patients (52 men, 33 women) answered a questionnaire and could be examined ophthalmologically. The median age at time of TBI was 38.5 years, with a range of 15-59 years.

RESULTS

The median follow-up is now 5.8 years, with a range of 1.7-13 years. Cataract occurred in 28/85 patients (32.9%) after a median of 47 months (1-104 months). In 6 of 28 patients who developed a cataract, surgery of the cataract was performed. Whole-brain irradiation prior to TBI had been performed more often in the group of patients developing cataract (14.3%) versus 10.7% in the group of patients without cataract. However, there was no statistical difference (Chi-square, p>0.05).

CONCLUSION

Cataract is a common side effect of TBI. Cataract incidence found in our patients is comparable to results of other centers using a fractionated regimen for TBI. To assess the incidence of cataract after TBI, a long-term follow-up is required.

Autologous bone marrow transplantation in acute leukemia

Autologous bone marrow transplantation can induce long-term LFS in 20% to 40% of patients with relapsed acute leukemia and should be considered as salvage therapy for patients who lack an HLA-matched donor and for patients over 45. Adult ALL patients and children with ALL in extramedullary relapse beyond second CR should receive alloBMT if at all possible. The role of ABMT in acute leukemia patients in first CR remains unclear despite randomized trials (Table 2). Because protocol deviations, early relapse, and inappropriately high treatment-related mortality unequally affected the ABMT cohort, and because recent randomized trials have used old purging methodologies, it is not possible to conclude that ABMT is not beneficial. More recent studies show that most patients are able to proceed with the intended ABMT and that modern purging may be associated with a treatment-related mortality rate of less then 5%. Immunomodulation and graft engineering uniquely suited to autologous progenitor cells indicate that ABMT should continue to be studied in the management of acute leukemia.

Low-dose total body irradiation and G-CSF without hematopoietic stem cell support in the treatment of relapsed or refractory acute myelogenous leukemia (AML), or AML in second or subsequent remission

PURPOSE

Patients with relapsed acute myelogenous leukemia (AML), who are not eligible for bone marrow transplantation, have a poor prognosis when treated with chemotherapy alone. Total body irradiation (TBI) is an effective modality against AML when used in doses of 1000-1400 cGy with hematopoietic stem cell support. We undertook a phase I study of TBI with granulocyte-colony-stimulating factor (G-CSF) support, without stem cell support in patients with AML either in relapse or second or subsequent remission.

METHODS AND MATERIALS

Patients with relapsed AML, or AML in second or subsequent remission were treated in a phase I study of TBI followed by G-CSF. The first dose level was 200 cGy. After the initial cohort of patients it was clear that patients with overt leukemia did not benefit from this treatment, and subsequent patients were required to be in remission at the time of TBI.

RESULTS

Eleven patients were treated, 4 in overt relapse, and 7 in remission. 200 cGy was used in all, and dose escalation was not possible due to prolonged thrombocytopenia in all patients but one. Neutrophil recovery was adequate in those patients who remained in remission after TBI. Patients with overt leukemia had transient reduction in blast counts, but rapid recurrence of their leukemia. Patients treated in remission had short remissions, with the exception of one patient who is in remission 32 months after treatment.

CONCLUSION

There is some antileukemic effect of TBI even at 200 cGy, though this dose appears to be too low to help a significant number of patients. If TBI is to be escalated without stem cell support, then a thrombopoietic agent will need to be used.

Total body irradiation for marrow or stem-cell transplantation

Although the best TBI-containing regimen may not yet have been found, data suggest that for greatest leukemic cell kill with minimum morbidity, a highly fractionated TBI regimen (10-13 fractions) to a high total dose (14-15 Gy) may be optimum. Bu-Cy may be able to replace TBI for CML, but results reported in the literature are still of an early nature. The addition of boost radiation has proven useful for treatment of the testes in leukemia patients, the spleen in some CML patients, and probably of the IF for lymphoma patients with residual or refractory disease. In the future, newer techniques, such as radiolabeled antibodies for better targeting of tumor cells, may prove useful and enter the therapeutic armamentarium (58).

