Abstract 2950: CD16A shedding facilitates repetitive targeting of tumor cells by AFM13-armed NK cells

Antibody-Dependent Cellular Cytotoxicity (ADCC) is a powerful mechanism of Natural Killer (NK) cells to kill antibody-opsonized target cells. However, ADCC mediated by conventional antibodies has its limitations in killing of tumor cells commonly being characterized by low tumor antigen expression. Several strategies have been implemented to boost ADCC including shedding inhibition of CD16A, a key ADCC-mediating Fc receptor on the plasma membrane of NK cells. However, previous results have shown that genetic engineering of the cleavage site of CD16A leads to decreased serial engagement of target cells. Another approach to boost ADCC is provided by tetravalent-bispecific innate cell engagers (ICE®) cross-linking CD16A and tumor antigens triggering anti-tumoral cytotoxicity.

In the current study, we have investigated whether ICE molecules can induce effective ADCC while maintaining the natural function of CD16A with a particular focus on preserved CD16A shedding. To study cytotoxicity and contact dynamics, we have used an in-house developed live-cell microchip screening with single cell resolution together with a microcontact printing-based assay combined with an ICE®.

Single cell analysis using microchip screening revealed that the CD16A/CD30 targeting ICE® AFM13 induces stronger ADCC of NK cells towards CD30+ target cells when compared to anti-CD30 antibodies. This stronger response was reached through increasing both the overall number of cytotoxic NK cells and the fraction of NK serial killers i.e., NK cells performing three or more kills in sequence. Interestingly, the differences were most prominent towards target cells expressing low levels of CD30.

Combination of AFM13 and inhibition of CD16 shedding increased NK cell conjugation time with target cells, which could potentially limit targeting of additional tumor cells located at a distance from the primary target. To investigate this phenomenon further, we used a microcontact printing assay. Here, a grid of spatially distributed protein patches consisting of AFM13 and anti-LFA-1 was printed on glass surfaces enabling the formation of “artificial immune synapses” when probed by NK cells. On these “artificial immune synapses” we investigated the influence of shedding inhibition on NK cell migration and interaction dynamics.

In conclusion, we show that AFM13 increases both the fraction of tumor-target responsive NK cells and the fraction of serial killing NK cells compared to conventional monoclonal antibodies. Based on our data we hypothesize that CD16A shedding facilitates AFM13 induced ADCC potential of NK cells by allowing potent migration to distantly located tumor cells and serial killing. Especially in the context of AFM13 primary indications, Hodgkin and peripheral T cell lymphoma, migration of NK cells might have a particularly strong impact when treating cancer patients due to the disseminated nature of the disease.

Citation Format: Chiara Zambarda, Karolin Guldevall, Damien Toullec, Susanne Wingert, Christian Breunig, Sheena Pinto, Jacopo Fontana, Joachim Koch, Björn Önfelt. CD16A shedding facilitates repetitive targeting of tumor cells by AFM13-armed NK cells [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 2950.

Epithelial cell cluster size affects force distribution in response to EGF-induced collective contractility

Several factors present in the extracellular environment regulate epithelial cell adhesion and dynamics. Among them, growth factors such as EGF, upon binding to their receptors at the cell surface, get internalized and directly activate the acto-myosin machinery. In this study we present the effects of EGF on the contractility of epithelial cancer cell colonies in confined geometry of different sizes. We show that the extent to which EGF triggers contractility scales with the cluster size and thus the number of cells. Moreover, the collective contractility results in a radial distribution of traction forces, which are dependent on integrin β1 peripheral adhesions and transmitted to neighboring cells through adherens junctions. Taken together, EGF-induced contractility acts on the mechanical crosstalk and linkage between the cell-cell and cell-matrix compartments, regulating collective responses.

Live single cell imaging assays in glass microwells produced by laser-induced deep etching

Miniaturization of cell culture substrates enables controlled analysis of living cells in confined micro-scale environments. This is particularly suitable for imaging individual cells over time, as they can be monitored without escaping the imaging field-of-view (FoV). Glass materials are ideal for most microscopy applications. However, with current methods used in life sciences, glass microfabrication is limited in terms of either freedom of design, quality, or throughput. In this work, we introduce laser-induced deep etching (LIDE) as a method for producing glass microwell arrays for live single cell imaging assays. We demonstrate novel microwell arrays with deep, high-aspect ratio wells that have rounded, dimpled or flat bottom profiles in either single-layer or double-layer glass chips. The microwells are evaluated for microscopy-based analysis of long-term cell culture, clonal expansion, laterally organized cell seeding, subcellular mechanics during migration and immune cell cytotoxicity assays of both adherent and suspension cells. It is shown that all types of microwells can support viable cell cultures and imaging with single cell resolution, and we highlight specific benefits of each microwell design for different applications. We believe that high-quality glass microwell arrays enabled by LIDE provide a great option for high-content and high-resolution imaging-based live cell assays with a broad range of potential applications within life sciences.

