Scan factors and practices associated with radiation doses for chest CT: current Brazilian scenario

The main purpose of this study was to compare the parameters of computed tomography (CT) and the corresponding patient doses undergoing chest CT scan examinations in different regions of Brazil, providing the current scenario of how these procedures are being carried out in the country as well as the patient dose distribution. Thirty institutions, across 17 states and the Federal District, participated in the survey. The evaluation included 30 multislice CTs of seven different models, manufactured by General Electric (GE) Healthcare. For each institution, data from 10 adult chest CT examinations, performed without contrast, were collected remotely. The analysis of the results showed a significant difference of the CTDI_volvalues, ranging from 1.1 mGy to 46.6 mGy in seven institutions. The mean value of CTDI_volwas higher than values found in the literature and the UK Reference Levels. It was also observed that, regardless of the region of the country, for the same CT model, different scanning parameters were used, which resulted in CTDI_volup to 5 times higher in some institutions. Repetitions of CT acquisitions and scouts with radiation field dimensions larger than the region of interest were found in 25% of chest examinations, resulting in higher absorbed doses. The results of this work show a mapping of the chest CT procedures, which enables the establishment of strategic plans for the country. In addition, each institution will be able to implement an appropriate optimization program and establish institutional reference levels.

First Latin American and Caribbean interlaboratory comparison exercise for SSDLs on reference irradiation capabilities in personal dose equivalent

A comparison exercise of Latin American and Caribbean Secondary Standards Dosimetry Laboratories (SSDLs) was jointly organized by the International Atomic Energy Agency (IAEA) and the Ionizing Radiation Metrology Laboratory at the Federal University of Pernambuco (LMRI-DEN/UFPE). This exercise was organized during an IAEA regional meeting on the review and update of calibration capabilities in Latin America, held in Recife, during the period from 23 to 27 April 2018 under the technical cooperation project ME-RLA 9085-170572. Fifteen participating SSDLs were required to irradiate optically stimulated personal dosimeters in terms of the personal dose equivalent Hp(10) in¹³⁷Cs radiation quality. In addition, the IAEA Dosimetry Laboratory in Seibersdorf, Austria, and the National Physical Laboratory in Teddington, Middlesex, UK participated in this exercise as reference institutes. Each participant received 10 dosimeters that were hand-carried directly to the SSDL. Two nominal dose values of 2 mSv and 4 mSv were selected for this exercise. The participants irradiated the dosimeters using the setup and the procedures which are normally used in their standard laboratory for Hp(10) dosimeter irradiations. The dosimeters were evaluated as they were received by the coordinating laboratory, using a single BeOSL Reader. The results show that, except for one laboratory, the differences between the dosimeter reading and the assigned values were within 10%; this is consistent with the expanded uncertainty. The results indicate that most of the participant laboratories have a good capability to irradiate personal dosimeters in the quantity Hp(10).

Evaluation of a 3D printed OSL eye lens dosimeter for photon dosimetry

This work demonstrates the use of high-resolution 3D printing to fine-tune the low energy dependence of an eye lens dosimeter holder associated to a BeO OSL detector element (ezClip). Five geometries of the denominated iBe dosimeter were developed, three with a variation in the thickness of the wall in front of the sensitive element that tailor the response at low radiation energies; and three with variations of width and curvature in order to vary the angular response of the dosimeter badges. Additive manufacturing was accomplished using stereolithography which gave a high degree of accuracy and precision. The optimised dosimeter badges showed a low energy and angular dependence, within -20% to +20% in the energy range of 24 keV to 662 keV and from 0 to 60° incidence; and within -10% to +10% in the energy range of 24 keV to 164 keV and from 0 to 60° incidence. In contrast to other dosimeters with higher effective atomic numbers, the use of BeO as the sensitive element resulted in a flat energy and angular dependence response at low energies. A significant reduction in the measurement uncertainty in the diagnostic radiology energy range was achieved.

REDUCTION OF STAFF RADIATION DOSE IN PROSTATIC ARTERY EMBOLISATION

Prostatic artery embolisation (PAE) is used to treat patients with benign prostatic hyperplasia and with lower urinary obstructive tract symptoms. It is an interventional procedure which uses fluoroscopy equipment and can result in exposure to high doses of radiation in patients and staff. We aimed to demonstrate the reduction of radiation doses received by staff during PAE by implementing an optimised protocol called Radiation Exposure Curtailment for Embolisation (RECiFE). This protocol was implemented in cooperation with the medical team and technical team using Siemens Combined Applications to Reduce Exposure (CARE) protocol. The results showed approximately 83% reduction in the radiation doses received by the main physician during PAE. Thus, by adjusting the acquisition parameters of the angiographic equipment and implementing the RECiFE protocol, it is possible to optimise the PAE procedure and reduce the staff radiation dose.

RADIATION DOSES TO ANAESTHETISTS DURING PROSTATIC ARTERY EMBOLIZATION INTERVENTIONAL PROCEDURES

The objective of this study was to assess the radiation doses received by anaesthetists from prostatic artery embolization (PAE) procedures. Ten PAE procedures conducted in a reference hospital in the city of Recife, Brazil were investigated. Occupational dosimetry was performed using thermoluminescent dosemeters which were located next to the eyes, close to the thyroid (over the shielding), on the thorax (under the apron), on the wrist and on the feet of the physician's body. The results showed that the anaesthetist's feet received the highest doses followed by the eyes and the hands. In some complex PAE procedures the doses received by anaesthetists on the lens of the eyes and the effective dose were higher than those received by the main operator due to the anaesthetist's close position to the patient's table and the use of oblique projections. The personal dose equivalent Hp(3) per procedure for the anaesthetist's right eyebrow ranged from 20.2 μSv to 568.3 μSv. This result shows that anaesthetists assisting PAE procedures can exceeds the annual eye lens dose limit of 20 mSv recommended by the ICRP with only one procedure per week if radiation protection measures are not implemented during procedures.

Development of a realistic 3D printed eye lens dosemeter using CAD integrated with Monte Carlo simulation

Recent epidemiological studies suggested to lower the threshold dose for radiation induced cataract in the eye lens. Therefore, eye lens radiation protection became to play a more important role in personal dosimetry. The main objective of this work is to propose a new methodology for prototyping and benchmarking of an eye lens dosimter based on the equivalent dose to the sensitive part of the eye lens, using CAD Software and Geant4 Monte Carlo simulations with mesh modelling and 3D printing. A 3D printed dosemeter was type tested based on IEC 62387:2012, in terms of energy and angular dependence for the measurements of Hp(3). The results show that the methodology employed is suitable for the development of new eye lens dosemeters.

The performance of a multi guard ring (MGR) diode for clinical electron beams dosimetry

The dosimetric response of a multi guard ring structure (MGR) diode has been studied with clinical electron beam energies from 5 MeV to 15 MeV. The results showed that the MGR dose response is linear in the range of 5-320 cGy and presents reproducibility with variation coefficients less than 0.4%. The field output factors measured with the MGR agreed within 2% with those measured with an ionization chamber. This study evidences that this diode can be used for clinical electron beam dosimetry.

