All-optical subcycle microscopy on atomic length scales

Bringing optical microscopy to the shortest possible length and time scales has been a long-sought goal, connecting nanoscopic elementary dynamics with the macroscopic functionalities of condensed matter. Super-resolution microscopy has circumvented the far-field diffraction limit by harnessing optical nonlinearities1. By exploiting linear interaction with tip-confined evanescent light fields2, near-field microscopy3,4 has reached even higher resolution, prompting a vibrant research field by exploring the nanocosm in motion5-19. Yet the finite radius of the nanometre-sized tip apex has prevented access to atomic resolution20. Here we leverage extreme atomic nonlinearities within tip-confined evanescent fields to push all-optical microscopy to picometric spatial and femtosecond temporal resolution. On these scales, we discover an unprecedented and efficient non-classical near-field response, in phase with the vector potential of light and strictly confined to atomic dimensions. This ultrafast signal is characterized by an optical phase delay of approximately π/2 and facilitates direct monitoring of tunnelling dynamics. We showcase the power of our optical concept by imaging nanometre-sized defects hidden to atomic force microscopy and by subcycle sampling of current transients on a semiconducting van der Waals material. Our results facilitate access to quantum light-matter interaction and electronic dynamics at ultimately short spatio-temporal scales in both conductive and insulating quantum materials.

Build-up and dephasing of Floquet-Bloch bands on subcycle timescales

Strong light fields have created opportunities to tailor novel functionalities of solids1-5. Floquet-Bloch states can form under periodic driving of electrons and enable exotic quantum phases6-15. On subcycle timescales, lightwaves can simultaneously drive intraband currents16-29 and interband transitions18,19,30,31, which enable high-harmonic generation16,18,19,21,22,25,28-30 and pave the way towards ultrafast electronics. Yet, the interplay of intraband and interband excitations and their relation to Floquet physics have been key open questions as dynamical aspects of Floquet states have remained elusive. Here we provide this link by visualizing the ultrafast build-up of Floquet-Bloch bands with time-resolved and angle-resolved photoemission spectroscopy. We drive surface states on a topological insulator32,33 with mid-infrared fields-strong enough for high-harmonic generation-and directly monitor the transient band structure with subcycle time resolution. Starting with strong intraband currents, we observe how Floquet sidebands emerge within a single optical cycle; intraband acceleration simultaneously proceeds in multiple sidebands until high-energy electrons scatter into bulk states and dissipation destroys the Floquet bands. Quantum non-equilibrium calculations explain the simultaneous occurrence of Floquet states with intraband and interband dynamics. Our joint experiment and theory study provides a direct time-domain view of Floquet physics and explores the fundamental frontiers of ultrafast band-structure engineering.

Discovery of 1'-(1-phenylcyclopropane-carbonyl)-3H-spiro[isobenzofuran-1,3'-pyrrolidin]-3-one as a novel steroid mimetic scaffold for the potent and tissue-specific inhibition of 11β-HSD1 using a scaffold-hopping approach

11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) has been identified as the primary enzyme responsible for the activation of hepatic cortisone to cortisol in specific peripheral tissues resulting in the concomitant antagonism of insulin action within these tissues. Dysregulation of 11β-HSD1, particularly in adipose tissues, has been associated with metabolic syndrome and type 2 diabetes mellitus. Therefore, inhibition of 11β-HSD1 with a small nonsteroidal molecule is therapeutically desirable. Implementation of a scaffold-hopping approach revealed a three-point pharmacophore for 11β-HSD1 that was utilized to design a steroid mimetic scaffold. Reiterative optimization provided valuable insight into the bioactive conformation of our novel scaffold and led to the discovery of INCB13739. Clinical evaluation of INCB13739 confirmed for the first time that tissue-specific inhibition of 11β-HSD1 in patients with type 2 diabetes mellitus was efficacious in controlling glucose levels and reducing cardiovascular risk factors.

Intersubband Polariton-Polariton Scattering in a Dispersive Microcavity

The ultrafast scattering dynamics of intersubband polaritons in dispersive cavities embedding GaAs/AlGaAs quantum wells are studied directly within their band structure using a noncollinear pump-probe geometry with phase-stable midinfrared pulses. Selective excitation of the lower polariton at a frequency of ∼25  THz and at a finite in-plane momentum k_{‖} leads to the emergence of a narrowband maximum in the probe reflectivity at k_{‖}=0. A quantum mechanical model identifies the underlying microscopic process as stimulated coherent polariton-polariton scattering. These results mark an important milestone toward quantum control and bosonic lasing in custom-tailored polaritonic systems in the mid and far infrared.

Characterization of INCB086550: A Potent and Novel Small-Molecule PD-L1 Inhibitor

Blocking the activity of the programmed cell death protein 1 (PD-1) inhibitory receptor with therapeutic antibodies against either the ligand (PD-L1) or PD-1 itself has proven to be an effective treatment modality for multiple cancers. Contrasting with antibodies, small molecules could demonstrate increased tissue penetration, distinct pharmacology, and potentially enhanced antitumor activity. Here, we describe the identification and characterization of INCB086550, a novel, oral, small-molecule PD-L1 inhibitor. In vitro, INCB086550 selectively and potently blocked the PD-L1/PD-1 interaction, induced PD-L1 dimerization and internalization, and induced stimulation-dependent cytokine production in primary human immune cells. In vivo, INCB086550 reduced tumor growth in CD34+ humanized mice and induced T-cell activation gene signatures, consistent with PD-L1/PD-1 pathway blockade. Preliminary data from an ongoing phase I study confirmed PD-L1/PD-1 blockade in peripheral blood cells, with increased immune activation and tumor growth control. These data support continued clinical evaluation of INCB086550 as an alternative to antibody-based therapies.

SIGNIFICANCE

We have identified a potent small-molecule inhibitor of PD-L1, INCB086550, which has biological properties similar to PD-L1/PD-1 monoclonal antibodies and may represent an alternative to antibody therapy. Preliminary clinical data in patients demonstrated increased immune activation and tumor growth control, which support continued clinical evaluation of this approach. See related commentary by Capparelli and Aplin, p. 1413. This article is highlighted in the In This Issue feature, p. 1397.

Field-resolved high-order sub-cycle nonlinearities in a terahertz semiconductor laser

The exploitation of ultrafast electron dynamics in quantum cascade lasers (QCLs) holds enormous potential for intense, compact mode-locked terahertz (THz) sources, squeezed THz light, frequency mixers, and comb-based metrology systems. Yet the important sub-cycle dynamics have been notoriously difficult to access in operational THz QCLs. Here, we employ high-field THz pulses to perform the first ultrafast two-dimensional spectroscopy of a free-running THz QCL. Strong incoherent and coherent nonlinearities up to eight-wave mixing are detected below and above the laser threshold. These data not only reveal extremely short gain recovery times of 2 ps at the laser threshold, they also reflect the nonlinear polarization dynamics of the QCL laser transition for the first time, where we quantify the corresponding dephasing times between 0.9 and 1.5 ps with increasing bias currents. A density-matrix approach reproducing the emergence of all nonlinearities and their ultrafast evolution, simultaneously, allows us to map the coherently induced trajectory of the Bloch vector. The observed high-order multi-wave mixing nonlinearities benefit from resonant enhancement in the absence of absorption losses and bear potential for a number of future applications, ranging from efficient intracavity frequency conversion, mode proliferation to passive mode locking.

