The pharmacokinetics and pharmacodynamics of esomeprazole in sheep after intravenous dosing

Abomasal (gastric) ulceration is a morbidity in sheep, and currently, there is a paucity of pharmacokinetic and pharmacodynamic data for gastroprotectant drugs reported for this species. The proton pump inhibitor esomeprazole has been used in small animal and human patients for gastroprotection via increasing the gastric pH. The objective of this study was to report the pharmacokinetic parameters and pharmacodynamic effect of esomeprazole in sheep after single intravenous dosing. Four healthy adult Southdown cross ewes had blood collected over a 24  h time period after single intravenous dosing of esomeprazole at 1.0  mg/kg. Abomasal fluid was sampled over 24  h before and after esomeprazole administration. Plasma samples were analyzed for concentrations of esomeprazole and the esomeprazole metabolite, esomeprazole sulfone by high performance liquid chromatography. Pharmacokinetic and pharmacodynamic data were evaluated with specialized software. Esomeprazole was rapidly eliminated after IV administration. Elimination half-life, area under the curve, initial concentration (C0), and clearance were 0.2  h, 1,197  h*ng/mL, 4,321  ng/mL, and 0.83  mL/h/kg, respectively. For the sulfone metabolite elimination half-life, area under the curve and maximum concentration were 0.16  h, 22.5  h*ng/mL, and 65.0  ng/mL, respectively. Abomasal pH was significantly elevated from 1 to 6  h after administration and remained above 4.0 for at least 8 h after administration. No adverse effects were noted in these sheep. Esomeprazole was rapidly eliminated in sheep, similar to goats. Abomasal pH was increased, but future studies will be necessary to develop a clinical management approach to the use of esomeprazole in sheep.

941. Clinical Outcomes of Vancomycin Area-Under-the-Curve Monitoring: A Quasi-Experimental Study Interim Analysis

Background

The 2020 Infectious Diseases Society of America vancomycin guidelines recommend the use of area-under-the-curve (AUC) monitoring instead of trough concentration monitoring. These guidelines changed due to evidence showing decreased rates of nephrotoxicity and lack of correlation between vancomycin troughs and patient treatment outcomes. Two common methodologies of calculating AUC exist in clinical practice, including two level kinetic calculations and Bayesian software programs. Previous studies used two levels for calculating the AUC. The purpose of this study is to evaluate if the same reduction in acute kidney injury (AKI) is achieved while using a Bayesian software program.

Methods

This retrospective quasi-experiment was performed at two sites within the same health system. The primary objective of this study was to assess the rate of AKI, as defined by the Acute Kidney Injury Network (AKIN) criteria, between patients receiving vancomycin dosed by trough monitoring as compared to AUC monitoring. Secondary objectives include mean daily dose of vancomycin, number of vancomycin levels, and severity of AKI. Patients were included in the study if they were 18 years or older, with at least one vancomycin concentration drawn. Patients were excluded if they had a baseline serum creatine greater than 2 mg/dL, received renal replacement therapy of any type, or received > 1 doses of vancomycin prior to admission. After screening for inclusion criteria, patients were matched 1:1 based on APACHE II score and vancomycin indication.

Results

One hundred and thirty patients met inclusion criteria at the interim analysis. Overall, baseline characteristics were similar between groups. No statistical difference was detected regarding the rate of acute kidney injury between the vancomycin trough group and AUC group (12% vs 14% p=0.971). The mean total daily doses of vancomycin were 1642 mg per day in the AUC group and 1838 mg per day in the trough group (p=0.08).

Conclusion

No statistical difference in rates of AKI were detected at the interim analysis, likely due to small sample size. Further data collection is ongoing to meet power and full results will be presented.

Disclosures

All Authors: No reported disclosures.

Mortality in Hip Fracture Patients During the COVID-19 Pandemic: A Retrospective Analysis in a District General Hospital in the United Kingdom

Introduction

Hip fracture is commonly seen in elderly patients because of low-energy trauma. It carries significant morbidity and mortality. Scoring systems such as the Nottingham hip fracture score (NHFS) have shown a good correlation with increased mortality as the value of these scores increases. In our study, we aim to ascertain the hip fracture mortality in our population, compare the mortality in hip fractures compared to previously reported figures in literature and nationally reported figures during the first year of the COVID-19 pandemic, and also ascertain the usefulness of NHFS in predicting mortality in hip fractures.

Methods

We gathered mortality data on hip fracture patients admitted to our unit from January 1, 2020 to December 31, 2020. NHFS was calculated for all patients and the 30-day mortality rate was compared to previously reported hip fracture mortality rates using the standard mortality ratio (SMR). One-year mortality was stratified by placing patients in high and low NHFS groups. The log-rank test was used to compare hip fracture survival at one month and at one year in the high NHFS (NHFS >4) group and low NHFS group (NHFS value 4 or below). Additionally, a log-rank test was used to compare one-month and one-year survival in hip fractures managed with hemiarthroplasty, dynamic hip screw and intramedullary nail.

Results

In 2020, 388 patients were admitted with hip fractures to our unit. The crude mortality rate was 3.9% at 30 days and 20.88% at one year. Compared to the National Hip Fracture Database report for 2020, the incidence risk ratio for mortality was 0.46 (p-value<0.05). The SMR at 30 days was 0.34 (CI=0.17-0.51) and the SMR at one year was 0.63 (CI=0.49-0.77). The survival rate was higher at 30 days and one year in the low NHFS group compared to the high NHFS group (p-value<0.01). The survival rate at one month and one year were similar in groups managed with hemiarthroplasty, dynamic hip screws, and intramedullary nails (p-value>0.05).

Conclusions

Hip fracture mortality has been decreasing steadily and we noted a lower rate of hip fracture mortality compared to figures reported previously as per NHFS studies even though the study was conducted during the COVID-19 pandemic period. We also noted lower 30-day mortality in our hospital as compared to the national 30-day mortality rate for hip fracture patients in 2020.

Impact of COVID-19 Pandemic on the Length of Hospital Stay in Hip Fracture Patients: A Single Centre Study

Background

Hip fracture is a debilitating injury, especially in older individuals, which is associated with significant morbidity and mortality. In recent decades, there has been a great focus on early rehabilitation and discharge after hip fractures. The aim of such efforts is to minimize the financial and clinical burden of this condition. We conducted our study during the COVID-19 pandemic and compared the length of hospital stay (LOS) in 2020 to the LOS in 2019. Additionally, we studied the factors which may impact the LOS, such as premorbid status according to established scoring systems, the type of fracture, an operation performed, and time to surgery.

