Training during the COVID-19 pandemic: the experience of public health registrars in the London and Kent, Surrey, Sussex training programme

BACKGROUND

Public Health registrars (SpRs) were an important component of the workforce that contributed to the COVID-19 response. This study explores their contribution and the impact the early stages of the pandemic had on their learning and training.

METHODS

Data were collected from SpRs in the London and Kent, Surrey, Sussex training programme between July and September 2020 through a mixture of questionnaires and semi-structured interviews. A thematic analysis of interview transcripts was undertaken to identify themes.

RESULTS

35/128 SpRs responded to the survey and 11 were interviewed. SpRs were placed across a range of organizations and made a significant contribution to the COVID-19 response. Overall, SpRs learned important skills but working on the response may for some have impacted negatively on training. A number of facilitators and barriers to learning were identified.

CONCLUSION

The study findings highlight the opportunities for learning created by the pandemic. However, changing projects and the desire of SpRs to contribute to the response meant the impacts on training were mixed. Future deployment of SpRs should consider the balance of responsibility and pace when delegating work, as well as the need to supervise effectively and support remote working to maintain good mental wellbeing.

Abstract 5162: Discovery of INCB098377: a potent inhibitor of phosphoinositide 3-kinase gamma (PI3Kγ)

Immune checkpoint blockade has shown impressive efficacy in patients with inflamed tumors, although minimal activity has been observed in tumors lacking T cells. Myeloid cells are one of the most abundant cell types in both inflamed and non-inflamed tumors, and may contribute to immune checkpoint blockade resistance. The plasticity of macrophages enables them to directly and indirectly modulate T cell responses, and directly kill tumor cells via phagocytosis. This suggests that targeting myeloid cells could be an effective therapeutic approach. Class I PI3Ks are a family of dual specificity lipid and protein kinases. Unlike other class I PI3Ks, PI3Kγ is predominantly expressed in myeloid cells. PI3Kγ has been shown to be a key mediator that drives the immunosuppressive macrophage program by stimulating AKT/mTOR signaling and promote C/EBPβ expression while inhibiting NF-кB activity (Keneda MM. Nature. 2016;17:437-442). Here, we present the discovery and characterization of INCB098377, a potent and selective PI3Kγ inhibitor. Specific inhibition of PI3Kγ with INCB098377 may induce anti-tumor activity by reshaping the tumor immune microenvironment. In cell-based assays, INCB098377 has an IC50 of 1.4 nM and is greater than 100-fold selective over other PI3K isoforms. It also shows a favorable PK profile in several animal species. Treatment of M2 polarized macrophages with INCB098377 resulted in changes towards a more pro-inflammatory phenotype. CD163 and CD206 were decreased, whereas HLA-DR and co-stimulatory CD80/86 molecules were increased. MHC-I expression was unchanged, suggesting a role for these macrophages in MHC-II-mediated antigen presentation. Furthermore, INCB098377 treatment reduced macrophage-mediated immunosuppression and restored T cell proliferation in M2 polarized macrophages co-cultured with allogeneic human T cells. In vivo, significant tumor growth inhibition was observed with once-daily dosing of 10 mg/kg INCB098377 in both syngeneic and humanized mouse tumor models without toxicity. Moreover, efficacy was observed in inflamed and non-inflamed tumor models. Consistent with the proposed mechanism of action, INCB098377 inhibited phospho-AKT levels in vivo and in human PBMCs. Treatment with INCB098377 induced pro-inflammatory responses without macrophage depletion suggests that robust tumor microenvironment changes are responsible for observed anti-tumor efficacy. In addition, INCB098377 inhibited neutrophil migration in the Carrageenan-induced paw inflammation model. INCB098377, a potent and selective inhibitor of PI3Kγ, shows effective anti-tumor activity in a variety of mouse and humanized cancer models through the inhibition of immunosuppressive cells trafficking into the tumor, modulation of myeloid cell function, and enhancement of T cell proliferation.

Acknowledgments: Diana Alvarez Arias and Stephen Douglass contributed equally to this study.

Citation Format: Diana A. Arias, Stephen Douglass, Lisa Truong, Qian Wang, Kathy H. Wang, Gengjie Yang, Michael Hansbury, Sybil O’Connor, Kevin Bowman, Robert Collins, Matthew Stubbs, Leslie Hall, Christina Stevens, Christopher Maddage, Brent Douty, Maryanne Covington, Lynn Leffet, Eddy Yue, Andrew Combs, Sunkyu Kim, Niu Shin, Holly Koblish, Rodrigo Hess. Discovery of INCB098377: a potent inhibitor of phosphoinositide 3-kinase gamma (PI3Kγ). [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5162.

Exploring postgraduate epidemiology competencies: Preparing our students for a post-COVID world

OBJECTIVE

This research sought consensus from both experts and graduates on postgraduate epidemiology competencies.

METHODS

In 2021, a two-round online survey using a modified Delphi method was undertaken exploring competencies across six domains. Focus groups were conducted with recent postgraduate epidemiology graduates to assess their viewpoints on learning experiences and employability.

RESULTS

Forty-one experts participated in the first Delphi round. Nineteen factors reached consensus (>70% agreement) for importance and feasibility after two survey rounds in the following domains: general epidemiologic methods/concepts (n=8/13), advanced analytic/statistical skills (n=2/7), applied epidemiology/specialised fields (n=1/4), professional/transferrable skills (n=5/14), general public health knowledge/skills (n=2/4), independent research and work-integrated learning (n=1/3). Nine graduates participated in focus groups. A main theme was the substantial value gained in undertaking a dissertation, acknowledging its benefit for applying research skills and for networking opportunities.

CONCLUSIONS

To ensure that high-quality epidemiological research and practice continues, we need consensus on the set of essential skills required of graduating students.

IMPLICATIONS FOR PUBLIC HEALTH

Competencies for postgraduate epidemiology students require periodic review to safeguard a workforce that can meet emerging challenges and work across academia, research, policy, and practice.

Health service COVID-19 wellbeing and support initiatives: a mixed-methods evaluation

BACKGROUND

Health services implemented a range of initiatives during the COVID-19 pandemic to support employee wellbeing and assist employees to manage the professional and personal challenges they experienced. However, it is not known if such initiatives were acceptable to employees or met their needs.

AIMS

To evaluate the wellbeing and support initiatives implemented at an Australian health service during the COVID-19 pandemic from the perspectives of employees (both users and non-users) and key stakeholders.

METHODS

A mixed-methods design (survey, interviews and data audit) to investigate employees' and key stakeholders' perceptions, experiences and use of the wellbeing and support initiatives implemented at a large tertiary metropolitan health service in Melbourne, Australia.

