Adjuvant Radiotherapy in Stage II Endometrial Cancer: Selective De-intensification of Adjuvant Treatment

AIMS

Risk stratification, including nodal assessment, allows for selective de-intensification of adjuvant radiotherapy in stage II endometrial cancer. Patterns of treatment and clinical outcomes, including the use of reduced volume 'mini-pelvis' radiotherapy fields, were evaluated in a population-based study.

MATERIALS AND METHODS

All patients diagnosed with pathological stage II endometrial cancer between 2000 and 2014, and received adjuvant radiotherapy in a regional healthcare jurisdiction were reviewed. Registry data were supplemented by a comprehensive review of patient demographics, disease characteristics and treatment details. The Charlson Comorbidity Score was calculated. Survival and recurrence data were analysed.

RESULTS

In total, 264 patients met the inclusion criteria. Most patients had endometrioid histology (83%); 41% of patients had International Federation of Gynecologists and Obstetricians grade 1 disease. Half (49%) had surgical nodal evaluation; 11% received chemotherapy. Most patients (59%) were treated with full pelvic radiotherapy fields ± brachytherapy. Seventeen per cent of patients received mini-pelvis radiotherapy ± brachytherapy, whereas 24% received brachytherapy alone. Five-year recurrence-free survival was 87% for the entire cohort, with no significant difference by adjuvant radiotherapy approach. Only one patient receiving mini-pelvis radiotherapy ± brachytherapy recurred in the pelvis but outside of the mini-pelvis field. Recorded late toxicity rates were highest for full pelvis radiotherapy + brachytherapy.

CONCLUSION

Risk stratification in a real-world setting allowed for selective de-intensification of adjuvant radiation with equivalent outcomes for stage II endometrial cancer. Mini-pelvis radiotherapy combined with brachytherapy is effective in highly selected patients, with the potential to decrease toxicity without compromising local control. Brachytherapy should be considered in low-risk stage II patients.

Prognostic value of strain by feature-tracking cardiac magnetic resonance in arrhythmogenic right ventricular cardiomyopathy

AIMS

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by ventricular dysfunction and ventricular arrhythmias (VA). Adequate arrhythmic risk assessment is important to prevent sudden cardiac death. We aimed to study the incremental value of strain by feature-tracking cardiac magnetic resonance imaging (FT-CMR) in predicting sustained VA in ARVC patients.

METHODS AND RESULTS

CMR images of 132 ARVC patients (43% male, 40.6 ± 16.0 years) without prior VA were analysed for global and regional right and left ventricular (RV, LV) strain. Primary outcome was sustained VA during follow-up. We performed multivariable regression assessing strain, in combination with (i) RV ejection fraction (EF); (ii) LVEF; and (iii) the ARVC risk calculator. False discovery rate adjusted P-values were given to correct for multiple comparisons and c-statistics were calculated for each model. During 4.3 (2.0-7.9) years of follow-up, 19% of patients experienced sustained VA. Compared to patients without VA, those with VA had significantly reduced RV longitudinal (P ≤ 0.03) and LV circumferential (P ≤ 0.04) strain. In addition, patients with VA had significantly reduced biventricular EF (P ≤ 0.02). After correcting for RVEF, LVEF, and the ARVC risk calculator separately in multivariable analysis, both RV and LV strain lost their significance [hazard ratio 1.03-1.18, P > 0.05]. Likewise, while strain improved the c-statistic in combination with RVEF, LVEF, and the ARVC risk calculator separately, this did not reach statistical significance (P ≥ 0.18).

CONCLUSION

Both RV longitudinal and LV circumferential strain are reduced in ARVC patients with sustained VA during follow-up. However, strain does not have incremental value over RVEF, LVEF, and the ARVC VA risk calculator.

Expanding control of the tumor cell cycle with a CDK2/4/6 inhibitor

The CDK4/6 inhibitor, palbociclib (PAL), significantly improves progression-free survival in HR⁺/HER2^- breast cancer when combined with anti-hormonals. We sought to discover PAL resistance mechanisms in preclinical models and through analysis of clinical transcriptome specimens, which coalesced on induction of MYC oncogene and Cyclin E/CDK2 activity. We propose that targeting the G₁ kinases CDK2, CDK4, and CDK6 with a small-molecule overcomes resistance to CDK4/6 inhibition. We describe the pharmacodynamics and efficacy of PF-06873600 (PF3600), a pyridopyrimidine with potent inhibition of CDK2/4/6 activity and efficacy in multiple in vivo tumor models. Together with the clinical analysis, MYC activity predicts (PF3600) efficacy across multiple cell lineages. Finally, we find that CDK2/4/6 inhibition does not compromise tumor-specific immune checkpoint blockade responses in syngeneic models. We anticipate that (PF3600), currently in phase 1 clinical trials, offers a therapeutic option to cancer patients in whom CDK4/6 inhibition is insufficient to alter disease progression.

POS0224 SELECTIVITY OF CLINICAL JAK INHIBITORS AND THE IMPACT ON NATURAL KILLER (NK) CELL FUNCTIONAL RESPONSES

Background:

Janus kinase (JAK) inhibitors (JAKinibs) show similar efficacy in rheumatoid arthritis (RA). However, in vitro studies have shown differences in JAK selectivity profiles for baricitinib (BARI), tofacitinib (TOFA), upadacitinib (UPA) and filgotinib (FIL).1,2 These lead to distinct pharmacologic profiles in cellular signaling assays that may impact clinical efficacy or safety1. NK cells are innate lymphocytes important in anti-pathogen responses and immune surveillance, which function via production of cytokines and cell killing3. NK cell proliferation and IFNγ production are JAK-dependent pathways and may be modulated by JAKinibs. Clinical findings show transient decreases in NK cell numbers in patients treated with JAKinibs, but the link to safety is unclear4

Objectives:

To extend upon findings in proximal cell signaling assays, we compared the selectivity and potency of clinical JAKinibs on NK cell function by assessing proliferation mediated by IL-15 (JAK1/3) and IFN-γ production driven by IL-12 (JAK2/TYK2)+IL-18.