From Alpha Diversity to Zzz: Interactions among sleep, the brain, and gut microbiota in the first year of life

Sleep disorders have been linked to alterations of gut microbiota composition in adult humans and animal models, but it is unclear how this link develops. With longitudinal assessments in 162 healthy infants, we present a so far unrecognized sleep-brain-gut interrelationship. First, we report a link between sleep habits and gut microbiota: daytime sleep is associated with bacterial diversity, and nighttime sleep fragmentation and variability link with bacterial maturity and enterotype. Second, we demonstrate a sleep-brain-gut link: bacterial diversity and enterotype are associated with sleep neurophysiology. Third, we show that the sleep-brain-gut link is relevant in development: sleep habits and bacterial markers predict behavioral-developmental outcomes. Our results demonstrate the dynamic interplay between sleep, gut microbiota, and the maturation of brain and behavior during infancy, which aligns with the lately emerging concept of a sleep-brain-gut axis. Importantly, sleep and gut microbiota represent promising health targets since both can be modified non-invasively. As many adult diseases root in early childhood, leveraging protective factors of adequate sleep and age-appropriate gut microbiota in infancy could constitute a health promoting factor across the entire human lifespan.

Apixaban for treatment of embolic stroke of undetermined source (ATTICUS) randomized trial – update of patient characteristics and study timeline after interim analysis

Background

Secondary prevention after embolic stroke of undetermined source (ESUS) has not yet been established. ESUS is associated with high risk of recurrent ischemic stroke and clinically silent ischemic lesions. Secondary prevention with aspirin is the current standard therapy in ESUS patients, despite high prevalence of occult atrial fibrillation (AF).

Purpose

To determine whether the direct oral factor Xa inhibitor apixaban, started within 28 days after index stroke, is superior to aspirin in preventing new ischemic lesions in subjects with remote cardiac monitoring. Primary endpoint was detection of new ischemic lesions in flair and diffusion-weighted (DWI) MR imaging at 12 months follow-up.

Methods

The study enrolled ESUS patients with risk profile for cardiac thromboembolism (i.e., left atrium (LA) size >45 mm, spontaneous echo contrast in LA appendage, LA appendage flow velocity ≤0.2 cm/s, atrial high rate episodes, CHA2DS2-Vasc score ≥4, patent foramen ovale). Patients were randomized 1:1 into the aspirin and apixaban arms. Study drug was initiated within 3–28 days after minor/moderate stroke and 14–28 days after major stroke. MRI (Flair/DWI) was conducted within 7 days of AF detection by remote cardiac monitors and at 12 months. ClinicalTrials.gov Identifier: NCT02427126. Funding: The trial is supported by BMS-Pfizer Alliance.

Results

Enrollment was stopped after interims analysis (including 200 patients) due to futility. Overall, 373 patients were screened with 353 being enrolled (178 and 175 in apixaban and ASA arms, respectively). So far, 130 (73.0%) and 120 (68.6%) subjects from apixaban and ASA arms, respectively, completed the study. 2% death, 1.7% withdrawal, and 1.7% were lost to follow-up. 3.9% did not completed the study for other reasons. Mean age of the ATTICUS population was 68.5 years with 51% males. 80% of the subjects suffered from hypertension. Mean systolic blood pressure at enrollment was 132 mmHg, BMI was 27.7, and CHA2DS-VASc-Score was 4.9. So far, adverse events (AE) occurred in 63% of the subjects, 30% was documented as severe. 6.8% cases of recurrent ischemic stroke and no case of hemorrhagic stroke were reported. Only 1 case of severe bleeding was reported in the aspirin arm. Newly detected AF was reported in 80 patients (23%), 42 occurring in the aspirin arm. As required by protocol, latter were immediately switched from aspirin to apixaban. Due to ongoing data clearing, numbers and % will change until presentation.

Conclusions

In contrast to the recently published NAVIGATE and RESPECT ESUS trials, patients enrolled in ATTICUS need to exhibit additional AF predicting factors. Furthermore, mandatory cardiac remote monitoring will help to elucidate the impact of AF and the effects of early oral anticoagulation with apixaban compared to antiplatelet therapy with aspirin on the incidence of new ischemic lesions after ESUS. Preliminary data will be presented and discussed in the context of current literature.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): The trial is supported by BMS-Pfizer Alliance.

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.

Discovery of Pemigatinib: A Potent and Selective Fibroblast Growth Factor Receptor (FGFR) Inhibitor

Aberrant activation of FGFR has been linked to the pathogenesis of many tumor types. Selective inhibition of FGFR has emerged as a promising approach for cancer treatment. Herein, we describe the discovery of compound 38 (INCB054828, pemigatinib), a highly potent and selective inhibitor of FGFR1, FGFR2, and FGFR3 with excellent physiochemical properties and pharmacokinetic profiles. Pemigatinib has received accelerated approval from the U.S. Food and Drug Administration for the treatment of adults with previously treated, unresectable locally advanced or metastatic cholangiocarcinoma with a FGFR2 fusion or other rearrangement. Additional clinical trials are ongoing to evaluate pemigatinib in patients with FGFR alterations.

Tunable non-integer high-harmonic generation in a topological insulator

When intense lightwaves accelerate electrons through a solid, the emerging high-order harmonic (HH) radiation offers key insights into the material^1-11. Sub-optical-cycle dynamics-such as dynamical Bloch oscillations^2-5, quasiparticle collisions^6,12, valley pseudospin switching¹³ and heating of Dirac gases¹⁰-leave fingerprints in the HH spectra of conventional solids. Topologically non-trivial matter^14,15 with invariants that are robust against imperfections has been predicted to support unconventional HH generation^16-20. Here we experimentally demonstrate HH generation in a three-dimensional topological insulator-bismuth telluride. The frequency of the terahertz driving field sharply discriminates between HH generation from the bulk and from the topological surface, where the unique combination of long scattering times owing to spin-momentum locking¹⁷ and the quasi-relativistic dispersion enables unusually efficient HH generation. Intriguingly, all observed orders can be continuously shifted to arbitrary non-integer multiples of the driving frequency by varying the carrier-envelope phase of the driving field-in line with quantum theory. The anomalous Berry curvature warranted by the non-trivial topology enforces meandering ballistic trajectories of the Dirac fermions, causing a hallmark polarization pattern of the HH emission. Our study provides a platform to explore topology and relativistic quantum physics in strong-field control, and could lead to non-dissipative topological electronics at infrared frequencies.