Methods

We collected the data regarding the length of stay (in days) for all hip fracture patients admitted to our unit from 1^st January 2019 until 31^st December 2020. We then compared the mean LOS for both years using the t-test. We calculated the Nottingham Hip Fracture Score (NHFS) and American Society of Anaesthesiologists (ASA) scores for patients admitted in 2020 and calculated the correlation between increasing values of these scores and the LOS. We also compared the mean LOS for patients admitted in 2020 based on the type of fracture and type of management. We studied the correlation between the time to surgery and the LOS for patients admitted in 2020.

Results

Three hundred and eighty-eight patients were admitted with hip fractures in 2020, and 452 were admitted in 2019. LOS in 2020 was significantly lower (23.39 days) compared to 2019 (31.36 days) with p<0.01. While evaluating data from 2019, it was noted that there was a small positive correlation between LOS and NHFS (r=0.231, p<0.001) and LOS and ASA (r=0.18, p<0.001). The mean LOS for intracapsular fractures was noted to be lower than that of extracapsular fractures, but this was not statistically significant (p=0.17). An ANOVA test showed that the mean LOS for patients undergoing hemiarthroplasty, dynamic hip screws (DHS), and intramedullary nails (IMN) was significantly longer than for patients managed with total hip replacement or patients managed non-operatively (F=3.551, p<0.01).

Conclusion

Hip fracture patients admitted to our department were discharged quicker during the first year of the COVID-19 pandemic. The LOS for hip fractures increases with an increase in their NHFS or ASA scores. Extracapsular and intracapsular fractures lead to roughly the same periods of inpatient stay. Patients undergoing hemiarthroplasty, DHS, or IMN stay longer in the hospital compared to other treatment modalities.

BET-bromodomain and EZH2 inhibitor-treated chronic GVHD mice have blunted germinal centers with distinct transcriptomes

Despite advances in the field, chronic graft-versus-host-disease (cGVHD) remains a leading cause of morbidity and mortality following allogenic hematopoietic stem cell transplant. Because treatment options remain limited, we tested efficacy of anticancer, chromatin-modifying enzyme inhibitors in a clinically relevant murine model of cGVHD with bronchiolitis obliterans (BO). We observed that the novel enhancer of zeste homolog 2 (EZH2) inhibitor JQ5 and the BET-bromodomain inhibitor JQ1 each improved pulmonary function; impaired the germinal center (GC) reaction, a prerequisite in cGVHD/BO pathogenesis; and JQ5 reduced EZH2-mediated H3K27me3 in donor T cells. Using conditional EZH2 knockout donor cells, we demonstrated that EZH2 is obligatory for the initiation of cGVHD/BO. In a sclerodermatous cGVHD model, JQ5 reduced the severity of cutaneous lesions. To determine how the 2 drugs could lead to the same physiological improvements while targeting unique epigenetic processes, we analyzed the transcriptomes of splenic GCB cells (GCBs) from transplanted mice treated with either drug. Multiple inflammatory and signaling pathways enriched in cGVHD/BO GCBs were reduced by each drug. GCBs from JQ5- but not JQ1-treated mice were enriched for proproliferative pathways also seen in GCBs from bone marrow-only transplanted mice, likely reflecting their underlying biology in the unperturbed state. In conjunction with in vivo data, these insights led us to conclude that epigenetic targeting of the GC is a viable clinical approach for the treatment of cGVHD, and that the EZH2 inhibitor JQ5 and the BET-bromodomain inhibitor JQ1 demonstrated clinical potential for EZH2i and BETi in patients with cGVHD/BO.

Targeting the Retinoid X Receptor Pathway Prevents and Ameliorates Murine Chronic Graft-Versus-Host Disease

Most allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients receive peripheral blood stem cell grafts resulting in a 30%-70% incidence of chronic graft-versus-host disease (cGVHD), a major cause of mortality and morbidity in long-term survivors. While systemic steroids remain the standard of care for first-line therapy, patients may require long-term administration, and those with steroid-resistant or refractory cGVHD have a worse prognosis. Although durable and deep responses with second-line therapies can be achieved in some patients, there remains an urgent need for new therapies. In this study, we evaluated the efficacy of IRX4204, a novel agonist that activates RXRs and is in clinical trials for cancer treatment to prevent and treat cGVHD in two complementary murine models. In a major histocompatibility complex mismatched, non-sclerodermatous multiorgan system model with bronchiolitis obliterans, IRX4204 prevented and reversed cGVHD including associated pulmonary dysfunction with restoration of germinal center T-follicular helper: T-follicular regulatory cell balance. In a minor histocompatibility antigen disparate sclerodermatous model, IRX4204 treatment significantly prevented and ameliorated skin cGVHD by reducing Th1 and Th17 differentiation due to anti-inflammatory properties. Together, these results indicate that IRX4204 is a promising therapeutic option to treat cGVHD with bronchiolitis obliterans or sclerodermatous manifestations.

Reducing MRI-guided radiotherapy planning and delivery times via efficient leaf sequencing and segment shape optimization algorithms

Objective. Extended treatment session times are an operational limitation in magnetic resonance imaging guided adaptive radiotherapy (MRIgRT). In this study a novel leaf sequencing algorithm called optimal fluence levels (OFL) and an optimization algorithm called pseudo gradient descent (PGD) are evaluated with respect to plan quality, beam complexity, and the ability to reduce treatment session times on the Elekta Unity MRIgRT system. Approach. Ten total patients were evaluated on this Institutional Review Board approved study: three with prostate cancer, three with oligometastases, two with pancreatic cancer, and two with liver cancer. Plans were generated using the clinical Monaco Hyperion optimizer and leaf sequencer and then re-optimized using OFL and PGD (OFL + PGD) while holding all IMRT constraints and planning parameters constant. All plans were normalized to ensure 95% of the PTV received the prescription dose. A paired t-test was used to evaluate statistical significance. Main Results. Plan quality in terms of dosimetric OAR sparing was found to be equivalent between the OFL + PGD and conventional Monaco Hyperion optimizer plans. The OFL + PGD plans had a reduction in optimization time of 51.4% ± 5.0% (p = 0.002) and reduction in treatment delivery time of 10.6% ± 7.5% (p = 0.005). OFL + PGD generated plans had on average 13.2% ± 12.6% fewer multi-leaf collimator (MLC) segments (p = 0.009) and 0.1 ± 0.1 lower plan averaged beam modulation (PM) (p = 0.004) relative to the Monaco Hyperion plans. Significance. The OFL + PGD algorithms more quickly generate Unity treatment plans that are faster to deliver than with the conventional approach and without compromising dosimetric plan quality. This is likely due to a delivery complexity reduction enabled by OFL + PGD relative to the Monaco Hyperion plans.