RESULTS

Ten employees participated in an interview and 907 completed a survey. The initiatives were well used and appreciated by staff. There was no significant difference in the proportion of clinical staff who had used the initiatives compared to non-clinical staff (44% versus 39%; P=0.223). Survey respondents reported the initiatives improved their mental health (n = 223, 8%), ability to cope with COVID-19 related stress and anxiety (n = 206, 79%), do their work (n = 200, 77%) and relationships with colleagues (n = 174, 67%). Staff would like many of the initiatives (with some modifications) to continue after the COVID-19 pandemic.

CONCLUSIONS

The findings suggest a high level of staff satisfaction with the implemented wellbeing and support initiatives, and confirm the need for, and importance of, developing and implementing initiatives to support health service staff during outbreaks of infectious diseases such as the COVID-19 pandemic.

How RIVM is responding to the challenge of protecting human health from the effects of climate change – now and in the future

In 2020 the Dutch National Institute for Public Health and the Environment (RIVM) published its vision on climate change and health. This vision reflects the position of RIVM in society and highlights the transdisciplinary and collaborative nature of our work on this topic. We define this societal challenge as: protecting and promoting the health of people throughout society with regard to climate change and climate measures. The purpose of our work on this challenge is to support all levels of Dutch government with policy development and implementation and to forge links with both national and international organisations to further knowledge and expertise.

The focus of our work, in collaboration with the aforementioned actors, is as follows:

1. Knowledge translation of the health impacts of climate change for the public and government.

2. Developing instruments to promote health in relation to climate change and mitigation and adaptation measures.

3. Implementation research on solutions to mitigate and adapt to climate change.

4. Strengthening national and international cooperation to enhance synergies in our work.

In the workshop we will present examples of our work:

• Quantifying the health impacts of climate change, now and in the future under different global warming scenarios.

• Developing a set of indicators to monitor the health impacts of climate change and mitigation and adaptation plans and actions.

• Collating and disseminating easily digestible information for public health services on evidence-based, effective adaptation measures.

• Developing tools and instruments to ensure health benefits and limit unintended consequences of adaptation measures, such as green and blue spaces.

• Prioritising research on climate change and health through a research agenda.

Workshop participants will be encouraged to provide feedback to inform RIVM's future work and that of other national public health institutes, and to ensure we are fully supporting our stakeholders.

Clinical characteristics with inflammation profiling of long COVID and association with 1-year recovery following hospitalisation in the UK: a prospective observational study

BACKGROUND

No effective pharmacological or non-pharmacological interventions exist for patients with long COVID. We aimed to describe recovery 1 year after hospital discharge for COVID-19, identify factors associated with patient-perceived recovery, and identify potential therapeutic targets by describing the underlying inflammatory profiles of the previously described recovery clusters at 5 months after hospital discharge.

METHODS

The Post-hospitalisation COVID-19 study (PHOSP-COVID) is a prospective, longitudinal cohort study recruiting adults (aged ≥18 years) discharged from hospital with COVID-19 across the UK. Recovery was assessed using patient-reported outcome measures, physical performance, and organ function at 5 months and 1 year after hospital discharge, and stratified by both patient-perceived recovery and recovery cluster. Hierarchical logistic regression modelling was performed for patient-perceived recovery at 1 year. Cluster analysis was done using the clustering large applications k-medoids approach using clinical outcomes at 5 months. Inflammatory protein profiling was analysed from plasma at the 5-month visit. This study is registered on the ISRCTN Registry, ISRCTN10980107, and recruitment is ongoing.

FINDINGS

2320 participants discharged from hospital between March 7, 2020, and April 18, 2021, were assessed at 5 months after discharge and 807 (32·7%) participants completed both the 5-month and 1-year visits. 279 (35·6%) of these 807 patients were women and 505 (64·4%) were men, with a mean age of 58·7 (SD 12·5) years, and 224 (27·8%) had received invasive mechanical ventilation (WHO class 7-9). The proportion of patients reporting full recovery was unchanged between 5 months (501 [25·5%] of 1965) and 1 year (232 [28·9%] of 804). Factors associated with being less likely to report full recovery at 1 year were female sex (odds ratio 0·68 [95% CI 0·46-0·99]), obesity (0·50 [0·34-0·74]) and invasive mechanical ventilation (0·42 [0·23-0·76]). Cluster analysis (n=1636) corroborated the previously reported four clusters: very severe, severe, moderate with cognitive impairment, and mild, relating to the severity of physical health, mental health, and cognitive impairment at 5 months. We found increased inflammatory mediators of tissue damage and repair in both the very severe and the moderate with cognitive impairment clusters compared with the mild cluster, including IL-6 concentration, which was increased in both comparisons (n=626 participants). We found a substantial deficit in median EQ-5D-5L utility index from before COVID-19 (retrospective assessment; 0·88 [IQR 0·74-1·00]), at 5 months (0·74 [0·64-0·88]) to 1 year (0·75 [0·62-0·88]), with minimal improvements across all outcome measures at 1 year after discharge in the whole cohort and within each of the four clusters.

INTERPRETATION

The sequelae of a hospital admission with COVID-19 were substantial 1 year after discharge across a range of health domains, with the minority in our cohort feeling fully recovered. Patient-perceived health-related quality of life was reduced at 1 year compared with before hospital admission. Systematic inflammation and obesity are potential treatable traits that warrant further investigation in clinical trials.

FUNDING

UK Research and Innovation and National Institute for Health Research.

Service evaluation of the efficiency of moving discharge medicine request screening from the dispensary to hospital wards over a two-year period

Introduction

It is a common patient perception that their discharge from hospital is delayed by waiting for medicines (1). However, it is important to consider the entire discharge process when addressing this problem (2). In our large tertiary referral hospital, clinical pharmacy services were moved from wards to the dispensary following a staffing crisis during 2018. Ward-based services were reintroduced in 2020, but doubts remained over the practicality and benefits of doing this.

Aim

To compare the efficiency of ward and dispensary based clinical pharmacy services in our hospital in terms of interventions made and time taken.

Methods

We completed an observational service evaluation. Data on the time taken to process discharge medication requests with the dispensary-based service were collected retrospectively from the hospital electronic discharge system for 12 months (2018) for five medical wards. Equivalent data for the ward-based service were collected prospectively over three days (2020) by pharmacists delivering the service to seven medical wards, as this was considered more accurate, and several process steps did not exist in the ward-based model. For example, prescriber sending request to pharmacy and pharmacy acknowledging receipt of a request. The prospective data collection period was curtailed by Covid-19. Descriptive statistics were produced using Excel.

Results

Using the dispensary-based service (2018), 4459 medicine requests were processed from 5 medical wards, during a 12-month period. The mean time between prescribing and reaching the screening pharmacist was 175 minutes [95%CI ± 25.4]. It took an estimated time of 62 minutes [95%CI ± 2.99] to screen and resolve an intervention, with a mean of 3 interventions/ward/day. In 2020, using the ward-based approach to clinical pharmacy which screened medicine requests on the ward, 142 requests were screened over three days from seven wards, with no delay between prescribing and clinical screening. It took a mean of 17 minutes [95%CI ± 10.63] to screen and resolve an intervention, with a mean of 15 interventions/ward/day.