Addressing COVID-19 challenges in a randomised controlled trial on exercise interventions in a high-risk population

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic is a threat to ongoing clinical trials necessitating regular face-to-face, in-person meetings, particularly in participants with a high risk of complications. Guidance on how to handle and safely continue such trials is lacking. Chronically ill elderly individuals require-in addition to protection from infection-regular physical exercise and social contact to remain healthy. Solutions on how to handle these conflicting necessities are needed. The ENTAIER-randomised controlled trial was investigating the influence of mindful movements on fall risk, fear of falling, mobility, balance, life quality, and other outcomes. The study population was planned to comprise of 550 chronically ill elderly individuals with a high risk of falling. The movements were regularly performed in coached groups over 6 months. After the trial began, COVID-19 lockdowns stopped all in-person meetings, and it was expected that the limitations of this pandemic would continue for a long term. Therefore, the exercise programme, which involved complex movements and was typically conducted face-to-face in groups, had to be substituted by a telemedicine programme within a short timeframe. The objectives, therefore, were to identify challenges and tasks that could to be resolved and steps that could to be taken to achieve high-quality, efficacy, safety, and enable human encounter and motivation.

METHODS

We proceeded with four steps: 1) A literature review on the quality and feasibility issues of telemedicine in general, and specifically, in exercise training in elderly individuals. 2) Participation in two international telemedicine task forces on integrative medicine, particularly, mind-body medicine. 3) Interviews with study therapists, (for practical purposes, eurythmy therapists and Tai Chi teachers are summarized here as therapists) personnel, and international experts on providing mindful movement exercises and other physiotherapies via live telecommunication technology, and with scientists and patient representatives. 4) Final evaluation by the core trial team and subsequent planning and implementation of changes in the trial organisation.

RESULTS

Various tasks and challenges were identified: for the technical equipment for therapists and patients; for the ability of therapists and trial participants to adequately manage the technology and telemedicine intervention; the reservations and concerns about the technology among therapists and participants; safety and data protection in using the technology; and study design. The two major options found on how to continue the trial in the COVID-19 situation were a complete switch to telemedicine and a partial switch in the form of risk management implemented into the former design.

CONCLUSIONS

The management of an ongoing clinical trial in a national or international crisis with a minimum of available time and extra financial resources, alongside with two checklists on steps and procedures for trial continuation and telemedicine implementation, may be informative for other researchers or healthcare providers faced with similar challenges and making similar decisions in the current situation or similar future scenarios. TRAIL REGISTRATION: www.drks.de . DRKS00016609. Registered July 30, 2019.

Tailored Subcycle Nonlinearities of Ultrastrong Light-Matter Coupling

We explore the nonlinear response of tailor-cut light-matter hybrid states in a novel regime, where both the Rabi frequency induced by a coherent driving field and the vacuum Rabi frequency set by a cavity field are comparable to the carrier frequency of light. In this previously unexplored strong-field limit of ultrastrong coupling, subcycle pump-probe and multiwave mixing nonlinearities between different polariton states violate the normal-mode approximation while ultrastrong coupling remains intact, as confirmed by our mean-field model. We expect such custom-cut nonlinearities of hybridized elementary excitations to facilitate nonclassical light sources, quantum phase transitions, or cavity chemistry with virtual photons.

Super-resolution lightwave tomography of electronic bands in quantum materials

Searching for quantum functionalities requires access to the electronic structure, constituting the foundation of exquisite spin-valley-electronic, topological, and many-body effects. All-optical band-structure reconstruction could directly connect electronic structure with the coveted quantum phenomena if strong lightwaves transported localized electrons within preselected bands. Here, we demonstrate that harmonic sideband (HSB) generation in monolayer tungsten diselenide creates distinct electronic interference combs in momentum space. Locating these momentum combs in spectroscopy enables super-resolution tomography of key band-structure details in situ. We experimentally tuned the optical-driver frequency by a full octave and show that the predicted super-resolution manifests in a critical intensity and frequency dependence of HSBs. Our concept offers a practical, all-optical, fully three-dimensional tomography of electronic structure even in microscopically small quantum materials, band by band.

Non-adiabatic stripping of a cavity field from deep-strongly coupled electrons

Atomically strong light pulses can drive sub-optical-cycle dynamics. When the Rabi frequency - the rate of energy exchange between light and matter - exceeds the optical carrier frequency, fascinating non-perturbative strong-field phenomena emerge, such as high-harmonic generation and lightwave transport. Here, we explore a related novel subcycle regime of ultimately strong light-matter interaction without a coherent driving field. We use the vacuum fluctuations of nanoantennas to drive cyclotron resonances of two-dimensional electron gases to vacuum Rabi frequencies exceeding the carrier frequency. Femtosecond photoactivation of a switch element inside the cavity disrupts this 'deep-strong coupling' more than an order of magnitude faster than the oscillation cycle of light. The abrupt modification of the vacuum ground state causes spectrally broadband polarisation oscillations confirmed by our quantum model. In the future, this subcycle shaping of hybrid quantum states may trigger cavity-induced quantum chemistry, vacuum-modified transport, or cavity-controlled superconductivity, opening new scenarios for non-adiabatic quantum optics.

Ultrafast electron diffraction from nanophotonic waveforms via dynamical Aharonov-Bohm phases

Electron interferometry via phase-contrast microscopy, holography, or picodiffraction can provide a direct visualization of the static electric and magnetic fields inside or around a material at subatomic precision, but understanding the electromagnetic origin of light-matter interaction requires time resolution as well. Here, we demonstrate that pump-probe electron diffraction with all-optically compressed electron pulses can capture dynamic electromagnetic potentials in a nanophotonic material with sub-light-cycle time resolution via centrosymmetry-violating Bragg spot dynamics. The origin of this effect is a sizable quantum mechanical phase shift that the electron de Broglie wave obtains from the oscillating electromagnetic potentials within less than 1 fs. Coherent electron imaging and scattering can therefore reveal the electromagnetic foundations of light-matter interaction on the level of the cycles of light.

Immunomodulatory effects of some Namibian plants traditionally used for treating inflammatory diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Acanthosicyos naudininus, Gomphocarpus fruticosus, and Cryptolepis decidua are, according to the knowledge of traditional healers, used in Namibia to treat inflammatory disorders such as pain, fever and skin rashes.

AIM OF THE STUDY

The present study was conducted to evaluate the immunomodulatory effects and the possible underlying mechanisms of action of the plant extracts on peripheral blood mononuclear cells (PBMCs) such as T-lymphocytes.

