OP0307 A NOVEL TARGETED APPROACH TO ACHIEVE IMMUNE SYSTEM RESET: CD45-TARGETED ANTIBODY DRUG CONJUGATES AMELIORATE DISEASE IN PRECLINICAL AUTOIMMUNE DISEASE MODELS AND ENABLE AUTO-HSCT

Background:

Resetting the immune system through autologous hematopoietic stem cell transplant (autoHSCT) is a highly effective treatment in selected patients with autoimmune diseases. AutoHSCT can induce long-term remission with 80% progression free survival in multiple sclerosis patients (Muraro 2017, Burt 2019). Use of autoHSCT in scleroderma patients has achieved superior outcomes in two randomized studies compared to standard of care (Tyndall 2014, Sullivan 2018). These impressive results are achieved by a combination of the eradication of autoreactive immune effector cells and re-establishment of self-tolerance, i.e., immune system reset. However, only a small fraction of eligible patients undergo autoHSCT, largely due to toxicity associated with current conditioning protocols.

Objectives:

As part of our goal to enable more patients to benefit from immune system reset, we have generated novel anti-human CD45 ADCs that cross react with nonhuman primates (NHP) and an anti-mouse CD45 ADC to model the approach in mouse models of AID.

Methods:

The human-targeted CD45-ADC is an affinity-matured mAb that targets an epitope present on all human CD45 isoforms, is cross-reactive with NHP CD45, and is conjugated to a payload that efficiently kills both quiescent and cycling cells. This ADC is engineered to eliminate Fc-mediated effector function, enable site-specific conjugation of linker/payload, and enable rapid clearance. This ADC was evaluated in vitro and in vivo in hNSG and NHPs. The murine tool ADC specifically targets the CD45.2 isoform of mouse CD45, and is also engineered to eliminate effector function, allow for site-specific conjugation of linker payload, and be rapidly cleared. The payload for this murine tool ADC is potent and preferentially kills dividing cells. This ADC was tested for the ability to enable immune reset and ameliorate autoimmune disease in multiple disease models.

Results:

The anti-human CD45-ADC showed efficient killing of human HSCs and human and cyno PBMC, including CD3+cells from healthy donors and patients with MS. In hNSG, single doses of the CD45-ADC were well-tolerated and led to substantial depletion of human cells. In NHPs, single doses of CD45-ADC were well tolerated and depleted both peripheral lymphocytes and HSCs. Administration of a single dose of anti-human CD45-ADC to hNSGs with sclerodermatous xenoGVHD resulted in depletion of human T cells and resolution of symptoms. A single-dose of the anti-mouse CD45-ADC enabled full myeloablation and complete durable donor chimerism with congenic HSCT at 16 weeks. In a murine immunization model of MS, MOG-induced EAE, a single dose of the CD45-ADC followed by congenic HSCT prior to disease onset enabled full donor chimerism, significantly delayed disease onset and reduced disease severity. We are generating additional data in an adoptive transfer model of EAE to confirm and extend these results. In a murine model of arthritis, therapeutic treatment with a single dose of the CD45-ADC followed by congenic HSCT enabled complete donor chimerism and halted disease progression, comparable to with the effects of an anti-TNFα antibody. The ADC is being further evaluated in a model of type 1 diabetes and those data will be presented. These data demonstrate that CD45-ADC conditioning followed by congenic HSCT is sufficient for full myeloablation and immune reset.

Conclusion:

These results demonstrate that targeted immune depletion with a single dose of CD45-ADC can enable auto-HSCT and immune reset in multiple AID indications without toxic side effects. Targeted conditioning with CD45-ADC may represent a better tolerated approach for removing disease-causing cells as part of immune reset through auto-HSCT and enable more patients to benefit.