Upper gastrointestinal acute graft-versus-host disease adds minimal prognostic value in isolation or with other graft-versus-host disease symptoms as currently diagnosed and treated

Upper gastrointestinal acute graft-versus-host disease is reported in approximately 30% of hematopoietic stem cell transplant recipients developing acute graft-versus-host disease. Currently classified as Grade II in consensus criteria, upper gastrointestinal acute graft-versus-host disease is often treated with systemic immunosuppression. We reviewed the Center for International Blood and Marrow Transplant Research database to assess the prognostic implications of upper gastrointestinal acute graft-versus-host disease in isolation or with other acute graft-versus-host disease manifestations. 8567 adult recipients of myeloablative allogeneic hematopoietic stem cell transplant receiving T-cell replete grafts for acute leukemia, chronic myeloid leukemia or myelodysplastic syndrome between 2000 and 2012 were analyzed. 51% of transplants were from unrelated donors. Reported upper gastrointestinal acute graft-versus-host disease incidence was 12.1%; 2.7% of recipients had isolated upper gastrointestinal acute graft-versus-host disease, of whom 95% received systemic steroids. Patients with isolated upper gastrointestinal involvement had similar survival, disease-free survival, transplant-related mortality, and relapse as patients with Grades 0, I, or II acute graft-versus-host disease. Unrelated donor recipients with isolated upper gastrointestinal acute graft-versus-host disease had less subsequent chronic graft-versus-host disease than those with Grades I or II disease (P=0.016 and P=0.0004, respectively). Upper gastrointestinal involvement added no significant prognostic information when present in addition to other manifestations of Grades I or II acute graft-versus-host disease. If upper gastrointestinal symptoms were reclassified as Grade 0 or I, 425 of 2083 patients (20.4%) with Grade II disease would be downgraded, potentially impacting the interpretation of clinical trial outcomes. Defining upper gastrointestinal acute graft-versus-host disease as a Grade II entity, as it is currently diagnosed and treated, is not strongly supported by this analysis. The general approach to diagnosis, treatment and grading of upper gastrointestinal symptoms and their impact on subsequent acute graft-versus-host disease therapy warrants reevaluation.

Practical management of toxicities associated with bosutinib in patients with Philadelphia chromosome-positive chronic myeloid leukemia

Bosutinib (SKI-606) is an oral, dual Src/Abl tyrosine kinase inhibitor (TKI) approved for treatment of patients with Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia (CML) that is resistant or intolerant to prior TKI therapy or for whom other TKIs are not appropriate choices. The objective of this review is to provide a longitudinal summary of toxicities that may arise during treatment with second-line or later bosutinib in patients with Ph+ chronic phase CML and to provide strategies for managing these toxicities. As bosutinib is not currently indicated for newly diagnosed CML, toxicities associated with first-line treatment are not reviewed. Recognition and optimal management of these toxicities can facilitate patient compliance and affect treatment outcomes.

HMG-CoA synthase 1 is a synthetic lethal partner of BRAFV600E in human cancers

Contributions of metabolic changes to cancer development and maintenance have received increasing attention in recent years. Although many human cancers share similar metabolic alterations, it remains unclear whether oncogene-specific metabolic alterations are required for tumor development. Using an RNAi-based screen targeting the majority of the known metabolic proteins, we recently found that oncogenic BRAF^V600E up-regulates HMG-CoA lyase (HMGCL), which converts HMG-CoA to acetyl-CoA and a ketone body, acetoacetate, that selectively enhances BRAF^V600E-dependent MEK1 activation in human cancer. Here, we identified HMG-CoA synthase 1 (HMGCS1), the upstream ketogenic enzyme of HMGCL, as an additional "synthetic lethal" partner of BRAF^V600E Although HMGCS1 expression did not correlate with BRAF^V600E mutation in human melanoma cells, HMGCS1 was selectively important for proliferation of BRAF^V600E-positive melanoma and colon cancer cells but not control cells harboring active N/KRAS mutants, and stable knockdown of HMGCS1 only attenuated colony formation and tumor growth potential of BRAF^V600E melanoma cells. Moreover, cytosolic HMGCS1 that co-localized with HMGCL and BRAF^V600E was more important than the mitochondrial HMGCS2 isoform in BRAF^V600E-expressing cancer cells in terms of acetoacetate production. Interestingly, HMGCL knockdown did not affect HMGCS1 expression levels, whereas HMGCS1 knockdown caused a compensating increase in HMGCL protein level because of attenuated protein degradation. However, this increase did not reverse the reduced ketogenesis in HMGCS1 knockdown cells. Mechanistically, HMGCS1 inhibition decreased intracellular acetoacetate levels, leading to reduced BRAF^V600E-MEK1 binding and consequent MEK1 activation. We conclude that the ketogenic HMGCS1-HMGCL-acetoacetate axis may represent a promising therapeutic target for managing BRAF^V600E-positive human cancers.

Immune responses and long-term disease recurrence status after telomerase-based dendritic cell immunotherapy in patients with acute myeloid leukemia

BACKGROUND

Telomerase activity in leukemic blasts frequently is increased among patients with high-risk acute myeloid leukemia (AML). In the current study, the authors evaluated the feasibility, safety, immunogenicity, and therapeutic potential of human telomerase reverse transcriptase (hTERT)-expressing autologous dendritic cells (hTERT-DCs) in adult patients with AML.

METHODS

hTERT-DCs were produced from patient-specific leukapheresis, electroporated with an mRNA-encoding hTERT and a lysosomal-targeting sequence, and cryopreserved. A total of 22 patients with a median age of 58 years (range, 30-75 years) with intermediate-risk or high-risk AML in first or second complete remission (CR) were enrolled. hTERT-DCs were generated for 24 patients (73%). A median of 17 intradermal vaccinations (range, 6-32 intradermal vaccinations) containing 1×10⁷ cells were administered as 6 weekly injections followed by 6 biweekly injections. A total of 21 patients (16 in first CR, 3 in second CR, and 2 with early disease recurrence) received hTERT-DCs.

RESULTS

hTERT-DCs were well tolerated with no severe toxicities reported, with the exception of 1 patient who developed idiopathic thrombocytopenic purpura. Of the 19 patients receiving hTERT-DCs in CR, 11 patients (58%) developed hTERT-specific T-cell responses that primarily were targeted toward hTERT peptides with predicted low human leukocyte antigen (HLA)-binding affinities. With a median follow-up of 52 months, 58% of patients in CR (11 of 19 patients) were free of disease recurrence at the time of their last follow-up visit; 57% of the patients who were aged ≥60 years (4 of 7 patients) also were found to be free of disease recurrence at a median follow-up of 54 months.

CONCLUSIONS

The generation of hTERT-DCs is feasible and vaccination with hTERT-DCs appears to be safe and may be associated with favorable recurrence-free survival. Cancer 2017;123:3061-72. © 2017 American Cancer Society.