MATERIALS AND METHODS

Methanolic and EtOAc extracts of A. naudinianus, G. fruticosus and C. decidua were analysed for their immunomodulatory potential. PBMCs were isolated from the blood of healthy donors and incubated with the plant extracts at concentrations 100, 30, 10, 3, 1 and 0.3 μg/mL. Effects on proliferation and viability of activated human lymphocytes were assessed in comparison to ciclosporin A by flow cytometry using carboxyfluorescein succinimidyl ester (CFSE) and WST-1 assay. Flow cytometry by annexin V/propidium iodide (PI) staining was performed to investigate the necrotic/apoptotic effect of the plant extracts on mitogen-activated human lymphocytes. In addition, analysis of the influence of plant extracts on the regulatory mechanisms of T-lymphocytes was performed using activation marker and cytokine production assays. An HPLC-PDA-ELSD-ESIMS profile was recorded for each of the extracts.

RESULTS

T-lymphocyte proliferation was inhibited in a dose-dependent manner by the extracts of A. naudinianus, G. fruticosus, and C. decidua in concentrations not causing apoptosis or necrosis. This effect was mediated by inhibition of lymphocyte activation, specifically the suppression of CD25 and CD69 surface receptor expression. Moreover, the extracts suppressed effector functions, as indicated by reduced production of IFN-γ and IL-2. Based on the HPLC profile, possible responsible compound classes could be identified for the extracts of A. naudinianus (cucurbitacins) and C. decidua (indole alkaloids), but not for G. fruticosus.

CONCLUSIONS

The data show that the extracts of A. naudinianus, G. fruticosus and C. decidua have in vitro immunomodulatory activity and they interfere with the function of immunocompetent cells, suggesting an anti-inflammatory mode-of-action. The present chemical determination and pattern recognition results explain the therapeutic potency. However, further studies to investigate the therapeutic potential of the plants in inflammatory disorders should be done.

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.

INCB054828 (pemigatinib), a potent and selective inhibitor of fibroblast growth factor receptors 1, 2, and 3, displays activity against genetically defined tumor models

Alterations in fibroblast growth factor receptor (FGFR) genes have been identified as potential driver oncogenes. Pharmacological targeting of FGFRs may therefore provide therapeutic benefit to selected cancer patients, and proof-of-concept has been established in early clinical trials of FGFR inhibitors. Here, we present the molecular structure and preclinical characterization of INCB054828 (pemigatinib), a novel, selective inhibitor of FGFR 1, 2, and 3, currently in phase 2 clinical trials. INCB054828 pharmacokinetics and pharmacodynamics were investigated using cell lines and tumor models, and the antitumor effect of oral INCB054828 was investigated using xenograft tumor models with genetic alterations in FGFR1, 2, or 3. Enzymatic assays with recombinant human FGFR kinases showed potent inhibition of FGFR1, 2, and 3 by INCB054828 (half maximal inhibitory concentration [IC₅₀] 0.4, 0.5, and 1.0 nM, respectively) with weaker activity against FGFR4 (IC₅₀ 30 nM). INCB054828 selectively inhibited growth of tumor cell lines with activation of FGFR signaling compared with cell lines lacking FGFR aberrations. The preclinical pharmacokinetic profile suggests target inhibition is achievable by INCB054828 in vivo with low oral doses. INCB054828 suppressed the growth of xenografted tumor models with FGFR1, 2, or 3 alterations as monotherapy, and the combination of INCB054828 with cisplatin provided significant benefit over either single agent, with an acceptable tolerability. The preclinical data presented for INCB054828, together with preliminary clinical observations, support continued investigation in patients with FGFR alterations, such as fusions and activating mutations.

A multi-centre, parallel-group, randomised controlled trial to assess the efficacy and safety of eurythmy therapy and tai chi in comparison with standard care in chronically ill elderly patients with increased risk of falling (ENTAiER): a trial protocol

BACKGROUND

In elderly poeple, multimorbidity and polypharmacy increase while sensory, motor and cognitive functions decrease. Falls occur in 30% of people aged 65 years and older at least once per year, with injuries at 10-20%. Reducing falls and enhancing physical, emotional and cognitive capacities are essential for healthy aging despite chronic disease. Eurythmy therapy (EYT) and Tai Chi train balance, mobility and concentrative and sensory capacities.

METHODS

In eight trial sites (academic or community hospitals), 550 outpatients aged 65 years and older with chronic disease and increased risk of falling (history of imbalance, Berg Balance Scale (BBS) score ≤ 49) will be randomly assigned (1:1:1) to receive either EYT or Tai Chi (each provided in one-hour group sessions, twice, later once per week plus practice at home, for over 24 weeks) added to standard care or standard care alone. Standard care includes a detailed written recommendation on fall prevention and the visit of a primary care doctor. Seniors living a reclusive life or economically disadvantaged elderly will be particularly addressed. A motivation and communication concept supports the trial participants' compliance with trial procedures and practicing. Public and patient representatives are involved in the planning and conduction of the trial. Falls will be documented daily in a diary by the participants. These falls as well as injuries and complications will be ascertained during monthly phone visits. The falls efficacy scale, BBS, cognition (MoCA), Mood (GDS-15), quality of life (SF12), instrumental activities of daily living (IADL), use of medical and non-medical services (FIMA) and adherence will be assessed at months 3, 6, and 12 and inner correspondence with practices (ICPH) at month 6. The trial is funded by the Federal Ministry of Education and Research (BMBF 01GL1805).

DISCUSSION

This study will determine whether EYT and Tai Chi reduce falls, injurious falls, fear of falling and healthcare utilisation and improve mobility, cognition, mood, quality of life and functional independence. A reduction of fall risk and fear of falling and an improvement of mobility, autonomy, quality of life, mood, and cognition are highly relevant for older people to cope with aging and diseases and to reduce healthcare costs. TRAIL REGISTRATION: www.drks.de. DRKS00016609. Registered 30th July 2019.

Abstract 541: An unbiased screen identifies a CD137xPD-L1 bispecific IgG1 antibody with unique T cell activation and binding properties

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. CD137 signaling requires receptor clustering normally facilitated by the trimeric CD137 ligand (CD137L). Alternatively, CD137 signaling can be triggered either directly by agonistic monoclonal antibodies (mAbs) or indirectly via crosslinking of CD137 binding mAbs by Fcγ receptors on neighboring cells. 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. To address the issues of toxicity and efficacy a highly selective and potent CD137xPD-L1 bispecific antibody (bAb) was identified by applying an unbiased functional screening approach. Collections of common light chain Fabs recognizing CD137 and PD-L1 were produced based on antibody panels from immunized MeMo® mice. A large and diverse panel of CD137xPD-L1 bAbs was then produced by combining different CD137 and PD-L1 Fabs based on epitope and sequence diversity in the IgG1 Biclonics® format. The bAbs were screened for activity in reporter cell lines expressing the receptors. This unbiased combinatorial screening identified a CD137xPD-L1 bAb (MCLA-145) for which CD137 mediated activation is dependent on the presence of PD-L1 on a neighboring cell and, as such, the antibody acts in ‘trans’. Flow cytometry experiments demonstrated that MCLA-145 is fully cross-reactive to cynomolgus monkey CD137 and PD-L1. The CD137 Fab arm blocks the interaction of CD137 with CD137L as demonstrated in a competition assay by flow cytometry. The PD-L1 Fab arm blocks the interaction between PD-1 and PD-L1 as demonstrated in ELISA. Binding epitopes were mapped by shotgun mutagenesis using a flow-based screen. In addition, hydrogen-deuterium exchange experiments were performed to map the binding domain on CD137. Data show that MCLA-145 binds the ligand binding domain of CD137 domain (CRDII). The PD-L1 Fab arm binds PD-L1 in the PD-1 binding N-terminal V domain. Both epitope mapping data sets are consistent with the CD137 and PD-L1 ligand blocking activity of MCLA-145. Monovalent binding affinities were measured by surface plasma resonance (SPR) and radioactive iodine labeling and demonstrated affinities in the low nM (CD137) and subnanomolar (PD-L1) range. SPR experiments also confirmed that MCLA-145 was able to bind simultaneously to both CD137 and PD-L1 recombinant proteins. The unique binding properties of MCLA-145 may result in an increased therapeutic window by specifically activating CD137 expressing cells in the tumor niche where PD-L1 is expressed while simultaneously blocking inhibitory input from the PD-1/PD-L1 axis.