Lethal pulmonary toxicity after autologous bone marrow transplantation/peripheral blood stem cell transplantation for hematological malignancies

BACKGROUND AND PURPOSE

Retrospective evaluation of the incidence of lethal pulmonary complications (LPC) with special emphasis on interstitial pneumonia (IP) in a large group of patients homogeneously treated with hyperfractionated total body irradiation (HTBI) before autologous bone marrow transplantation (ABMT) or peripheral blood stem cell transplantation (PBSCT) for hematological malignancy. The factors influencing IP are discussed.

MATERIALS AND METHODS

Of 260 patients (maximum follow-up 137 months) that were treated with ABMT or PBSCT for hematological neoplasms between 1982 and 1994, 209 patients received HTBI and could be evaluated with respect to lethal pulmonary complications and especially lethal interstitial pneumonia. For most patients (n = 155), the HTBI dose was 14.4 Gy (lung dose 9-9.5 Gy) given in 12 fractions over 4 days. Twenty-one patients received a total dose of > or =15 Gy with pulmonary doses of 9-10.5 Gy.

RESULTS

The actuarial overall 5-year survival for all 209 patients evaluated was 44 +/- 4%, enabling valid evaluation with respect to lethal pulmonary toxicity. The actuarial incidence of all LPC during the first year was calculated as being 8 +/- 2%. The actuarial incidence of lethal IP is certainly lower and was estimated to be between 3 and 5% for all patients. The overall treatment-related mortality was 12% in 188 patients that received a total dose of <15 Gy and 24% among the patients treated with a total dose of > or =15 Gy.

CONCLUSION

ABMT/PBSCT, like other transplant modalities without significant graft versus host disease (GvHD), has a low transplant-related mortality, a very small rate of overall LPC and a low incidence of lethal IP after HTBI. Doses up to 14.4 Gy with lung doses of 9-9.5 Gy can be administered safely. For total doses of > or =15 Gy with lung doses of 9-10.5 Gy, the risk of serious transplant-related complications cannot yet be finally assessed but such higher doses should be considered with caution because of the possibility of increasing toxicity in organs other than the lung.

[Total body irradiation: current indications]

The choice of dose and fractionation for total body irradiation is made difficult by the large number of considerations to be taken into account. The outcome of bone marrow transplantation after total body irradiation can be understood in terms of tumour cell killing, engraftment, and normal tissue damage, each of these endpoints being influenced by irradiation-, disease-, transplant-, and patient-related factors. Interpretation of clinical data is further hampered by the overwhelming influence of logistic constraints, the small numbers of randomised studies, and the concomitant variations in total dose and fraction size or dose rate. So far, three cautious conclusions can be drawn in order to tentatively adapt the total body irradiation schedule to clinically-relevant situations. Firstly, the organs at risk for normal tissue damage (lung, liver, lens, kidney) are protected by delivering small doses per fraction at low dose rate. This suggests that, when toxicity is at stake (e.g., in children), fractionated irradiation should be preferred, provided that interfraction intervals are long enough. Secondly, fractionated irradiation should be avoided in case of T-cell depleted transplant, given the high risk of graft rejection in this setting. An alternative would be to increase total (or fractional) dose of fractionated total body irradiation, but this approach is likely to induce more normal tissue toxicity. Thirdly, clinical data have shown higher relapse rates in chronic myeloid leukaemia after fractionated or low dose rate total body irradiation, suggesting that fractionated irradiation should not be recommended, unless total (or fractional) dose is increased. Total body irradiation-containing regimens, primarily cyclophosphamide/total body irradiation, are either equivalent to or better than the chemotherapy-only regimens, primarily busulfan/cyclophosphamide. Busulfan/cyclophosphamide certainly represents a reasonable alternative, especially in patients who may not be eligible for total body irradiation because of prior irradiation to critical organs.

High-energy total body irradiation as preparation for bone marrow transplantation in leukemia patients: treatment technique and related complications

PURPOSE

Bone marrow transplantation with conditioning regimens that include total-body irradiation (TBI) is widely used in patients with acute lymphoblastic and acute myelocytic leukemias. The major causes of death in this population are relapse of leukemia, infection, and treatment related complications. Our purpose was to achieve a homogenous radiation dose distribution and to minimize the dose to the lungs, liver, and kidneys so that the incidence of organ injury was reduced.