Molecular impact of selective NFKB1 and NFKB2 signaling on DLBCL phenotype

Diffuse large B-cell lymphoma (DLBCL) has been categorized into two molecular subtypes that have prognostic significance, namely germinal center B-cell like (GCB) and activated B-cell like (ABC). Although ABC-DLBCL has been associated with NF-κB activation, the relationships between activation of specific NF-κB signals and DLBCL phenotype remain unclear. Application of novel gene expression classifiers identified two new DLBCL categories characterized by selective p100 (NF-κB2) and p105 (NF-κB1) signaling. Interestingly, our molecular studies showed that p105 signaling is predominantly associated with GCB subtype and histone mutations. Conversely, most tumors with p100 signaling displayed ABC phenotype and harbored ABC-associated mutations in genes such as MYD88 and PIM1. In vitro, MYD88 L265P mutation promoted p100 signaling through TAK1/IKKα and GSK3/Fbxw7a pathways, suggesting a novel role for this protein as an upstream regulator of p100. p100 signaling was engaged during activation of normal B cells, suggesting p100's role in ABC phenotype development. Additionally, silencing p100 in ABC-DLBCL cells resulted in a GCB-like phenotype, with suppression of Blimp, IRF4 and XBP1 and upregulation of BCL6, whereas introduction of p52 or p100 into GC cells resulted in differentiation toward an ABC-like phenotype. Together, these findings identify specific roles for p100 and p105 signaling in defining DLBCL molecular subtypes and posit MYD88/p100 signaling as a regulator for B-cell activation.

Improved survival after acute graft-versus-host disease diagnosis in the modern era

A cute graft-versus-host disease remains a major threat to a successful outcome after allogeneic hematopoietic cell transplantation. While improvements in treatment and supportive care have occurred, it is unknown whether these advances have resulted in improved outcome specifically among those diagnosed with acute graft-versus-host disease. We examined outcome following diagnosis of grade II-IV acute graft-versus-host disease according to time period, and explored effects according to original graft-versus-host disease prophylaxis regimen and maximum overall grade of acute graft-versus-host disease. Between 1999 and 2012, 2,905 patients with acute myeloid leukemia (56%), acute lymphoblastic leukemia (30%) or myelodysplastic syndromes (14%) received a sibling (24%) or unrelated donor (76%) blood (66%) or marrow (34%) transplant and developed grade II-IV acute graft-versus-host disease (n=497 for 1999–2001, n=962 for 2002–2005, n=1,446 for 2006–2010). The median (range) follow-up was 144 (4–174), 97 (4–147) and 60 (8–99) months for 1999–2001, 2002–2005, and 2006–2010, respectively. Among the cohort with grade II-IV acute graft-versus-host disease, there was a decrease in the proportion of grade III-IV disease over time with 56%, 47%, and 37% for 1999–2001, 2002–2005, and 2006–2012, respectively (P<0.001). Considering the total study population, univariate analysis demonstrated significant improvements in overall survival and treatment-related mortality over time, and deaths from organ failure and infection declined. On multivariate analysis, significant improvements in overall survival (P=0.003) and treatment-related mortality (P=0.008) were only noted among those originally treated with tacrolimus-based graft-versus-host disease prophylaxis, and these effects were most apparent among those with overall grade II acute graft-versus-host disease. In conclusion, survival has improved over time for tacrolimus-treated transplant recipients with acute graft-versus-host disease.

Prevention of Dietary-Fat-Fueled Ketogenesis Attenuates BRAF V600E Tumor Growth

Lifestyle factors, including diet, play an important role in the survival of cancer patients. However, the molecular mechanisms underlying pathogenic links between diet and particular oncogenic mutations in human cancers remain unclear. We recently reported that the ketone body acetoacetate selectively enhances BRAF V600E mutant-dependent MEK1 activation in human cancers. Here we show that a high-fat ketogenic diet increased serum levels of acetoacetate, leading to enhanced tumor growth potential of BRAF V600E-expressing human melanoma cells in xenograft mice. Treatment with hypolipidemic agents to lower circulating acetoacetate levels or an inhibitory homolog of acetoacetate, dehydroacetic acid, to antagonize acetoacetate-BRAF V600E binding attenuated BRAF V600E tumor growth. These findings reveal a signaling basis underlying a pathogenic role of dietary fat in BRAF V600E-expressing melanoma, providing insights into the design of conceptualized "precision diets" that may prevent or delay tumor progression based on an individual's specific oncogenic mutation profile.

Allogeneic transplantation for advanced acute myeloid leukemia: The value of complete remission

BACKGROUND

Patients with acute myeloid leukemia (AML) without complete remission (CR) or in first relapse (Rel1) can have extended leukemia control and survival after allogeneic hematopoietic cell transplantation (HCT). For patients in Rel1 or primary induction failure (PIF), transplantation versus treatment to achieve a second CR (CR2) and subsequent HCT might yield similar outcomes, but available comparative data are scarce.

METHODS

Survival was analyzed in 4682 HCT recipients according to disease status: PIF (N = 1440), Rel1 (failing ≥1 reinduction; N = 1256), and CR2 (N = 1986).

RESULTS

Patient, disease, and transplantation characteristics were similar, except that patients in CR2 more often had performance scores of 90% to 100%, de novo AML, and longer CR1 duration. Adverse cytogenetics were more common in patients who experienced PIF. The 5-year survival rate adjusted for performance score, cytogenetic risk, and donor type for CR2 was 39% (95% confidence interval [CI], 37%-41%) compared with 18% (95% CI, 16%-20%) for HCT in Rel1 and 21% (95% CI, 19%-23%) in PIF (P < .0001).

CONCLUSIONS

Although survival is superior for patients who undergo HCT in CR2, transplantation for selected patients in Rel1 or PIF may still be valuable. These data can guide decision making about additional salvage therapy versus prompt HCT for patients not in CR, but they also highlight that AML is intrinsically more treatable in patients who have favorable-risk cytogenetics, those with longer CR1 duration, and younger patients with better performance status. Cancer 2017;123:2025-2034. © 2017 American Cancer Society.

Mathematical modelling of scanner-specific bowtie filters for Monte Carlo CT dosimetry

The purpose of bowtie filters in CT scanners is to homogenize the x-ray intensity measured by the detectors in order to improve the image quality and at the same time to reduce the dose to the patient because of the preferential filtering near the periphery of the fan beam. For CT dosimetry, especially for Monte Carlo calculations of organ and tissue absorbed doses to patients, it is important to take the effect of bowtie filters into account. However, material composition and dimensions of these filters are proprietary. Consequently, a method for bowtie filter simulation independent of access to proprietary data and/or to a specific scanner would be of interest to many researchers involved in CT dosimetry. This study presents such a method based on the weighted computer tomography dose index, CTDI_w, defined in two cylindrical PMMA phantoms of 16 cm and 32 cm diameter. With an EGSnrc-based Monte Carlo (MC) code, ratios CTDI_w/CTDI_100,a were calculated for a specific CT scanner using PMMA bowtie filter models based on sigmoid Boltzmann functions combined with a scanner filter factor (SFF) which is modified during calculations until the calculated MC CTDI_w/CTDI_100,a matches ratios CTDI_w/CTDI_100,a, determined by measurements or found in publications for that specific scanner. Once the scanner-specific value for an SFF has been found, the bowtie filter algorithm can be used in any MC code to perform CT dosimetry for that specific scanner. The bowtie filter model proposed here was validated for CTDI_w/CTDI_100,a considering 11 different CT scanners and for CTDI_100,c, CTDI_100,p and their ratio considering 4 different CT scanners. Additionally, comparisons were made for lateral dose profiles free in air and using computational anthropomorphic phantoms. CTDI_w/CTDI_100,a determined with this new method agreed on average within 0.89% (max. 3.4%) and 1.64% (max. 4.5%) with corresponding data published by CTDosimetry (www.impactscan.org) for the CTDI HEAD and BODY phantoms, respectively. Comparison with results calculated using proprietary data for the PHILIPS Brilliance 64 scanner showed agreement on average within 2.5% (max. 5.8%) and with data measured for that scanner within 2.1% (max. 3.7%). Ratios of CTDI_100,c/CTDI₁₀₀, _p for this study and corresponding data published by CTDosimetry (www.impactscan.org) agree on average within about 11% (max. 28.6%). Lateral dose profiles calculated with the proposed bowtie filter and with proprietary data agreed within 2% (max. 5.9%), and both calculated data agreed within 5.4% (max. 11.2%) with measured results. Application of the proposed bowtie filter and of the exactly modelled filter to human phantom Monte Carlo calculations show agreement on the average within less than 5% (max. 7.9%) for organ and tissue absorbed doses.