Citation Format: Cecile A. Geuijen, Paul Tacken, Rinse Klooster, Horacio Nastri, Shaun Stewart, Jing Zhou, Steve Wang, Cheng-Yen Huang, Arjen Kramer, Linda Kaldenberg-Hendriks, John de Kruif, Renate den Blanken-Smit, Vanessa Zondag-van de Zande, Abdul Basmeleh, Willem Bartelink, Patrick Mayes, Gregory Hollis, Reid Huber, Mark Throsby. An unbiased screen identifies a CD137xPD-L1 bispecific IgG1 antibody with unique T cell activation and binding properties [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 541.

Abstract 4480: Preclinical characterization of potent and selective oral PD-L1 small-molecule antagonists

Monoclonal antibodies against PD-L1 or PD-1 have been approved for the treatment of multiple tumor histologies by virtue of their ability to restore T cell effector function, increase T cell proliferation and enhance infiltration of tumor-reactive T cells. A small molecule approach to PD-(L)1 axis blockade may offer distinct benefits over the use of monoclonal antibodies including improved tissue penetration, titratability, absence of immunogenicity, ease of administration, and potential for fixed dose oral-oral therapeutic combinations. We have identified a novel class of small molecule PD-L1 antagonists that are capable of functional PD-(L)1 axis blockade by virtue of their ability to induce PD-L1 internalization. In vitro, select small molecules demonstrate high affinity to human PD-L1, potently disrupt the PD-L1:PD-1 interaction (<4nM), and inhibit Src homology region 2 domain-containing phosphatase (SHP2) recruitment to PD-1 (<10nM). As a result, PD-1-mediated suppression of nuclear factor of activated T cells (NFAT) activation is reduced and IFNγ production by T cells is restored. These bioactive small molecule PD-L1 antagonists are shown to reduce surface PD-L1 levels in tumor cells and peripheral blood monocytes with IC50s ranging from 1-250nM, providing an in vivopharmacodynamic biomarker for compound activity. Using humanized NSG mice bearing MDA-MB-231 tumors, oral administration of small molecule PD-L1 antagonists for 28 days demonstrated a dose-dependent reduction in tumor growth with a concomitant and dose-dependent increase in the number of tumor-infiltrating T cells. These data were concordant with the dose-dependent reduction of surface PD-L1 levels seen on both tumor cells and tumor associated macrophages at the end of the study. Similar data, including dose-dependent tumor growth inhibition, PD-L1 internalization and increase in tumor-infiltrating T cells, were also obtained using a murine MC38 xenograft system genetically engineered to over express human PD-L1. No in vivo activity was observed when tumors were treated in immunocompromised mice, confirming the pharmacologic dependency on a competent immune system. Finally, these oral PD-L1 small molecule antagonists demonstrated equivalent anti-tumor activity in preclinical tumor models when compared head-to-head to clinically approved PD-(L)1 axis targeting monoclonal antibodies. In conclusion, effective PD-(L)1 axis blockade and functional activation of the immune system can be achieved in vivo through this novel series of orally bioavailable small molecule PD-L1 antagonists, supporting the clinical evaluation of the mechanism as a novel approach to immune therapy.

Citation Format: Liang-Chuan S. Wang, Holly Koblish, Yue Zhang, Ashwini Kulkarni, Maryanne Covington, Karen Gallagher, Gengjie Yang, Jonathan Rios-Doria, Christina Stevens, Michael Hansbury, Sybil O'Connor, Yan-ou Yang, Sharon Diamond, Krista Burke, Kaijiong Xiao, Jingwei Li, Wenqing Yao, Liangxing Wu, Peggy Scherle, Gregory Hollis, Reid Huber. Preclinical characterization of potent and selective oral PD-L1 small-molecule antagonists [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 4480.

Ultrafast transition between exciton phases in van der Waals heterostructures

Heterostructures of atomically thin van der Waals bonded monolayers have opened a unique platform to engineer Coulomb correlations, shaping excitonic^1-3, Mott insulating⁴ or superconducting phases^5,6. In transition metal dichalcogenide heterostructures⁷, electrons and holes residing in different monolayers can bind into spatially indirect excitons^1,3,8-11 with a strong potential for optoelectronics^11,12, valleytronics^1,3,13, Bose condensation¹⁴, superfluidity^14,15 and moiré-induced nanodot lattices¹⁶. Yet these ideas require a microscopic understanding of the formation, dissociation and thermalization dynamics of correlations including ultrafast phase transitions. Here we introduce a direct ultrafast access to Coulomb correlations between monolayers, where phase-locked mid-infrared pulses allow us to measure the binding energy of interlayer excitons in WSe₂/WS₂ hetero-bilayers by revealing a novel 1s-2p resonance, explained by a fully quantum mechanical model. Furthermore, we trace, with subcycle time resolution, the transformation of an exciton gas photogenerated in the WSe₂ layer directly into interlayer excitons. Depending on the stacking angle, intra- and interlayer species coexist on picosecond scales and the 1s-2p resonance becomes renormalized. Our work provides a direct measurement of the binding energy of interlayer excitons and opens the possibility to trace and control correlations in novel artificial materials.

