PAX8 lineage-driven T cell engaging antibody for the treatment of high-grade serous ovarian cancer

High-grade serous ovarian cancers (HGSOC) represent the most common subtype of ovarian malignancies. Due to the frequency of late-stage diagnosis and high rates of recurrence following standard of care treatments, novel therapies are needed to promote durable responses. We investigated the anti-tumor activity of CD3 T cell engaging bispecific antibodies (TCBs) directed against the PAX8 lineage-driven HGSOC tumor antigen LYPD1 and demonstrated that anti-LYPD1 TCBs induce T cell activation and promote in vivo tumor growth inhibition in LYPD1-expressing HGSOC. To selectively target LYPD1-expressing tumor cells with high expression while sparing cells with low expression, we coupled bivalent low-affinity anti-LYPD1 antigen-binding fragments (Fabs) with the anti-CD3 scFv. In contrast to the monovalent anti-LYPD1 high-affinity TCB (VHP354), the bivalent low-affinity anti-LYPD1 TCB (QZC131) demonstrated antigen density-dependent selectivity and showed tolerability in cynomolgus monkeys at the maximum dose tested of 3 mg/kg. Collectively, these data demonstrate that bivalent TCBs directed against LYPD1 have compelling efficacy and safety profiles to support its use as a treatment for high-grade serous ovarian cancers.

Development of Anti-CD32b Antibodies with Enhanced Fc Function for the Treatment of B and Plasma Cell Malignancies

The sole inhibitory Fcγ receptor CD32b (FcγRIIb) is expressed throughout B and plasma cell development and on their malignant counterparts. CD32b expression on malignant B cells is known to provide a mechanism of resistance to rituximab that can be ameliorated with a CD32b-blocking antibody. CD32b, therefore, represents an attractive tumor antigen for targeting with a monoclonal antibody (mAb). To this end, two anti-CD32b mAbs, NVS32b1 and NVS32b2, were developed. Their complementarity-determining regions (CDR) bind the CD32b Fc binding domain with high specificity and affinity while the Fc region is afucosylated to enhance activation of FcγRIIIa on immune effector cells. The NVS32b mAbs selectively target CD32b⁺ malignant cells and healthy B cells but not myeloid cells. They mediate potent killing of opsonized CD32b⁺ cells via antibody-dependent cellular cytotoxicity and phagocytosis (ADCC and ADCP) as well as complement-dependent cytotoxicity (CDC). In addition, NVS32b CDRs block the CD32b Fc-binding domain, thereby minimizing CD32b-mediated resistance to therapeutic mAbs including rituximab, obinutuzumab, and daratumumab. NVS32b mAbs demonstrate robust antitumor activity against CD32b⁺ xenografts in vivo and immunomodulatory activity including recruitment of macrophages to the tumor and enhancement of dendritic cell maturation in response to immune complexes. Finally, the activity of NVS32b mAbs on CD32b⁺ primary malignant B and plasma cells was confirmed using samples from patients with B-cell chronic lymphocytic leukemia (CLL) and multiple myeloma. The findings indicate the promising potential of NVS32b mAbs as a single agent or in combination with other mAb therapeutics for patients with CD32b⁺ malignant cells.

Abstract C028: Discovery and characterization of next generation monoclonal antibodies targeting the inhibitory Fc gamma receptor CD32b for the treatment of B and plasma cell malignancies

CD32b (FcγR2b), the sole inhibitory Fcγ receptor, negatively regulates immune function and is expressed throughout B cell development and on their malignant counterparts with the highest expression found on multiple myeloma. Additionally, CD32b expression on tumor cells is known to sequester IgG Fc thereby providing a mechanism of resistance to therapeutic monoclonal antibodies (mAb) with Fc dependent activity. Taken together, CD32b represents an attractive tumor antigen for targeting with a mAb. To this end, two anti-CD32b mAbs, NVS32b1 and NVS32b2, were developed. The complementarity-determining regions (CDRs) of these antibodies bind the CD32b Fc binding domain with high specificity and affinity while the Fc region is afucosylated enabling enhanced activation of FcγR on immune effector cells. This specificity and optimized potency is highlighted in whole blood assays where NVS32b2 depletes CD32b positive B cells but spares immune subsets with low CD32b expression or expression of the homologous CD32a. The antibodies mediate potent killing of opsonized cells via antibody dependent cell-mediated cytotoxicity, antibody dependent cellular phagocytosis, and complement dependent cytotoxicity. Additionally, NVS32b mAbs’ CDR block the CD32b Fc binding domain, thereby minimizing CD32b mediated resistance to therapeutic mAbs with Fc dependent activity including rituximab, obinutuzumab, and daratumumab. In vivo, NVS32b mAbs demonstrate robust antitumor activity against CD32b positive xenografts and immunomodulatory activity including recruitment of intratumoral macrophages. The NVS32b mAbs’ activity against malignant B and plasma cells featuring a range of CD32b expression demonstrates their therapeutic potential, as a single agent or in combination with therapeutics including mAbs with Fc dependent activity.