Long-term bosutinib for chronic phase chronic myeloid leukemia after failure of imatinib plus dasatinib and/or nilotinib

Bosutinib is an Src/Abl tyrosine kinase inhibitor (TKI) indicated for adults with Ph+ chronic myeloid leukemia (CML) resistant/intolerant to prior TKIs. This long-term update of an ongoing phase 1/2 study evaluated the efficacy and safety of third-/fourth-line bosutinib in adults with chronic phase (CP) CML. Median durations of treatment and follow-up were 8.6 (range, 0.2-87.7) months and 32.7 (0.3-93.3) months, respectively. Cumulative confirmed complete hematologic response (cCHR) and major cytogenetic response (MCyR) rates were 74% (95% CI, 65-81%) and 40% (31-50%), respectively; Kaplan-Meier (K-M) probability of maintaining cCHR or MCyR at 4 years was 63% (95% CI, 50-73%) and 69% (52-81%). Cumulative incidence of on-treatment disease progression (PD)/death at 4 years was 24% (95% CI, 17-33%); K-M 4-year overall survival was 78% (68-85%). Baseline Ph+ cells ≤35 vs. ≥95% was prognostic of MCyR and CCyR by 3 and 6 months, increased baseline basophils was prognostic of PD/death, and no prior response to second-line TKI was prognostic of death. Common adverse events included diarrhea (83%), nausea (48%), vomiting (38%), and thrombocytopenia (39%). Bosutinib demonstrates durable efficacy and a toxicity profile similar to previous bosutinib studies in CP CML patients resistant/intolerant to multiple TKIs, representing an important treatment option for patients in this setting. This trial is registered at www.clinicaltrials.gov (NCT00261846). Am. J. Hematol. 91:1206-1214, 2016. © 2016 Wiley Periodicals, Inc.

Tetrameric Acetyl-CoA Acetyltransferase 1 Is Important for Tumor Growth

Mitochondrial acetyl-CoA acetyltransferase 1 (ACAT1) regulates pyruvate dehydrogenase complex (PDC) by acetylating pyruvate dehydrogenase (PDH) and PDH phosphatase. How ACAT1 is "hijacked" to contribute to the Warburg effect in human cancer remains unclear. We found that active, tetrameric ACAT1 is commonly upregulated in cells stimulated by EGF and in diverse human cancer cells, where ACAT1 tetramers, but not monomers, are phosphorylated and stabilized by enhanced Y407 phosphorylation. Moreover, we identified arecoline hydrobromide (AH) as a covalent ACAT1 inhibitor that binds to and disrupts only ACAT1 tetramers. The resultant AH-bound ACAT1 monomers cannot reform tetramers. Inhibition of tetrameric ACAT1 by abolishing Y407 phosphorylation or AH treatment results in decreased ACAT1 activity, leading to increased PDC flux and oxidative phosphorylation with attenuated cancer cell proliferation and tumor growth. These findings provide a mechanistic understanding of how oncogenic events signal through distinct acetyltransferases to regulate cancer metabolism and suggest ACAT1 as an anti-cancer target.

European LeukemiaNet recommendations for the management and avoidance of adverse events of treatment in chronic myeloid leukaemia

Most reports on chronic myeloid leukaemia (CML) treatment with tyrosine kinase inhibitors (TKIs) focus on efficacy, particularly on molecular response and outcome. In contrast, adverse events (AEs) are often reported as infrequent, minor, tolerable and manageable, but they are increasingly important as therapy is potentially lifelong and multiple TKIs are available. For this reason, the European LeukemiaNet panel for CML management recommendations presents an exhaustive and critical summary of AEs emerging during CML treatment, to assist their understanding, management and prevention. There are five major conclusions. First, the main purpose of CML treatment is the antileukemic effect. Suboptimal management of AEs must not compromise this first objective. Second, most patients will have AEs, usually early, mostly mild to moderate, and which will resolve spontaneously or are easily controlled by simple means. Third, reduction or interruption of treatment must only be done if optimal management of the AE cannot be accomplished in other ways, and frequent monitoring is needed to detect resolution of the AE as early as possible. Fourth, attention must be given to comorbidities and drug interactions, and to new events unrelated to TKIs that are inevitable during such a prolonged treatment. Fifth, some TKI-related AEs have emerged which were not predicted or detected in earlier studies, maybe because of suboptimal attention to or absence from the preclinical data. Overall, imatinib has demonstrated a good long-term safety profile, though recent findings suggest underestimation of symptom severity by physicians. Second and third generation TKIs have shown higher response rates, but have been associated with unexpected problems, some of which could be irreversible. We hope these recommendations will help to minimise adverse events, and we believe that an optimal management of them will be rewarded by better TKI compliance and thus better CML outcomes, together with better quality of life.

Targeting 6-phosphogluconate dehydrogenase in the oxidative PPP sensitizes leukemia cells to antimalarial agent dihydroartemisinin

The oxidative pentose phosphate pathway (PPP) is crucial for cancer cell metabolism and tumor growth. We recently reported that targeting a key oxidative PPP enzyme, 6-phosphogluconate dehydrogenase (6PGD), using our novel small molecule 6PGD inhibitors Physcion and its derivative S3, shows anti-cancer effects. Notably, humans with genetic deficiency of either 6PGD or another oxidative PPP enzyme, glucose-6-phosphate dehydrogenase (G6PD), exhibit non-immune hemolytic anemia upon exposure to aspirin and various anti-malarial drugs. Inspired by these clinical observations, we examined the anti-cancer potential of combined treatment with 6PGD inhibitors and anti-malarial drugs. We found that stable knockdown of 6PGD sensitizes leukemia cells to anti-malarial agent dihydroartemisinin (DHA). Combined treatment with DHA and Physcion activates AMP-activated protein kinase, leading to synergistic inhibition of human leukemia cell viability. Moreover, our combined therapy synergistically attenuates tumor growth in xenograft nude mice injected with human K562 leukemia cells and cell viability of primary leukemia cells from human patients, but shows minimal toxicity to normal hematopoietic cells in mice as well as red blood cells and mononucleocytes from healthy human donors. Our findings reveal the potential for combined therapy using optimized doses of Physcion and DHA as a novel anti-leukemia treatment without inducing hemolysis.

