Total Marrow Irradiation for Second Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Advanced Acute Leukemia.

Second allogeneic hematopoietic stem cell transplantation (HSCT) is a treatment option for patients with acute leukemia who relapse after a first HSCT. Although myeloablative conditioning (MAC) regimens before the first HSCT are considered superior to reduced- intensity conditioning (RIC) in terms of disease control in acute leukemia patients, the optimal conditioning regimen for the second allogeneic HSCT remains controversial. The most important prognostic factors are the remission disease phase at the time of the second HSCT and an interval >12 months from the first HSCT to the second HSCT. Total marrow irradiation (TMI) is an advanced high-precision radiation treatment that delivers therapeutic doses over extensively selected targets while substantially reducing radiation to vital organs compared to conventional total body irradiation (TBI). Here we report the results of a retrospective analysis of second allogeneic HSCT treated with TMI as an MAC regimen with the intent of limiting toxicity. We investigated the efficacy of high dose per fraction TMI in combination with thiotepa, fludarabine, and melphalan in 13 consecutive patients with acute leukemia who had relapsed after a first allogeneic HSCT treated between March 2018 and November 2021. Donor type was haploidentical in 10 patients, unrelated in 2 patients, and HLA-identical sibling in 1 patient. The conditioning regimen consisted of 8 Gy TMI in 5 patients on days -8 and -7 and 12 Gy TMI in 8 patients on days -9 to -7, plus thiotepa 5 mg/kg on day -6, fludarabine 50 mg/day on days -5 to -3, and melphalan 140 mg/day on day -2. The TMI was delivered at the dosage og 4 GY for 2 consecutive days (total = 8 GY) or for 3 consecutive days (total = 12 GY). The median patient age was 45 years (range, 19 to 70 years); 7 patients were in remission, and 6 had active disease at the time of their second allogeneic HSCT. The median time to a neutrophil count of >.5 × 109/L was 16 days (range, 13 to 22 days), and the median time to a platelet count of >20 × 109/L was 20 days (range, 14 to 34 days). All patients showed complete donor chimerism on day +30 post-transplantation. The cumulative incidence of grade I-II acute graft-versus-host disease (GVHD) was 43%, and that of chronic GVHD was 30%. The median duration of follow-up was 1121 days (range, 200 to 1540 days). Day +30 and +100 transplantation-related mortality (TRM) was 0. The overall cumulative incidence of TRM, relapse rate, and disease free-survival were 27%, 7%, and 67%, respectively. This retrospective study demonstrates the safety and efficacy of a hypofractionated TMI conditioning regimen in patients with acute leukemia undergoing second HSCT with encouraging outcomes in terms of engraftment, early toxicity, GVHD, and relapse.

Where do we stand with radioimmunotherapy for acute myeloid leukemia?

INTRODUCTION: Despite the approval of several new drugs, deaths from acute myeloid leukemia (AML) remain common. Because of well-defined cell surface antigens, easy accessibility, and radiosensitivity of leukemia cells, there is long-standing interest in radiolabeled antibodies (radioimmunotherapy [RIT]) to complement or replace existing treatments and improve outcomes in AML. AREAS COVERED: Targeting primarily CD33, CD45, or CD66, early RIT efforts have focused on ß-emitters, including iodine-131 (131I) and yttrium-90, mostly to intensify conditioning therapy before allogeneic hematopoietic cell transplantation (HCT). An 131I-labeled CD45 antibody (Iomab-B [apamistamab-I131]) is currently studied in the registration-type phase 3 SIERRA trial (NCT02665065) for this purpose. Of growing interest as therapeutic payloads are α-particle emitting radionuclides such as actinium-225 (225Ac) or astatine-211 (211At) since they deliver substantially higher decay energies over a much shorter distance than ß-emitters, rendering them more suitable for precise, potent, and efficient target cell killing while minimizing toxicity to surrounding bystander cells, possibly allowing use outside of HCT. Clinical efforts with 211At-labeled CD45 antibodies and 225Ac-labeled CD33 antibodies (e.g. 225Ac-lintuzumab [Actimab-A]) are ongoing. EXPERT OPINION: A first anti-AML RIT may soon become available. This might propel further work to develop RIT-based treatments for AML, with many such efforts already ongoing.