Abstract 4483: Novel small-molecule antagonists of the PD-1/PD-L1 axis that mediate cell surface PD-L1 dimerization and internalization

Blocking the PD-(L)1 immune checkpoint axis with therapeutic antibodies against either the receptor or the ligand has proven to be an effective treatment modality for multiple cancer histologies. We describe the identification and characterization of novel small molecule antagonists of the PD-(L)1 axis that function by inducing dimerization and subsequent internalization of the PD-L1 protein, effectively depleting the ligand from the cell membrane and preventing PD-1 activation on T cells. Compound-dependent PD-L1 dimerization was characterized using several biophysical techniques including fluorescence resonance energy transfer (FRET) measurements, size exclusion chromatography and thermal shift analysis. Experimental evidence demonstrates compound-dependent dimer conformation with slow dissociation kinetics and significantly enhanced thermal stability. Many of the PD-L1-directed small molecules blocked binding of soluble PD-1 to either native PD-L1 expressed on cancer cell lines or PD-L1 expressed in CHO cells with low nanomolar potency. However, only a subset of the small molecules caused loss of cell surface PD-L1 in a time- and concentration-dependent manner. Importantly, there was a strict correlation between the promotion of PD-L1 internalization secondary to dimerization and the induction of an NFAT response element-luciferase reporter gene. Strikingly, only those small molecules that could produce a specific dimeric PD-L1 conformation as measured using FRET were associated with functional activity in cells, suggesting that PD-L1 dimerization was necessary but not sufficient for internalization and cellular activity. A cell-active tool compound (cell binding IC50 <5 nM, internalization EC50 <10 nM) was fluorescently labeled to enable direct visualization of intracellular trafficking. Confocal microscopy with this PD-L1 antagonist showed time-dependent increases in intracellular fluorescence in PD-L1 expressing, but not PD-L1 deleted, cells. The internalized antagonist showed punctate staining coincident with markers of the early endosome, and independent studies confirmed that the internalized PD-L1 also trafficked to the early endosome. By disrupting the suppressive activity of PD-L1 on PD-1, these inhibitors result in functional activation of T cells in ex vivo cellular assays in a manner equivalent to antibodies directed against either PD-1 or PD-L1. In summary, we have identified a series of potent, small molecule PD-L1 antagonists that induce dimerization of the protein; inhibitors that trigger an appropriate dimeric conformation can also induce PD-L1 internalization thereby alleviating PD-L1-induced suppression of T cell activation.

Citation Format: Phillip C.C. Liu, Richard Wynn, Liangxing Wu, Alla Volgina, Nina Zolotarjova, Luping Lin, Pramod Thekkat, Alex Margulis, Ronald Klabe, Wenqing Yao, Kaijiong Xiao, Jingwei Li, Xin He, Mark Rupar, Hong Chang, Paul Waeltz, Yanlong Li, Peggy Scherle, Reid Huber, Gregory Hollis. Novel small-molecule antagonists of the PD-1/PD-L1 axis that mediate cell surface PD-L1 dimerization and internalization [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 4483.

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.

The Novel Bromodomain and Extraterminal Domain Inhibitor INCB054329 Induces Vulnerabilities in Myeloma Cells That Inform Rational Combination Strategies

PURPOSE

Bromodomain and extraterminal domain (BET) proteins regulate the expression of many cancer-associated genes and pathways; BET inhibitors have demonstrated activity in diverse models of hematologic and solid tumors. We report the preclinical characterization of INCB054329, a structurally distinct BET inhibitor that has been investigated in phase I clinical trials.

EXPERIMENTAL DESIGN

We used multiple myeloma models to investigate vulnerabilities created by INCB054329 treatment that could inform rational combinations.

RESULTS

In addition to c-MYC, INCB054329 decreased expression of oncogenes FGFR3 and NSD2/MMSET/WHSC1, which are deregulated in t(4;14)-rearranged cell lines. The profound suppression of FGFR3 sensitized the t(4;14)-positive cell line OPM-2 to combined treatment with a fibroblast growth factor receptor inhibitor in vivo. In addition, we show that BET inhibition across multiple myeloma cell lines resulted in suppressed interleukin (IL)-6 Janus kinase-signal transducers and activators of transcription (JAK-STAT) signaling. INCB054329 displaced binding of BRD4 to the promoter of IL6 receptor (IL6R) leading to reduced levels of IL6R and diminished signaling through STAT3. Combination with JAK inhibitors (ruxolitinib or itacitinib) further reduced JAK-STAT signaling and synergized to inhibit myeloma cell growth in vitro and in vivo. This combination potentiated tumor growth inhibition in vivo, even in the MM1.S model of myeloma that is not intrinsically sensitive to JAK inhibition alone.

CONCLUSIONS

Preclinical data reveal insights into vulnerabilities created in myeloma cells by BET protein inhibition and potential strategies that can be leveraged in clinical studies to enhance the activity of INCB054329.

Abstract 1893: The evaluation of INCB059872, an FAD-directed inhibitor of LSD1, in preclinical models of T-ALL

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological tumor that is derived from the clonal expansion of immature T-cell progenitors. Multiple genetic and epigenetic alterations are attributed to the development of malignant T cell transformation. Among these, there is supporting evidence for a role of lysine specific demethylase (LSD1) in T-ALL. Oncogenic transcription factors, such as TAL-1, Notch, and ZEB2, form a complex with LSD1 to alter gene expression in T-ALL cells. In addition, LSD1 is aberrantly expressed in ALL, including B-ALL and T-ALL. Furthermore, the overexpression of LSD1 under control of the Sca-1 promoter in transgenic mice triggered T leukemogenesis via acquisition of self-renewal activity and alteration in the differentiation program to T-cell lineages. Together with the known function of LSD1 in regulating the activity of self-renewal in hematological malignancies, these studies prompted evaluation of the efficacy of the potent, selective, and orally bioavailable FAD-directed LSD1 inhibitor, INCB059872, in preclinical models of T-ALL. Expression of LSD1 was abundant in human-T-ALL cell lines as detected by immunoblotting. In vitro, INCB059872 treatment significantly inhibited the proliferation of a subset of human T-ALL cell lines. In vivo, once daily oral administration of INCB059872 inhibited tumor growth significantly in multiple human T-ALL subcutaneous xenograft models including Molt-4, RPMI-8402, CCRF-HSB-2, and CCRF-CEM, but was ineffective against DND-41 xenografts. The anti-tumor efficacy observed with INCB059872 had no clear genetic correlation with Notch mutation status of T-ALL tumors. Combination efficacy studies of INCB059872 with standard care of agents or targeted therapeutic agents in T-ALL models are currently being evaluated. These data suggest exploring the potential clinical development of INCB059872 as a therapy for T-ALL patients.

Citation Format: Melody Diamond, Yvonne Lo, Antony Chadderton, Min Ye, Valerie Roman, Michael Weber, Chunhong He, Liangxing Wu, Swamy Yeleswaram, Alan Roberts, Wenqing Yao, Gregory Hollis, Reid Huber, Peggy Scherle, Bruce Ruggeri, Sang Hyun Lee. The evaluation of INCB059872, an FAD-directed inhibitor of LSD1, in preclinical models of T-ALL [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1893.