Prostatic artery embolization: radiation exposure to patients and staff

The aim of this study was to evaluate the radiation doses to patients and staff received from the first cases of prostatic artery embolization (PAE) conducted in a public hospital in Recife, Brazil. Five PAE procedures for 5 men diagnosed with benign prostatic hyperplasia were investigated. In order to characterize patient exposure, dosimetric quantities, such as the air kerma-area product (P KA), the cumulative air kerma at the interventional reference point (Ka,r), the number of images, etc, were registered. To evaluate the possibility for deterministic effects, the peak skin dose (PSD) was measured using radiochromic films. For evaluation of personal dose equivalent and effective dose to the medical staff, thermoluminescent dosemeters (TLD-100) were used. The effective dose was estimated using the double dosimetry alghoritm of von Boetticher. The results showed that the mean patient's PSD per procedure was 2674.2 mGy. With regard to the medical staff, the mean, minimum and maximum effective doses estimated per procedure were: 18 μSv, 12 μSv and 21 μSv respectively. High personal equivalent doses were found for the feet, hands and lens of the eye, due to the use of multiple left anterior oblique projections and the improper use of the suspended lead screen and the lead curtain during procedures.

Evaluation of staff, patient and foetal radiation doses due to endoscopic retrograde cholangiopancreatography (ERCP) procedures in a pregnant patient

The use of endoscopic retrograde cholangiopancreatography (ERCP) in pregnant patients is not rare. Most studies on the safety and efficacy of these procedures report short- and long-term pregnancy outcomes and but not foetal absorbed doses. This investigation reports on an ERCP procedure for a 40-y-old woman who was 32-34 weeks pregnant. Thermoluminescent dosemeters (TLD 100) were used to measure doses received by the patient and the staff. Additionally, Monte Carlo calculations were performed using a 3D computational phantom representing a 9-month pregnant patient to estimate the foetal absorbed dose. The results show that the spleen of the mother received the largest absorbed dose of 12.18 mGy since it was closer to the source than other internal organs. For the foetus and uterus, the lowest absorbed dose was found to be 0.01 mGy to the foetal brain, while the largest absorbed dose was estimated to be 0.13 mGy to the placenta.

Factors influencing long-term efficacy and tolerability of bosutinib in chronic phase chronic myeloid leukaemia resistant or intolerant to imatinib

The dual SRC/ABL1 tyrosine kinase inhibitor bosutinib is indicated for adults with Ph+ chronic myeloid leukaemia (CML) resistant/intolerant to prior therapy. This analysis of an ongoing phase 1/2 study (NCT00261846) assessed effects of baseline patient characteristics on long‐term efficacy and safety of bosutinib 500 mg/day in adults with imatinib (IM)‐resistant (IM‐R; n = 196)/IM‐intolerant (IM‐I; n = 90) chronic phase (CP) CML. Median treatment duration was 24·8 months (median follow‐up, 43·6 months). Cumulative major cytogenetic response (MCyR) rate [95% confidence interval (CI)], was 59% (53–65%); Kaplan‐Meier (KM) probability of maintaining MCyR at 4 years was 75% (66–81%). Cumulative incidence of on‐treatment progression/death at 4 years was 19% (95% CI, 15–24%); KM 2‐year overall survival was 91% (87–94%). Significant baseline predictors of both MCyR and complete cytogenetic response (newly attained/maintained from baseline) at 3 and 6 months included prior IM cytogenetic response, baseline MCyR, prior interferon therapy and <6 months duration from diagnosis to IM treatment initiation and no interferon treatment before IM. The most common adverse event (AE) was diarrhoea (86%). Baseline bosutinib‐sensitive BCR‐ABL1 mutation was the only significant predictor of grade 3/4 diarrhoea; no significant predictors were identified for liver‐related AEs. Bosutinib demonstrates durable efficacy and manageable toxicity in IM‐R/IM‐I CP‐CML patients.

6-Phosphogluconate dehydrogenase links oxidative PPP, lipogenesis and tumour growth by inhibiting LKB1-AMPK signalling

The oxidative pentose phosphate pathway (PPP) contributes to tumor growth, but the precise contribution of 6-phosphogluconate dehydrogenase (6PGD), the third enzyme in this pathway, to tumorigenesis remains unclear. We found that suppression of 6PGD decreased lipogenesis and RNA biosynthesis and elevated ROS levels in cancer cells, attenuating cell proliferation and tumor growth. 6PGD-mediated production of ribulose-5-phosphate (Ru-5-P) inhibits AMPK activation by disrupting the active LKB1 complex, thereby activating acetyl-CoA carboxylase 1 and lipogenesis. Ru-5-P and NADPH are thought to be precursors in RNA biosynthesis and lipogenesis, respectively; thus, our findings provide an additional link between oxidative PPP and lipogenesis through Ru-5-P-dependent inhibition of LKB1-AMPK signaling. Moreover, we identified and developed 6PGD inhibitors, Physcion and its derivative S3, that effectively inhibited 6PGD, cancer cell proliferation and tumor growth in nude mice xenografts without obvious toxicity, suggesting that 6PGD could be an anticancer target.

Long-term efficacy and safety of bosutinib in patients with advanced leukemia following resistance/intolerance to imatinib and other tyrosine kinase inhibitors

Long-term efficacy and safety of bosutinib (≥4 years follow-up from last enrolled patient) were evaluated in an ongoing phase 1/2 study in the advanced leukemia cohort with prior treatment failure (accelerated-phase [AP, n = 79] chronic myeloid leukemia [CML], blast-phase [BP, n = 64] CML, acute lymphoblastic leukemia [ALL, n = 24]). Fourteen AP, 2 BP, and 1 ALL patient remained on bosutinib at 4 years (vs. 38, 8, 1 at 1 year); median (range) treatment durations: 10.2 (0.1-88.6), 2.8 (0.03-55.9), 0.97 (0.3-89.2) months. Among AP and BP patients, 57% and 28% newly attained or maintained baseline overall hematologic response (OHR); 40% and 37% attained/maintained major cytogenetic response (MCyR) by 4 years (most by 12 months). In responders at 1 versus 4 years, Kaplan-Meier (KM) probabilities of maintaining OHR were 78% versus 49% (AP) and 28% versus 19% (BP); KM probabilities of maintaining MCyR were 65% versus 49% (AP) and 21% versus 21% (BP). Most common AEs (AP, BP) were gastrointestinal (96%; 83%), primarily diarrhea (85%; 64%), which was typically low grade (maximum grade 1/2: 81%; 59%) and transient; no patient discontinued due to diarrhea. Serious AEs occurred in 44 (56%) AP and 37 (58%) BP patients, most commonly pneumonia (n = 9) for AP and pyrexia (n = 6) for BP; 11 and 13 died within 30 days of last dose (2 considered bosutinib-related [AP] per investigator). Responses were durable in ∼50% AP responders at 4 years (∼25% BP patients responded at year 1, suggesting possible bridge-to-transplant role in BP patients); toxicity was manageable.