Citation Format: Haihui Lu, Dongshu Chen, Sunyoung Jang, Babette Wolf, Stefan Ewert, Meghan Flaherty, Fangmin Xu, Sinan Isim, Yeonjiu Shim, Christina Dornelas, Nicole Balke, Xavier Charles Leber, Meike Scharenberg, Johanna Koelln, Eugene Choi, Rebecca Ward, Jennifer Johnson, Thomas Calzascia, Isabelle Isnardi, Juliet Williams, Heather Huet, Emma Lees, Matthew J Meyer. Discovery and characterization of next generation monoclonal antibodies targeting the inhibitory Fc gamma receptor CD32b for the treatment of B and plasma cell malignancies [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C028. doi:10.1158/1535-7163.TARG-19-C028

Imaging and Mapping of Tissue Constituents at the Single-Cell Level Using MALDI MSI and Quantitative Laser Scanning Cytometry

For nearly a century, histopathology involved the laborious morphological analyses of tissues stained with broad-spectrum dyes (i.e., eosin to label proteins). With the advent of antibody-labeling, immunostaining (fluorescein and rhodamine for fluorescent labeling) and immunohistochemistry (DAB and hematoxylin), it became possible to identify specific immunological targets in cells and tissue preparations. Technical advances, including the development of monoclonal antibody technology, led to an ever-increasing palate of dyes, both fluorescent and chromatic. This provides an incredibly rich menu of molecular entities that can be visualized and quantified in cells-giving rise to the new discipline of Molecular Pathology. We describe the evolution of two analytical techniques, cytometry and mass spectrometry, which complement histopathological visual analysis by providing automated, cellular-resolution constituent maps. For the first time, laser scanning cytometry (LSC) and matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) are combined for the analysis of tissue sections. The utility of the marriage of these techniques is demonstrated by analyzing mouse brains with neuron-specific, genetically encoded, fluorescent proteins. We present a workflow that: (1) can be used with or without expensive matrix deposition methods, (2) uses LSC images to reveal the diverse landscape of neural tissue as well as the matrix, and (3) uses a tissue fixation method compatible with a DNA stain. The proposed workflow can be adapted for a variety of sample preparation and matrix deposition methods.

Physiological responses of growing large white boars in three management environments

Growth and physiological responses in Large White boars were studied under three different management environments at the Teaching and Research Farm of the Federal University of Technology, Akure. The management environments were shed with concrete floor (SCF), open space with concrete floor (OSCF) and open space with earth floor (OSEF). Two studies were carried out, one between December 1990 and March 1991 and the other from December 1991 to April 1992. Meteorological parameters in all management environments were monitored simultaneously with physiological variables. Growth of the animals was assessed by monitoring body weights of the animals. Data analysis showed that mean ambient temperatures, mean relative humidity and net radiation differed significantly (P < 0.05) among the management environments. Ambient temperature and net radiation of the pigs were highest (P < 0.05) in the OSEF environment, which also had the lowest (P < 0.05) relative humidity. Although growth rates did not differ significantly among environments, body weight was lowest (P < 0.05) in the OSEF environment. Mean respiratory rates and rectal temperatures were lowest (P < 0.05) in the SCF environment. The study shows correlations between some meteorological parameters and body weights. Pigs under shade and in concrete-floored pens were more comfortable and had higher body weight and lower respiratory rates and rectal temperatures.