Methods:

NK cells were isolated from healthy donor PBMC, incubated in vitro with 8 concentrations of each evaluated JAKinib (TOFA, BARI, FIL, FIL metabolite, UPA) and stimulated with IL-15 for proliferation or IL-12/18 for IFNγ production. Proliferation was assessed by Cell Trace dye dilution after 6 days and IFNγ production by intracellular flow cytometry 4hrs post-stimulation. Half maximal inhibitory concentration (IC50) values were calculated for CD56bright, CD56dim, and total NK cells. Steady-state pharmacologic profile over a clinical dosing interval was modeled using concentration-time profiles from JAKinib population pharmacokinetic data in RA subjects under the therapeutic dose5-7. For each JAKinib, the time above IC50 and average daily inhibition of IFNγ or proliferation were calculated for each NK cell population in each donor.

Results:

Cellular assays in purified NK cells showed dose-dependent inhibition of IL-15-induced proliferation by all JAKinibs with TOFA showing the highest average inhibition and time above IC50 (35-60% inhibition for 8-15 hrs; TOFA>UPA>BARI≈FIL). The differences between JAKinibs are in line with differences in pSTAT inhibition downstream of IL-151. Interestingly, IL-12/18-induced production of IFNγ, which is mediated via JAK2/TYK2 (IL-12) and non-JAK dependent pathways (IL-18), showed weaker inhibition for all compounds. Moreover, all JAKinibs showed <25% average inhibition of IFNγ production over 24hrs and did not show any time above IC50 for IFNγ production or pSTAT4 inhibition at clinical doses. CD56dim and CD56bright sub-populations of NK cells are proposed to have distinct functions and unique expression of surface receptors. Analysis of the IC50 for pSTAT4 and IFNγ production showed ~2-10-fold weaker inhibition by JAKinibs in CD56bright NK cells, suggesting less dependence on JAK-dependent signals in CD56bright NK cells than CD56dim NK cells.

Conclusion:

NK cell proliferation depends on JAK1 and JAK3-mediated signaling and is differentially inhibited at clinical doses of distinct JAKinibs. In contrast, functional responses downstream of JAK2/TYK2-dependent IL-12/18 were not substantially inhibited by any of the JAKinibs studied. Inhibition of functional and proliferative responses in purified NK cells aligned well with proximal pSTAT inhibition. JAKinib modulation of NK cell proliferation, but not response to IL-12, reflects unique pharmacologic profiles of the drugs studied and could be one component underlying clinical safety observations, including increased risk of viral infections or malignancy4.

References:

[1]Traves PG et al. Ann Rheum Dis 2021 (in press)

[2]McInnes IB, et al. Arthritis Res Ther 2019;21:183.

[3]Cooper MA, Fehniger TA, Caligiuri MA. Trends Immunol 2001 Nov;22(11):633-40.

[4]Winthrop KL. Nat Rev Rheumatol 2017; 13(4):234-243

[5]Zhang X, et al. CPT Pharmacometrics Syst Pharmacol 2017;6(12):804-13.

[6]CDER. Application Number: 203214Orig1s000. NDA 203214: Tofacitinib.

[7]Klunder B et al. Clin Pharmacokinet 2019;58(8):1045-58.

Disclosure of Interests:

Paqui Gonzalez-Traves Shareholder of: Gilead Sciences, Employee of: Gilead Sciences, Laura Simpson Shareholder of: Gilead Sciences, Employee of: Gilead Sciences, Bernard Murray Shareholder of: Gilead Sciences, Employee of: Gilead Sciences, Amy Meng Shareholder of: Gilead Sciences, Employee of: Gilead Sciences, Julie A. Di Paolo Shareholder of: Gilead Sciences, Employee of: Gilead Sciences, Ethan Grant Shareholder of: Gilead Sciences, Employee of: Gilead Sciences, Gundula Min-Oo Shareholder of: Gilead Sciences, Employee of: Gilead Sciences

144 Probable Delirium is A Presenting Symptom of COVID-19 in Frail, Older Adults: A Study of Hospitalised and Community-Based Cohorts

Introduction

COVID-19 exhibits a more severe disease course in older adults with frailty. Awareness of atypical presentations is critical to facilitate early disease identification. This study aimed to assess how frailty affects presenting symptoms of COVID-19 in older adults.

Methods

Observational study of two distinct cohorts: (i) Hospitalised patients aged 65 and over; unscheduled admission to a large London teaching hospital between March 1st, 2020-May 5th, 2020; COVID-19 confirmed by RT-PCR of nasopharyngeal swab (n = 322); (ii) Community-based adults aged 65 and over enrolled in the COVID Symptom Study mobile application between March 24th (application launch)-May 8th, 2020; self-report or report-by-proxy data; reported test-positive for COVID-19 (n = 535). Multivariable logistic regression analysis performed on age-matched samples of both cohorts to determine associations between frailty and symptoms of COVID-19 including delirium, fever and cough.

Results

Hospital cohort: there was a significantly higher prevalence of delirium amongst the frail sample, with no difference in fever or cough. Of those presenting with delirium, 10/53 (18.9%) presented with delirium as the only documented symptom. Community-based cohort: there was a significantly higher prevalence of probable delirium in the frail sample, and also of fatigue and shortness of breath. Of those reporting probable delirium, 28/84 (33%) did not report fever or cough.

Conclusions

This study demonstrates a higher prevalence of delirium as a presenting symptom of COVID-19 infection in older adults with frailty compared to their age-matched non-frail counterparts. Clinicians should suspect COVID-19 in frail older adults presenting with delirium. Early detection facilitates infection control measures to mitigate against catastrophic spread and preventable hospitalisations and deaths amongst this population. Our findings emphasise the need for systematic frailty assessment for all acutely ill older patients in both hospital and community settings, as well as systematic evaluation of any change in mental status.

Diagnostic value of cutaneous manifestation of SARS-CoV-2 infection

Background

One of the challenging aspects of SARS‐CoV‐2 infection is its diverse multisystemic disease presentation.

Objectives

To evaluate the diagnostic value of cutaneous manifestations of SARS‐CoV‐2 infection and investigate their duration and timing in relation to other COVID‐19 symptoms.

Methods

We used data from 336 847 UK users of the COVID Symptom Study app to assess the diagnostic value of body rash or an acral rash in SARS‐CoV‐2 infection, and data from an independent online survey of 11 544 respondents to investigate skin‐specific symptoms and collect their photographs.