Estimation of organ doses to patients undergoing hepatic chemoembolization procedures

The aim of this study is to evaluate organ and tissue absorbed doses to patients undergoing hepatic chemoembolization procedures performed in two hospitals in the city of Recife, Brazil. Forty eight patients undergoing fifty hepatic chemoembolization procedures were investigated. For the 20 cases with PA projection only, organs and tissues dose to KAP conversion coefficients were calculated using the mesh-based anthropometric phantom series FASH and MASH coupled to the EGSnrc Monte Carlo code. Clinical, dosimetric and irradiations parameters were registered for all patients. The maximum organ absorbed doses found were 2.4 Gy, 0.85 Gy, 0.76 Gy and 0.44 Gy for skin, kidneys, adrenals and liver, respectively.

Radiation exposure to patients and medical staff in hepatic chemoembolisation interventional procedures in Recife, Brazil

The purpose of this study was to evaluate patient and medical staff absorbed doses received from transarterial chemoembolisation of hepatocellular carcinoma, which is the most common primary liver tumour worldwide. The study was performed in three hospitals in Recife, capital of the state of Pernambuco, located in the Brazilian Northeastern region. Two are public hospitals (A and B), and one is private (C). For each procedure, the number of images, irradiation parameters (kV, mA and fluoroscopy time), the air kerma-area product (PKA) and the cumulative air kerma (Ka,r) at the reference point were registered. The maximum skin dose (MSD) of the patient was estimated using radiochromic film. For the medical staff dosimetry, thermoluminescence dosemeters (TLD-100) were attached next to the eyes, close to the thyroid (above the shielding), on the thorax under the apron, on the wrist and on the feet. The effective dose to the staff was estimated using the algorithm of von Boetticher. The results showed that the mean value of the total PKA was 267.49, 403.83 and 479.74 Gy cm(2) for Hospitals A, B and C, respectively. With regard to the physicians, the average effective dose per procedure was 17 µSv, and the minimum and maximum values recorded were 1 and 41 µSy, respectively. The results showed that the feet received the highest doses followed by the hands and lens of the eye, since the physicians did not use leaded glasses and the equipment had no lead curtain.

Glutamate dehydrogenase 1 signals through antioxidant glutathione peroxidase 1 to regulate redox homeostasis and tumor growth

How mitochondrial glutaminolysis contributes to redox homeostasis in cancer cells remains unclear. Here we report that the mitochondrial enzyme glutamate dehydrogenase 1 (GDH1) is commonly upregulated in human cancers. GDH1 is important for redox homeostasis in cancer cells by controlling the intracellular levels of its product alpha-ketoglutarate and subsequent metabolite fumarate. Mechanistically, fumarate binds to and activates a reactive oxygen species scavenging enzyme glutathione peroxidase 1. Targeting GDH1 by shRNA or a small molecule inhibitor R162 resulted in imbalanced redox homeostasis, leading to attenuated cancer cell proliferation and tumor growth.

A phase I study of oral ARRY-614, a p38 MAPK/Tie2 dual inhibitor, in patients with low or intermediate-1 risk myelodysplastic syndromes

PURPOSE

Data suggest that activity of p38 MAPK and Tie2 kinases is dysregulated in myelodysplastic syndromes (MDS) and may be targets for novel therapies. A phase I study of ARRY-614, an oral dual inhibitor of p38 MAPK and Tie2, was conducted in patients with low or intermediate-1 International Prognostic Scoring System risk MDS to evaluate safety, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary responses by International Working Group 2006 criteria.

EXPERIMENTAL DESIGN

Forty-five patients received ARRY-614 either once daily or twice daily in dose escalation (400, 600, 900, or 1,200 mg once daily; 200 or 300 mg twice daily) or expansion cohorts.

RESULTS

The 300 mg twice daily schedule was not tolerated, and an MTD was not reached for once daily dosing. Treatment-related adverse events were primarily grade 1-2, with the most common being rash, diarrhea, dry skin, fatigue and anorexia. Interpatient PK variability was high, although exposure was sufficient to achieve reduction in p38 MAPK activation in bone marrow and in the levels of circulating biomarkers. Disease responses were observed in 14 of 44 (32%) evaluable patients, 13 (93%) of whom had previously been treated with a hypomethylating agent. Responses were observed in all lineages, with 5 patients experiencing bilineage responses. Three of 25 red blood cell transfusion-dependent (TD) patients achieved transfusion independence (TI) and 5 of 7 platelet TD patients achieved TI.

CONCLUSIONS

ARRY-614 was well tolerated and has sufficient activity to warrant further evaluation in this patient population. We recommend 1,200 mg once daily as the optimal dose for further study.

Abstract 961: 6-phosphogluconate dehydrogenase links oxidative PPP, lipogenesis and tumor growth by inhibiting LKB1-AMPK signaling

6-phosphogluconate dehydrogenase (6PGD) in the oxidative pentose phosphate pathway (PPP) is upregulated in many cancers. However, how 6PGD is activated and provides a metabolic advantage to tumor growth is unknown. Here we show that 6PGD is commonly activated in human cancers by acetylation at K76 and K294,We found that 6PGD is commonly activated in human cancers by lysine acetylation. Acetylation at K76 and K294 promotes NADP+-binding to 6PGD and formation of active 6PGD dimers, respectively. Moreover, we found that lysine acetylation of 6PGD is important for cancer cell metabolism, proliferation and tumor growth. We also performed systematic RNAi screens and identified DLAT and ACAT2 as 6PGD acetyltransferases and HDAC4 as 6PGD deacetylase, using two novel “targeted” shRNA libraries that target the majority of acetyltransferases and deacetylases in the human genome, respectively. In addition, we found that 6PGD controls intracellular levels of its product ribulose-5-phosphate (Ru-5-P) to regulate lipogenesis. Ru-5-P inhibits LKB1 by disrupting active LKB1 complex, leading to inhibition of AMPK and subsequent activation of acetyl-CoA carboxylase 1 and lipogenesis. Furthermore, we screened out Physcion and its derivative S3 as novel 6PGD inhibitors, which are efficacious in treatment of xenograft nude mice and primary leukemia cells from human patients with minimal toxicity and no off-target effect.

Our findings for the first time decipher the molecular mechanisms underlying 6PGD upregulation in cancer cells and suggest that 6PGD provides an additional and novel link between oxidative PPP and lipogenesis through Ru-5-P-dependent inhibition of LKB1-AMPK signaling. Moreover, identification and characterization of 6PGD inhibitors in translational/pre-clinical studies for the first time provide “proof of principle” to suggest 6PGD as an attractive anti-cancer target.

Citation Format: Changliang Shan, Shannon E. Elf, Ting-Lei Gu, Hanna J. Khoury, Titus Boggon, Sumin Kang, Jing Chen. 6-phosphogluconate dehydrogenase links oxidative PPP, lipogenesis and tumor growth by inhibiting LKB1-AMPK signaling. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 961. doi:10.1158/1538-7445.AM2014-961

BCR-ABL1 compound mutations combining key kinase domain positions confer clinical resistance to ponatinib in Ph chromosome-positive leukemia

Ponatinib is the only currently approved tyrosine kinase inhibitor (TKI) that suppresses all BCR-ABL1 single mutants in Philadelphia chromosome-positive (Ph(+)) leukemia, including the recalcitrant BCR-ABL1(T315I) mutant. However, emergence of compound mutations in a BCR-ABL1 allele may confer ponatinib resistance. We found that clinically reported BCR-ABL1 compound mutants center on 12 key positions and confer varying resistance to imatinib, nilotinib, dasatinib, ponatinib, rebastinib, and bosutinib. T315I-inclusive compound mutants confer high-level resistance to TKIs, including ponatinib. In vitro resistance profiling was predictive of treatment outcomes in Ph(+) leukemia patients. Structural explanations for compound mutation-based resistance were obtained through molecular dynamics simulations. Our findings demonstrate that BCR-ABL1 compound mutants confer different levels of TKI resistance, necessitating rational treatment selection to optimize clinical outcome.