894 The bispecific innate cell engagers AFM13 (CD30/CD16A) and AFM24 (EGFR/CD16A) increase the fraction of tumor target-responsive NK cells and boost serial killing

Background

The use of bispecific natural killer (NK) cell engagers has emerged as a successful strategy for immune cell activation and killing of tumor cells through antibody-dependent cellular cytotoxicity (ADCC). Among these, tetravalent, bispecific innate cell engagers (ICE®) with specificity for the activating receptor CD16A selectively triggering innate responses from NK cells or macrophages represent the most clinically advanced concept. The CD30/CD16A specific ICE® AFM13, has shown efficacy in patients with CD30+ lymphomas as monotherapy1 and combination therapy with check-point inhibitors2 and most recently in combination with adoptive NK cell therapy.3 The EGFR/CD16A specific ICE® AFM24, targeting a variety of solid tumors like colorectal, or lung cancer with a unique mode of action independent of EGFR signaling inhibition, is currently evaluated in an ongoing Ph1/2a clinical study.

Methods

We used a microchip-based screening with single cell resolution4 to elucidate the dynamic responses of individual NK cells towards tumor target cells upon treatment with AFM13 or AFM24.

Results

We found that AFM13 and AFM24 mediated potent activation of NK cells, leading to increased responsive cytotoxic NK cells and significantly increased the number of NK cells that exerted engagement with multiple target cells rendering these NK cells serial killers. Strikingly, bispecific ICE® molecules triggered stronger cytotoxic responses compared to monoclonal antibodies. One suggested strategy to boost killing by NK cells is to use molecular inhibitors or protein constructs that prevent shedding of CD16.5 However, previous results have shown that this can lead to impaired detachment from target cells, reducing the capacity for an individual NK cell to form serial contacts to target cells.6 We observed that the elevated NK cell killing induced by ICE® molecules was largely conserved when cells were treated with the shedding inhibitor Batimastat. Analysis of the functional dynamics of NK cells revealed that inhibition of CD16 shedding prevented NK cell detachment from target cells, resulting in cell cluster formation. This might strongly impact targeting of distant tumor cells by an individual NK cell thus limiting its anti-tumoral activity.

Conclusions

In conclusion, we show that both AFM13 and AFM24 increase the fraction of tumor-target responsive NK cells and boost serial killing of target cells by individual NK cells. Based on these data, ICE® molecules can be characterized as potent anti-tumoral agents leveraging the enormous potential of NK cells while maintaining crucial features of NK cell biology.

Acknowledgements

We thank members of the Önfelt lab for their valuable help and feedback.

References

Sawas A, Elgedawe H, Vlad G, Lipschitz M, Chen P-H, Rodig SJ, et al. Clinical and biological evaluation of the novel CD30/CD16A tetravalent bispecific antibody (AFM13) in relapsed or refractory CD30-positive lymphoma with cutaneous presentation: a biomarker phase Ib/IIa study (NCT03192202). Blood 2018;132(Supplement 1):2908–2908.

Bartlett NL, Herrera AF, Domingo-Domenech E, Mehta A, Forero-Torres A, Garcia-Sanz R, et al. A phase 1b study of AFM13 in combination with pembrolizumab in patients with relapsed or refractory Hodgkin lymphoma. Blood 2020. Blood 2020;136(21):2401–2409.

Kerbauy LN, Marin ND, Kaplan M, Banerjee PP, Berrien-Elliott MM, Becker-Hapak M, et al. Combining AFM13, a bispecific CD30/CD16 antibody, with cytokine-activated blood and cord blood–derived NK cells facilitates CAR-like responses against CD30 + malignancies. Clin Cancer Res Epub 2021.

Guldevall K, Brandt L, Forslund E, Olofsson K, Frisk TW, Olofsson PE, et al. Microchip screening platform for single cell assessment of NK cell cytotoxicity. Front Immunol 2016;7:119.

Romee R, Foley B, Lenvik T, Wang Y, Zhang B, Ankarlo D, et al. NK cell CD16 surface expression and function is regulated by a disintegrin and metalloprotease-17 (ADAM17). Blood 2013;121(18):3599–608.

Srpan K, Ambrose A, Karampatzakis A, Saeed M, Cartwright ANR, Guldevall K, et al. Shedding of CD16 disassembles the NK cell immune synapse and boosts serial engagement of target cells. J Cell Biol 2018;217(9):3267–83.

Ethics Approval

This work was performed with NK cells from healthy anonymous blood donors, which requires no ethical permit according to local regulations.