Results

Using data from the app, we show significant association between skin rashes and a positive swab test result (odds ratio 1·67, 95% confidence interval 1·42–1·97). Strikingly, among the respondents of the independent online survey, we found that 17% of SARS‐CoV‐2‐positive cases reported skin rashes as the first presentation, and 21% as the only clinical sign of COVID‐19. Together with the British Association of Dermatologists, we have compiled a catalogue of images of the most common skin manifestations of COVID‐19 from 400 individuals (https://covidskinsigns.com), which we have made publicly available to assist clinicians in recognition of this early clinical feature of COVID‐19.

Conclusions

Skin rashes cluster with other COVID‐19 symptoms, are predictive of a positive swab test, and occur in a significant number of cases, either alone or before other classical symptoms. Recognizing rashes is important in identifying new and earlier cases of COVID‐19.

What is already known about this topic?

Several studies conducted in hospital settings reported that patients with COVID‐19 presented with unusual skin rashes, including urticarial rashes, vesicular lesions and, less frequently, chilblains in fingers or toes.

What does this study add?

We confirmed, in a community‐based setting that also includes milder forms of the disease, that the presence of a skin rash is predictive of SARS‐CoV‐2 infection.

We provide a website with photos of skin manifestations to help healthcare professionals in diagnosing COVID‐19.

Skin rashes should be taken into account to provide a quick COVID‐19 diagnosis to curb the spread of the disease.

Linked Comment: Naldi. Br J Dermatol 2021; 184:793–794.

Optimal symptom combinations to aid COVID-19 case identification: Analysis from a community-based, prospective, observational cohort

Objectives

Diagnostic work-up following any COVID-19 associated symptom will lead to extensive testing, potentially overwhelming laboratory capacity whilst primarily yielding negative results. We aimed to identify optimal symptom combinations to capture most cases using fewer tests with implications for COVID-19 vaccine developers across different resource settings and public health.

Methods

UK and US users of the COVID-19 Symptom Study app who reported new-onset symptoms and an RT-PCR test within seven days of symptom onset were included. Sensitivity, specificity, and number of RT-PCR tests needed to identify one case (test per case [TPC]) were calculated for different symptom combinations. A multi-objective evolutionary algorithm was applied to generate combinations with optimal trade-offs between sensitivity and specificity.

Findings

UK and US cohorts included 122,305 (1,202 positives) and 3,162 (79 positive) individuals. Within three days of symptom onset, the COVID-19 specific symptom combination (cough, dyspnoea, fever, anosmia/ageusia) identified 69% of cases requiring 47 TPC. The combination with highest sensitivity (fatigue, anosmia/ageusia, cough, diarrhoea, headache, sore throat) identified 96% cases requiring 96 TPC.

Interpretation

We confirmed the significance of COVID-19 specific symptoms for triggering RT-PCR and identified additional symptom combinations with optimal trade-offs between sensitivity and specificity that maximize case capture given different resource settings.

Optimal symptom combinations to aid COVID-19 case identification: analysis from a community-based, prospective, observational cohort

OBJECTIVES

Diagnostic work-up following any COVID-19 associated symptom will lead to extensive testing, potentially overwhelming laboratory capacity whilst primarily yielding negative results. We aimed to identify optimal symptom combinations to capture most cases using fewer tests with implications for COVID-19 vaccine developers across different resource settings and public health.

METHODS

UK and US users of the COVID-19 Symptom Study app who reported new-onset symptoms and an RT-PCR test within seven days of symptom onset were included. Sensitivity, specificity, and number of RT-PCR tests needed to identify one case (test per case [TPC]) were calculated for different symptom combinations. A multi-objective evolutionary algorithm was applied to generate combinations with optimal trade-offs between sensitivity and specificity.

FINDINGS

UK and US cohorts included 122,305 (1,202 positives) and 3,162 (79 positive) individuals. Within three days of symptom onset, the COVID-19 specific symptom combination (cough, dyspnoea, fever, anosmia/ageusia) identified 69% of cases requiring 47 TPC. The combination with highest sensitivity (fatigue, anosmia/ageusia, cough, diarrhoea, headache, sore throat) identified 96% cases requiring 96 TPC.

INTERPRETATION

We confirmed the significance of COVID-19 specific symptoms for triggering RT-PCR and identified additional symptom combinations with optimal trade-offs between sensitivity and specificity that maximize case capture given different resource settings.

Identification of Lupus Podocytopathy with Coexistent Glomerular Diseases – A Case Report

Introduction/Objective

Lupus podocytopathy (LP), featured by nephrotic syndrome, is a unique subtype of lupus nephritis that mimics minimal change disease or primary focal segmental glomerulosclerosis (FSGS) on renal biopsy with diffuse podocyte foot process effacement and no capillary-loop immune deposits. LP usually presents on a background of ISN/RPS class I or class II lupus nephritis, and very rarely may present without immune deposits.

Diagnosis of LP, when confounded by other glomerular diseases associated with nephrotic syndrome, can be very challenging and requires thorough clinical and pathology correlations.

Methods

Here we report a case of LP in a patient with nephrotic syndrome and multiple comorbidities affecting kidneys. A 24-year-old female with type-I diabetes, psoriasis, and intermittent arthritis/rash of unknown etiology, presented with abrupt onset of nephrotic proteinuria attributed to recent low dose prednisone therapy, and renal insufficiency. A renal biopsy showed nodular glomerulosclerosis and FSGS. No immune deposits were identified by immunofluorescence or electron microscopy. Ultrastructurally there was also diffuse glomerular basement membrane thickening and over 90% podocyte foot process effacement. With no established systemic lupus erythematosus (SLE), the case was initially diagnosed as diabetic nephropathy with coexistent FSGS as the etiologies for nephrotic proteinuria, and the patient was put on ACEI and diuretics. However, massive proteinuria persisted, and the patient also developed pancytopenia. Serology concurrent with the biopsy came out later showing positive autoantibodies against dsDNA, Smith, and Histone. With continued worsening of creatinine, a renal biopsy was repeated revealing essentially similar findings to the first biopsy.