Disclosure of Interests:

Geoffrey Gillard Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Jennifer Proctor Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Sharon Hyzy Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Oliver Mikse Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Tahirih Lamothe Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Sean McDonough Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Nicholas Clark Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Rahul Palchaudhuri Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Anjali Bhat Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Melissa Brooks Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Ganapathy Sarma Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Prashant Bhattarai Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Pranoti Sawant Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Brad Pearse Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Charlotte McDonagh Shareholder of: Magenta Therapeutics, Employee of: Magenta Therapeutics, Tony Boitano Shareholder of: Magenta, Employee of: Magenta, Michael Cooke Shareholder of: Magenta, Employee of: Magenta

Differences in caregiver behaviors of infants at-risk for autism and typically developing infants from 9 to 15 months of age

During an object sharing paradigm, we compared infant-caregiver interactions between two groups: i) infants at high-risk (HR) for being diagnosed with Autism Spectrum Disorder (ASD) and ii) low-risk (LR) infants, observed at 9, 12, and 15 months of age. 16 HR infants (14 infants with an older sibling diagnosed with ASD and 2 preterm infants that received a diagnosis of ASD at 2 years) and 16 LR infants (typically developing infants without older siblings diagnosed with ASD) were included in the study. At each visit, infants played with objects in the presence of their caregivers as crawlers or walkers. Previously, we found that HR infants are less likely to share their object play with caregivers at walker ages. The present study found that caregivers of HR infants used greater directive bids including being more proximal to infants and using greater verbal and non-verbal bids to sustain their infant's attention and to ensure their compliance during the task compared to caregivers of LR infants. Our study emphasizes the bidirectional and dynamic nature of infant-caregiver interactions. Our findings have implications for caregiver training programs that teach parents appropriate strategies to promote early social communication skills in at-risk infants.

P1709 Left atrial strain: a novel prognostic marker in patients with chronic kidney disease

Funding Acknowledgements

Nil

Background and objectives

Patients with chronic kidney disease (CKD) are at increased risk of adverse cardiovascular events that are underestimated by traditional risk stratification algorithms. We sought to determine clinical and echocardiographic predictors of adverse outcomes in CKD patients.

Methods

Stage 3 and 4 CKD patients without previous cardiac disease underwent a comprehensive transthoracic and stress echocardiogram, with left ventricular (LV) and left atrial (LA) strain analysis. Participants were followed for the primary end point of a composite of all-cause death and major adverse cardiovascular events (MACE). The secondary end point was a composite of cardiovascular death and MACE.

Results

243 patients (male 63%; mean age 59.2 ± 14.4 years) were followed for a median of 3.9 ± 2.7 years. 69 patients met the primary endpoint and 58 the secondary end point. Age (p < 0.01), history of diabetes mellitus (p < 0.01), indexed LV mass(LVMI) (p < 0.01), LV global longitudinal strain(GLS) (p < 0.01), indexed LA volume(LAVI) (p < 0.01), E/e’ ratio (p < 0.01) and LA strain (LAs) (p < 0.01) were independent predictors of death and MACE. On Cox proportional hazards regression analysis, LAs (p < 0.01) was the only independent predictor for the primary end point in a model accounting for age, diabetes mellitus, LVMI, LVGLS, E/e’ and LAVI. LAs remained an independent predictor for the secondary end point.

Conclusions

LAs is an independent predictor of death and MACE in CKD patients, in whom the predominant cardiac abnormality is diastolic impairment. LAs is a prognostic biomarker, reflecting alterations in diastolic function in CKD.

Abstract P1709 Figure. Kaplan Meier curve of LAs

1679 E/e predicts exercise capacity and adverse cardiovascular outcomes in patients with chronic kidney disease

Funding Acknowledgements

Nil

OnBehalf

NA

Background

Patients with chronic kidney disease(CKD) have reduced physical fitness that contributes to the disproportionately elevated risk of cardiovascular disease in this population. Our aim was to assess the association between E/e’ and exercise capacity in CKD patients and the prognostic role of E/e’.

Methods

Patients with Stage 3/4 CKD, without previous cardiac disease were prospectively recruited. Recruited patients underwent transthoracic echocardiogram and exercise stress echocardiogram with assessment of exercise E/e’. Patients were compared, one to one, to age, gender and risk factor matched controls and were followed annually for 5 years for cardiovascular death and major adverse cardiovascular events (MACE). Exercise capacity was assessed as metabolic equivalents (METs) with reduced exercise capacity defined as METS of ≤7. Raised exercise E/e’ was defined as exercise E/average e’ of >13.