Abstract 3819: INCAGN02385 is an antagonist antibody targeting the co-inhibitory receptor LAG-3 for the treatment of human malignancies

Lymphocyte activation gene 3 (LAG-3) is a cell surface receptor that negatively regulates antigen-specific T cell responses. LAG-3 expression is generally restricted to populations of recently activated and chronically stimulated exhausted T cells, and is often correlated with general T cell dysfunction across several human malignancies. Accordingly, the LAG-3 pathway has been identified as a potential barrier to productive tumor-specific T cell immunity generated by PD-1/PD-L1 blockade. The antitumor activity from targeting the LAG-3 pathway in preclinical models has provided further rationale for pharmacologic modulation of the LAG-3 axis in cancer patients. INCAGN02385 is an Fc-engineered IgG1κ antibody chosen for development based on its high-affinity binding to human LAG-3, cross-reactivity with cynomolgus monkey LAG-3, and ability to potently block LAG-3 binding with its MHC class II ligand. INCAGN02385 also enhances T cell responsiveness to TCR stimulation alone or in combination with PD-1/PD-L1 axis blockade. Evaluation of INCAGN02385 in cynomolgus monkeys was well-tolerated and demonstrated the expected pharmacokinetic profile. Altogether, these data support assessment of INCAGN02385 in patients with advanced or metastatic solid tumors.

Citation Format: David Savitsky, Rebecca Ward, Christina Riordan, Cornelia Mundt, Shawn Jennings, Joe Connolly, Mark Findeis, Michele Sanicola, Dennis Underwood, Horacio Nastri, Peggy Scherle, Gregory Hollis, Reid Huber, Robert Stein, Marc van Dijk, Nicholas S. Wilson. INCAGN02385 is an antagonist antibody targeting the co-inhibitory receptor LAG-3 for the treatment of human malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3819.

Abstract 3825: INCAGN02390, a novel antagonist antibody that targets the co-inhibitory receptor TIM-3

Unprecedented rates of durable clinical responses have been observed for antibody-based therapeutics targeting immune checkpoint proteins such as cytotoxic T lymphocyte antigen-4 (CTLA-4) or programmed death receptor-1 (PD-1). Nonetheless, a significant number of patients experience de novo resistance or relapse due to adaptive resistance mechanisms. T-cell immunoglobulin and mucin domain containing-3 (TIM-3) is an inhibitory receptor involved in immune tolerance often co-opted by tumors to prevent successful antitumor responses. Accordingly, TIM-3 is frequently expressed on myeloid and so-called exhausted T and NK cells within the tumor microenvironment. Targeting the TIM-3 pathway in preclinical models has provided additional rationale for pharmacologic modulation of this axis in cancer patients. INCAGN02390 is a novel and fully human Fc-engineered IgG1κ antibody developed to antagonize the TIM-3 pathway for the treatment of human malignancies. INCAGN02390 forms a high-affinity interaction with TIM-3, occluding access to the CC'-FG binding cleft and blocking phosphatidylserine binding. In addition, INCAGN02390 elicits rapid receptor internalization, potentially obviating interactions with other described or undescribed ligands. INCAGN02390 also enhances IFN-γ production from T cells undergoing tonic TCR stimulation when combined with PD-1 blockade. Finally, to demonstrate combinatorial potential, we show potent antitumor activity of an anti-mouse TIM-3 antibody in concert with other checkpoint antibodies in vivo. In summary, these data support assessment of INCAGN02390 in patients with advanced or metastatic solid tumors.

Citation Format: Jeremy Waight, Priyadarshini Iyer, Ekaterina Breous-Nystrom, Christina Riordan, Mark Findeis, Dennis Underwood, Joseph Connolly, Michele Sanicola-Nadel, Horacio Nastri, Peggy Scherle, Gregory Hollis, Reid Huber, Robert Stein, Mark van Dijk, Nicholas S. Wilson. INCAGN02390, a novel antagonist antibody that targets the co-inhibitory receptor TIM-3 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3825.

Abstract 1888: The FAD-directed LSD1 specific inhibitor, INCB059872, is a promising epigenetic agent for AML therapy by inducing differentiation of leukemic stem/progenitor cells

Numerous studies have elucidated that the most pivotal functions of lysine specific demethylase-1 (LSD1) are associated with regulating normal or malignant hematopoiesis by maintaining stem cell self-renewal and regulating myeloid differentiation. In preclinical models, studies with either pharmacological inhibition or genetic knockdown of LSD1 demonstrated that LSD1 is essential for differentiation of progenitor cells during normal hematopoiesis. In the clinic, AML manifests itself via clonal expansion of abnormal differentiation and proliferation of myeloid cells and, therefore, the inhibition of LSD1 activity with small molecule inhibitors could be a promising therapeutic approach for AML. Previously, we reported upon the identification of a flavin adenine dinucleotide (FAD) directed LSD1 specific inhibitor, INCB059872, which is efficacious in preclinical mouse models utilizing human AML cell lines and primary AML cells by inducing cell differentiation as indicated by the induction of CD11b and CD86 markers. Using a larger panel of myeloid and HSC flow cytometry markers, our currents efforts expanded upon these observations to ascertain whether INCB059872 enhanced lineage commitment at hematopoietic stem cell (HSC) and/ or promoted monocytic/granulocytic differentiation of human primary AML cells ex vivo and in human systemic AML PDX models. In both human AML PDX models and human primary AML samples, INCB059872 increased myeloid differentiation with increasing populations of monocytes (CD14+) and granulocytes (CD15+). Furthermore, INCB059872 induced the differentiation of early hematopoietic progenitors, CD34+/CD38- to more committed CD34+/CD38+ multipotent/oligopotent progenitors, which in turn gave rise to lineage specific progenitors in the human AML PDX models. These studies support further exploration of INCB059872 as a promising novel epigenetic agent for AML therapy whose mechanism of action lies in part through the induction of differentiation of leukemic stem/progenitor cells to more committed hematopoietic lineages.

Citation Format: Antony Chadderton, Min Ye, Melody Diamond, Valerie Roman, Michael Weber, Chunhong He, Liangxing Wu, Swamy Yeleswaram, Alan Roberts, Wenqing Yao, Gregory Hollis, Reid Huber, Peggy Scherle, Bruce Ruggeri, Sang Hyun Lee. The FAD-directed LSD1 specific inhibitor, INCB059872, is a promising epigenetic agent for AML therapy by inducing differentiation of leukemic stem/progenitor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1888.