Results

Integrating the serology results and clinical presentation, SLE was favored. The pathology findings were re- evaluated and considered to be most consistent with LP and coexistent diabetic nephropathy, with FSGS either a component of LP or an independent lesion secondary to diabetes or hypertension. The patient was started with high dose prednisone at 60 mg/day. One month later, her proteinuria, serum creatinine, pancytopenia, skin rash, and arthritis were all significantly improved.

Conclusion

LP can be easily masked by coexistent glomerular diseases. Sufficient awareness of the entity is necessary for the appropriate diagnosis and treatment.

Abstract 1958: Repotrectinib increases effectiveness of KRAS-G12C inhibitors in KRAS-G12C mutant cancer models via simultaneous SRC/FAK/JAK2 inhibition

KRAS is frequently mutated in multiple cancer types. Therapeutic targeting of KRAS has proven challenging until recent success of KRAS-G12C inhibitor AMG510 that demonstrated tumor regression in lung and colon cancer patients with a KRAS-G12C mutation. However, resistance via feedback reactivation or development of a bypass are expected to limit anti-tumor efficacy of KRAS-G12C inhibitors, favoring a combination approach. Adaptive upregulation of the PI3K/AKT signaling pathway has been recognized as a common resistance mechanism that promotes cancer cell survival and may temper efficacy of KRAS-G12C inhibitors. SRC/FAK signaling promotes tumor cell survival by activation of the PI3K/AKT survival pathway supporting concomitantly targeting SRC/FAK as a promising strategy to potentiate KRAS G12C inhibitors. In addition, oncogenic KRAS induces secretion of various cytokines and growth factors leading to modulation of the tumor microenvironment to promote tumor growth. Targeting the cytokine secretion pathway via JAK2/STAT3 modulation may be important to overcome the resistance to direct KRAS inhibition. Therefore, combinations of KRAS inhibitors with agents that target apoptotic processes and feedback reactivation may represent a promising therapeutic approach. Repotrectinib, a next generation ROS1/TRK/ALK inhibitor, also inhibits SRC/FAK/JAK2 at therapeutically relevant concentrations. Here, we present synergistic effects of repotrectinib in combination with a KRAS-G12C inhibitor in KRAS-G12C mutant cancer models via simultaneous inhibition of SRC/FAK/JAK2. Adding repotrectinib to AMG510 improves AMG510 effectiveness on KRAS-G12C mutant cancer cells with notably increased apoptosis. For example, repotrectinib (1 μM) shifted the antiproliferation IC50 of AMG510 from 213 nM to 3 nM in KRAS-G12C mutant H358 cells. Treatment of H358 cells with AMG510 alone (100 nM) or repotrectinib alone (1 µM) resulted in slight increases in cleaved PARP and caspase-3 proteins, whereas larger increases were observed with the combination. Although high levels of phosphorylated ERK, AKT, STAT3 and FAK were detected in H358 cells, AMG510 (100 nM) was only able to partially modulate phospho-ERK (pERK) with no modulation on pAKT, pSTAT3 and pFAK and repotrectinib (1 μM) suppressed pSTAT3 and pFAK with minimum modulation on pERK and pAKT. The combination in H358 cells results in stronger suppression of pERK and pAKT than either single agent alone, which is consistent with the observed increase in activation of apoptosis. Additional combination data in KRAS-G12C mutant cancer models will be presented. Overall, these studies warrant further clinical investigation on the combination of KRAS-G12C inhibitors with repotrectinib in patients with KRAS-G12C mutation for potential response and duration improvement of current investigational KRAS-G12C inhibitors.

Citation Format: J. Jean Cui, Dayong Zhai, Wei Deng, Laura Rodon, Nathan Lee, Brion Murray. Repotrectinib increases effectiveness of KRAS-G12C inhibitors in KRAS-G12C mutant cancer models via simultaneous SRC/FAK/JAK2 inhibition [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1958.

THU0067 JAK SELECTIVITY AND THE IMPACT ON CYTOKINE SIGNALING INHIBITION AT CLINICAL RHEUMATOID ARTHRITIS DOSES

Background:

Janus kinase 1 (JAK1) inhibitors are efficacious in rheumatoid arthritis (RA). Despite having similar efficacy, in vitro studies have shown differences in JAK selectivity profiles for the small-molecule JAK inhibitors (JAKi) baricitinib (BARI), tofacitinib (TOFA), and upadacitinib (UPA).1For example, BARI and UPA are JAK1/JAK2 selective, while TOFA is JAK1/JAK3 selective, but each JAKi has some activity against other JAKs. As JAKs form signaling pairs, differences in selectivity could lead to distinct pharmacologic profiles that may impact clinical efficacy and safety.

Objectives:

As a first step to understand the basis of potential differences at therapeutic doses, we compared the selectivity and potency of filgotinib (FIL) and its major metabolite (MET) to those of BARI, TOFA, and UPA in cytokine-stimulated peripheral blood mononuclear cells (PBMCs) and whole blood (WB).

Methods:

PBMCs and WB from healthy donors were incubated in vitro with 8 doses of each JAKi, and levels of signal transducer and activator of transcription phosphorylation (pSTAT) were measured following cytokine stimulation. Half maximal inhibitory concentration (IC50) values were calculated in phenotypically sorted leukocyte populations by flow cytometry. Therapeutic dose relevance of the in vitro analyses was assessed using calculated mean concentration-time profiles from JAKi population pharmacokinetic data in RA subjects. For each JAKi, the time above IC50and average daily pSTAT inhibition were calculated for each cytokine/STAT pair in B cells, CD4+ T cells, CD8+ T cells, monocytes, and/or NK cells.

Results:

Cellular assays in PBMCs and WB showed dose-dependent inhibition of cytokine-induced pSTATs with all JAKi (correlation between the protein-adjusted IC50values from PBMCs and IC50values from WB, r2=0.98). Among the most potently inhibited pathways were JAK1/TYK2-dependent cytokine, interferon alpha (IFNα), and the JAK1/2-dependent cytokine, interleukin (IL)-6. FIL and MET had weaker potencies against JAK2/TYK2 (G-CSF/pSTAT3), JAK1/2 (IFNƴ/pSTAT1), and JAK2/2 (granulocyte-macrophage colony-stimulating factor [GM-CSF])-dependent pathways compared to JAK1/TYK2 (IFNα/pSTAT5). FIL and MET showed the greatest selectivity vs the JAK2/2 pathway (GM-CSF/pSTAT3) in monocytes.