Are radiation-induced cavernomas clinically relevant findings? Results from long-term follow-up with brain magnetic resonance imaging of childhood cancer survivors.

INTRODUCTION: Radiation-induced cavernomas (RIC) after cranial radiotherapy have an unknown risk of hemorrhage. Zabramski magnetic resonance imaging (MRI) classification is touted as being able to indicate non-radiation-induced cavernomas hemorrhage risk. The aim of our study was to assess the hemorrhage risk of RIC during long-term follow-up of childhood cancer survivors based on brain MRI examinations. PATIENTS AND METHODS: We analyzed retrospectively long-term follow-up data of 36 childhood cancer survivors after initial diagnosis with acute leukemia (n = 18) or brain tumor (n = 18), all treated with cranial radiotherapy. Detected RIC in long-term follow-up brain MRI (1.5 or 3 Tesla) were classified following the Zabramski MRI classification and were categorized into "high" (Zabramski type I, II or V) or "low" (type III or IV) risk of hemorrhage. RESULTS: 18 patients (50%) showed RIC with a significant relation to the original tumor entity (p = 0.023) and the cumulative radiation dose to the brain (p = 0.016): all 9 childhood cancer survivors diagnosed with medulloblastoma developed RIC. We classified RIC in only 3/36 childhood cancer survivors (8%) (1 patient with acute lymphoblastic leukemia [Zabramski type II] and 2 patients with medulloblastoma [type I and type II]) as high risk for hemorrhage, the remaining RIC were classified as Zabramski type IV with low risk for hemorrhage. None of the childhood cancer survivors with RIC showed symptomatic hemorrhages. CONCLUSIONS: RIC are common late effects in childhood cancer survivors treated with cranial radiotherapy affecting half of these patients. However, only a few RIC (occurring in 8% of all reviewed childhood cancer survivors) were classified as high risk for hemorrhage and none of the childhood cancer survivors with RIC developed symptomatic hemorrhages. Thus, we conclude that RIC are low-risk findings in brain MRI and the course is mainly benign.

Therapy-related myeloid neoplasm after peptide receptor radionuclide therapy (PRRT) in 1631 patients from our 20 years of experiences: prognostic parameters and overall survival.

PURPOSE: To determine prognostic factors and overall survival (OS) in therapy-related myeloid neoplasm (t-MN) of patients after receiving peptide receptor radionuclide therapy (PRRT). METHODS: All patients treated from February 1999 until September 2019 at our center who had bone marrow biopsy-proven t-MN after PRRT were included. Patient characteristics, laboratory results, and all tumor-directed therapies before t-MN diagnosis were collected. Cox regression analysis was performed to identify parameters associated with OS. Receiver operating characteristic (ROC) curve analysis was used to define cutoff values as well as sensitivity and specificity of the parameters. RESULTS: Out of 1631 patients treated with PRRT, 30 patients developed t-MN comprising myelodysplastic syndrome (MDS) in 23 patients (77%) and acute myeloid leukemia (AML) in 7 patients (23%). The median OS of t-MN patients was 13 months (range 9.1-16.9 months): 6 months for AML and 15 months for the MDS subgroup, respectively. Higher platelet level was a significant prognostic parameter for longer OS (hazard ratio (HR): 0.99, P < 0.05). Using ROC analysis, the best cutoff value for thrombocyte count was 183.5 Gpt/L, resulting in a sensitivity of 92.3% and a specificity of 50%. Other factors, such as hemoglobin level, did not show a significant correlation with OS. CONCLUSION: Even rarely occurred, the OS is gravely compromised in t-MN patients after PRRT, and even less in the AML subgroup (6 months). Higher platelet value was a significant prognostic parameter for longer OS in t-MN patients.

Towards homogenization of total body irradiation practices in pediatric patients across SIOPE affiliated centers. A survey by the SIOPE radiation oncology working group.