Mechanical Characterization and Validation of the Dynamic Collimation System Prototype for Proton Radiotherapy

Radiation therapy is integral to cancer treatments for more than half of patients. Pencil beam scanning (PBS) proton therapy is the latest radiation therapy technology that uses a beam of protons that are magnetically steered and delivered to the tumor. One of the limiting factors of PBS accuracy is the beam cross-sectional size, similar to how a painter is only as accurate as the size of their brush allows. To address this, collimators can be used to shape the beam along the tumor edge to minimize the dose spread outside of the tumor. Under development is a dynamic collimation system (DCS) that uses two pairs of nickel trimmers that collimate the beam at the tumor periphery, limiting dose from spilling into healthy tissue. Herein, we establish the dosimetric and mechanical acceptance criteria for the DCS based on a functioning prototype and Monte Carlo methods, characterize the mechanical accuracy of the prototype, and validate that the acceptance criteria are met. From Monte Carlo simulations, we found that the trimmers must be positioned within ±0.5mm and ±1.0° for the dose distributions to pass our gamma analysis. We characterized the trimmer positioners at jerk values up to 400 m/s3 and validated their accuracy to 50 µm. We measured and validated the rotational trimmer accuracy to ±0.5° with a FARO® ScanArm. Lastly, we calculated time penalties associated with the DCS and found that the additional time required to treat one field using the DCS varied from 25-52 seconds.

Analyses and Correlation of Pathologic and Ocular Cutaneous Changes in Murine Graft versus Host Disease

Graft versus host disease (GVHD) is initiated by donor allo-reactive T cells activated against recipient antigens. Chronic GVHD (cGVHD) is characterized by immune responses that may resemble autoimmune features present in the scleroderma and Sjogren's syndrome. Unfortunately, ocular involvement occurs in approximately 60-90% of patients with cGVHD following allo-hematopoietic stem cell transplants (aHSCT). Ocular GVHD (oGVHD) may affect vision due to ocular adnexa damage leading to dry eye and keratopathy. Several other compartments including the skin are major targets of GVHD effector pathways. Using mouse aHSCT models, the objective was to characterize cGVHD associated alterations in the eye and skin to assess for correlations between these two organs. The examination of multiple models of MHC-matched and MHC-mismatched aHSCT identified a correlation between ocular and cutaneous involvement accompanying cGVHD. Studies detected a "positive" correlation, i.e., when cGVHD-induced ocular alterations were observed, cutaneous compartment alterations were also observed. When no or minimal ocular signs were detected, no or minimal skin changes were observed. In total, these findings suggest underlying cGVHD-inducing pathological immune mechanisms may be shared between the eye and skin. Based on the present observations, we posit that when skin involvement is present in aHSCT patients with cGVHD, the evaluation of the ocular surface by an ophthalmologist could potentially be of value.

This study aimed to explore women’s experiences of infant feeding in Ireland

Background

While breastfeeding may be among the most effective ways to ensure child health and survival, breastfeeding rates in Ireland are consistently low. This study aimed to explore women's experiences of infant feeding in Ireland.

Methods

Thematic analysis of feeding-related free-text comments from the National Maternity Experience Survey 2020 was undertaken. The survey collected data on the experiences of women who were 16 years or older and gave birth in one of Ireland's 19 maternity hospitals or units or had a home birth.

Results

3,204 women participated in the survey (50% response rate). In the first few days after birth, 41.9% of women breastfed exclusively, 29.0% used formula and breast milk, and 29.1% bottle fed only. 824 comments related to feeding were received. A number of themes were identified, including support and encouragement from healthcare professionals, information and education regarding feeding, and pressure and respect for personal preferences. Women highlighted that while breastfeeding was encouraged in antenatal care, this was not always the case in the postnatal ward, where formula was readily available, with an apparent lack of resources for breastfeeding women. Some women described feeling pressured to use a feeding method that was not their first preference, with some feeling pushed to breastfeed when this may not have been their wish, while women who wished to breastfeed felt pressured to supplement with formula. Staffing shortages on postnatal wards, a lack of lactation consultants and contradictory advice from healthcare professionals exacerbated difficulties with both feeding methods.

Conclusions

Some women experience a lack of practical support with infant feeding, regardless of feeding method, and clear and concise information on feeding practices is needed. The addition of lactation consultants, home supports and further education and training could benefit mothers on their breastfeeding journey.

Key messages

Barriers to breastfeeding included a lack of support from healthcare professionals and conflicting information. It is important to support women regardless of their chosen feeding method.

AAPM Task Group 198 Report: An implementation guide for TG 142 quality assurance of medical accelerators

The charges on this task group (TG) were as follows: (a) provide specific procedural guidelines for performing the tests recommended in TG 142; (b) provide estimate of the range of time, appropriate personnel, and qualifications necessary to complete the tests in TG 142; and (c) provide sample daily, weekly, monthly, or annual quality assurance (QA) forms. Many of the guidelines in this report are drawn from the literature and are included in the references. When literature was not available, specific test methods reflect the experiences of the TG members (e.g., a test method for door interlock is self-evident with no literature necessary). In other cases, the technology is so new that no literature for test methods was available. Given broad clinical adaptation of volumetric modulated arc therapy (VMAT), which is not a specific topic of TG 142, several tests and criteria specific to VMAT were added.

401 Three Birds with One Stone: Ureteric Calculus Precipitates Diagnosis and Resection of Three Primary Neoplasms

A 67 year-old female presented to our centre with a 2 day history of right flank pain, clinically suggestive of ureteric colic. Computed tomography (CT) confirmed a 6mm right ureteric calculus. However, CT also revealed a large 13cm ipsilateral renal mass, concerning for renal cell carcinoma (RCC). At ureteroscopy for management of the obstructing calculus, a small papillary lesion was noted in the bladder, and excised. Histology confirmed pTa low-grade transitional cell carcinoma.

Following discussion at the Urology multidisciplinary tumour board, MRI venogram (MRV) was recommended to delineate the extension of tumour into the renal vein, and to characterise a pelvic mass seen on original CT. MRV showed enhancing material extending into the IVC, consistent with tumour thrombus. However, it also identified a concerning 6cm solid ovarian mass.

The patient proceeded to open right radical nephrectomy and IVC thrombectomy, hysterectomy, bilateral salpingo-oopherectomy, and omental biopsy, with combined input from Urological, Gynaecological and Vascular surgical teams. Post-operative course was uneventful. Histology showed an 11cm pT3a G2 clear cell RCC, and 7.5cm ovarian fibroma, both fully excised. This case demonstrated the serendipity of a simple ureteric calculus precipitating a cascade of investigations, that ultimately led to complete resection of three primary neoplasms.

Absorbed dose distributions from beta-decaying radionuclides: Experimental validation of Monte Carlo tools for radiopharmaceutical dosimetry

PURPOSE

This study aims to experimentally validate the Monte Carlo generated absorbed doses from the beta particles emitted by ⁹⁰ Y and ¹⁷⁷ Lu using radiochromic EBT3 film-based dosimetry.