Conclusion

Ward based pharmacy yielded five times more interventions, took an average of 45 minutes less to screen and resolve issues per request and removed 175 minutes of process time. The additional time required to resolve issues identified in the dispensary-based screening process was thought to be the delay in contacting either the appropriate member of the ward staff referencing a particular patient for information or identifying and contacting the prescriber, or a combination of both. This study is limited by the long delay between data collection periods and the small sample size in 2020, but the differences between the two systems were large and there had been few other changes to hospital systems. Other limitations include changes related to Covid-19 and the lack of a control group, so it is not possible to establish a causal relationship between the type of pharmacy service and study outcomes.

References

(1) Wright S, Morecroft CW, Mullen R, Ewing AB. UK hospital patient discharge: the patient perspective. Eur J Hosp Pharm. 2017 Nov;24(6):338-342.

(2) Green CF, Hunter L, Jones L, Morris K. The TTO Journey: How much of it is actually in pharmacy? Pharm Man. 2015 Oct;31(4):16-20.

Changes to objective structured clinical examinations (OSCE) at Australian medical schools in response to the COVID-19 pandemic

INTRODUCTION

Objective Structured Clinical Examinations (OSCE) are used to assess clinical skills. We investigated how exit OSCEs changed in Australian medical schools in response to the COVID-19 pandemic.

MATERIALS AND METHODS

The lead ACCLAiM assessment academic from 12 eligible Australian medical school members of the Australian Collaboration for Clinical Assessment in Medicine (ACCLAiM) received a 45-item semi-structured online questionnaire.

RESULTS

All schools (12/12) responded. Exit OSCEs were not used by one school in 2019, and 3/11 schools in 2020. Of eight remaining schools, four reduced station numbers and testing time. The minimum OSCE testing time decreased from 64 min in 2019 to 54 min in 2020. Other modifications included: a completely online 'e-OSCE' (n = 1); hybrid delivery (n = 4); stations using: videos of patient encounters (n = 3), telephone calls (n = 2), skill completion without face-to-face patient encounters (n = 3). The proportion of stations involving physical examination reduced from 33% to 17%. Fewer examiners were required, and university faculty staff formed a higher proportion of examiners.

CONCLUSIONS

All schools changed their OSCEs in 2020 in response to COVID-19. Modifications varied from reducing station numbers and changing delivery methods to removing OSCE and complete assessment re-structuring. Several innovative methods of OSCE delivery were implemented to preserve OSCE validity and reliability whilst balancing feasibility.

Abstract P245: Synergistic effect of combination of pemigatinib with enfortumab vedotin (EV) in human bladder cancer models

Bladder cancer is among the most prevalent cancers worldwide, with urothelial carcinoma accounting for approximately 90% of cases. Until recently, poor overall survival after chemotherapy combined with immune checkpoint blockade therapies for patients with advanced urothelial carcinoma highlighted the need for new therapies. Although data supports the use of targeted therapies, such as FGFR inhibitors, recent advances in the treatment of bladder cancer are changing the landscape. Enfortumab vedotin (EV) is an antibody drug conjugate (ADC) consisting of an anti-Nectin-4 antibody conjugated to monomethyl auristatin E, which specifically delivers the auristatin payload to Nectin-4 high-expressing urothelial carcinomas. While activity and durability of response from both monotherapy trials as well as combination with pembrolizumab are favorable, additional treatment options might be required for either patients not responding to treatment or those who might develop resistance. Importantly, FGFR activation through rearrangement or mutation is frequently found in the luminal papillary subtype which also expresses high levels of Nectin-4. Thus, we sought to test the potential of combining pemigatinib and EV in models of human bladder cancer which express both activated FGFR3 and Nectin-4. Our initial analysis show that FGFR3 mutant tumors express high levels of Nectin-4. We further demonstrated that two bladder cancer cell lines RT112/84 (FGFR3-TACC3 fusion) and UM-UC-14 (FGFR3S249C) are sensitive to both pemigatinib and EV in vitro and in vivo. Notably, synergistic anti-tumor effects were observed when pemigatinib was combined with EV in vivo. In addition, combination of pemigatinib with EV significantly improved overall survival when compared to single treatments in these models. Altogether, our data strongly suggest a potential for combination of these therapies in the clinic.

Citation Format: Rodrigo A. Hess, Lisa Truong, Antony Chadderton, Michelle Frascella, Leslie Hall, Holly Koblish. Synergistic effect of combination of pemigatinib with enfortumab vedotin (EV) in human bladder cancer models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P245.

232 INCB090244, a potent small molecule that inhibits the PD-L1/PD-1 axis and functions similarly to PD-L1 antibodies

Background

Blocking the PD-L1 immune checkpoint axis with therapeutic antibodies against either the ligand or PD-1 has proven to be an effective treatment modality for multiple cancer histologies. Small molecules targeting the PD-L1/PD-1 axis represent an alternate modality of blocking this pathway. INCB090244 is a small molecule that blocks the PD-L1/PD-1 interaction and restores T cell function similar to the clinical stage PD-L1 inhibitor INCB086550.

Methods

MDA-MB-231 or CHO cells overexpressing PD-L1 were used to investigate effects of INCB090244 on PD-L1 dimerization, and intracellular trafficking. In vivo, CD34+ humanized mice harboring MDA-MB-231 tumors or C57Bl/6 mice bearing GL261 subcutaneous or orthotopic tumors were used to investigate the efficacy, biodistribution, and pharmacodynamic effects of INCB090244. Human specific gene expression changes in tumors from MDA-MB-231 bearing humanized mice were analyzed by RNA sequencing.

Results

In vitro, INCB090244 potently disrupted the PD-L1:PD-1 interaction, induced PD-L1 dimerization, and inhibited PD-1-mediated negative signaling, resulting in enhanced IFN gamma and IL-2 production in primary human immune cells. Following dimerization, INCB090244 induced internalization of PD-L1 resulting in co-localization with the Golgi apparatus and partial localization in the nucleus. After cell treatment and washing, full restoration of PD-L1 at the cell surface was observed after 5 days of culture in vitro. In vivo, INCB090244 reduced tumor growth in CD34+ humanized mice bearing MDA-MB-231 tumors, to similar levels as atezolizumab. Antitumor activity was completely abrogated in immunodeficient mice, confirming the pharmacologic dependency on a competent immune system. RNA sequencing analysis on tumors from these mice demonstrated similar T cell activation gene signatures as clinical checkpoint blockade antibodies. Biodistribution studies in mice bearing both subcutaneous and orthotopically implanted GL261 glioma tumors demonstrated higher accumulation of INCB090244 in tumor tissue compared to PD-L1 antibodies.