The mean concentration-time profiles and time above IC50over 24 hr for each cytokine/STAT pathway showed that JAK1/2 (IL-6/pSTAT1) and JAK1/TYK2 (IFNα/pSTAT1) pathways were strongly modulated with all tested JAKi. FIL (200 mg) showed similar activity in average target coverage and time above IC50to the approved low doses of TOFA (5 mg) and UPA (15 mg); conversely, FIL had reduced mean average inhibition and time above IC50levels against JAK1/2 (IFNƴ/pSTAT1), JAK1/3-dependent cytokines (IL-2, -4, and -15), JAK2/TYK2 (G-CSF/pSTAT3), and JAK2/2 (GM-CSF/pSTAT5)-dependent pathways compared to TOFA and UPA, and in certain cases to BARI (2 mg).

Conclusion:

Different JAKi modulate distinct cytokine pathways to varying degrees, and no agent potently and continuously inhibited an individual cytokine signaling pathway throughout the dosing interval. FIL (200 mg) showed a similar inhibition profile to TOFA, BARI, and UPA against the JAK1/TYK2- (IFNα/pSTAT1) or JAK1/2-dependent (IL-6/pSTAT1) responses, consistent with the role of these pathways in clinical efficacy.2However, FIL displayed a differentiated pharmacologic profile from the other JAKi, showing biologically reduced activity on the JAK1/2 (IFNγ)-, JAK1/3 (IL-2, -4 and -15)-, JAK2/TYK2 (G-CSF)-, and JAK2/2 (GM-CSF)-dependent pathways, which play important roles in hematopoiesis and immune function. These data suggest that FIL (200 mg) may have less impact on a subset of homeostatic immune functions signaling via JAK2 and JAK3 than those observed at the clinically approved doses of TOFA (5 mg and 10 mg), UPA (15 mg), and BARI (4 mg).

References:

[1]McInnes IB, et al. Arthritis Res Ther. 2019;21:183.

[2]Banerjee S, et al. Drugs. 2017;77:521-546.

Disclosure of Interests:

Paqui Gonzalez-Traves Employee of: Gilead, Bernard Murray Employee of: Gilead, Federico Campigotto Employee of: Gilead, Amy Meng Shareholder of: Gilead Sciences, Employee of: Gilead, Julie A. Di Paolo Employee of: Gilead

Abstract P6-20-06: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Dann S, Chionis J, Eisele K, Zhang Q, Liu C, Yuan J, Miller N, Murray B, Xu M, Solowiej J, Wei P, Weinrich S, Sutton S, Behenna D, Ninkovic S, Hoffman R, Freeman-Cook K, Jessen B, Huser N, Zhang C, Visswanathan R, Boras B, VanArsdale T, White MA. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-20-06.

On the direct acquisition of beam's-eye-view images in MRI for integration with external beam radiotherapy

The recent interest in the integration of external beam radiotherapy with a magnetic resonance (MR) imaging unit offers the potential for real-time adaptive tumour tracking during radiation treatment. The tracking of large tumours which follow a rapid trajectory may best be served by the generation of a projection image from the perspective of the beam source, or 'beam's eye view' (BEV). This type of image projection represents the path of the radiation beam, thus enabling rapid compensations for target translations, rotations and deformations, as well time-dependent critical structure avoidance. MR units have been traditionally incapable of this type of imaging except through lengthy 3D acquisitions and ray tracing procedures. This work investigates some changes to the traditional MR scanner architecture that would permit the direct acquisition of a BEV image suitable for integration with external beam radiotherapy. Based on the theory presented in this work, a phantom was imaged with nonlinear encoding-gradient field patterns to demonstrate the technique. The phantom was constructed with agarose gel tubes spaced two cm apart at their base and oriented to converge towards an imaginary beam source 100 cm away. A corresponding virtual phantom was also created and subjected to the same encoding technique as in the physical demonstration, allowing the method to be tested without hardware limitations. The experimentally acquired and simulated images indicate the feasibility of the technique, showing a substantial amount of blur reduction in a diverging phantom compared to the conventional imaging geometry, particularly with the nonlinear gradients ideally implemented. The theory is developed to demonstrate that the method can be adapted in a number of different configurations to accommodate all proposed integration schemes for MR units and radiotherapy sources. Depending on the configuration, the implementation of this technique will require between two and four additional nonlinear encoding coils.

Raccoon roundworm (Baylisascaris procyonis) as an occupational hazard: 2. Use of personal protective equipment and infection control practices among raccoon rehabilitators

Baylisascaris procyonis, the raccoon roundworm, is a zoonotic ascarid of importance to human and animal health. Wildlife rehabilitators who care for raccoons may be at an increased risk for exposure to the parasite, especially if proper precautions are not taken. In a wider effort to evaluate awareness regarding B. procyonis in the wildlife rehabilitation community, an online survey (38-39 questions) including questions about B. procyonis knowledge and attitudes was developed and administered to wildlife rehabilitators. To assess precautions taken among raccoon rehabilitators, participants who rehabilitated raccoons (n = 447) answered additional questions about use of personal protective equipment (PPE) and infection control practices (ICPs). Reported use of gloves was variable, but hand hygiene was generally consistent. Masks and gowns were seldom used. Part-time or infrequent volunteers and rehabilitators located in the Central, Midwest and Southeast were significantly less likely to report consistent use of PPE. A total knowledge score from the survey was used to predict the likelihood of reporting the use of particular ICPs/PPE. Knowledge score had a highly significant but small effect on the likelihood of prophylactic use of anthelmintics, anthelmintics use for B. procyonis specifically, cleaning appropriately, and using species-dedicated housing. Risk factor analysis was performed on data from a prior serologic survey to evaluate factors associated with exposure to B. procyonis and inconsistent handwashing after contact with live raccoons and their faeces; practising rehabilitation in B. procyonis hyperendemic regions and practising rehabilitation in the western region were significant risk factors for being seropositive. These data further demonstrate that correct PPE/ICPs are critical in mitigating the risk of B. procyonis exposure among raccoon rehabilitators and among other captive species.