METHODS AND MATERIALS

Dose to the bone marrow, midplane, and periphery was quantified by use of thermoluminescent detectors in a bone-equivalent tissue phantom. In an effort to reduce the risk of complications, we treated relapsed or refractory leukemia patients with TBI administered in fractionated, parallel opposed large fields with 24 MV photons, using tissue compensation and partial-transmission lung shielding. Tissue toxicities were then determined.

RESULTS

Dose quantitation in bone-equivalent and tissue-equivalent phantoms demonstrated that backscatter and pair production interactions adjacent to bone increased the bone marrow dose by 6 to 11%. At an SSD of 400 cm and at patient diameters of 20 to 40 cm, the percent inhomogeneity across the phantom with 24 MV photons was 0 to 0.3%, compared to 4 to 6% for 6 MV photons. End-organ toxicities consisted of clinical interstitial pneumonitis in six patients, idiopathic interstitial pneumonitis in three patients, renal toxicity in seven patients, and veno-occlusive disease of the liver in one patient. Toxicities did not correlate with fractionation schedule.

CONCLUSIONS

Total-body irradiation administered with 24 MV photons increases the dose deposition in bone marrow through pair production and backscatter interactions occurring in bone. Because percent depth dose increases with SSD, the 24 MV beam is more penetrating at a 400 cm distance than at 100 cm and dose homogeneity is improved with higher energies. Thus, the incidence of radiation-mediated injury to lung, liver, and kidney is reduced. This is an effective preparatory regimen for patients with high-risk leukemias requiring bone marrow transplantation.

The critical early proinflammatory events associated with idiopathic pneumonia syndrome in irradiated murine allogeneic recipients are due to donor T cell infusion and potentiated by cyclophosphamide

We have hypothesized that lung damage occurring in the peri-bone marrow transplant (BMT) period is critical for the subsequent generation of idiopathic pneumonia syndrome (IPS), a major complication following human BMT. The proinflammatory events induced by a common pre-BMT conditioning regimen, cyclophosphamide (Cytoxan(R)) (Cy) and total body irradiation, were analyzed in a murine BMT model. Electron microscopy indicated that Cy exacerbated irradiation-induced epithelial cell injury as early as day 3 after BMT. Allogenicity was an important contributing factor to lung injury as measured by lung wet and dry weights and decreased specific lung compliance. The most significant pulmonary dysfunction was seen in mice receiving both allogeneic T cells and Cy conditioning. IPS was associated with an influx of T cells, macrophages, and neutrophils early post-BMT. Hydroxyproline levels were not increased, indicating that the injury was not fibrotic early post-BMT. As early as 2 h after chemoradiation, host macrophages increased in number in the lung parenchyma. Continued increases in macrophages occurred if splenic T cells were administered with the donor graft. The expression of costimulatory B7 molecules correlated with macrophage numbers. Frequencies of cells expressing mRNA for the inflammatory proteins TNF-alpha, IL-1beta, and TGFbeta were increased. Cy accelerated the upregulation of TGFbeta and increase in host macrophages. The exacerbation of macrophage activation and severity of IPS was dependent on allogeneic T cells, implicating immune-mediated mechanisms as critical to the outcome of IPS. This demonstration of early injury after BMT indicates the need for very early therapeutic intervention before lung damage becomes profound and irreversible.

The Role of B7 Costimulation by Murine Acute Myeloid Leukemia in the Generation and Function of a CD8+ T-Cell Line With Potent In Vivo Graft-Versus-Leukemia Properties