Results

156 CKD patients (62.8 ± 10.6 yrs, male 62%) were compared to 156 matched controls. CKD patients had higher rates of anemia (p < 0.01), larger left ventricular indexed mass (p < 0.01), larger LAVI (p < 0.01) and higher resting (p < 0.01) and exercise E/e’ (p < 0.01). Overall, CKD patients achieved lower METs (p < 0.01) with exercise and a greater proportion of CKD patients had METs ≤7 (p < 0.01). Receiver operating curves (Figure1) showed exercise E/e’ (AUC 0.89, CI 0.84-0.95, p < 0.01) to be the strongest predictor of reduced exercise capacity in CKD patients. Exercise E/e’ of >13 was also associated with higher rates of cardiovascular death and MACE amongst CKD patients.

Conclusion

Exercise E/e’ is a strong predictor of exercise capacity amongst CKD patients, who commonly have reduced exercise capacity presumably consequent to diastolic dysfunction. Raised exercise E/e’ in CKD patients is predictor of cardiovascular death and MACE.

Abstract 1679 Figure.

P246 Exercise E/e refines diagnosis of diastolic impairment in patients with chronic kidney disease

Background

Diastolic dysfunction is common in chronic kidney disease (CKD) patients and is associated with reduced exercise capacity. The ratio of early diastolic mitral inflow velocity to early diastolic mitral annulus velocity (E/e’) correlates with invasively measured left ventricular pressures, both at rest and during exercise. The aim of our study was to evaluate the relationship of resting and exercise E/e’ to exercise capacity in patients with stage 3 and 4 CKD.

Methods

CKD patients were prospectively recruited. All patients were required to be in sinus rhythm, without previous cardiac disease and with normal LVEF. The E/e’ ratio was assessed at rest and patients were stratified into 3 groups based on conventional clinical classifications (normal: ≤8, indeterminate: 8-14, raised: >14). Patients then underwent a symptom limited exercise stress echocardiogram whereby patients with resting E/e’ <14 additionally had post exercise E/e’ measured. Exercise capacity was assessed as metabolic equivalents (METs). A raised exercise E/e’ was defined as exercise E/e’ of ≥13. Lastly, we grouped patients based on abnormalities of baseline and exercise E/e’ (resting E/e’<14 & exercise E/e’<13, resting E/e’<14 & exercise E/e ≥13, resting E/e’ ≥14) and the relationship to METs achieved was evaluated.

Results

The cohort consisted of 156 CKD patients (62.8 ± 10.6 yrs, male 62%). 85% had hypertension and 39% had diabetes mellitus. 52/156 (34%) CKD patients had resting E/e’ of ≥14. Of the 104/156 (66%) CKD patients with normal/indeterminate resting E/e’, 66/104(63%) had normal exercise E/e’ <13 whilst 38/104(37%) had exercise E/e’ ≥13. Patients with resting E/e" & raised exercise E/e’ ≥13 achieved significantly lower METs compared to CKD patients with resting E/e’ <14 & exercise E/e’ <13 (5.0 ± 2.2 vs 8.8 ± 2.5, p< 0.01). Of note, METs achieved in this group were comparable to that achieved by CKD patients with raised resting E/e’ ≥ 14 (5.0 ± 2.2 METs vs 5.3 ± 2.6 METs, p = 0.55).

Conclusion

In CKD patients with normal/indeterminate resting E/e’, there is utility in performing exercise E/e’, which was increased in 37% of patients. Raised exercise E/e’ is associated with poorer exercise capacity and is a potential tool to refine diastolic abnormalities in patients with CKD.

Group Total (n,%) METs Achieved Exercise Duration (minutes) Resting E/e’ ≤ 14 & Exercise E/e’ ≤ 13 66/156 (42%) 8.8 ± 2.5 8.4 ± 3.1 Resting E/e’ ≤ 14 & Exercise E/e’ ≥ 13 38/156 (24%) 5.0 ± 2.2 6.0 ± 3.1 Resting E/e’ ≥ 14 52/156 (34%) 5.3 ± 2.6 5.6 ± 2.2

P2468Clinical and cardiac structural differences between paroxysmal and persistent/permanent non-valvular atrial fibrillation

Background

Atrial Fibrillation (AF) is a heterogeneous condition and is traditionally classified by duration (paroxysmal, persistent and permanent). There is a relationship between AF and left atrial (LA) remodeling, with increased likelihood of AF recurrence and maintenance with increasing LA volumes.