Application of Genetically-Engineered Anti-CEA Antibodies for Potential Immunotherapy of Colorectal Cancer

Hitherto anti-CEA monoclonal antibodies (MAbs), normally of mouse origin, have been used primarily for clinical diagnosis of colorectal cancer, either as a tumor marker in serum to monitor tumor recurrence, or latterly as a means to localize in vivo CEA-bearing tumors and metastases in patients. In vivo diagnosis using mouse anti-CEA MAbs has so far had limited clinical utility because the antibodies elicit a strong anti-mouse immunoglobulin immune response on repeated administration in man. This problem has been addressed by the development of various strategies for “humanization” of mouse anti-CEA MAbs by genetic manipulation of immunoglobulin genes. Such humanized, engineered antibodies markedly attenuate the antigenic response directed against the MAb, such that safe, repeated administration to patients has become feasible. Such humanized anti-CEA antibodies can thus be radioactively-labelled and applied for in vivo monitoring and detection of recurrent malignant disease, or used for therapeutic strategies which similarly take advantage of the ability of the antibodies to target cytotoxic agents selectively to tumor cells. The application of these novel procedures for manipulating MAb structure presents entirely new opportunities for diagnosis and treatment of human colorectal cancer.

Current and Emerging Therapies in Multiple Sclerosis: Implications for the Radiologist, Part 2-Surveillance for Treatment Complications and Disease Progression

An understanding of the new generation of MS drugs in conjunction with the key role MR imaging plays in the detection of disease progression, opportunistic infections, and drug-related adverse effects is of vital importance to the neuroradiologist. Part 1 of this review outlined the current treatment options available for MS and examined the mechanisms of action of the various medications. It also covered specific complications associated with each form of therapy. Part 2, in turn deals with the subject of pharmacovigilance and the optimal frequency of MRI monitoring for each individual patient, depending on his or her unique risk profile. Special attention is given to the diagnosing of progressive multifocal leukoencephalopathy in patients treated with natalizumab as this is a key area in which neuroradiologists can contribute to improved patient outcomes. This article also outlines the aims of treatment and reviews the possibility of "no evidence of disease activity" becoming a treatment goal with the availability of more effective therapies. Potential future areas and technologies including image subtraction, brain volume measurement and advanced imaging techniques such as double inversion recovery are also reviewed. It is anticipated that such advancements in this rapidly developing field will improve the accuracy of monitoring an individual patient's response to treatment.

Current and Emerging Therapies in Multiple Sclerosis: Implications for the Radiologist, Part 1-Mechanisms, Efficacy, and Safety

Imaging for the diagnosis and follow-up of patients with suspected or confirmed multiple sclerosis is a common scenario for many general radiologists and subspecialty neuroradiologists. The field of MS therapeutics has rapidly evolved with multiple new agents now being used in routine clinical practice. To provide an informed opinion in discussions concerning newer MS agents, radiologists must have a working understanding of the strengths and limitations of the various novel therapies. The role of imaging in MS has advanced beyond monitoring and surveillance of disease activity to include treatment complications. An understanding of the new generation of MS drugs in conjunction with the key role that MR imaging plays in the detection of disease progression, opportunistic infections, and drug-related adverse events is of vital importance to the radiologist and clinical physician alike. Radiologists are in a unique position to detect many of the described complications well in advance of clinical symptoms. Part 1 of this review outlines recent developments in the treatment of MS and discusses the published clinical data on the efficacy and safety of the currently approved and emerging therapies in this condition as they apply to the radiologist. Part 2 will cover pharmacovigilance and the role the neuroradiologist plays in monitoring patients for signs of opportunistic infection and/or disease progression.

A role for susceptibility weighted imaging in progressive multifocal leukoencephalopathy

We report a radiologic finding on magnetic resonance imaging (MRI) of the brain of two cases of progressive multifocal leukoencephalopathy (PML) of hypointense signal of subcortical U-fibres on susceptibility weighted (SW) sequence. The first case is a 50-year-old man recently treated with chemotherapy including rituximab for non-Hodgkin's lymphoma. The second case is a 64-year-old woman with human immunodeficiency virus (HIV) infection. Iron deposition is a likely causative factor. We propose that SWI may be especially useful in the assessment of indeterminate cases to reduce the likelihood of a missed diagnosis of PML.

Adherence and persistence of mirabegron and anticholinergic therapies in patients with overactive bladder: a real-world claims data analysis

BACKGROUND

Adherence and persistence rates of anticholinergic (ACH) therapies have been well described. To date, few studies describe these metrics for mirabegron in patients with overactive bladder.

METHODS

This retrospective analysis of MarketScan^® database assessed adherence and persistence of patients receiving either mirabegron or ACH. Study eligibility required an index date (first prescription filled) between July 2012 and June 2013 with 12 months of continuous enrolment preindex date and 12 months of follow-up. Adherence was defined as a proportion of days covered of ≥ 80% among patients with at least 2 fills of index medication. Persistence measures included treatment failure described as either treatment discontinuation (medication supply gap ≥ 30 days) or switching to a different medication. A medication supply gap of ≥ 45 days was used as a sensitivity analysis.

RESULTS

The mean age of mirabegron users (n = 4037) was 67 years and 43% were ACH naïve while the mean age of ACH users was 62 years (n = 67,943). Over the 12-month follow-up period, 44% of patients treated with mirabegron and 31% of patients treated with ACH were adherent to their indexed medications. Treatment failure was 81% for mirabegron and 88% for ACH. Most mirabegron treatment failures were because of treatment discontinuation (67%) versus switching to ACH therapy (14%). The ACH discontinuation rate was 84% and treatment switching rate was 4%. The mean (standard deviation) time to treatment failure was 143 (130) days for mirabegron and 69 (69) days for ACH. Adherence and persistence patterns were similar in the sensitivity analysis using a ≥ 45-day supply gap threshold.

CONCLUSIONS

This real-world study demonstrated low adherence and persistence to mirabegron similar to ACH therapies.