METHODS

Line sources of ⁹⁰ Y and ¹⁷⁷ Lu were inserted longitudinally through blocks of low-density polyethylene and tissue-equivalent slabs of cortical bone and lung equivalent plastics. Radiochromic film (Gafchromic EBT3) was laser cut to accommodate orthogonal line sources of radioactivity, and the film was sandwiched intimately between the rectangular blocks to achieve charged particle equilibrium. Line sources consisted of plastic capillary tube of length (13 ± 0.1) cm, with 0.42-mm inner diameter and a wall thickness of 0.21 mm. ⁹⁰ Y line sources were prepared from a solution of dissolved ⁹⁰ Y resin microspheres. ¹⁷⁷ Lu line sources were prepared from an aliquot of ¹⁷⁷ Lu-DOTATATE. Film exposures were conducted for durations ranging from 10 min to 38 h. Radiochromic film calibration was performed by irradiation with 6-MV-bremsstrahlung x rays from a calibrated linear accelerator, in accordance with literature recommendations. Experimental geometries were precisely simulated within the GATE Monte Carlo toolkit, which has previously been used for the generation of dose point kernels.

RESULTS

The mean percentage difference between measured and simulated absorbed doses were 5.04% and 7.21% for ⁹⁰ Y and ¹⁷⁷ Lu beta absorbed dose in the range of (0.1-10) Gy. Additionally, 1D gamma analysis using a local 10%/1 mm gamma criterion was performed to compare the absorbed dose distributions. The percentage of measurement points passing the gamma criterion, averaged over all tests, was 93.5%.

CONCLUSIONS

We report the experimental validation of Monte Carlo derived beta absorbed dose distributions for ⁹⁰ Y and ¹⁷⁷ Lu, solidifying the validity of using Monte Carlo-based methods for estimating absorbed dose from beta emitters. Overall, excellent agreement was observed between the experimental beta absorbed doses in the linear region of the radiochromic film and the GATE Monte Carlo simulations demonstrating that radiochromic film dosimetry has sufficient sensitivity and spatial resolution to be used as a tool for measuring beta decay absorbed dose distributions.

PD-1 blockade later but not at post-transplant attenuates chronic graft-versus-host disease

PD-1 and its ligand PD-L1 are widely appreciated as targets of immune checkpoint blockade. We sought to investigate the role of the PD-1 pathway in the context of chronic graft-versus-host disease (cGVHD). To induce cGVHD, mice are conditioned with Cytoxan and radiation prior to MHC disparate bone marrow (BM) + T cells (70k) and develop multi-organ symptoms with bronchiolitis obliterans lung manifestations. CGHVD mice have high survival rates past 50 days, with &lt;15% weight loss over this period. Anti-PD-1 mAb given to mice with established cGVHD resulted in disease attenuation assessed by significantly improved pulmonary function tests compared to irrelevant mAb controls. PD-1 blockade significantly reduced germinal center (GC)-promoting GC B and T follicular helper (Tfh) cell and increased GC-suppressing T-follicular regulatory (Tfr) cell frequencies. However, in studies with mice given five percent higher T cell dose, resulting in T cell rather than GC-mediated disease, anti-PD-1 mAb dramatically worsened cGVHD severity. To assess GC cell-specific effects, recipients were given PD-1-deficient cells in graft compartments. Mice receiving PD-1 KO T cells predictably exhibited marked escalation of cGVHD severity and lethality, while mice receiving PD-1 KO B cells showed diminished disease, with significant improvement in pulmonary function. Co-culture of isolated B, Tfh and Tfr cells from NP-OVA immunized mice to determine effects of individual GC cell populations on Ig class switching demonstrated significant increase in Tfr suppressive capacity with addition of anti-PD-1 mAb. Together, these data provide evidence for PD-1 support of the GC reaction and identifies the PD-1/PD-L1 axis as a potential target for cGVHD therapy.

Targeting PI3Kδ function for amelioration of murine chronic graft-versus-host disease

Chronic graft-versus-host disease (cGVHD) is a leading cause of morbidity and mortality following allotransplant. Activated donor effector T cells can differentiate into pathogenic T helper (Th)-17 cells and germinal center (GC)-promoting T follicular helper (Tfh) cells, resulting in cGVHD. Phosphoinositide-3-kinase-δ (PI3Kδ), a lipid kinase, is critical for activated T cell survival, proliferation, differentiation, and metabolism. We demonstrate PI3Kδ activity in donor T cells that become Tfh cells is required for cGVHD in a nonsclerodermatous multiorgan system disease model that includes bronchiolitis obliterans (BO), dependent upon GC B cells, Tfhs, and counterbalanced by T follicular regulatory cells, each requiring PI3Kδ signaling for function and survival. Although B cells rely on PI3Kδ pathway signaling and GC formation is disrupted resulting in a substantial decrease in Ig production, PI3Kδ kinase-dead mutant donor bone marrow-derived GC B cells still supported BO cGVHD generation. A PI3Kδ-specific inhibitor, compound GS-649443, that has superior potency to idelalisib while maintaining selectivity, reduced cGVHD in mice with active disease. In a Th1-dependent and Th17-associated scleroderma model, GS-649443 effectively treated mice with active cGVHD. These data provide a foundation for clinical trials of US Food and Drug Administration (FDA)-approved PI3Kδ inhibitors for cGVHD therapy in patients.

Inhibiting EZH2 function prevents and treats chronic graft vs host disease (cGVHD) by disrupting germinal center formation and plasma cell maturation

To determine whether targeting EZH2, a histone methyltransferase necessary for germinal center (GC) formation, could reduce murine cGVHD (cGVHD), we first used a clinically relevant murine model of cGVHD, which recapitulates multi-organ cGVHD with bronchiolitis obliterans (BOS). Bone marrow (BM) from EZH2 fl/fl CD19 Cre B6 mice and WT T cells, or WT B6 BM and EZH2 fl/fl CD4 Cre B6 T cells were given to conditioned B10.BR mice. EZH2 expression in BM and T cells was obligatory for cGVHD. To determine whether EZH2 function could be targeted to treat cGVHD, we tested a novel EZH2 small molecule inhibitor, JQ5 with a favorable toxicity and efficacy profile to other inhibitors. Mice with established cGVHD given JQ5 had dramatically improved cGVHD. Similar results were seen in a sclerodermatous cGVHD model. To assess possible causes of this improvement we performed RNA-seq and ATAC-seq data of MACS purified CD19+ B cells obtained from control and JQ5 treated BOS cGVHD mice. Unsupervised gene set enrichment analysis and weighted gene correlation network analysis showed that among gene clusters associated with JQ5 treatment there was an enrichment for genes expressed in naïve B cells compared to plasma cells (GSEA4142) and an impairment of genes associated with late stage GC B cells compared to early follicular B cells (GSEA11961). This suggested that JQ5 impaired GC B cell and plasma cell maturation. Consistent with these data, splenic follicular cells, GC size and number, and lung resident PCs were reduced compared to cGVHD controls. Taken together these results show that EZH2 is necessary for the initiation of cGVHD and show for the first time that EZH2 inhibition using a novel inhibitor JQ5 can reverse established cGVHD in mice with BOS or scleroderma.