BACKGROUND AND PURPOSE: To reduce relapse risk, Total Body Irradiation (TBI) is part of conditioning regimens for hematopoietic stem cell transplantation (HSCT) in pediatric acute leukemia. The study purpose was to evaluate clinical practices regarding TBI, such as fractionation, organ shielding and delivery techniques, among SIOPE affiliated radiotherapy centers. METHODS: An electronic survey was sent out to 233 SIOPE affiliated centers, containing 57 questions about clinical practice of TBI. Surveys could be answered anonymously. RESULTS: From over 25 countries, 82 responses were collected. For TBI-performing centers, 40/48 irradiated ≤10 pediatric patients annually (range: 1-2 to >25). Most indications concerned acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML). Four different fractionation schedules were used, of which 12 Gy in 6 fractions was applied in 91% for ALL and 86% for AML. Dose reduction to the lungs, mostly to a mean dose of 8-10 Gy, was applied by 28/33 centers for ALL and 19/21 centers for AML, in contrast to much less applied dose reduction to the kidneys (7/33 ALL and 7/21 AML), thyroid (2/33 ALL and 2/21 AML), liver (4/33 ALL and 3/21 AML) and lenses (4/33 ALL and 4/21 AML). Conventional TBI techniques were used by 24/29 responding centers, while 5/29 used advanced optimized planning techniques. CONCLUSION: Across SIOPE, there is a high level of uniformity in fractionation and use of lung shielding. Practices vary regarding other organs-at-risk shielding and implementation of advanced techniques. A SIOPE radiotherapy working group will be established to define international guidelines for pediatric TBI.

Role of radiotherapy and chemotherapy in the risk of leukemia after childhood cancer: An international pooled analysis.

Childhood cancer survivors are at increased risk for second primary leukemia (SPL), but there is little consensus on the magnitude of some risk factors because of the small size of previous studies. We performed a pooled analysis of all published studies with detailed treatment data, including estimated active bone marrow (ABM) dose received during radiation therapy and doses of specific chemotherapeutic agents for childhood cancer diagnosed from 1930 through 2000, in order to more thoroughly investigate treatment-related risks of SPL. A total of 147 SPL cases (of which 69% were acute myeloid leukemia [AML]) were individually matched to 522 controls, all from four case-control studies including patients from six countries (France, United Kingdom, United States, Canada, Italy and Netherlands). Odds ratios (OR) and corresponding 95% confidence intervals (CIs) were calculated using conditional logistic regression, and the excess OR per Gray (EOR/Gy) was also calculated. After accounting for the other therapies received, topoisomerase II inhibitor was associated with an increased SPL risk (highest tertile vs none: OR = 10.0, 95% CI: 3.7-27.3). Radiation dose to the ABM was also associated with increased SPL risk among those not receiving chemotherapy (EOR/Gy = 1.6, 95% CI: 0.1-14.3), but not among those who received chemotherapy (CT). SPL were most likely to occur in the first decade following cancer treatment. Results were similar when analyses were restricted to AML. The evidence of interaction between radiation and CT has implications for leukemogenic mechanism. The results for topoisomerase II inhibitors are particularly important given their increasing use to treat childhood cancer.

Technical note: factors affecting dose distribution in the overlap region of two-segment total body irradiation by helical tomotherapy.

OBJECTIVE: To assess the effects of various treatment planning parameters to identify the optimal gap distance for precise two-segment total body irradiation (TBI) using helical tomotherapy (HT) with fixed jaw mode. METHODS AND MATERIALS: Data of a treatment plan for 8 acute leukemia patients (height range: 109-130 cm) were analyzed. All patients underwent total-body computed tomography (CT) with 5-mm slice thickness. A lead wire, placed at 10 cm above the patella, was used to mark the boundary between the two segments. Target volumes and organs at risk were delineated using a Varian Eclipse 10.0 physician's workstation. Different distances between the lead wire and the boundary of the two targets were used. CT images were transferred to the HT workstation to design the treatment plans, by adjusting parameters, including the field width (FW; 2.5 cm, and 5 cm), pitch (0.287 and 0.430), modulation factor (1.8). The plans were superimposed to analyze the dose distributions in the overlap region when varying target gap distances, FWs, pitches to determine the optimal combinations. RESULTS: The pitch did not affect the dose distribution in the overlap region. The dose distribution in the overlap region was mostly homogeneous when the target gap distance was equal to the FW. Increased FW diminished the effect of the target gap distance on the heterogeneous index of the overlap region. CONCLUSIONS: In two-segment TBI treatments by HT with Helix mode, a gap distance equal to the FW may achieve optimal dose distribution in the overlap region.