Purpose

To assess clinical and cardiac structural differences between the subtypes of AF.

Methods

We examined 1247 (68±13.4y; 50% men) consecutive admissions presenting to our institution with the primary diagnosis of AF. Repeat admissions (n=263) were excluded. Of remaining 984 subjects, a majority had diagnosed paroxysmal (72.2%), with lower numbers of persistent (23.4%) and permanent (4.4%) AF. Echo parameters of cardiac chamber size and function were examined in a subset of subjects with complete echo (n=646) performed during incident hospital admission.

Results

There were significantly higher rates of diabetes mellitus (p=0.03), ischaemic heart disease (IHD; p=0.04) and peripheral vascular disease (PVD; p=0.02) in those with persistent/permanent AF compared to paroxysmal AF. No significant differences in age (p=0.19), BMI (p=0.42), OSA (p=0.05), or hypertension (p=0.76) was noted. There were significant differences in left ventricular (LV) mass and systolic function, LA size and function between the two groups (Table 1). Receiver operator curve analysis revealed that LAEF was a discriminator for persistent/permanent AF with an area under the curve of 0.689 (95% CI, 0.646 to 0.732; p<0.001).

Echo parameters in AF subtype Echocardiographic Parameters Paroxysmal AF (n=433) Persistent and Permanent AF (n=213) Significance (p value) LVEDD (cm) 4.8±3.0 5.0±0.9 0.29 LVESD (cm) 3.3±1.3 3.7±1.1 <0.01 IVS thickness (cm) 1.2±0.7 1.1±0.3 0.44 PW thickness (cm) 1.1±0.7 1.1±0.2 0.77 LV mass (g) 92.3±28.3 108.2±35.3 <0.01 LVEF (%) 56.1±14.1 47.4±16.8 <0.01 LA Expansion Index 89.4±69.1 53.4±40.3 <0.01 Min LA Volume indexed (ml/m2) 18.9±17.2 27.3±20.6 0.01 Max LA Volume indexed (ml/m2) 32.5±19.2 37.7±15.3 <0.01 LAEF (%) 41.8±16.4 31.5±13.6 <0.01

Conclusions

Our results suggest diabetes, IHD and PVD are associated with persistent/permanent AF. Additionally, greater LA remodeling and reduced atrial function was noted in this group, suggestive of an association between duration of AF electrical burden and LA remodeling and function.

P4353Global longitudinal strain is a measure of subclinical left ventricular dysfunction in chronic inflammatory autoimmune conditions

Background

Myocardial deformation indices are proposed to be a more sensitive marker of subclinical dysfunction compared to standard measures of left ventricular (LV) systolic function. We hypothesize that subclinical myocardial dysfunction is present in chronic inflammatory autoimmune diseases such as Systemic Lupus Erythematosus (SLE) and Rheumatoid Arthritis (RA), despite both conditions being mediated by different pro-inflammatory modulators.

Purpose

Identify subclinical myocardial dysfunction through assessment of global longitudinal strain in two different chronic autoimmune conditions, SLE and RA.

Methods

Consecutive patients admitted to our institution with known history of SLE or RA (>1 year disease activity) were examined. Patients with preexisting cardiac disease, LVEF <50% and those without comprehensive transthoracic echocardiograms (TTE) were excluded. Mean longitudinal LV strain was performed offline using vendor-independent software (TomTec v4.6) and compared to age- and gender-matched controls with normal LV function and no history of cardiac disease.

Results

Of the 86 patients examined (mean age 53.01±21.74, 85.4% female), 51 (59.3%) had SLE and 35 (40.7%) had RA. No significant difference in BMI, hypertension, hypercholesterolemia, diabetes, obesity, obstructive sleep apnea and stroke was observed between controls and patients with SLE or RA. While there was no significant difference in LVEF between RA patients and matched controls, there was a significantly lower GLS in the RA cohort. Conversely, patients with SLE had significantly lower LVEF and GLS when compared to matched controls, despite LVEF being in the normal range. See Table 1. Receiver operator curve analysis revealed that mean GLS is a better discriminator for autoimmune disease with an area under the curve of 0.829 (95% CI, 0.77 to 0.89; p<0.01) compared to LVEF with an area under the curve of 0.632 (95% CI, 0.55 to 0.72; p<0.01).