Disposable platform provides visual and color-based point-of-care anemia self-testing

BACKGROUND

Anemia, or low blood hemoglobin (Hgb) levels, afflicts 2 billion people worldwide. Currently, Hgb levels are typically measured from blood samples using hematology analyzers, which are housed in hospitals, clinics, or commercial laboratories and require skilled technicians to operate. A reliable, inexpensive point-of-care (POC) Hgb test would enable cost-effective anemia screening and chronically anemic patients to self-monitor their disease. We present a rapid, stand-alone, and disposable POC anemia test that, via a single drop of blood, outputs color-based visual results that correlate with Hgb levels.

METHODS

We tested blood from 238 pediatric and adult patients with anemia of varying degrees and etiologies and compared hematology analyzer Hgb levels with POC Hgb levels, which were estimated via visual interpretation using a color scale and an optional smartphone app for automated analysis.

RESULTS

POC Hgb levels correlated with hematology analyzer Hgb levels (r = 0.864 and r = 0.856 for visual interpretation and smartphone app, respectively), and both POC test methods yielded comparable sensitivity and specificity for detecting any anemia (n = 178) (<11 g/dl) (sensitivity: 90.2% and 91.1%, specificity: 83.7% and 79.2%, respectively) and severe anemia (n = 10) (<7 g/dl) (sensitivity: 90.0% and 100%, specificity: 94.6% and 93.9%, respectively).

CONCLUSIONS

These results demonstrate the feasibility of this POC color-based diagnostic test for self-screening/self-monitoring of anemia.

TRIAL REGISTRATION

Not applicable.

FUNDING

This work was funded by the FDA-funded Atlantic Pediatric Device Consortium, the Georgia Research Alliance, Children's Healthcare of Atlanta, the Georgia Center of Innovation for Manufacturing, and the InVenture Prize and Ideas to Serve competitions at the Georgia Institute of Technology.

Tyr-301 phosphorylation inhibits pyruvate dehydrogenase by blocking substrate binding and promotes the Warburg effect

The mitochondrial pyruvate dehydrogenase complex (PDC) plays a crucial role in regulation of glucose homoeostasis in mammalian cells. PDC flux depends on catalytic activity of the most important enzyme component pyruvate dehydrogenase (PDH). PDH kinase inactivates PDC by phosphorylating PDH at specific serine residues, including Ser-293, whereas dephosphorylation of PDH by PDH phosphatase restores PDC activity. The current understanding suggests that Ser-293 phosphorylation of PDH impedes active site accessibility to its substrate pyruvate. Here, we report that phosphorylation of a tyrosine residue Tyr-301 also inhibits PDH α 1 (PDHA1) by blocking pyruvate binding through a novel mechanism in addition to Ser-293 phosphorylation. In addition, we found that multiple oncogenic tyrosine kinases directly phosphorylate PDHA1 at Tyr-301, and Tyr-301 phosphorylation of PDHA1 is common in EGF-stimulated cells as well as diverse human cancer cells and primary leukemia cells from human patients. Moreover, expression of a phosphorylation-deficient PDHA1 Y301F mutant in cancer cells resulted in increased oxidative phosphorylation, decreased cell proliferation under hypoxia, and reduced tumor growth in mice. Together, our findings suggest that phosphorylation at distinct serine and tyrosine residues inhibits PDHA1 through distinct mechanisms to impact active site accessibility, which act in concert to regulate PDC activity and promote the Warburg effect.

Lysine acetylation activates 6-phosphogluconate dehydrogenase to promote tumor growth

Although the oxidative pentose phosphate pathway is important for tumor growth, how 6-phosphogluconate dehydrogenase (6PGD) in this pathway is upregulated in human cancers is unknown. We found that 6PGD is commonly activated in EGF-stimulated cells and human cancer cells by lysine acetylation. Acetylation at K76 and K294 of 6PGD promotes NADP(+) binding to 6PGD and formation of active 6PGD dimers, respectively. Moreover, we identified DLAT and ACAT2 as upstream acetyltransferases of K76 and K294, respectively, and HDAC4 as the deacetylase of both sites. Expressing acetyl-deficient mutants of 6PGD in cancer cells significantly attenuated cell proliferation and tumor growth. This is due in part to reduced levels of 6PGD products ribulose-5-phosphate and NADPH, which led to reduced RNA and lipid biosynthesis as well as elevated ROS. Furthermore, 6PGD activity is upregulated with increased lysine acetylation in primary leukemia cells from human patients, providing mechanistic insights into 6PGD upregulation in cancer cells.

Tyr-94 phosphorylation inhibits pyruvate dehydrogenase phosphatase 1 and promotes tumor growth

Many cancer cells rely more on aerobic glycolysis (the Warburg effect) than mitochondrial oxidative phosphorylation and catabolize glucose at a high rate. Such a metabolic switch is suggested to be due in part to functional attenuation of mitochondria in cancer cells. However, how oncogenic signals attenuate mitochondrial function and promote the switch to glycolysis remains unclear. We previously reported that tyrosine phosphorylation activates and inhibits mitochondrial pyruvate dehydrogenase kinase (PDK) and phosphatase (PDP), respectively, leading to enhanced inhibitory serine phosphorylation of pyruvate dehydrogenase (PDH) and consequently inhibition of pyruvate dehydrogenase complex (PDC) in cancer cells. In particular, Tyr-381 phosphorylation of PDP1 dissociates deacetylase SIRT3 and recruits acetyltransferase ACAT1 to PDC, resulting in increased inhibitory lysine acetylation of PDHA1 and PDP1. Here we report that phosphorylation at another tyrosine residue, Tyr-94, inhibits PDP1 by reducing the binding ability of PDP1 to lipoic acid, which is covalently attached to the L2 domain of dihydrolipoyl acetyltransferase (E2) to recruit PDP1 to PDC. We found that multiple oncogenic tyrosine kinases directly phosphorylated PDP1 at Tyr-94, and Tyr-94 phosphorylation of PDP1 was common in diverse human cancer cells and primary leukemia cells from patients. Moreover, expression of a phosphorylation-deficient PDP1 Y94F mutant in cancer cells resulted in increased oxidative phosphorylation, decreased cell proliferation under hypoxia, and reduced tumor growth in mice. Together, our findings suggest that phosphorylation at different tyrosine residues inhibits PDP1 through independent mechanisms, which act in concert to regulate PDC activity and promote the Warburg effect.

A phase 2 trial of ponatinib in Philadelphia chromosome-positive leukemias

BACKGROUND

Ponatinib is a potent oral tyrosine kinase inhibitor of unmutated and mutated BCR-ABL, including BCR-ABL with the tyrosine kinase inhibitor-refractory threonine-to-isoleucine mutation at position 315 (T315I). We conducted a phase 2 trial of ponatinib in patients with chronic myeloid leukemia (CML) or Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph-positive ALL).