Optic neuropathy as the first sign of central nervous system relapse in acute myeloid leukaemia: MRI findings and its diagnostic challenge.

We describe the case of a 22-year-old man who presented with right eye visual impairment and oral mucositis. MRI revealed findings compatible with right optic neuritis. Herpes simplex virus 1 was detected in oral swab. He has a previous history of acute myeloid leukaemia (AML) and was in clinical remission. Initial investigations for possible relapse of AML with central nervous system (CNS) involvement were negative. Treatment for HSV-related optic neuritis was initiated but the patient's vision deteriorated. Repeat MRI revealed right optic nerve infarct, new left optic nerve abnormality and new leptomeningeal enhancement in the brain. Repeated cerebrospinal fluid analysis confirmed CNS relapse of AML. Despite prompt initiation of pulse steroid and high dose intrathecal cytarabine followed by cranial irradiation, the patient never regained his vision. We present a case of unexpected optic neuropathy as first and sole presentation of CNS relapse of AML.

Novel rotatable tabletop for total-body irradiation using a linac-based VMAT technique.

BACKGROUND: Volumetric Modulated Arc Therapy (VMAT) techniques have recently been implemented in clinical practice for total-body irradiation (TBI). To date, most techniques still use special couches, translational tables, or other self-made immobilization devices for dose delivery. Aim of the present study was to report the first results of a newly developed rotatable tabletop designed for VMAT-TBI. METHODS: The VMAT-TBI technique theoretically allows the use of any standard positioning device at the linear accelerator. Nevertheless, the main problem is that patients taller than 120 cm cannot be treated in one position due to the limited cranial-caudal couch shift capacities of the linac. Therefore, patients are usually turned from a head-first supine position (HFS) to a feet-first supine position (FFS) to overcome this limitation. The newly developed rotatable tabletop consists completely of carbon fiber, including the ball bearing within the base plate of the rotation unit. The patient can be turned 180° from a HFS to a FFS position within a few seconds, without the need of repositioning. RESULTS: The first 20 patients had a median age of 47 years, and received TBI before bone marrow transplantation for acute myeloid leukemia. Most patients (13/20) received a TBI dose of 4 Gy in 2 fractions, twice daily. The mean number of applied monitor units (MU) was 6476 MU using a multi-arcs and multi-isocenter VMAT-TBI technique. The tabletop has been successfully used in daily clinical practice and helped to keep the treatment times at an acceptable level. During the first treatment fraction, the mean overall treatment time (OTT) was 57 min. Since no additional image guidance was used in fraction 2 of the same day, the OTT was reduced to mean 38 min. CONCLUSIONS: The easy and reproducible rotation of the patient on the treatment couch using the rotatable tabletop, is time-efficient and overcomes the need of repositioning the patient after turning from a HFS to a FFS position during VMAT TBI. Furthermore, it prevents couch-gantry collisions, incorrect isocenter shifts and beam mix-up due to predicted absolute table coordinates, which are recorded to the R + V system with the corresponding beams.

Total-body irradiation using linac-based volumetric modulated arc therapy: Its clinical accuracy, feasibility and reliability.

PURPOSE: To report the feasibility, accuracy, and reliability of volumetric modulated arc therapy (VMAT)-based total-body irradiation (TBI) treatment in patients with acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL). MATERIALS AND METHODS: From 2015 to 2018, 30 patients with AML or ALL were planned and treated with VMAT-based TBI, which consisted of three isocenters and three overlapping arcs. TBI dose was prescribed to 90% of the planning treatment volume (PTV) receiving 12 Gy in six fractions, at two fractions per day. Mean lung and kidney doses were restricted less than 10 Gy, and maximum lens dose less than 6 Gy. Quality assurance (QA) comprised the verification of the irradiation plans via dose-volume histogram (DVH) based 3D patient QA system. RESULTS: Average mean lung dose was 9.7 ±â€¯0.2 Gy, mean kidney dose 9.6 ±â€¯0.2 Gy, maximum lens dose 4.5 ±â€¯0.4 Gy, mean PTV dose 12.7 ±â€¯0.1 Gy, and heterogeneity index of PTV was 1.16 ±â€¯0.02 in all patients. Grade 3 or more acute radiation toxicity was not observed. When comparing plan and DVH-based 3D patient QA results, average differences of 3.3% ±â€¯1.3 in mean kidney doses, 1.1% ±â€¯0.7 in mean lung doses, and 0.9% ±â€¯0.4 in mean target doses were observed. CONCLUSION: Linac-based VMAT increased the dose homogeneity of TBI treatment more than extended SSD techniques. Partial cone-beam CT and optical surface-guided system assure patient positioning. DVH-based 3D patient dose verification QA was possible with linac-based VMAT showing small differences between planned and delivered doses. It is feasible, accurate, and reliable.