Conclusions

INCB090244 effectively disrupted the PD-L1/PD-1 interaction, induced dimerization and internalization of PD-L1, restored immunity in in vitro and in vivo tumor models, and is a suitable surrogate for the clinical candidate INCB086550. RNA sequencing demonstrated T cell activation signatures similar to those observed in patients receiving checkpoint blockade antibodies. Biodistribution studies demonstrated higher subcutaneous and brain tumor penetration by INCB090244 compared to PD-L1 antibodies, suggesting a potential advantage of small molecule PD-L1 inhibitors in accessing intratumoral regions. These data further support the clinical evaluation of small molecule PD-L1 inhibitors as an alternative approach to immune therapy.

A human CD137×PD-L1 bispecific antibody promotes anti-tumor immunity via context-dependent T cell costimulation and checkpoint blockade

Immune checkpoint inhibitors demonstrate clinical activity in many tumor types, however, only a fraction of patients benefit. Combining CD137 agonists with these inhibitors increases anti-tumor activity preclinically, but attempts to translate these observations to the clinic have been hampered by systemic toxicity. Here we describe a human CD137xPD-L1 bispecific antibody, MCLA-145, identified through functional screening of agonist- and immune checkpoint inhibitor arm combinations. MCLA-145 potently activates T cells at sub-nanomolar concentrations, even under suppressive conditions, and enhances T cell priming, differentiation and memory recall responses. In vivo, MCLA-145 anti-tumor activity is superior to immune checkpoint inhibitor comparators and linked to recruitment and intra-tumor expansion of CD8 + T cells. No graft-versus-host-disease is observed in contrast to other antibodies inhibiting the PD-1 and PD-L1 pathway. Non-human primates treated with 100 mg/kg/week of MCLA-145 show no adverse effects. The conditional activation of CD137 signaling by MCLA-145, triggered by neighboring cells expressing >5000 copies of PD-L1, may provide both safety and potency advantages.

393 What Are the Risk Factors for Anastomotic Stricture After Bile Duct Injury Repair? A Systematic Review and Meta-Analysis

Introduction

Hepaticojejunostomy (HJ) is the standard repair following major bile duct injury (BDI), but anastomotic stricture can result in long-term morbidity. There is a need to assimilate high-level evidence to establish risk factors for the development of anastomotic stricture after HJ for BDI.

Method

A systematic review of studies reporting the rate of anastomotic stricture after HJ for BDI was performed according to PRISMA guidelines. Meta-analyses of proposed risk factors were then performed.

Results

Meta-analysis included five factors (n = 2,198 patients, 17 studies). Vascular injury (OR 2.71; 95%CI 1.37-5.35; p = 0.004), postoperative bile leak (OR: 8.03; 95%CI 2.04-31.71; p = 0.003), previous repair (OR: 5.36; 95%CI 1.04-27.76;p=0.05) and repair by non-specialist surgeon (OR 11.29; 95%CI 5.21-24.47; p < 0.0001) were associated with HJ stricture after BDI. Strasberg injury grade was not associated with HJ stricture (OR: 1.05; 95%CI 0.63-1.75; p = 0.86). Due to heterogeneity of reporting it was not possible to perform meta-analysis for impact of timing of repair on anastomotic stricture rate.

Conclusions

This meta-analysis identifies factors that significantly increase the rate of anastomotic stricture after HJ for BDI. Knowledge of these risk factors will allow risk stratification in terms of follow-up for individual cases, better informed consent, and guidance for medico-legal cases.

Longitudinal associations between exposure to anesthesia and neurocognitive functioning in pediatric medulloblastoma

AIM

To examine whether anesthesia exposure is associated with neurocognitive decline in pediatric medulloblastoma.

METHODS

Patients were treated at St. Jude Children's Research Hospital and completed ≥2 protocol-directed neurocognitive assessments (n = 107) as part of a multisite clinical trial for pediatric medulloblastoma (NCT00085202). Patients received risk-adapted craniospinal photon irradiation, followed by four cycles of high-dose chemotherapy and stem cell rescue. Neurocognitive testing was completed at study baseline (after surgery and <2 weeks of starting radiation therapy) and annually for 5 years. Data on anesthesia exposure during treatment was abstracted from medical records.

RESULTS

Patients were 10.2 years at diagnosis on average (SD = 4.5; 37% female, 73% average-risk). Mean cumulative anesthesia duration was 20.4 h (SD = 15.2; range 0.7-55.6 h). In the overall group, longer anesthesia duration was associated with greater declines in IQ (Estimate = -0.08, P < 0.001), attention (Estimate = -0.10, P < .001) and processing speed (Estimate = -0.13, P < 0.001). Similar results were shown in subgroups of patients who were <7 years at diagnosis (IQ = -0.14, P = 0.027; Attention = -0.25: P = 0.011), ≥7 years at diagnosis (Attention = -0.07, P = 0.039; Processing Speed = -0.08, P = 0.022), treated for high-risk disease (IQ = -0.09, P = 0.024; Attention = -0.11, P = 0.034; Processing Speed = -0.13, P = 0.001), or treated for average-risk disease (IQ = -0.05, P = .022; Attention = -0.08, P = 0.011; Processing Speed = -0.10, P < 0.001).

CONCLUSION

Greater anesthesia exposure is a risk factor for clinically significant neurocognitive decline, in addition to factors of age at diagnosis and treatment risk arm. This result is notable as there are evidence-based strategies that can limit the need for anesthesia. Limiting anesthesia exposure, as feasible, may mitigate neurocognitive late effects, and thus, improve quality of life for survivors.

Feed acidification and steam-conditioning temperature influence nutrient utilization in broiler chickens fed wheat-based diets

Two experiments were conducted to examine the effects of conditioning temperature (CT) and the interactive influence of feed acidification (FA) and CT on the performance, coefficient of apparent ileal digestibility (CAID) of nitrogen (N), starch, fat calcium (Ca) and phosphorus (P), and AME in broilers. In both experiments, each treatment was randomly allocated to 6 cages (8 birds per cage) and fed from 1 to 21 D posthatch. In experiment 1, the effect of CT was evaluated using a wheat-based diet at 3 CT: unconditioned, conditioned at 60°C or 90°C. All the diets by-passed the pellet press and collected in mash form. Birds fed the diet conditioned at 90°C consumed more (P < 0.05) feed and tended (P = 0.087) to have higher feed per gain (F:G) than those fed the unconditioned diet but similar to those fed the diet conditioned at 60°C. A tendency was noted for CT to affect the CAID of N (P = 0.071) and starch (P = 0.093), with reduced digestibility values in the diet conditioned at 90°C. Conditioning at 90°C resulted in lower (P < 0.05) AME. In experiment 2, three inclusions of an acidifier (0.0, 7.0, and 10 g/kg) and 2 CT of 60°C and 90°C were evaluated in a 3 × 2 factorial arrangement of treatments using pelleted diets. Neither the main effects nor the interaction between acidifier addition and CT was significant for weight gain, feed intake, and F:G. The FA increased (P < 0.05) the CAID of N, fat, and P at both inclusion levels and of starch at 10 g/kg. Conditioning at 90°C reduced (P < 0.05) the CAID of starch, fat, and Ca, regardless of FA level. Overall, the present data showed that the application of high CT for broiler feed manufacture can impair nutrient utilization and, consequently the feed efficiency in broilers. Feed acidification imparts some benefits to nutrient digestibility in broilers fed pelleted wheat-based diets.