Abstract 2594: Characterization of a novel irreversible third generation EGFR TKI that targets T790M-mediated resistant EGFR-mutant NSCLC while sparing wild type EGFR

Activating mutations in EGFR confer constitutive activity providing the oncogenic drive in EGFR-mutant NSCLC. First and 2nd generation EGFR tyrosine kinase inhibitors (TKIs) are effective drugs in this setting, but are constrained by dose-limiting toxicities attributed to inhibition of wild type (WT) EGFR and by drug resistance caused, in the majority of cases, via a T790M secondary mutation in EGFR. We report the pharmacology of a novel irreversible 3rd generation EGFR TKI active against EGFR with activating and T790M mutations, but sparing WT EGFR.

Our novel 3rd generation EGFR TKI was studied in a variety of in vitro and in vivo models to determine its inhibitory potencies on different EGFR variants, pharmacokinetics (PK), antitumor efficacy, exposure-response relationships, mechanism of action, and predicted human efficacious dose.

In enzyme and cell assays, our compound is a highly potent inhibitor of EGFR double mutants (L858R/T790M and Del/T790M) and EGFR activating mutants (L858R and Del), but a weak inhibitor of WT EGFR (26-fold margin over mutant target potencies). Effects on downstream signaling and function indicate the underlying mechanism of the compound is direct inhibition of EGFR, with subsequent inhibition of downstream signaling that results in apoptosis and viable cell decline. In xenograft mouse models, the compound demonstrates tumor growth inhibition and regression at well-tolerated doses in models driven by EGFR double mutants and EGFR activating mutants. The antitumor efficacy is dose-dependent and strongly correlates with inhibition of EGFR phosphorylation and EGFR-mediated downstream signaling, and induction of apoptosis. Plasma concentrations assumed to be sufficient for efficacy (Ceff) were defined using a mathematical model incorporating the plasma levels of the compound, the associated inhibitory effects on EGFR phosphorylation, and the antitumor efficacy in the double and activating mutant xenograft models. Ceff was in agreement across several models and was used with in vitro human PK properties to calculate required human dose.

While our compound possesses a similar profile as other recently disclosed 3rd generation EGFR TKIs, this molecule is distinguished by better potency on the activating mutants and by the widest potency margin on WT EGFR. Given that the target potencies and WT margins of 3rd generation EGFR TKIs have been sufficient for tolerated clinical efficacy in preliminary results, it can be inferred that our compound will have similar promise in the clinic. These results support our compound as a novel EGFR TKI with an inhibitory profile and favorable drug-like properties that suggest utility for treating patients with NSCLC with EGFR activating and resistance mutations.

Citation Format: Mike Zientek, Sangita Baxi, Henry Cheng, Valeria Fantin, Jun Li Feng, Allison Given, Zelanna Goldberg, Jie Guo, Michelle Hemkens, John Kath, Jennifer Lafontaine, Gary Li, Pramod Mehta, Brion Murray, Sajiv Nair, Simon Planken, Chad Ray, Yuli Wang, Manli Shi, Anand Sistla, Tod Smeal, Greg Stevens, Wei Tan, Paolo Vicini, Marlena Walls, Liu Yang, Min-Jean Yin, Scott L. Weinrich. Characterization of a novel irreversible third generation EGFR TKI that targets T790M-mediated resistant EGFR-mutant NSCLC while sparing wild type EGFR. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2594. doi:10.1158/1538-7445.AM2015-2594

Abstract 4456: Biochemical and structural characteristics of crizotinib-resistant ALK mutants

Anaplastic lymphoma kinase (ALK), when aberrantly regulated through gene translocations or mutations, has been implicated as an oncogenic driver in a variety of cancers. XALKORI (crizotinib) is an FDA-approved therapy for locally advanced or metastatic (ALK)-positive non-small cell lung cancer (NSCLC). Mutations of certain residues within the ALK kinase domain have been associated with crizotinib resistance. To understand the molecular basis of mutational resistance, we have kinetically and structurally characterized several clinical mutations of ALK kinase domain. In the basal-state (nonphosphorylated) proteins, mutations C1156Y, F1174L, L1152R and L1196M resulted in 14 to 52-fold increase in catalytic efficiency of phosphorylation of an activation loop peptide. Accordingly, these mutants were more rapidly autophosphorylated, compared to wild-type enzyme. In addition, F1174L, C1156Y and L1156Y had 2 to 6-fold higher catalytic efficiencies when fully activated by autophosphorylation. Conversely, catalytic efficiencies of nonphosphorylated and phosphorylated G1269A variant decreased by 1.2 and 1.6-fold, respectively. Inhibition of L1152R, L1196M and G1269A by crizotinib was reduced by 3-28-fold, compared to wild-type enzyme, from Ki determinations. From direct binding studies of the L1196M “gatekeeper” mutation, the loss of crizotinib binding occurred 6 and 13-fold for phosphorylated and nonphosphorylated proteins, respectively. By crystallographic studies apoenzyme and crizotinib complexes of ALK kinase domain displayed an inactive kinase conformation that is stabilized by an extended hydrophobic network of residues. F1174 and L1196 are part of this hydrophobic core, and mutations of these residues are predicted to destabilize the inactive ALK conformation. Taken together, these results suggest that most of the resistant mutations (e.g. L1196M, F1174L, C1156Y, L1152R) result in a more dynamic protein that increases substrate turnover. In addition, the reduction of crizotinib binding for the mutations in the vicinity of the inhibitor binding site (L1196M, G1269A) is likely a contributing factor for the resistance. This structural and kinetic analysis of mutational resistance may be useful for design of new inhibitors targeting multiple clinical mutations of ALK.

Citation Format: Sergei Timofeevski, Wei Liu, Ya-Li Deng, Alexei Brooun, Simon Bergqvist, Shannon Karlicek, Brion Murray, Ben Bolaños, Michele McTigue. Biochemical and structural characteristics of crizotinib-resistant ALK mutants. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4456. doi:10.1158/1538-7445.AM2013-4456

Immunomodulators for multiple sclerosis may ameliorate spinal bone loss

BACKGROUND

The effect of immunomodulator therapy (IMT) for multiple sclerosis (MS) on bone turnover is unknown.

AIM

The aim of this study was to assess bone turnover in MS patients on IMT.