Single-Dose Daily Fractionation Is Not Inferior to Twice-a-Day Fractionated Total-Body Irradiation Before Allogeneic Stem Cell Transplantation for Acute Leukemia: A Useful Practice Simplification Resulting From the SARASIN Study.

PURPOSE: Total-body irradiation (TBI) is a major constituent of myeloablative conditioning regimens. The standard technique consists of 12 Gy in 6 fractions over a period of 3 days. The Standard-fractionation compAred to one-daily fRaction total body irrAdiation prior to tranSplant In LEUkemia patieNts (SARASIN) study aimed to compare standard fractionation with once-daily fractionation before transplant in leukemia. METHODS AND MATERIALS: We retrospectively compared TBI regimens delivered in 2993 patients from the European Society for Blood and Marrow Transplantation database, who underwent transplantation between 2000 and 2014 for acute lymphoblastic leukemia (ALL, n = 1729) or acute myeloid leukemia (AML, n = 1264). TBI was delivered as either 12 Gy in 6 fractions (group 1, considered the reference group; 1362 ALL and 857 AML patients), 9 to 12 Gy in 2 fractions (group 2, 173 ALL and 256 AML patients), or 12 Gy in 3 to 4 fractions (group 3, 194 ALL and 151 AML patients). RESULTS: The median follow-up was 60 and 84 months in ALL and AML patients, respectively. At 5 years, the leukemia-free survival rate, overall survival rate, relapse incidence, and nonrelapse mortality rate were 46.6%, 50.4%, 28.8%, and 24.6%, respectively, in ALL patients and 46.6%, 48.9%, 29.7%, and 23.6%, respectively, in AML patients. In multivariate analyses, the outcomes of groups 2 and 3 were not statistically different from those in group 1. The cumulative incidence of secondary malignancies (SMs) was significantly higher in group 2 (7.2%; P < 10-6 for group 2 vs group 1). However, group 2 was not associated with an increase in SMs when we considered non-T-cell-depleted transplant patients. CONCLUSIONS: We showed that the 12-Gy fractionated TBI dose delivered either in 2 fractions or in 1 fraction per day over a period of 3 to 4 days resulted in nonsignificant differences in disease control and survival. However, 1-day fractionation may be associated with a higher risk of mucositis and hemorrhagic cystitis. The absence of a significant difference in the SM incidence in the non-T-cell-depleted group should be interpreted with caution in the context of a retrospective study design. Our findings are important to consider for radiation therapy department organization. In-depth analyses of other nonlethal toxicities and late effects are required.

Clinical Studies with Bismuth-213 and Actinium-225 for Hematologic Malignancies.

OBJECTIVES: Due to the shorter range and higher linear energy transfer of α-particles compared to ß-particles, targeted α-particle therapy may produce more efficient tumor killing while sparing neighboring healthy cells. We will review the clinical studies using α-particle therapy for Acute Myeloid Leukemia (AML). METHODS: A series of clinical trials were conducted to assess the safety, feasibility, and anti-leukemic effects of lintuzumab, an anti-CD33 humanized monoclonal antibody, labeled with the α-emitters bismuth- 213 (213Bi) and actinium-225 (225Ac). RESULTS: An initial phase I study conducted in 18 patients with relapsed or refractory AML demonstrated the safety and antitumor effects of 213Bi-lintuzumab. Subsequently, 213Bi-lintuzumab produced remissions in AML patients after partial cytoreduction with cytarabine in phase I/II trial. The 46- minute half-life of 213Bi and need for an onsite generator has limited its utility. Therefore, a secondgeneration construct was developed using 225Ac, a radiometal that yields four α-particle emissions. A phase I trial demonstrated that a single infusion of 225Ac-lintuzumab could be given safely at doses up to 111 kBq/kg with anti-leukemic activity across all dose levels studied. In a second phase I study, 28% of older patients with untreated AML had objective responses after receiving fractionated-dose 225Aclintuzumab and low-dose cytarabine. CONCLUSION: Based upon the encouraging results seen in phase I trials of 225Ac-lintuzumab, a phase II study of 225Ac-lintuzumab monotherapy for older patients with untreated AML is now in progress and is also being studied in a subset of patients with CD33-positive multiple myeloma.