Experiences of using the i-PARIHS framework: a co-designed case study of four multi-site implementation projects

BACKGROUND

The integrated-Promoting Action on Research Implementation in Health Services (i-PARIHS) framework is an implementation framework that has been developed and refined over the last 20 years. Its underlying philosophy is that implementing research into healthcare practice is complex, unpredictable and non-linear which therefore requires a flexible and responsive approach to implementation. Facilitation is recognized as the central ingredient of this approach, and i-PARIHS now provides a Facilitation Guide with associated tools. This multiple case study of four implementation projects explored how the i-PARIHS framework has been practically operationalized by diverse implementation project teams.

METHODS

A co-design approach was used to elicit the experiences of four implementation project teams who used the i-PARIHS framework to guide their implementation approach. We conducted the established co-design steps of (i) setting up for success, (ii) gathering the experience, and (iii) understanding the experience. In particular we explored teams' approaches to setting up their projects; why and how they used the i-PARIHS framework and what they learnt from the experience.

RESULTS

We found both commonalities and differences in the use of i-PARIHS across the four implementation projects: (i) all the projects used the Facilitation Checklist that accompanies i-PARIHS as a starting point, (ii) the projects differed in how facilitation was carried out, (iii) existing tools were adapted for distinct phases: pre-implementation, during implementation, and post-implementation stages; and (iv) project-specific tools were often developed for monitoring implementation activities and fidelity.

CONCLUSIONS

We have provided a detailed overview of how current users of i-PARIHS are operationalising the framework, which existing tools they are using or adapting to use, and where they have needed to develop new tools to best utilise the framework. Importantly, this study highlights the value of existing tools from the published i-PARIHS Facilitation Guide and provides a starting point to further refine and add to these tools within a future Mobilising Implementation of i-PARIHS (or "Mi-PARIHS") suite of resources. Specifically, Mi-PARIHS might include more explicit guidance and/or tools for developing a structured implementation plan and monitoring fidelity to the implementation plan, including recording how strategies are tailored to an evolving context.

Parsaclisib Is a Next-Generation Phosphoinositide 3-Kinase δ Inhibitor with Reduced Hepatotoxicity and Potent Antitumor and Immunomodulatory Activities in Models of B-Cell Malignancy

The clinical use of first-generation phosphoinositide 3-kinase (PI3K)δ inhibitors in B-cell malignancies is hampered by hepatotoxicity, requiring dose reduction, treatment interruption, and/or discontinuation of therapy. In addition, potential molecular mechanisms by which resistance to this class of drugs occurs have not been investigated. Parsaclisib (INCB050465) is a potent and selective next-generation PI3Kδ inhibitor that differs in structure from first-generation PI3Kδ inhibitors and has shown encouraging anti-B-cell tumor activity and reduced hepatotoxicity in phase 1/2 clinical studies. Here, we present preclinical data demonstrating parsaclisib as a potent inhibitor of PI3Kδ with over 1000-fold selectivity against other class 1 PI3K isozymes. Parsaclisib directly blocks PI3K signaling-mediated cell proliferation in B-cell lines in vitro and in vivo and indirectly controls tumor growth by lessening immunosuppression through regulatory T-cell inhibition in a syngeneic lymphoma model. Diffuse large B-cell lymphoma cell lines overexpressing MYC were insensitive to proliferation blockade via PI3Kδ signaling inhibition by parsaclisib, but their proliferative activities were reduced by suppression of MYC gene transcription. Molecular structure analysis of the first- and next-generation PI3Kδ inhibitors combined with clinical observation suggests that hepatotoxicity seen with the first-generation inhibitors could result from a structure-related off-target effect. Parsaclisib is currently being evaluated in multiple phase 2 clinical trials as a therapy against various hematologic malignancies of B-cell origin (NCT03126019, NCT02998476, NCT03235544, NCT03144674, and NCT02018861). SIGNIFICANCE STATEMENT: The preclinical properties described here provide the mechanism of action and support clinical investigations of parsaclisib as a therapy for B-cell malignancies. MYC overexpression was identified as a resistance mechanism to parsaclisib in DLBCL cells, which may be useful in guiding further translational studies for the selection of patients with DLBCL who might benefit from PI3Kδ inhibitor treatment in future trials. Hepatotoxicity associated with first-generation PI3Kδ inhibitors may be an off-target effect of that class of compounds.

INCB050465 (Parsaclisib), a Novel Next-Generation Inhibitor of Phosphoinositide 3-Kinase Delta (PI3Kδ)

A medicinal chemistry effort focused on identifying a structurally diverse candidate for phosphoinositide 3-kinase delta (PI3Kδ) led to the discovery of clinical candidate INCB050465 (20, parsaclisib). The unique structure of 20 contains a pyrazolopyrimidine hinge-binder in place of a purine motif that is present in other PI3Kδ inhibitors, such as idelalisib (1), duvelisib (2), and INCB040093 (3, dezapelisib). Parsaclisib (20) is a potent and highly selective inhibitor of PI3Kδ with drug-like ADME properties that exhibited an excellent in vivo profile as demonstrated through pharmacokinetic studies in rats, dogs, and monkeys and through pharmacodynamic and efficacy studies in a mouse Pfeiffer xenograft model.

Abstract 539: A bispecific Fc-silenced IgG1 antibody (MCLA-145) requires PD-L1 binding to activate CD137

CD137 (4-1BB) is a transmembrane costimulatory receptor on T and NK cells that enhances adaptive immune responses and is a critical mediator of antitumor immunity. The development of CD137 targeted agents for cancer therapy has been hampered by on-target off-tumor toxicity in the case of agonist monospecific, bivalent mAbs or limited antitumor activity in the case of crosslinking mAbs. Here we have developed an Fc-silenced bispecific IgG1 antibody to CD137 and PD-L1 with monovalent binding specificity to each target. MCLA-145 drives transactivation of CD137 in the vicinity of cells expressing PD-L1, such as in the immunosuppressive tumor microenvironment. The degree of CD137 agonistic activity in T cells correlated with the expression level of PD-L1 on neighboring cells, as demonstrated in transactivation assays whereby reporter T cells were co-cultured with cells expressing different levels of PD-L1. PD-L1 expression as low as 6000 receptors per cell was sufficient to activate CD137 in neighboring T cells. In contrast, MCLA-145 blocked PD-1 signaling without requirement for CD137 binding in a PD-1/PD-L1 reporter assay. CD137 signaling was induced by MCLA-145 in multiple primary human immune cell assays including the mixed lymphocyte reaction, human PBMC, and whole blood SEB stimulation assays. MCLA-145 reversed T cell suppression mediated by M2 macrophages or Tregs, in vitro. In addition, MCLA-145 enhanced Ag-specific expansion and differentiation of human naïve CD8+ T cells in vitro.