Echocardiographic Parameters SLE (n=51) Controls (n=51) Sig (p value) RA (n=35) Controls (n=35) Sig (p value) LVEDV (mls) 102±30 85±20 <0.01 84±28 89±30 0.43 LVESV (mls) 36±17 29±9 0.02 26±14 30±12 0.24 Biplane LVEF % 59±6 63±4 <0.01 62±6 62±5 0.81 LV Mass (grams/m2) 96±34 72±20 <0.01 79±26 82±23 0.67 LV Mean GLS % 16.7±2.8 21.3±2 <0.01 17.8±1.7 19.1±2.5 0.02

Conclusions

Our results suggest that chronic inflammatory conditions (SLE and RA) are associated with subclinical cardiac dysfunction. Impaired GLS may reflect early myocardial damage and be used as a tool for screening of patients with inflammatory conditions.

Acknowledgement/Funding

None

First Measurement of Inclusive Muon Neutrino Charged Current Differential Cross Sections on Argon at E_{ν}∼0.8 GeV with the MicroBooNE Detector

We report the first measurement of the double-differential and total muon neutrino charged current inclusive cross sections on argon at a mean neutrino energy of 0.8 GeV. Data were collected using the MicroBooNE liquid argon time projection chamber located in the Fermilab Booster neutrino beam and correspond to 1.6×10^{20} protons on target of exposure. The measured differential cross sections are presented as a function of muon momentum, using multiple Coulomb scattering as a momentum measurement technique, and the muon angle with respect to the beam direction. We compare the measured cross sections to multiple neutrino event generators and find better agreement with those containing more complete treatment of quasielastic scattering processes at low Q^{2}. The total flux integrated cross section is measured to be 0.693±0.010(stat)±0.165(syst)×10^{-38}  cm^{2}.

Therapeutic use of Lucilia sericata maggot in controlling bacterial bio-burden in Rat wound model

Delayed wound healing due to extraneous bacterial contamination, antibacterial resistance and other associated factors are of great concern in dealing patients having chronically infected wound. Medicinal properties of certain maggots of Calliphoridae family are known for its effective wound debridement therapy. The objective of the study was to evaluate the wound healing potential of maggots of Lucilia sericata in an experimentally infected cutaneous wound model in Wistar rat. The study was carried out by using male Wistar rats (n=48) by creating excisional wounds and later contaminated with mixed population of gram positive and gram-negative bacteria. Animals were divided randomly in to four groups with 12 individuals each, being denominated as control, antibiotic treated, maggot treated, and antibiotic plus maggot combination treated group. Ten pre-sterilized maggots were applied per centimetre square wound bed for 24 hours. Different wound kinetics in L. sericata maggot treated wounds revealed significant reduction in wound area with maximum contraction, early elimination of bacterial bioburden as compared to group of infected control and group of rats receiving only antibiotic treatment. The histopathological examination of wounded tissue of maggot treated groups showed early and better epithelialization, collagenation and neovascularization with complete healing of wound in two weeks. The maggot effects on healing when used singly or in combination with antibiotic were recorded to be similar. The results of the present study clearly demonstrate that the maggots of L. sericata possesses a definite antibacterial action along with removal of dead tissues and effectively reduced the bacterial bio-burden in infected wound and induced wound healing quickly.

Solitary fibrous tumor of the ischioanal fossa-a multidisciplinary approach to management with radiologic-pathologic correlation

Solitary fibrous tumors are primary mesenchymal tumors, which may occur in any part of the body. Overall, these tumors are considered to have intermediate malignant potential with 5- and 10-year metastasis-free and overall disease-specific survival rates of 74% and 55%, and 89% and 73%, respectively (Demicco et al, 2012). Herein we present an unusual case of solitary fibrous tumors involving the ischioanal fossa in a 19-year-old woman with radiologic-pathologic correlation. This case was complicated by extensive tumor vascularity and was thus managed with preoperative embolization followed by en bloc surgical resection.