Rapid Decrease in KRT14 and TP53 mRNA Expression in the Buccal Mucosa of Patients Receiving Total-Body Irradiation for Allogeneic Stem Cell Transplantation.

The only curative treatment option for relapsed patients with acute myeloid leukemia (AML) is allogeneic stem cell transplantation. Depletion of hematopoietic stem cells and leukemic blast cells is achieved through the systemic administration of DNA damaging agents, including total-body irradiation (TBI) prior to transplantation. Since other tissues are radiosensitive, the identification of biomarkers could facilitate the management of additional toxicities. Buccal keratinocytes are readily accessible and could provide a source of cells for RNA analysis. In this study, we obtained miRNAs and mRNAs from daily buccal swabs collected from patients undergoing allogeneic stem cell transplantation. Unexpectedly, there was no prominent p53-induced mRNA or miRNA response in these samples, despite the fact that the p53 pathway is a well-characterized radiation-inducible response. Instead, the expression of mRNAs encoding p53 and cytokeratin 14 (TP53 and KRT14, respectively) decreased precipitously within hours of the first radiation treatment. These patients went on to develop oral mucositis, however, it is unclear whether TP53 and/or KRT14 expression are predictive of this adverse event. Larger scale analysis of buccal epithelial samples from patients undergoing allogeneic stem cell transplantation appears to be warranted.

Analysis of factors affecting initial cyclosporine level and its impact on post transplant outcomes in acute leukemia.

BACKGROUND: Trough cyclosporine (CsA) blood level can influence incidence of graft-versus-host disease (GVHD) and relapse in patients with acute leukemia undergoing allogeneic hematopoietic stem cell transplant (HSCT). We sought to determine factors affecting initial trough CsA level (CsA-1) and its impact on transplant outcome in acute leukemia. MATERIALS AND METHODS: Seventy-seven patients underwent HSCT for acute leukemia between January 2008 and March 2013 and were included. GVHD prophylaxis included CsA + methotrexate. (MTX) in 53 patients and CsA + mycophenolate mofetil (MMF) in 24 patients CsA-1 was measured on day 3-5 of starting CsA and subsequent dose was modified to achieve therapeutic level of 150-200. ng/mL. According to CsA-1, patients were divided into three groups - 27 in Group A (dose escalated), 13 in Group B (dose de-escalated), and 37 in Group C (same dose continued). RESULTS: On univariate analysis, cyclophosphamide with total-body irradiation (TBI) based conditioning regimen and lower body mass index (BMI) were associated with lower CsA-1, while use of fludarabine and higher BMI were associated with higher CsA-1. On multivariate analysis, only fludarabine use and BMI affected CsA-1. Incidence of acute and chronic GVHD (aGVHD and cGVHD), transplant-related mortality, relapse incidence, and relapse-free and overall survival (OS) were similar in the three groups. CONCLUSION: While fludarabine use in conditioning regimen and higher BMI leads to higher CsA-1, transplant outcomes are not affected by CsA-1.

Urinary miRNAs as Biomarkers for Noninvasive Evaluation of Radiation-Induced Renal Tubular Injury.