Author Correction: An optochemical tool for light-induced dissociation of adherens junctions to control mechanical coupling between cells

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

An optochemical tool for light-induced dissociation of adherens junctions to control mechanical coupling between cells

The cadherin-catenin complex at adherens junctions (AJs) is essential for the formation of cell-cell adhesion and epithelium integrity; however, studying the dynamic regulation of AJs at high spatio-temporal resolution remains challenging. Here we present an optochemical tool which allows reconstitution of AJs by chemical dimerization of the force bearing structures and their precise light-induced dissociation. For the dimerization, we reconstitute acto-myosin connection of a tailless E-cadherin by two ways: direct recruitment of α-catenin, and linking its cytosolic tail to the transmembrane domain. Our approach enables a specific ON-OFF switch for mechanical coupling between cells that can be controlled spatially on subcellular or tissue scale via photocleavage. The combination with cell migration analysis and traction force microscopy shows a wide-range of applicability and confirms the mechanical contribution of the reconstituted AJs. Remarkably, in vivo our tool is able to control structural and functional integrity of the epidermal layer in developing Xenopus embryos.

Matrix-Immobilized BMP-2 on Microcontact Printed Fibronectin as an in vitro Tool to Study BMP-Mediated Signaling and Cell Migration

During development, growth factors (GFs) such as bone morphogenetic proteins (BMPs) exert important functions in several tissues by regulating signaling for cell differentiation and migration. In vivo, the extracellular matrix (ECM) not only provides support for adherent cells, but also acts as reservoir of GFs. Several constituents of the ECM provide adhesive cues, which serve as binding sites for cell trans-membrane receptors, such as integrins. In conveying adhesion-mediated signaling to the intracellular compartment, integrins do not function alone but rather crosstalk and cooperate with other receptors, such as GF receptors. Here, we present a strategy for the immobilization of BMP-2 onto cellular fibronectin (cFN), a key protein of the ECM, to investigate GF-mediated signaling and migration. Following biotinylation, BMP-2 was linked to biotinylated cFN using NeutrAvidin as cross-linker. Characterization with quartz crystal microbalance with dissipation monitoring and enzyme-linked immunosorbent assay confirmed the efficient immobilization of BMP-2 on cFN over a period of 24 h. To validate the bioactivity of matrix-immobilized BMP-2 (iBMP-2), we investigated short- and long-term responses of C2C12 myoblasts, which are an established in vitro model for BMP-2 signaling, in comparison to soluble BMP-2 (sBMP-2) or in absence of GFs. Similarly to sBMP-2, iBMP-2 triggered Smad 1/5 phosphorylation and translocation of the complex to the nucleus, corresponding to the activation of BMP-mediated Smad-dependent pathway. Additionally, successful suppression of myotube formation was observed after 6 days in sBMP-2 and iBMP-2. We next implemented this approach in the fabrication of cFN micropatterned stripes by soft lithography. These stripes allowed cell-surface interaction only on the patterned cFN, since the surface in between was passivated, thus serving as platform for studies on directed cell migration. During a 10-h observation time, the migratory behavior, especially the cells' net displacement, was increased in presence of BMP-2. As such, this versatile tool retains the bioactivity of GFs and allows the presentation of ECM adhesive cues.

[Risk factors for hip fracture in elderly persons]

OBJECTIVE

The aim of this observational study, promoted by the Health Authorities of the Regione Veneto (Italy), is to assess the prevalence of the most relevant environmental and individual risk factors in subjects with a recent hip fracture.

METHODS

Patients aged more than 60 years of both genders with a recent hip fracture not associated with malignancies, were administered questionnaires on dietary habits, sun exposure, and disability score. A complete family, pharmacological and pathology history was collected together with information on previous falls, details of the fracture index, and anthropometric data. In all subjects, blood was taken for the measurement of serum 25 hydroxy-vitamin D (25OHD).

RESULTS

The study included 704 patients (573 women and 131 men). Mean age was 81 ± 8 years (range 60-102). Severe pre-fracture disability was a common feature (58%) associated with multiple co-morbidities (84%), more frequently cardiovascular and neurological diseases, and specific medications. In a large proportion (86%) of the patients, environmental or individual risk factors for falling were found. Vitamin D insufficiency (serum 25OHD levels < 75 nmol/l) was quite common (70%), particularly in the regional Health Districts were strategies for preventing vitamin D deficiency were not implemented (91%). Only a small proportion (17%) of the study population had been evaluated and treated for osteoporosis.

CONCLUSIONS

In senile patients with a recent hip fracture, pre-existing disability, multiple co-morbidities, high risk of falling and inadequate intake of calcium and vitamin D is relatively common. Community and case-finding interventions aimed at selecting subjects at high risk of osteoporosis, preventing vitamin D and dietary calcium deficiency, and increasing awareness on the environmental risks of falling are highly warranted.