METHODS

MS patients (n = 29) on maintenance IMT had repeat measurement of bone mineral density (BMD) after a 4.0 ± 0.4 years; bone turnover markers (BTM) were measured at the time of repeat BMD.

RESULTS

BMD was unchanged at the spine but declined at the hip. BTMs, both resorption and formation, were reduced compared to normative range that may indicate an anti-resorptive action of IMT. Significant negative correlations were noted between BTMs and changes in BMD at spine but not hip.

CONCLUSION

These observations suggest that IMT may have a beneficial effect on spinal bone by an antiresorptive action. A prospective study of the effect of IMT on BMD and bone turnover is warranted.

Estimation of inhibitory quotient using a comparative equilibrium dialysis assay for prediction of viral response to hepatitis C virus inhibitors

The relationship of inhibitory quotient (IQ) with the virologic response to specific inhibitors of human hepatitis C virus (HCV) and the best method to correct for serum protein binding in calculating IQ have not been addressed. A common method is to determine a fold shift by comparing the EC(50) values determined in cell culture in the absence and presence of human serum (fold shift in EC(50) ), but this method has a number of disadvantages. In the present study, the fold shifts in drug concentrations between 100% human plasma (HP) and cell culture medium (CCM) were directly measured using a modified comparative equilibrium dialysis (CED) assay for three HCV protease inhibitors (PIs) and for a novel HCV inhibitor GS-9132. The fold shift values in drug concentration between the HP and CCM (CED ratio) were ∼1 for SCH-503034, VX-950 and GS-9132 and 13 for BILN-2061. These values were ∼3-10-fold lower than the fold shift values calculated from the EC(50) assay for all inhibitors except BILN-2061. Using the CED values, a consistent pharmacokinetic and pharmacodynamic relationship was observed for the four HCV inhibitors analysed. Specifically, an approximate 1 log(10) reduction in HCV RNA was achieved with an IQ close to 1, while 2-3 and greater log(10) reductions in HCV RNA were achieved with IQ values of 3-5 and greater, respectively. Thus, use of CED to define IQ provides a predictive and quantitative approach for the assessment of the in vivo potency of HCV PIs and GS-9132. This method provides a framework for the evaluation of other classes of drugs that are bound by serum proteins but require the presence of serum for in vitro evaluation.

Multiple sclerosis prevalence in Ireland: relationship to vitamin D status and HLA genotype

BACKGROUND

The relationship between prevalence of multiple sclerosis (MS) and latitude may be due to both genetic and environmental factors. The hypothesis that, in Ireland, MS prevalence is increasing and that north-south differences relate to variation in serum 25-hydroxyvitamin D (25(OH)D) levels was tested in this study.

PATIENTS AND METHODS

Patients and matched control subjects were identified in counties Donegal, Wexford and South Dublin through multiple sources. Prevalence was determined. Blood samples were taken for serum 25(OH)D and serum intact parathyroid hormone measurement, and DNA was extracted.

RESULTS

Prevalence in 2007 was significantly greater in Donegal (northwest) (290.3/105, 95% CI 262.3 to 321.7) compared with 2001 (184.6/105; 162 to 209.5). In Wexford (southeast), there was a non-significant increase in prevalence in 2007 compared with 2001. Prevalence was significantly higher in Donegal than in Wexford (144.8/105; 126.7 to 167.8, p<0.0001) and South Dublin (127.8/105; 111.3 to 148.2, p<0.0001). Overall, mean 25(OH)D levels were low and did not differ between patients (38.6 nmol/l) and controls (36.4 nmol/l) However, significantly more patients than controls had 25(OH)D levels <25 nmol/l (deficiency) (p=0.004). Levels of 25(OH)D (mean 50.74 nmol/l) were significantly higher in South Dublin (area with lowest prevalence) (p<0.0001) than in Donegal or Wexford. HLA DRB1*15 occurred most frequently in Donegal (greatest MS prevalence) and least frequently in South Dublin.

CONCLUSION

Vitamin D deficiency is common in Ireland. Latitudinal variation in MS probably relates to an interaction between genetic factors and environment (25(OH)D levels), and MS risk may be modified by vitamin D in genetically susceptible individuals.

Contribution of the epithelial-mesenchymal (EMT) phenotype to the sensitivity of colorectal cancer cell lines to the p21-activated kinase inhibitor, PF-3758309

438

Background: Increased expression of p21–activated kinase (PAK) family proteins has been observed in a range of malignancies including those of breast, ovarian, colorectal (CRC), and pancreatic origin. PAK (PAK 1-6) proteins are critical mediators of cell proliferation, motility, transcription, and translation. In initial studies, we demonstrated that the PAK4 inhibitor, PF-3758309, exhibited robust single agent efficacy against selected CRC cell lines, with IC50s of less than 0.015 uM, whereas some cell lines were relatively resistant to the agent, with IC50s of greater than 1 uM. In subsequent gene array analyses, CRC cell lines sensitive or resistant to PF-3758309 exhibited overexpression of core genes associated with a mesenchymal or epithelial phenotype, respectively. Thus, the goal of this study was to assess the functional consequences of altering the expression of EMT-associated genes and to seek rational combination partners in CRC.

Methods: CRC cell lines that were sensitive to PF-3758309 (IC50=0.015 uM) were transfected with selected short hairpin- (sh)RNAs or micro-(mi)RNAs that are known to regulate EMT. Semi-quantitative RT-PCR and immunoblotting were performed to confirm target knockdown. The transfected cell lines were then exposed to increasing concentrations of PF-3758309 to determine the functional role of these genes in conferring responsiveness to PF-3758309.

Results: Sensitive CRC cell lines were transfected with shRNAs to Zeb1, vimentin, and caldesmon, genes that are associated with a mesenchymal phenotype. Interestingly, when the cell lines were exposed to increasing concentrations of PF- 3758309 they demonstrated a ′right shift′ towards a more resistant phenotype. Likewise, transfection with miRNA 200c, a known suppressor of Zeb1, resulted in a similar shift towards resistance.

Conclusions: These data suggest that the EMT phenotype may play a functional role in determining CRC sensitivity to the PAK4 inhibitor PF-3758309, and in addition, a rational combination targeting the epithelial phenotype with epidermal growth factor receptor inhibitors, may be warranted.

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