Radiation nephropathy is one of the common late effects in cancer survivors who received radiotherapy as well as in victims of radiation accidents. The clinical manifestations of radiation nephropathy occur months after exposure. To date, there are no known early biomarkers to predict the future development of radiation nephropathy. This study focuses on the development of urinary biomarkers providing readout of acute responses in renal tubular epithelial cells. An amplification-free hybridization-based nCounter assay was used to detect changes in mouse urinary miRNAs after irradiation. After a single LD50 of total-body irradiation (TBI) or clinically relevant fractionated doses (2 Gy twice daily for 3 days), changes in urinary levels of microRNAs followed either an early pattern, peaking at 6-8 h postirradiation and gradually declining, or later pattern, peaking from 24 h to 7 days. Of 600 miRNAs compared, 12 urinary miRNAs showed the acute response and seven showed the late response, common to both irradiation protocols. miR-1224 and miR-21 were of particular interest, since they were the most robust acute and late responders, respectively. The early responding miR-1224 also exhibited good dose response after 2, 4, 6 and 8 Gy TBI, indicating its potential use as a biomarker for radiation exposure. In situ hybridization of irradiated mouse kidney sections and cultured mouse primary renal tubular cells confirmed the tubular origin of miR-1224. A significant upregulation in hsa-miR-1224-3p expression was also observed in human proximal renal tubular cells after irradiation. Consistent with mouse urine data, a similar expression pattern of hsa-miR-1224-3p and hsa-miR-21 were observed in urine samples collected from human leukemia patients preconditioned with TBI. This proof-of-concept study shows the potential translational utility of urinary miRNA biomarkers for radiation damage in renal tubules with possible prediction of late effects.

Craniospinal irradiation prior to stem cell transplant for hematologic malignancies with CNS involvement: Effectiveness and toxicity after photon or proton treatment.

PURPOSE/OBJECTIVE(S): Craniospinal irradiation (CSI) improves local control of leukemia/lymphoma with central nervous system (CNS) involvement; however, for adult patients anticipating stem cell transplant (SCT), cumulative treatment toxicity is a major concern. We evaluated toxicities and outcomes for patients receiving proton or photon CSI before SCT. METHODS AND MATERIALS: We identified 37 consecutive leukemia/lymphoma patients with CNS involvement who received CSI before SCT at our institution. Photon versus proton toxicities during CSI, transplant, and through 100 days posttransplant were compared using Fisher exact and Wilcoxon rank sum tests. Long-term neurotoxicity, disease response, and overall survival were analyzed. RESULTS: Thirty-seven patients (23 photon, 14 proton) underwent CSI for CNS involvement of acute lymphoblastic leukemia (49%), acute myeloblastic leukemia (22%), chronic lymphocytic leukemia (3%), chronic myelocytic leukemia (14%), lymphoma (11%), and myeloma (3%). CSI was used for consolidation (30 patients, 81%) and gross disease treatment (7 patients, 19%). Median radiation dose (interquartile range) was 24 Gy (23.4-24) for photons and 21.8 Gy (21.3-23.6) for protons (P = .03). Proton CSI was associated with lower rates of Radiation Therapy Oncology Group grade 1-3 mucositis during CSI (7% vs 44%, P = .03): 1 grade 3 with protons versus 5 grade 1, 3 grade 2, and 2 grade 3 with photons. During CSI, other toxicities (infection, gastrointestinal symptoms) did not differ. Allogeneic stem cell transplant (SCT) was used in 95% of patients, with 53% of patients in remission before SCT. Myeloablative conditioning was used for 76%. During SCT admission and 100 days post-SCT, toxicities did not differ by CSI technique. Successful engraftment occurred in 95% of patients (P = .67). Progression or death occurred for 47% of patients, with only 1 CNS relapse. CONCLUSION: In our cohort, CSI offered excellent local control for CNS-involved hematologic malignancies in the pre-SCT setting. Acute mucositis occurred less frequently with proton CSI with comparable peritransplant/long-term toxicity profile, suggesting the need to further explore the benefit/toxicity profile of this technique.

Ocular manifestation in myeloid/NK cell precursor acute leukemia: a case report. Diagnosed by flow cytometry and PCR from aqueous humor.