Relapse is more frequent after autologous than allogeneic bone marrow transplantation (BMT), due in part to lack of T-lymphocyte mediated allogeneic graft-versus-leukemia (GVL) effects. Infusions of leukemia-reactive T cells to patients after autologous BMT may be a means for providing a GVL effect. Costimulation of T cells by binding of the CD28 receptor on T cells with B7-counter receptors on antigen presenting cells amplifies antigen-specific T-cell responses. To enhance generation of leukemia reactive cytotoxic T lymphocytes (CTL), the murine B7-1– and B7-2–costimulatory molecule cDNAs were introduced into the MHC class I+, class II−, murine meyloid leukemia cell line C1498. B7-1 expression greatly enhanced the ability of the leukemia cells to generate and expand leukemia reactive CTL in vitro. A highly cytolytic and C1498 specific CD8+ CTL line was generated by B7-1 costimulation. This CTL line proliferated autonomously and produced interleukin-2 when provided B7-1 or B7-2 costimulation by C1498 leukemia cells. To test the in vivo antileukemia properties of this CTL line, irradiated syngeneic BMT recipients were given graded doses of leukemia cells on day 0, followed by CTL infusions beginning on day 1 post-BMT. Recipients of 107 CTL had a 3 log reduction in leukemia burden such that 100% of mice were protected from a supralethal leukemic cell dose. Sustained immune responses were detectable up to 3 months postinfusion of the CTL line. B7-1 or B7-2 costimulation in vivo did not augment antileukemia effects of infused CTL post BMT. These results suggest that B7 costimulation of leukemia reactive CTL may be important for their ex vivo generation and expansion for use in human adoptive immunotherapy of leukemia.

Autologous bone marrow transplantation in acute myeloid leukemia: the University of Minnesota experience

PURPOSE

To report the outcome of autologous bone marrow transplantation for patients with acute myeloid leukemia (AML) in first or greater complete remission (CR) treated by autologous bone marrow transplantation using two different preparatory regimens.

METHODS AND MATERIALS

Between September 1986 and August 1993, 75 patients with AML ranging in age from 6 months to 58 years underwent autologous bone marrow transplantation using previously harvested and frozen unpurged (n = 6) or 4-hydroperoxycyclophosphamide purged marrows (n = 69). Patients were in first CR (n = 44) or beyond first CR (n = 31). The preparative regimen consisted of 120 mg/kg of cyclophosphamide (CY) and 1320 cGy total body irradiation (TBI) in eight fractions over 4 days (CY/TBI) in 29 patients; and 16 mg/kg of Busulfan (BU) and 200 mg/kg of CY (BU/CY) in 46 patients. Thirty-five of these 75 patients (18 CY/TBI and 17 BU/CY) were part of a randomized trial comparing the two preparative regimens.

RESULTS

At 2 years, overall survival and disease-free survival (DFS) were 49% [95% confidence interval (C.I.) 37-61%] and 43% (95% C.I. 32-55%), respectively. Patients in first CR had a significantly better outcome than patients beyond first CR with an estimated 2-year DFS of 59% (95% C.I. 44-74%) vs. 21% (95% C.I. 5-36%, log-rank p = 0.0001), respectively. For patients conditioned with CY/TBI, the estimated 2-year DFS was 52% compared to 39% for BU/CY (log-rank p = 0.35). Estimated 2-year relapse rates were 44% vs. 56% (log-rank p = 0.40), respectively. For patients in first CR, no differences in DFS were observed between the two regimens (2-year estimates 69% vs. 55% log-rank p = 0.52). Patients beyond first CR had a significantly improved DFS with the CY/TBI regimen (2-year estimates of 38% vs. 7%, log-rank p = 0.04). No differences were found between the two regimens in terms of time to WBC engraftment, absolute neutrophil count of > 500, incidence of bacteremias, or median time to hospital discharge. Interstitial pneumonitis developed in two patients (one BU/CY, one CY/TBI) and venoocclusive disease developed in seven BU/CY patients (Fishers exact test p = 0.04).

CONCLUSIONS

For patients beyond first CR, the CY/TBI regiment provided a better outcome, with a significantly better disease-free survival and less venoocclusive disease. For patients in first CR, no significant difference between the two regimens was found. The high relapse rate, especially for patients with advanced disease, emphasizes the need for early transplantation and for new strategies to improve outcome.

Efficacy and toxicity of radiation in preparative regimens for pediatric stem cell transplantation. II: Deleterious consequences

There has been a dramatic improvement in the treatment of both allogeneic and autologous stem cell transplants, especially in children and young adults. However, attempts to apply more intensive conditioning treatments to the more refractory pediatric malignancies have also increased the risks of deleterious consequences. This review examines the risks, and reports important variations in the toxic effects of using different conditioning techniques.