In vivo, MCLA-145 treatment resulted in significant tumor immune activation and antitumor responses in two separate humanized mouse tumor models. In one model, human T cells expressing NY-ESO specific TCR were adoptively transferred to mice bearing A549 tumors which expressed NY-ESO antigen and human PD-L1. MCLA-145 treatment at 5 mg/kg resulted in 54% tumor growth inhibition (TGI) as compared to T cell only treated mice. In the tumors of MCLA-145 treated mice, the percentage of NY-ESO specific CD8+ T cells were significantly increased compared to controls. In a second model, mice engrafted with human CD34+ cells were implanted with the breast tumor cell line MDA-MB-231. MCLA-145 at 0.5 mg/kg and 5 mg/kg induced significant tumor growth inhibition (55 and 57% respectively) as compared to vehicle control or Fc-silenced huIgG1 controls. Additionally, two out of nine animals in the 5 mg/kg MCLA-145-treated group had complete tumor regression. MCLA-145 increased the number of infiltrating CD8+ T cells, as well as the percentage of central memory CD8+ T cells. The cured animals were then re-challenged with MDA-MB-231 tumor cells, and tumors of previously cured mice were rejected as compared to no growth inhibition in treatment-naïve CD34+ NSG mice. In conclusion, these data support the clinical evaluation of MCLA-145 as a novel, PD-L1 dependent CD137 agonist immune therapy.

Citation Format: Patrick Mayes, Paul Tacken, Steve Wang, Pieter-Fokko van Loo, Thomas Condamine, Hans van der Maaden, Eric Rovers, Steef Engels, Floris Fransen, Ashwini Kulkarni, Yao-bin Liu, Arpita Mondal, Leslie Hall, Soyeon Kim, Marina Martinez, Shaun O'Brien, Edmund Moon, Steven Albelda, Peggy Scherle, Gregory Hollis, Reid Huber, Mark Throsby, Cecile A. Geuijen. A bispecific Fc-silenced IgG1 antibody (MCLA-145) requires PD-L1 binding to activate CD137 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 539.

Polygenic risk for schizophrenia, transition and cortical gyrification: a high-risk study

BACKGROUND

Schizophrenia is a highly heritable disorder, linked to several structural abnormalities of the brain. More specifically, previous findings have suggested that increased gyrification in frontal and temporal regions are implicated in the pathogenesis of schizophrenia.

METHODS

The current study included participants at high familial risk of schizophrenia who remained well (n = 31), who developed sub-diagnostic symptoms (n = 28) and who developed schizophrenia (n = 9) as well as healthy controls (HC) (n = 16). We first tested whether individuals at high familial risk of schizophrenia carried an increased burden of trait-associated alleles using polygenic risk score analysis. We then assessed the extent to which polygenic risk was associated with gyral folding in the frontal and temporal lobes.

RESULTS

We found that individuals at high familial risk of schizophrenia who developed schizophrenia carried a significantly greater burden of risk-conferring variants for the disorder compared to those at high risk (HR) who developed sub-diagnostic symptoms or remained well and HC. Furthermore, within the HR cohort, there was a significant and positive association between schizophrenia polygenic risk score and bilateral frontal gyrification.

CONCLUSIONS

These results suggest that polygenic risk for schizophrenia impacts upon early neurodevelopment to confer greater gyral folding in adulthood and an increased risk of developing the disorder.

Preclinical characterization of INCB053914, a novel pan-PIM kinase inhibitor, alone and in combination with anticancer agents, in models of hematologic malignancies

The Proviral Integration site of Moloney murine leukemia virus (PIM) serine/threonine protein kinases are overexpressed in many hematologic and solid tumor malignancies and play central roles in intracellular signaling networks important in tumorigenesis, including the Janus kinase-signal transducer and activator of transcription (JAK/STAT) and phosphatidylinositol 3-kinase (PI3K)/AKT pathways. The three PIM kinase isozymes (PIM1, PIM2, and PIM3) share similar downstream substrates with other key oncogenic kinases and have differing but mutually compensatory functions across tumors. This supports the therapeutic potential of pan-PIM kinase inhibitors, especially in combination with other anticancer agents chosen based on their role in overlapping signaling networks. Reported here is a preclinical characterization of INCB053914, a novel, potent, and selective adenosine triphosphate-competitive pan-PIM kinase inhibitor. In vitro, INCB053914 inhibited proliferation and the phosphorylation of downstream substrates in cell lines from multiple hematologic malignancies. Effects were confirmed in primary bone marrow blasts from patients with acute myeloid leukemia treated ex vivo and in blood samples from patients receiving INCB053914 in an ongoing phase 1 dose-escalation study. In vivo, single-agent INCB053914 inhibited Bcl-2-associated death promoter protein phosphorylation and dose-dependently inhibited tumor growth in acute myeloid leukemia and multiple myeloma xenografts. Additive or synergistic inhibition of tumor growth was observed when INCB053914 was combined with selective PI3Kδ inhibition, selective JAK1 or JAK1/2 inhibition, or cytarabine. Based on these data, pan-PIM kinase inhibitors, including INCB053914, may have therapeutic utility in hematologic malignancies when combined with other inhibitors of oncogenic kinases or standard chemotherapeutics.

Radiomics in Brain Tumor: Image Assessment, Quantitative Feature Descriptors, and Machine-Learning Approaches

Radiomics describes a broad set of computational methods that extract quantitative features from radiographic images. The resulting features can be used to inform imaging diagnosis, prognosis, and therapy response in oncology. However, major challenges remain for methodologic developments to optimize feature extraction and provide rapid information flow in clinical settings. Equally important, to be clinically useful, predictive radiomic properties must be clearly linked to meaningful biologic characteristics and qualitative imaging properties familiar to radiologists. Here we use a cross-disciplinary approach to highlight studies in radiomics. We review brain tumor radiologic studies (eg, imaging interpretation) through computational models (eg, computer vision and machine learning) that provide novel clinical insights. We outline current quantitative image feature extraction and prediction strategies with different levels of available clinical classes for supporting clinical decision-making. We further discuss machine-learning challenges and data opportunities to advance radiomic studies.