METHODS

We enrolled 449 heavily pretreated patients who had CML or Ph-positive ALL with resistance to or unacceptable side effects from dasatinib or nilotinib or who had the BCR-ABL T315I mutation. Ponatinib was administered at an initial dose of 45 mg once daily. The median follow-up was 15 months.

RESULTS

Among 267 patients with chronic-phase CML, 56% had a major cytogenetic response (51% of patients with resistance to or unacceptable side effects from dasatinib or nilotinib and 70% of patients with the T315I mutation), 46% had a complete cytogenetic response (40% and 66% in the two subgroups, respectively), and 34% had a major molecular response (27% and 56% in the two subgroups, respectively). Responses were observed regardless of the baseline BCR-ABL kinase domain mutation status and were durable; the estimated rate of a sustained major cytogenetic response of at least 12 months was 91%. No single BCR-ABL mutation conferring resistance to ponatinib was detected. Among 83 patients with accelerated-phase CML, 55% had a major hematologic response and 39% had a major cytogenetic response. Among 62 patients with blast-phase CML, 31% had a major hematologic response and 23% had a major cytogenetic response. Among 32 patients with Ph-positive ALL, 41% had a major hematologic response and 47% had a major cytogenetic response. Common adverse events were thrombocytopenia (in 37% of patients), rash (in 34%), dry skin (in 32%), and abdominal pain (in 22%). Serious arterial thrombotic events were observed in 9% of patients; these events were considered to be treatment-related in 3%. A total of 12% of patients discontinued treatment because of an adverse event.

CONCLUSIONS

Ponatinib had significant antileukemic activity across categories of disease stage and mutation status. (Funded by Ariad Pharmaceuticals and others; PACE ClinicalTrials.gov number, NCT01207440 .).

Favorable impact of pre-transplant ATG on outcomes of reduced-intensity hematopoietic cell transplants from partially mismatched unrelated donors

Reduced-intensity conditioning (RIC) permits allogeneic hematopoietic progenitor cell transplantation in patients who would not be considered candidates for transplantation using a myeloablative preparative regimen because of age, comorbidities or prior therapy. In the setting of myeloablative transplantation, use of antithymocyte globulin (ATG) can reduce the risk of GVHD without negatively affecting transplant outcomes; however, limited data exist on the impact of ATG in the setting of RIC, particularly when there is HLA-mismatch. We performed a retrospective analysis of 85 patients who received unrelated donor transplants at our institution for hematologic malignancies following conditioning with fludarabine and melphalan (FluMel), with or without rabbit ATG (6 mg/kg). ATG was targeted to patients receiving HLA-mismatched grafts. With a median follow-up of 36 months, those receiving ATG and a mismatched graft had similar rates of acute and chronic GVHD, relapse, and similar OS compared with those receiving HLA-matched grafts without ATG. In a multivariate analysis, HLA-mismatched donor was not associated with a decrement in OS. We conclude that this intermediate dose of ATG is effective in preventing severe GVHD in the setting of HLA-mismatch, without undue compromise of the graft versus tumor effects on which RIC transplants depend.

Development of newborn and 1-year-old reference phantoms based on polygon mesh surfaces

The purpose of this study is the development of paediatric reference phantoms for newborn and 1-year-old infants to be used for the calculation of organ and tissue equivalent doses in radiation protection. The study proposes a method for developing anatomically highly sophisticated paediatric phantoms without using medical images. The newborn and 1-year-old hermaphrodite phantoms presented here were developed using three-dimensional (3D) modelling software applied to anatomical information taken from atlases, textbooks and images provided by the Department of Anatomy of the Federal University of Pernambuco, Brazil. The method uses polygon mesh surfaces to model body contours, the shape of organs as well as their positions and orientations in the human body. Organ and tissue masses agree with corresponding data given by the International Commission on Radiological Protection for newborn and 1-year-old reference children. Bones were segmented into cortical bone, spongiosa, medullary marrow and cartilage to allow for the use of μCT images of trabecular bone for skeletal dosimetry. Anatomical results show 3D images of the phantoms' surfaces, organs and skeletons, as well as tables with organ and tissue masses or skeletal tissue volumes. Dosimetric results present comparisons of organ and tissue absorbed doses or specific absorbed fractions between the newborn and 1-year-old phantoms and corresponding data for other paediatric stylised or voxel phantoms. Most differences were found to be below 10%.

Autologous haematopoietic cell transplantation for non-Hodgkin lymphoma with secondary CNS involvement

Pre-existing central nervous system (CNS) involvement may influence referral for autologous haematopoietic cell transplantation (AHCT) for patients with non-Hodgkin lymphoma (NHL). The outcomes of 151 adult patients with NHL with prior secondary CNS involvement (CNS(+) ) receiving an AHCT were compared to 4688 patients without prior CNS lymphoma (CNS(-) ). There were significant baseline differences between the cohorts. CNS(+) patients were more likely to be younger, have lower performance scores, higher age-adjusted international prognostic index scores, more advanced disease stage at diagnosis, more aggressive histology, more sites of extranodal disease, and a shorter interval between diagnosis and AHCT. However, no statistically significant differences were identified between the two groups by analysis of progression-free survival (PFS) and overall survival (OS) at 5 years. A matched pair comparison of the CNS(+) group with a subset of CNS(-) patients matched on propensity score also showed no differences in outcomes. Patients with active CNS lymphoma at the time of AHCT (n = 55) had a higher relapse rate and diminished PFS and OS compared with patients whose CNS lymphoma was in remission (n = 96) at the time of AHCT. CNS(+) patients can achieve excellent long-term outcomes with AHCT. Active CNS lymphoma at transplant confers a worse prognosis.

Mobilization of hematopoietic progenitors from normal donors using the combination of granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor results in fewer plasmacytoid dendritic cells in the graft and enhanced donor T cell engraftment with Th1 polarization: results from a randomized clinical trial

Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) both mobilize CD34(+) stem cells into the blood when administered before apheresis but have distinct effects on dendritic cell (DC) differentiation. We previously demonstrated that the combination of GM+G-CSF results in fewer plasmacytoid DCs (pDCs) when used to mobilize peripheral blood stem cells for autologous transplantation. To test the hypothesis that the content of pDCs in an allograft can be modulated with the cytokines used for mobilization, we randomized the human leukocyte antigen-matched sibling donors of 50 patients with hematological malignancies to a mobilization regimen of either GM+G-CSF (n = 25) or G-CSF alone (n = 25). Primary and secondary endpoints included the cellular constituents of the mobilized grafts, the kinetics of posttransplantation immune reconstitution, and clinical outcomes of the transplantation recipients. Grafts from donors receiving GM+G-CSF contained equivalent numbers of CD34(+) cells with fewer pDCs and T cells, with a higher fraction of Th1-polarized donor T cells than G-CSF mobilized grafts. Immune recovery was enhanced among recipients of GM+G-CSF. Survival was not significantly different between transplantation recipients in the two arms. The use of GM+G-CSF modulates immune function and recovery after allogeneic transplantation and should be explored in larger studies powered to evaluate clinical outcomes.