C5aR1 regulates T follicular helper differentiation and chronic graft-versus-host disease bronchiolitis obliterans

CD4+ follicular helper T (Tfh) cells are specialized providers of T cell help to B cells and can function as pathogenic mediators of murine antibody-dependent chronic graft-versus-host disease (GvHD). Using a parent→F1 model of lupus-like chronic GvHD, in which Tfh cell and germinal center (GC) B cell differentiation occurs over 14 days, we demonstrate that absence of CD4+ T cell-expressed C5a receptor 1 (C5ar1) or pharmacological C5aR1 blockade abrogated generation/expansion of Tfh cells, GC B cells, and autoantibodies. In a Tfh cell-dependent model of chronic GvHD manifested by bronchiolitis obliterans syndrome (BOS), C5aR1 antagonism initiated in mice with established disease ameliorated BOS and abolished the associated differentiation of Tfh and GC B cells. Guided by RNA-sequencing data, mechanistic studies performed using murine and human T cells showed that C5aR1 signaling amplifies IL-6-dependent expression of the transcription factor c-MAF and the cytokine IL-21 via phosphorylating phosphokinase B (AKT) and activating the mammalian target of rapamycin (mTOR). In addition to linking C5aR1-initiated signaling to Tfh cell differentiation, our findings suggest that C5aR1 may be a useful therapeutic target for prevention and/or treatment of individuals with Tfh cell-dependent diseases, including those chronic GvHD patients who have anti-host reactive antibodies.

Notch signaling mediated by Delta-like ligands 1 and 4 controls the pathogenesis of chronic GVHD in mice

Chronic graft-versus-host disease (cGVHD) is a major complication of allogeneic hematopoietic cell transplantation (allo-HCT) and remains an area of unmet clinical need with few treatment options available. Notch blockade prevents acute GVHD in multiple mouse models, but the impact of Notch signaling on cGVHD remains unknown. Using genetic and antibody-mediated strategies of Notch inhibition, we investigated the role of Notch signaling in complementary mouse cGVHD models that mimic several aspects of human cGVHD in search of candidate therapeutics. In the B10.D2→BALB/c model of sclerodermatous cGVHD, Delta-like ligand 4 (Dll4)-driven Notch signaling was essential for disease development. Antibody-mediated Dll4 inhibition conferred maximum benefits when pursued early in a preventative fashion, with anti-Dll1 enhancing early protection. Notch-deficient alloantigen-specific T cells showed no early defects in proliferation or helper polarization in vivo but subsequently exhibited markedly decreased cytokine secretion and enhanced accumulation of FoxP3+ regulatory T cells. In the B6→B10.BR major histocompatibility complex-mismatched model with multi-organ system cGVHD and prominent bronchiolitis obliterans (BO), but not skin manifestations, absence of Notch signaling in T cells provided long-lasting disease protection that was replicated by systemic targeting of Dll1, Dll4, or both Notch ligands, even during established disease. Notch inhibition decreased target organ damage and germinal center formation. Moreover, decreased BO-cGVHD was observed upon inactivation of Notch1 and/or Notch2 in T cells. Systemic targeting of Notch2 alone was safe and conferred therapeutic benefits. Altogether, Notch ligands and receptors regulate key pathogenic steps in cGVHD and emerge as novel druggable targets to prevent or treat different forms of cGVHD.

Murine chronic graft-versus-host disease proteome profiling discovers CCL15 as a novel biomarker in patients

Improved diagnostic and treatment methods are needed for chronic graft-versus-host disease (cGVHD), the leading cause of late nonrelapse mortality (NRM) in long-term survivors of allogenic hematopoietic cell transplantation. Validated biomarkers that facilitate disease diagnosis and classification generally are lacking in cGVHD. Here, we conducted whole serum proteomics analysis of a well-established murine multiorgan system cGVHD model. We discovered 4 upregulated proteins during cGVHD that are targetable by genetic ablation or blocking antibodies, including the RAS and JUN kinase activator, CRKL, and CXCL7, CCL8, and CCL9 chemokines. Donor T cells lacking CRK/CRKL prevented the generation of cGVHD, germinal center reactions, and macrophage infiltration seen with wild-type T cells. Whereas antibody blockade of CCL8 or CXCL7 was ineffective in treating cGVHD, CCL9 blockade reversed cGVHD clinical manifestations, histopathological changes, and immunopathological hallmarks. Mechanistically, elevated CCL9 expression was present predominantly in vascular smooth muscle cells and uniquely seen in cGVHD mice. Plasma concentrations of CCL15, the human homolog of mouse CCL9, were elevated in a previously published cohort of 211 cGVHD patients compared with controls and associated with NRM. In a cohort of 792 patients, CCL15 measured at day +100 could not predict cGVHD occurring within the next 3 months with clinically relevant sensitivity/specificity. Our findings demonstrate for the first time the utility of preclinical proteomics screening to identify potential new targets for cGVHD and specifically CCL15 as a diagnosis marker for cGVHD. These data warrant prospective biomarker validation studies.

Image guidance doses delivered during radiotherapy: Quantification, management, and reduction: Report of the AAPM Therapy Physics Committee Task Group 180

BACKGROUND

With radiotherapy having entered the era of image guidance, or image-guided radiation therapy (IGRT), imaging procedures are routinely performed for patient positioning and target localization. The imaging dose delivered may result in excessive dose to sensitive organs and potentially increase the chance of secondary cancers and, therefore, needs to be managed.

AIMS

This task group was charged with: a) providing an overview on imaging dose, including megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), Tomotherapy MV-CT, megavoltage cone-beam CT (MV-CBCT) and kilovoltage cone-beam CT (kV-CBCT), and b) providing general guidelines for commissioning dose calculation methods and managing imaging dose to patients.

MATERIALS & METHODS

We briefly review the dose to radiotherapy (RT) patients resulting from different image guidance procedures and list typical organ doses resulting from MV and kV image acquisition procedures.

RESULTS

We provide recommendations for managing the imaging dose, including different methods for its calculation, and techniques for reducing it. The recommended threshold beyond which imaging dose should be considered in the treatment planning process is 5% of the therapeutic target dose.

DISCUSSION

Although the imaging dose resulting from current kV acquisition procedures is generally below this threshold, the ALARA principle should always be applied in practice. Medical physicists should make radiation oncologists aware of the imaging doses delivered to patients under their care.