Abstract 2618: Agonist antibodies targeting OX40 and GITR enhance the activity of the IDO1-selective inhibitor epacadostat in preclinical models

The majority of immunotherapeutic agents developed thus far either attempt to stimulate a more productive anti-tumor immune response or to inhibit key proteins in the immunosuppressive tumor milieu. PD-1/PD-L1 axis blockade, CTLA-4 blockade and IDO1 inhibition are examples of the latter approach and have been utilized to reverse the suppressive tumor microenvironment, resulting in clinical benefit for cancer patients. Recent clinical and preclinical data have also demonstrated that combining these approaches results in enhanced therapeutic benefit. Notably, the IDO1-selective inhibitor epacadostat has been shown to increase the efficacy of two checkpoint inhibitors, the anti-CTLA-4 antibody ipilimumab and the anti-PD-1 antibody pembrolizumab, in patients with melanoma. Because both checkpoint receptors and IDO1 serve as negative regulators of the immune response, we also explored the ability of IDO1 inhibition to combine with agents that directly activate T cells through costimulatory receptors of the tumor necrosis factor receptor (TNFR) superfamily. Rodent active surrogate agonist antibodies to 4-1BB, OX40 and GITR were tested with epacadostat in multiple preclinical models. In the B16-SIY melanoma model that does not express IDO1 in tumor cells, both epacadostat and anti-OX40 had little effect, but the combination resulted in enhanced efficacy. This was associated with increased infiltrates of CD8+ T cells and decreased numbers of FoxP3+ TILs. Increased numbers of SIY-reactive T cells were found in both the tumor and the TDLN post-therapy. In contrast, epacadostat did not provide any enhancement to the activity seen with 4-1BB. Clear combinatorial effects were seen with anti-GITR and epacadostat in the more inflamed, IDO1-expressing PAN02 pancreatic cancer model. These data suggest that IDO1 inhibition can be effective in combination with agents that agonize T cell costimulatory receptors as well as with agents that block coinhibitory receptors.

Citation Format: Holly K. Koblish, Brendan Horton, Michael Hansbury, Sybil O'Connor, Kerri Lasky, Christina Stevens, Thomas Condamine, Leslie Hall, Liang-Chuan Wang, Yue Zhang, Horacio Nastri, Gregory Hollis, Reid Huber, Thomas Gajewski, Peggy Scherle. Agonist antibodies targeting OX40 and GITR enhance the activity of the IDO1-selective inhibitor epacadostat in preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2618. doi:10.1158/1538-7445.AM2017-2618

Abstract 143: Preclinical studies on potential therapeutic combination partners for the potent and selective PI3Kδ inhibitor INCB050465 in DLBCL

The delta isoform of PI3K (PI3Kδ) plays an essential role in B-cell development and function by mediating the signaling of key receptors on B cells. Increased malignant B cell proliferation and survival has also been associated with aberrant activation of PI3Kδ, making selective inhibition of this isoform an attractive therapeutic approach for the treatment of B cell malignancies. INCB050465 is a potent inhibitor of PI3Kδ, with a &gt;20,000 fold selectivity over other PI3K isoforms. Emerging clinical data indicate that INCB050465 monotherapy is well tolerated and results in promising clinical responses in patients with various lymphoma histologies, including those with DLBCL. We therefore sought to explore rational combination strategies for INCB050465 using mouse xenograft models of ABC-subtype (HBL-1), GCB-subtype (Pfeiffer), and GCB/double-hit (WILL-2) human DLBCL, evaluating standard of care agents such as bendamustine and rituximab, as well as with targeted agents. PIM inhibition is a logical addition to PI3Kδ inhibition as a therapeutic approach as both kinases play a critical role in the AKT signaling pathway, having overlapping substrates. Likewise BET inhibition is a rational addition to PI3Kδ inhibition in “double-hit” DLBCL due to de-regulation of MYC transcriptional activity. In vivo studies performed in the Pfeiffer xenograft model demonstrate that INCB050465 combined with the pan-PIM inhibitor INCB053914 yielded complete tumor regressions. This profound decrease in tumor cell survival was due in part to the significant reduction in pBAD levels resulting from dual PIM and PI3Kδ inhibition. Despite modest single agent activity in vivo, the combination of INCB050465 with BET inhibitors, INCB054329 or INCB057643, resulted in significant anti-tumor efficacy in all of the DLBCL models studied, and caused a marked repression in tumor MYC expression. To study the transcriptional effects of combining PI3Kδ and BET inhibitors in this lymphoma model, WILL-2 xenograft tumors from mice treated with single dose INCB050465, INCB054329, the combination, or vehicle control were analyzed by RNAseq. INCB050465 enhanced the ability of INCB054329 to repress a MYC-driven transcriptional program, and the combination also regulated multiple developmental and inflammatory pathways. Together, these data support the clinical evaluation of the PI3Kδ inhibitor INCB050465 as part of a combination regimen with PIM or BET inhibitors for the treatment of DLBCL.

Citation Format: Matthew C. Stubbs, Robert Collins, Leslie Hall, Alla Volgina, Holly Koblish, Sang Hyun Lee, Timothy Burn, Phillip C. Liu, Jin Lu, Eddy Yue, Yun-Long Li, Andrew P. Combs, Wenqing Yao, Gregory Hollis, Reid Huber, Bruce Ruggeri, Peggy Scherle. Preclinical studies on potential therapeutic combination partners for the potent and selective PI3Kδ inhibitor INCB050465 in DLBCL [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 143. doi:10.1158/1538-7445.AM2017-143

Using chiral ionic liquid additives to enhance asymmetric induction in a Diels–Alder reaction

A bis-oxazoline ligand has been complexed using Cu(ii) and Zn(ii) trifluoromethanesulfonate and a range of chiral ionic liquid (CIL) additives based on natural products were used as a co-catalyst for a Diels–Alder reaction.

Primary Hypoparathyroidism Resistant to Conventional Therapy

A 28 year old man with primary hypoparathyroidism failed to respond to treatment with calcium and vitamin D analogues. Despite extensive investigation no reason for this was found and he is now successfully treated with teriparatide (synthetic human PTH)

Streptococcus grouping latex kits: evaluation of five commercially available examples

This study compares a recently introduced latex agglutination test for the serogrouping of beta-haemolytic streptococci against four internationally used commercial kits. The new kit is Prolex-Blue (Pro-Lab Diagnostics) and the comparators are Streptex (Murex), PathoDx (DPC), Streptococcus Grouping kit (Oxoid) and Prolex-White (Pro-Lab Diagnostics). A total of 302 consecutive clinical isolates are tested against all five kits, following the individual manufacturer's protocol, for both accuracy and speed. In addition, the data produced permits determination of the strengths or weaknesses of the kits against individual serotypes. Prolex-Blue proved to be both accurate and rapid, with a sensitivity of 99% and a specificity of 100%. Furthermore, average time to agglutination was substantially less than achieved by three of the other four kits evaluated.