Abstract 2938: In vivo assessment of the combination of the JAK1 selective inhibitor itacitinib with first- and second-generation EGFR inhibitors in models of non-small cell lung cancer

Non-small cell lung cancers (NSCLC) make up the majority of lung cancers, and are predominantly driven by aberrant kinase pathway signaling. Oncogenic mutations leading to activation of the epidermal growth factor receptor (EGFR) have been identified in a substantial fraction of NSCLC patients, leading to EGFR-targeted therapies such as erlotinib that have improved patient outcome. However, inhibition of EGFR consistently leads to drug resistance through multiple pathways, creating a therapeutic need in NSCLC. One particular route to resistance of EGFR inhibitors is activation of pathways that can bypass the need for signaling through the EGFR, such as the JAK/STAT pathway. To explore the impact of JAK/STAT pathway modulation on EGFR inhibitor resistance, combination efficacy studies evaluating the JAK1 selective inhibitor itacitinib with either erlotinib or the EGFR T790M mutant inhibitor osimertinib, were conducted in xenograft models of activated and erlotinib resistant NSCLC. The HCC827 xenograft (EGFR-activating deletion in exon 19) model was very sensitive to both erlotinib and osimertinib, while the NCI-H1975 xenograft (EGFR T790M/L858R) model responded only to osimertinib. Itacitinib was efficacious in the HCC827 model, while only marginal tumor growth inhibition was observed with itacitinib in the NCI-H1975 model despite both models having detectable levels of pSTAT3. The combination of itacitinib with either erlotinib or osimertinib inhibited tumor growth to a greater degree than monotherapies in the HCC827 model. Despite marginal single agent efficacy from itacitinib in the NCI-H1975 model, itacitinib enhanced the efficacy of osimertinib at several dose levels in this model. Importantly, itacitinib and erlotinib administration had synergistic efficacy in this erlotinib-resistant model, indicating that JAK1 specific signaling may be a critical bypass mechanism for resistance to EGFR inhibitors. Downstream of EGFR, both erlotinib and osimertinib inhibited different signaling pathways when combined with itacitinib in the NCI-H1975 model: STAT signaling was regulated by erlotinib, while the AKT/S6 and ERK pathways were regulated by osimertinib. An analysis of possible upstream activators of signaling pathways relevant to NSCLC survival revealed that IL-6, MCP-1 and IL-8 levels were altered in H1975 tumors from mice treated with the combination of itacitinib and osimertinib, and to a lesser extent with the combination of itacitinib and erlotinib. These data demonstrate the potential utility of the JAK1 specific inhibitor itacitinib in EGFR activated NSCLC, or for patients with EGFR mutations who are no longer responsive to a first generation EGFR inhibitor such as erlotinib. The combination of itacitinib and osimertinib is currently in a Phase I/II study (NCT02917993).

Citation Format: Matthew C. Stubbs, Xiaoming Wen, Chu-Biao Xue, Taisheng Huang, Wenqing Yao, Brian Metcalf, Reid Huber, Peggy Scherle, Bruce Ruggeri. In vivo assessment of the combination of the JAK1 selective inhibitor itacitinib with first- and second-generation EGFR inhibitors in models of non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2938.

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.

Lightwave valleytronics in a monolayer of tungsten diselenide

As conventional electronics is approaching its ultimate limits1, nanoscience has urgently sought for novel fast control concepts of electrons at the fundamental quantum level2. Lightwave electronics3 – the foundation of attosecond science4 – utilizes the oscillating carrier wave of intense light pulses to control the translational motion of the electron’s charge faster than a single cycle of light5–15. Despite being particularly promising information carriers, the internal quantum attributes of spin16 and valley pseudospin17–19 have not been switchable on the subcycle scale20–21. Here we demonstrate lightwave-driven changes of the valley pseudospin and introduce distinct signatures in the optical read out. Photogenerated electron–hole pairs in a monolayer of tungsten diselenide are accelerated and collided by a strong lightwave. The emergence of high odd-order sidebands and anomalous changes in their polarization direction directly attest to the ultrafast pseudospin dynamics. Quantitative computations combining density-functional theory with a non-perturbative quantum many-body approach assign the polarization of the sidebands to a lightwave-induced change of the valley pseudospin and confirm that the process is coherent and adiabatic. Our work opens the door to systematic valleytronic logic at optical clock rates.

Abstract A168: The LSD1 specific inhibitor INCB059872 enhances the activity of mechanistically distinct immunotherapeutic agents in the syngeneic 4T1 mouse mammary tumor model

Despite the successes of immune checkpoint blockade for the treatment of a variety of cancers, effective combinatorial therapy strategies are needed to achieve more durable and complete clinical responses in patients. Pharmacologically inducing a more permissive tumor microenvironment to enhance patient responsiveness to immune modulatory therapies may offer a rational approach to address this medical need. In particular, targeting immune suppressive myeloid cells, including myeloid-derived suppressor cells (MDSC), tumor-associated macrophages (TAM), and polymorphonuclear (PMN) cells in the tumor microenvironment may enhance the effectiveness of immune checkpoint blockade. Since MDSCs abundantly infiltrate syngeneic 4T1 mammary tumors compared with other commonly used syngeneic tumor models, this model was chosen for testing the hypothesis that the modulation of MDSC activity enhances antitumor activity driven by adaptive immunity. We have recently demonstrated (#4635, AACR 2017) that the selective Lysine Specific Demethylase 1 (LSD1) inhibitor, INCB059872, redirected myeloid differentiation toward monocyte/macrophages in vitro and in vivo and reduced the PMN-MDSC population in the syngeneic 4T1 murine mammary tumor model. The combination of INCB059872 and PD1/PDL1 axis blockade enhanced antitumor activity and was well tolerated in this model. In this study, we further tested if modulation of MDSCs with INCB059872 could enhance the effect of mechanistically distinct immunotherapeutic agents. The combination of INCB059872 with agonist anti-OX40 or anti-GITR T cell costimulatory monoclonal antibodies significantly augmented antitumor efficacy in the 4T1 model. These results consistently demonstrated that the inhibition of immune suppressive MDSCs increased antitumor activity of immune checkpoint modulatory monoclonal antibodies. Next, we tested the combination of INCB059872 with small-molecule inhibitors targeting the tumor microenvironment. The combination of INCB059872 with highly selective small-molecule immunotherapeutic inhibitors such as epacadostat (IDO1 inhibitor) and ruxolitinib (JAK1/JAK2 inhibitor) demonstrated similar marked increases in antitumor efficacy. The studies to understand mechanism of enhanced activity are under way. In summary, consistent with previous findings, the combination of INCB059872 with a variety of mechanistically distinct immunotherapeutic agents significantly enhanced antitumor efficacy in the syngeneic 4T1 murine mammary tumor model. These results strongly support the hypothesis that reshaping the tumor microenvironment by redirecting myeloid differentiation as a result of LSD1 inhibition enhances the responsiveness of the tumor microenvironment to immunotherapies, supporting the therapeutic rationale for the combination of an LSD1 inhibitor with various immunotherapeutic agents to improve clinical responses in cancer patients.

Citation Format: Sang Hyun Lee, Melody Diamond, Antony Chadderton, Thomas Condamine, Huiqing Liu, Valerie Roman, Jin Lu, Yan Zhang, Maxim Soloviev, Chunhong He, Liangxing Wu, Holly Koblish, Timothy Burn, Andrew Combs, Swamy Yeleswaram, Alan Roberts, Wenqing Yao, Gregory Hollis, Reid Huber, Peggy Scherle, Bruce Ruggeri. The LSD1 specific inhibitor INCB059872 enhances the activity of mechanistically distinct immunotherapeutic agents in the syngeneic 4T1 mouse mammary tumor model [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A168.