CONCLUSION

Balancing ALARA with the requirement for effective target localization requires that imaging dose be managed based on the consideration of weighing risks and benefits to the patient.

Primary Renal Carcinoid - A Case Report

Carcinoid tumours in the abdomen are uncommon, but typically occur in the gastrointestinal tract. Primary renal carcinoid is an extremely rare tumour, poorly described in the literature. We describe an unusual case where an atypical renal mass on imaging led to a preoperative diagnosis of renal carcinoid on imaging guiding biopsy.

Design of a compact collimator and 3D imaging system for a scanning beam low-energy intraoperative radiation therapy system for pancreatic cancer

Intraoperative radiation therapy (IORT) involves delivering high doses of radiation directly to tumors while sparing healthy tissues in a surgical setting. Current IORT systems are limited in their lack of image guidance and variable needs for shielded operating rooms. They also lack the capability to deliver non-uniform therapeutic radiation to irregular shaped clinical targets. We developed a scanning beam IORT system (SBIORT) to overcome these limitations. SBIORT consists of a low energy x-ray source, a custom compact dynamic x-ray collimator system, a robotic arm, and a 3D surface imaging module. Here we describe the design and validation of the compact dynamic x-ray collimator system and the 3D surface imaging module for use in SBIORT. The proposed collimator can achieve a leaf position accuracy of ± 0.25 mm (95% confidence interval). Phantom studies indicated the 3D surface-imaging module has an accuracy of 1.0 ± 0.6 mm with ability to obtain high resolution surface image within 5 seconds. SBIORT is a novel approach to deliver conformal intensity-modulated intraoperative radiation therapy.

An activated Th17-prone T cell subset involved in chronic graft-versus-host disease sensitive to pharmacological inhibition

Chronic graft-versus-host disease (cGvHD) remains a major complication of allogeneic stem cell transplantation requiring novel therapies. CD146 and CCR5 are expressed by activated T cells and associated with increased T cell migration capacity and Th17 polarization. We performed a multiparametric flow cytometry analysis in a cohort of 40 HSCT patients together with a cGvHD murine model to understand the role of CD146-expressing subsets. We observed an increased frequency of CD146+ CD4 T cells in the 20 patients with active cGvHD with enhanced RORγt expression. This Th17-prone subset was enriched for cells coexpressing CD146 and CCR5 that harbor mixed Th1/Th17 features and were more frequent in cGvHD patients. Utilizing a murine cGvHD model with bronchiolitis obliterans (BO), we observed that donor T cells from CD146-deficient mice versus those from WT mice caused significantly reduced pulmonary cGvHD. Reduced cGvHD was not the result of failed germinal center B cell or T follicular helper cell generation. Instead, CD146-deficient T cells had significantly lower pulmonary macrophage infiltration and T cell CCR5, IL-17, and IFN-γ coexpression, suggesting defective pulmonary end-organ effector mechanisms. We, thus, evaluated the effect of TMP778, a small-molecule RORγt activity inhibitor. TMP778 markedly alleviated cGvHD in murine models similarly to agents targeting the Th17 pathway, such as STAT3 inhibitor or IL-17-blocking antibody. Our data suggest CD146-expressing T cells as a cGvHD biomarker and suggest that targeting the Th17 pathway may represent a promising therapy for cGvHD.

Inositol kinase Itpkb is a novel therapeutic target for chronic graft versus host disease (cGVHD)

Chronic graft versus host disease (cGVHD) is a common and life-threatening complication of allogeneic hematopoietic stem cell transplantation. cGVHD is mediated by donor T cells recognizing and attacking host tissues followed by activation of effector cells such as B cells to product pathogenic autoantibodies and macrophages to mediate fibrotic responses. Safer and more effective therapies are needed for cGVHD treatment. Inositol 1,4,5-trisphosphate 3-kinase B (Itpkb) is a Ca2+ dependent kinase downstream of lymphocyte receptor signaling that regulates T and B cell homeostasis and function by controlling the intracellular Ca2+ level, thus regulating apoptotic responses. Genetic deletion of Itpkb results in apoptosis. GNF362, a LMW Itpkb inhibitor blocks T cell driven autoimmunity. In this study, we explore the role of Itpkb in cGVHD pathogenesis and hypothesize that cGVHD can be prevented by disrupting the Itpkb signaling pathway. We test the hypothesis in two preclinical cGVHD models with distinct clinical manifestations and pathophysiology, including a multi-organ system cGVHD mouse model that is characterized by bronchiolitis obliterans (BO) driven by spontaneous germinal center reactions and antibody deposition, and a scleroderma model that is characterized by macrophage infiltration and skin fibrosis. This study demonstrates that depleting Itpkb in donor T cells, but not in donor bone marrow blocked cGVHD lung disease and germinal center reaction in the BO model. In addition, pharmaceutical inhibition of Itpkb with GNF362 significantly reduced cGVHD manifestations in both models. These data identify Itpkb as an essential mediator of cGVHD pathogenesis and suggest Itpkb inhibition as a novel approach to treat cGVHD.

Modulation of the immune response to Mycobacterium tuberculosis during malaria/M. tuberculosis co-infection

Tuberculosis (TB) causes significant morbidity and mortality on a global scale. The African region has 24% of the world's TB cases. TB overlaps with other infectious diseases such as malaria and HIV, which are also highly prevalent in the African region. TB is a leading cause of death among HIV-positive patients and co-infection with HIV and TB has been described as a syndemic. In view of the overlapping epidemiology of these diseases, it is important to understand the dynamics of the immune response to TB in the context of co-infection. We investigated the cytokine response to purified protein derivative (PPD) in peripheral blood mononuclear cells from TB patients co-infected with HIV or malaria and compared it to that of malaria- and HIV-free TB patients. A total of 231 subjects were recruited for this study and classified into six groups; untreated TB-positive, TB positive subjects on TB drugs, TB- and HIV-positive, TB- and malaria-positive, latent TB and apparently healthy control subjects. Our results demonstrate maintenance of interferon (IFN)-γ production in HIV and malaria co-infected TB patients in spite of lower CD4 counts in the HIV-infected cohort. Malaria co-infection caused an increase in the production of the T helper type 2 (Th2)-associated cytokine interleukin (IL)-4 and the anti-inflammatory cytokine IL-10 in PPD-stimulated cultures. These results suggest that malaria co-infection diverts immune response against M. tuberculosis towards a Th-2/anti-inflammatory response which might have important consequences for disease progression.