Abstract 4904: The BET inhibitor INCB054329 enhances the activity of checkpoint modulation in syngeneic tumor models

Inhibitors of the BET family of bromodomain proteins have been shown to be growth inhibitory across a spectrum of tumor types due to their ability to regulate the expression of key survival and cell fate determining genes such as c-myc. In addition to their role in cancer, studies using genetic knockdown and small molecule inhibitors have demonstrated that targeting BET proteins controls the expression of pro-inflammatory cytokine genes in macrophages and is therapeutic in models of acute inflammation. These data suggest that in addition to their tumor intrinsic effects, BET inhibitors may also regulate the cytokine milieu within the tumor microenvironment and have immunomodulatory activity in cancer. To study this aspect, we evaluated INCB054329, a novel and selective BET inhibitor currently in Phase 1 trials, alone and in combination either with epacadostat, a highly selective IDO1 inhibitor, or with PD-1/PD-L1 axis blockade in syngeneic tumor models using immunocompetent animals. When used alone, INCB054329 suppressed a panel of cytokines and chemokines in a whole blood assay, confirming that INCB054329 can antagonize a pro-inflammatory response. The potency of INCB054329 in reducing the levels of these inflammatory mediators in the whole blood assay was similar to that for inhibition of c-myc, suggesting that the effects were on-target. INCB054329 was capable of inhibiting the growth of multiple syngeneic tumor models in immunocompetent mice, whereas only modest tumor growth inhibition was observed in immunodeficient mice and a lack of activity was observed in vitro, supporting the immunomodulatory activity of the compound. Because maximal in vivo tumor growth inhibition required an intact immune system, we investigated the impact of INCB054329 on various immune cell subsets, both in vitro and in vivo. Of note, increases in effector T cell populations were observed and efforts are ongoing to further characterize the tumor infiltrating immune cells following INCB054329 treatment. The mechanistic complimentarity of this novel BET inhibitor-mediated immunomodulation was also evaluated in combination with other therapeutically relevant mechanisms, including IDO1 inhibition and PD-1 axis blockade. Enhanced efficacy was observed with all INCB054329-containing regimens. These data demonstrate for the first time that BET inhibition can suppress tumor growth through both tumor-intrinsic and immune modulatory mechanisms, and support the potential of epigenetic-based, immunotherapy combinations as a novel approach to cancer therapy.

Citation Format: Holly K. Koblish, Michael Hansbury, Leslie Hall, Liang-Chuan Wang, Yue Zhang, Maryanne Covington, Timothy Burn, Mark Rupar, Christine Gardiner, Thomas Condamine, Kerri Lasky, Matthew C. Stubbs, Eddy Yue, Richard Sparks, Richard Sparks, Thomas Maduskuie, Andrew P. Combs, Gregory Hollis, Reid Huber, Phillip CC Liu, Peggy Scherle. The BET inhibitor INCB054329 enhances the activity of checkpoint modulation in syngeneic tumor models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4904.

MaxiK channel interactome reveals its interaction with GABA transporter 3 and heat shock protein 60 in the mammalian brain

Large conductance voltage and calcium-activated potassium (MaxiK) channels are activated by membrane depolarization and elevated cytosolic Ca(2+). In the brain, they localize to neurons and astrocytes, where they play roles such as resetting the membrane potential during an action potential, neurotransmitter release, and neurovascular coupling. MaxiK channels are known to associate with several modulatory proteins and accessory subunits, and each of these interactions can have distinct physiological consequences. To uncover new players in MaxiK channel brain physiology, we applied a directed proteomic approach and obtained MaxiK channel pore-forming α subunit brain interactome using specific antibodies. Controls included immunoprecipitations with rabbit immunoglobulin G (IgG) and with anti-MaxiK antibodies in wild type and MaxiK channel knockout mice (Kcnma1(-/-)), respectively. We have found known and unreported interactive partners that localize to the plasma membrane, extracellular space, cytosol and intracellular organelles including mitochondria, nucleus, endoplasmic reticulum and Golgi apparatus. Localization of MaxiK channel to mitochondria was further confirmed using purified brain mitochondria colabeled with MitoTracker. Independent proof of MaxiK channel interaction with previously unidentified partners is given for GABA transporter 3 (GAT3) and heat shock protein 60 (HSP60). In human embryonic kidney 293 cells containing SV40 T-antigen (HEK293T) cells, both GAT3 and HSP60 coimmunoprecipitated and colocalized with MaxiK channel; colabeling was observed mainly at the cell periphery with GAT3 and intracellularly with HSP60 with protein proximity indices of ∼ 0.6 and ∼ 0.4, respectively. In rat primary hippocampal neurons, colocalization index was identical for GAT3 (∼ 0.6) and slightly higher for HSP60 (∼ 0.5) association with MaxiK channel. The results of this study provide a complete interactome of MaxiK channel the mouse brain, further establish the localization of MaxiK channel in the mouse brain mitochondria and demonstrate the interaction of MaxiK channel with GAT3 and HSP60 in neurons. The interaction of MaxiK channel with GAT3 opens the possibility of a role of MaxiK channel in GABA homeostasis and signaling.

Abstract B191: Preclinical assessment of targeting the PI3K/AKT pathway in combination with other signal transduction pathway inhibitors

Inhibitors targeting the phosphoinositide 3-kinase (PI3K)/serine-threonine protein kinase B (AKT) pathway have been developed and have shown efficacy in inhibiting tumor growth both in preclinical models and in the clinic. The effectiveness of PI3K/AKT inhibitors, however, is attenuated by the activation of alternative signaling pathways. Conversely, the PI3K/AKT pathway is considered to be a resistance mechanism for other therapeutic or cytotoxic agents. Therefore, understanding these mechanisms may help to inform the most optimal combinations for advancement into clinical studies. Here, we explored the potential of targeting the JAK/STAT or PIM signaling pathways in combination with a novel, potent and selective AKT inhibitor, INCB047775. Consistent with published data, pharmacological inhibition of AKT by INCB047775 caused the upregulation of PIM kinases. The combined therapies of PIM inhibition and AKT inhibition exhibited significant synergistic anti-tumor effects. Combination of PIM inhibition with AKT inhibition resulted in synergistic induction of apoptosis in cancer cells. Similarly, the combination of JAK tyrosine kinase inhibition with INCB047775 exerted synergistic inhibition of the proliferation of multiple myeloma cell lines. Similar data were observed with an inhibitor of PI3Kδ in combination with both PIM and JAK inhibition, demonstrating significant crosstalk between the PI3K/AKT pathway and other critical signaling pathways. These data provide the rationale for combinatorial therapies with inhibitors targeting JAK or PIM kinases with PI3K/AKT pathway inhibitors in the clinic.

Citation Format: Sang Hyun Lee, Holly Koblish, Xiangdong Liu, Haifen Ye, Jun Li, Xuesong Liu, Melody Diamond, Yue Zhang, Leslie Hall, Valerie Dostalik, Margaret Favata, Elham Behshad, Richard Wynn, Yun-long Li, Andrew Combs, Chu-Bio Xue, Wenqing Yao, Gregory Hollis, Reid Huber, Peggy Scherle. Preclinical assessment of targeting the PI3K/AKT pathway in combination with other signal transduction pathway inhibitors. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B191.