BACKGROUND: Myeloid/NK cell precursor acute leukemia (MNKL) is a rare type of leukemia, and ocular complications have not previously been reported. We now report a patient with MNKL who developed intraocular infiltrates during follow-up. METHODS AND RESULTS: A 13-year-old boy diagnosed with MNKL developed left eye pain 3 months after starting treatment. Examination of the left eye revealed a visual acuity of counting fingers at 20 cm, ciliary hyperemia, small corneal keratic precipitates, hypopyon, grade 4 vitreous opacities, and an obscured fundus. The differential diagnosis was between an opportunistic infection associated with immunodeficiency and an intraocular leukemic cell infiltrate. Therefore, a sample of aqueous humor was aspirated. Multiplex PCR/broad-range PCR of the aqueous humor was below detection limits for viruses, bacteria, and fungi. Flow cytometry (FCM) detected NK-related CD56-positive cells, thus leading to a diagnosis of ocular infiltrates due to MNKL. With treatment of the ocular infiltrates by consolidation systemic chemotherapy including intrathecal methotrexate (MTX), there was clearing of the vitreous opacities; and optic disc swelling, retinal hemorrhages, exudates, and protuberant lesions were now seen. With the addition of local radiation therapy to the eye, there was a dramatic treatment response, with regression of the optic disc findings and retinal lesions, and an improved visual acuity of 1.5. CONCLUSION: We encountered the first case of MNKL in which ocular infiltrates developed during follow-up. Multiplex PCR and FCM of the aqueous humor were useful in rapidly distinguishing leukemic cell infiltrates from an opportunistic infection. This case highlights the usefulness of intrathecal MTX and local radiotherapy in treating ocular infiltrates in patients with MNKL.

Gli-1/PI3K/AKT/NF-kB pathway mediates resistance to radiation and is a target for reversion of responses in refractory acute myeloid leukemia cells.

Total body irradiation combined with chemotherapy is currently the most effective procedure as a preparative myeloablative regimen. However, resistance to radiotherapy and chemotherapy in refractory acute myeloid leukemia is associated with short-time recurrence after allogeneic hematopoietic stem cell transplantation. To address this issue, we used three cell lines, HL60, HL60/ADR (adriamycin-resistant cells), and HL60/RX (a radiation-resistant cell line established from HL60 cells), as cellular models to investigate the mechanism of the Hedgehog (Hh) signaling pathway resulting in radioresistance, and the efficacy of LDE225 (an inhibitor of the Hh pathway) to enhance radiation sensitivity. Our results indicated that HL60/RX and HL60/ADR cells showed an increased in radioresistance and elevated activity of Hh pathway proteins compared with HL60 cells (P<0.001). In addition, LDE225 significantly reduced clonogenic survival with a sensitivity enhancement ratio (SER) of 1.283 for HL60/ADR and 1.245 for HL60/RX cells. The combination of LDE225 with irradiation significantly increased radiation-induced apoptosis and expression of γ-H2AX and BAK compared with single-treatment groups in both HL60/RX and HL60/ADR cells (P<0.001). In vivo, the combination of LDE225 with irradiation exerted a significant antitumor effect compared with the control and single agents in HL60/RX- and HL60/ADR-xenografted mouse models (P<0.001). Furthermore, our data obtained from western blot and IHC analyses showed that the activation of pAKT and NF-kB was reduced by LDE225 treatment in both HL60/ADR and HL60/RX cells. This demonstrates that the Gli-1/PI3K/AKT/NF-kB pathway plays a key role in resistance to radiation, and that inhibition of the Hh pathway sensitizes cells to radiation by overcoming radioresistance.

Auger electron-emitting (111)In-DTPA-NLS-CSL360 radioimmunoconjugates are cytotoxic to human acute myeloid leukemia (AML) cells displaying the CD123(+)/CD131(-) phenotype of leukemia stem cells.

Chimeric IgG1 monoclonal antibody CSL360 recognizes the CD123(+)/CD131(-) phenotype expressed by leukemic stem cells (LSC). Auger electron-emitting (111)In-DTPA-NLS-CSL360 radioimmunoconjugates incorporating nuclear translocation sequence (NLS) peptides bound specifically to Raji cells transfected with CD123 and exhibited a KD of 11nmols/L in a competition receptor-binding assay using CD123-transfected CHO cells. (111)In-DTPA-NLS-CSL360 was bound, internalized and transported to the nucleus of human AML-5 myeloid leukemia cells. The clonogenic survival of AML-5 cells was reduced by (111)In-DTPA-NLS-CSL360 up to 3.7-fold. Isotype control (111)In-DTPA-chIgG1 was 2-fold less cytotoxic, and unlabeled CSL360, DTPA-NLS-CSL360 or free (111)In acetate did not decrease cell survival. These results are promising for further evaluation of (111)In-DTPA-NLS-CSL360 for Auger electron radioimmunotherapy of AML targeting the critical LSC subpopulation.