Transcriptome analysis of GVHD reveals aurora kinase A as a targetable pathway for disease prevention

Graft-versus-host disease (GVHD) is the most common complication of hematopoietic stem cell transplant (HCT). However, our understanding of the molecular pathways that cause this disease remains incomplete, leading to inadequate treatment strategies. To address this, we measured the gene expression profile of nonhuman primate (NHP) T cells during acute GVHD. Utilizing microarray technology, we measured the expression profiles of CD3(+) T cells from five cohorts: allogeneic transplant recipients receiving (i) no immunoprophylaxis (No Rx), (ii) sirolimus monotherapy (Siro), (iii) tacrolimus-methotrexate (Tac-Mtx), as well as (iv) autologous transplant recipients (Auto) and (v) healthy controls (HC). This comparison allowed us to identify transcriptomic signatures specific for alloreactive T cells and determine the impact of both mTOR (mechanistic target of rapamycin) and calcineurin inhibition on GVHD. We found that the transcriptional profile of unprophylaxed GVHD was characterized by significant perturbation of pathways regulating T cell proliferation, effector function, and cytokine synthesis. Within these pathways, we discovered potentially druggable targets not previously implicated in GVHD, prominently including aurora kinase A (AURKA). Utilizing a murine GVHD model, we demonstrated that pharmacologic inhibition of AURKA could improve survival. Moreover, we found enrichment of AURKA transcripts both in allo-proliferating T cells and in sorted T cells from patients with clinical GVHD. These data provide a comprehensive elucidation of the T cell transcriptome in primate acute GVHD and suggest that AURKA should be considered a target for preventing GVHD, which, given the many available AURKA inhibitors in clinical development, could be quickly deployed for the prevention of GVHD.

ROCK2 signaling is required to induce a subset of T follicular helper cells through opposing effects on STATs in autoimmune settings

Rho-associated kinase 2 (ROCK2) determines the balance between human T helper 17 (TH17) cells and regulatory T (Treg) cells. We investigated its role in the generation of T follicular helper (TFH) cells, which help to generate antibody-producing B cells under normal and autoimmune conditions. Inhibiting ROCK2 in normal human T cells or peripheral blood mononuclear cells from patients with active systemic lupus erythematosus (SLE) decreased the number and function of TFH cells induced by activation ex vivo. Moreover, inhibition of ROCK2 activity decreased the abundance of the transcriptional regulator Bcl6 (B cell lymphoma 6) and increased that of Blimp1 by reducing the binding of signal transducer and activator of transcription 3 (STAT3) and increasing that of STAT5 to the promoters of the genes Bcl6 and PRDM1, respectively. In the MRL/lpr murine model of SLE, oral administration of the selective ROCK2 inhibitor KD025 resulted in a twofold reduction in the numbers of TFH cells and antibody-producing plasma cells in the spleen, as well as a decrease in the size of splenic germinal centers, which are the sites of interaction between TFH cells and B cells. KD025-treated mice showed a substantial improvement in both histological and clinical scores compared to those of untreated mice and had reduced amounts of Bcl6 and phosphorylated STAT3, as well as increased STAT5 phosphorylation. Together, these data suggest that ROCK2 signaling plays a critical role in controlling the development of TFH cells induced by autoimmune conditions through reciprocal regulation of STAT3 and STAT5 activation.

Isoform-specific targeting of ROCK proteins in immune cells

Rho-associated kinase 1 (ROCK1) and ROCK2 are activated by Rho GTPase and control cytoskeleton rearrangement through modulating the phosphorylation of their down-stream effector molecules. Although these 2 isoforms share more than 90% homology within their kinase domain the question of whether ROCK proteins function identically in different cell types is not clear. By using both pharmacological inhibition and genetic knockdown approaches recent studies suggest that the ROCK2 isoform plays an exclusive role in controlling of T-cell plasticity and macrophage polarization. Specifically, selective ROCK2 inhibition shifts the balance between pro-inflammatory and regulatory T-cell subsets via concurrent regulation of STAT3 and STAT5 phosphorylation, respectively. Furthermore, the administration of an orally available selective ROCK2 inhibitor effectively ameliorates clinical manifestations in experimental models of autoimmunity and chronic graft-vs.-host disease (cGVHD). Because ROCK2 inhibition results in the suppression of M2-type macrophages while favoring polarization of M1-type macrophages, ROCK2 inhibition can correct the macrophage imbalance seen during age-related macular degeneration (AMD). In summary, the exclusive role of ROCK2 in immune system modulation argues for the development and testing of isoform-specific ROCK2 inhibitors for the treatment of inflammatory disorders.

Proteomics analysis reveals a Th17-prone cell population in presymptomatic graft-versus-host disease

Gastrointestinal graft-versus-host-disease (GI-GVHD) is a life-threatening complication occurring after allogeneic hematopoietic cell transplantation (HCT), and a blood biomarker that permits stratification of HCT patients according to their risk of developing GI-GVHD would greatly aid treatment planning. Through in-depth, large-scale proteomic profiling of presymptomatic samples, we identified a T cell population expressing both CD146, a cell adhesion molecule, and CCR5, a chemokine receptor that is upregulated as early as 14 days after transplantation in patients who develop GI-GVHD. The CD4⁺CD146⁺CCR5⁺ T cell population is Th17 prone and increased by ICOS stimulation. shRNA knockdown of CD146 in T cells reduced their transmigration through endothelial cells, and maraviroc, a CCR5 inhibitor, reduced chemotaxis of the CD4⁺CD146⁺CCR5⁺ T cell population toward CCL14. Mice that received CD146 shRNA-transduced human T cells did not lose weight, showed better survival, and had fewer CD4⁺CD146⁺CCR5⁺ T cells and less pathogenic Th17 infiltration in the intestine, even compared with mice receiving maraviroc with control shRNA- transduced human T cells. Furthermore, the frequency of CD4⁺CD146⁺CCR5⁺ Tregs was increased in GI-GVHD patients, and these cells showed increased plasticity toward Th17 upon ICOS stimulation. Our findings can be applied to early risk stratification, as well as specific preventative therapeutic strategies following HCT.

Targeting PI3K signaling to ameliorate chronic graft versus host disease

The phosphoinositide 3-kinase (PI3K) pathway is a key signaling pathway necessary for T cell activation, differentiation and metabolism. T effector cells rely on increased PI3K signaling to fuel glycolysis for their metabolic needs, while T regulatory cells downregulate PI3K and favor lipid oxidation. The metabolic processes of lymphocytes modulating chronic graft versus host disease (cGVHD) have remained largely unexamined and represent a novel therapeutic strategy for this disease. Here, we investigated the role of PI3K signaling in a murine model of cGVHD that is etiologically linked to up regulated germinal centers (GCs) and characterized by multisystem organ disease; including fibrosis of the lung, which results in pulmonary dysfunction. We hypothesized that inhibition of PI3K signaling would alter the activation and/or function of GC-facilitating T follicular helper (TFH) cells resulting in lessened disease. The findings in this study are that mice treated with a PI3Kd inhibitor had decreased pulmonary dysfunction similar to that of the control, non-cGVHD mice. The frequencies of splenic TFH cells as well as GC B cells were decreased by a PI3K delta inhibitor compared to non-treated cGVHD controls. In a similar manner, mice that received PI3K kinase delta dead Tregs also had decreased TFH frequency as well as reduced pulmonary dysfunction. Our results indicate the differential requirement for signaling through PI3K delta and suggest that targeting this pathway may be a potential new therapy for treatment of cGVHD. Additional studies are required to validate the potential therapeutic use.

Evaluating the cost of iatrogenic urethral catheterisation injuries

INTRODUCTION

Technique is vital to prevent urethral trauma during urethral catheterisation (UC). Education programmes are helpful but are not compulsory and safe UC remains operator dependent. Traumatic UC is associated with increased morbidity, length of stay, resource utilisation and surgical intervention.

AIM

To determine the cost of iatrogenic urethral injuries managed in a tertiary referral centre over a 6-month period.

METHODS

A 6-month prospective study monitored iatrogenic urethral injuries secondary to traumatic UC. Included were referrals from district hospitals and inpatient consultations relating to urethral injury caused by traumatic UC. The added cost of management was estimated.

RESULTS

Thirteen iatrogenic urethral injuries were recorded in 6 months. Management included open surgery for a ruptured bladder (n = 1), flexible cystourethroscopy (n = 10), suprapubic catherisation (n = 4), 3-way catheterisation (n = 4) and catheter re-insertion under direct vision (n = 6). The cost of acute management of these injuries was approximately €50,000 including theatre costs, ambulance transfer, hospital stay, procedural and equipment costs and short-term follow-up care.

CONCLUSION

Iatrogenic injuries during UC represent a significant cost burden to the healthcare system. Training programmes should be compulsory for all healthcare professionals routinely involved in catheterisation procedures.

Improving Head and Neck Cancer Treatments Using Dynamic Collimation in Spot Scanning Proton Therapy

Purpose

Interest in using collimation for spot scanning proton therapy has recently increased in an attempt to improve the lateral penumbra. To investigate the advantages of such an approach for complex targets, a plan comparison between uncollimated and collimated beam spots was performed for patients with head and neck cancer.

Patients and Methods

For 10 patients with head and neck cancer, previously treated with spot scanning proton therapy, uncollimated and collimated treatment plans were created using an in-house treatment-planning system capable of modeling asymmetric-beamlet dose distributions resulting from the use of a dynamic collimation system. Both uncollimated and collimated plans reproduced clinically delivered plans in terms of target coverage. A relative plan comparison was performed using both physical and radiobiological metrics on the organs at risk.

Results

The dynamic collimation system improved dose-distribution conformity while preserving target coverage. The median reduction of the mean dose to the esophagus, uninvolved larynx, and uninvolved parotids were -11.9% (minimum to maximum, -6.4% to -24.1%), -7.2% (-0.8% to -60.1%), and -5.2% (-0.2% to -21.5%), respectively, and depended on the organ location relative to the target and radiation beam angle. The collimation did not improve dose to some organs at risk surrounded by the target or located upstream of Bragg peaks because of the priority on the target coverage.

Conclusion

In spot scanning proton therapy, the dynamic collimation system generally affords better target conformity, which results in improvement in organ-at-risk sparing in the head and neck region while preserving target coverage. However, the benefits of collimation and the increased complexity should be considered for each patient. Patients with large bilateral targets or organs at risk surrounded by the target showed the least benefit.

Ruxolitinib in corticosteroid-refractory graft-versus-host disease after allogeneic stem cell transplantation: a multicenter survey

Despite major improvements in allogeneic hematopoietic cell transplantation over the past decades, corticosteroid-refractory (SR) acute (a) and chronic (c) graft-versus-host disease (GVHD) cause high mortality. Preclinical evidence indicates the potent anti-inflammatory properties of the JAK1/2 inhibitor ruxolitinib. In this retrospective survey, 19 stem cell transplant centers in Europe and the United States reported outcome data from 95 patients who had received ruxolitinib as salvage therapy for SR-GVHD. Patients were classified as having SR-aGVHD (n=54, all grades III or IV) or SR-cGVHD (n=41, all moderate or severe). The median number of previous GVHD-therapies was 3 for both SR-aGVHD (1-7) and SR-cGVHD (1-10). The overall response rate was 81.5% (44/54) in SR-aGVHD including 25 complete responses (46.3%), while for SR-cGVHD the ORR was 85.4% (35/41). Of those patients responding to ruxolitinib, the rate of GVHD-relapse was 6.8% (3/44) and 5.7% (2/35) for SR-aGVHD and SR-cGVHD, respectively. The 6-month-survival was 79% (67.3-90.7%, 95% confidence interval (CI)) and 97.4% (92.3-100%, 95% CI) for SR-aGVHD and SR-cGVHD, respectively. Cytopenia and cytomegalovirus-reactivation were observed during ruxolitinib treatment in both SR-aGVHD (30/54, 55.6% and 18/54, 33.3%) and SR-cGVHD (7/41, 17.1% and 6/41, 14.6%) patients. Ruxolitinib may constitute a promising new treatment option for SR-aGVHD and SR-cGVHD that should be validated in a prospective trial.

Spot Weight Adaptation for Moving Target in Spot Scanning Proton Therapy

Purpose

This study describes a real-time spot weight adaptation method in spot-scanning proton therapy for moving target or moving patient, so that the resultant dose distribution closely matches the planned dose distribution.

Materials and methods

The method proposed in this study adapts the weight (MU) of the delivering pencil beam to that of the target spot; it will actually hit during patient/target motion. The target spot that a certain delivering pencil beam may hit relies on patient monitoring and/or motion modeling using four-dimensional (4D) CT. After the adapted delivery, the required total weight [Monitor Unit (MU)] for this target spot is then subtracted from the planned value. With continuous patient motion and continuous spot scanning, the planned doses to all target spots will eventually be all fulfilled. In a proof-of-principle test, a lung case was presented with realistic temporal and motion parameters; the resultant dose distribution using spot weight adaptation was compared to that without using this method. The impact of the real-time patient/target position tracking or prediction was also investigated.

Results

For moderate motion (i.e., mean amplitude 0.5 cm), D95% to the planning target volume (PTV) was only 81.5% of the prescription (R_X) dose; with spot weight adaptation PTV D95% achieves 97.7% R_X. For large motion amplitude (i.e., 1.5 cm), without spot weight adaptation PTV D95% is only 42.9% of R_X; with spot weight adaptation, PTV D95% achieves 97.7% R_X. Larger errors in patient/target position tracking or prediction led to worse final target coverage; an error of 3 mm or smaller in patient/target position tracking is preferred.

Conclusion

The proposed spot weight adaptation method was able to deliver the planned dose distribution and maintain target coverage when patient motion was involved. The successful implementation of this method would rely on accurate monitoring or prediction of patient/target motion.