Svarovsky, Sergei

ABSTRACTCoccidioidesspp. are dimorphic fungi that are capable of infecting human and non-human mammals and can cause diverse manifestations of coccidioidomycosis or Valley fever (VF). In combination with clinical symptoms and radiographic findings, antibody-based diagnostic tests are often used to diagnose and monitor patients with VF. Chitinase 1 (CTS1) has previously been identified as the seroreactive antigen used in these diagnostic assays to detect anticoccidial IgG. Here, an indirect enzyme-linked immunosorbent assay to detect IgG to CTS1 demonstrated 165 of 178 (92.7%) patients with a positive result by immunodiffusion (ID) and/or complement fixation (CF) had antibodies to the single antigen CTS1. We then developed a rapid antibody lateral flow assay (LFA) to detect anti-CTS1 antibodies. Out of 143 samples tested, the LFA showed 92.9% positive percent agreement [95% confidence interval (CI), 84.3%–96.9%] and 97.7% negative percent agreement (95% CI, 87.9%–99.6%) with ID and CF assays. Serum or plasma from canines, macaques, and dolphins was also tested by the CTS1 LFA. Test line densities of the CTS1 LFA correlated in a linear manner with the reported CF and ID titers for human and non-human samples, respectively. This 10-min point-of-care test for the rapid detection of anti-coccidioidal antibodies could help to inform healthcare providers in real-time, potentially improving the efficiency of healthcare delivery.

Abstract Background While evaluating COVID-19 vaccine responses using a rapid neutralizing antibody (NAb) test, we observed that 25% of RNA vaccine recipients did not neutralize >50%. We termed this group “vaccine poor responders” (VPRs). The objective of this study was to determine if individuals who neutralized <50% would remain VPRs, or if a third dose would elicit high levels of NAbs. Methods 269 healthy individuals ranging in age from 19 to 80 (Average age = 51; 165 females and 104 males) who received either BNT162b2 (Pfizer) or mRNA1273 (Moderna) vaccines were evaluated. NAb levels were measured: i) 2-4 weeks after a second vaccine dose, ii) 2-4 months after the second dose, iii) within 1-2 weeks prior to a third dose and iv) 2-4 weeks after a third RNA vaccine dose. Results Analysis of vaccine recipients revealed that 25% did not neutralize above 50% (Median neutralization = 21%, titers <1:80) within a month after their second dose. Twenty-three of these VPRs obtained a third dose of either BNT162b2 or mRNA-1273 vaccine 1-8 months (average = 5 months) after their second dose. Within a month after their third dose, VPRs showed an average 20-fold increase in NAb levels (range: 46%-99%). Conclusions The results suggest that VPRs are not permanently poor responders; they can generate high NAb levels with an additional vaccine dose. Although it is not known what levels of NAbs protect from infection or disease, those in high-risk professions may wish to keep peripheral NAb levels high, limiting infection, and potential transmission.

Longitudinal studies assessing durability of the anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) humoral immune response have generated conflicting results. This has been proposed to be due to differences in patient populations, the lack of standardized methodologies, and the use of assays that measure distinct aspects of the humoral response.

Abstract Purpose: Quiescin Sulfhydryl Oxidase 1 (QSOX1) is an enzyme over-expressed by tumor cells. Our group and others have shown that QSOX1 is involved in invasion and metastasis. We previously reported that a small molecule, SBI-183, inhibited the enzymatic activity of QSOX1 and suppressed tumor cell invasion in vitro and metastasis of MDA-MB-231 breast tumor cells in vivo. In our current work we tested SPX-009, an analog of SBI-183 with increased potency, to suppress invasion and metastasis in vitro and in vivo. Methods: Commercially available analogs for SBI-183 were screened in a cell-free fluorescent screening assay for the ability to inhibit QSOX1. Analog compounds that inhibited QSOX1 in a concentration-dependent manner were then tested for the ability to inhibit growth and invasion of triple negative breast cancer (TNBC) cells (MDA-MB-231), sarcomatoid kidney cancer cells (RCJ-41T2) and pancreatic adenocarcinoma cells (MIAPaCa2). MTT assays were used to measure the effect of the compounds on tumor growth. 2D invasion assays and 3D tumor spheroid assays were employed to measure the effect of the analogs on invasion. One potent analog (SPX-009) was evaluated for the ability to suppress tumor growth and metastasis in mice bearing MDA-MB-231-luc breast cancer orthotopic xenografts. Results: Three of 53 analogs inhibited the enzymatic activity of QSOX1 at levels similar to the parent compound. However, one of those compounds, SPX-009, suppressed invasion of breast, kidney and pancreas tumor cells in 2D and 3D invasion assays at &gt;10-fold lower concentrations than the parent compound (SBI-183). In a non-metastatic xenograft of kidney cancer SBI-183 suppressed primary kidney tumor growth by 51%, but in a metastatic xenograft breast cancer model (MDA-MB-231-luc TNBC), SBI-183 reduced lung metastasis by 76% compared to control. Human-mouse xenograft studies are ongoing with the more potent analog (SPX-009) and will also be presented. Conclusions: Chemical inhibitors of QSOX1 have a minor effect on tumor cell viability, but a major effect on tumor cell invasion in vitro and metastasis in vivo. This finding suggests that combining a QSOX1 inhibitor with a cytotoxic agent might provide a means to inhibit metastasis of cells that are resistant to cytotoxic agents. Citation Format: Amber Fifield, Thai H. Ho, Douglas O. Faigel, Sergei Svarovsky, Eduard Sergienko, Thomas C. Chung, Douglas F. Lake. Chemical inhibitors of quiescin sulfhydryl oxidase (QSOX1) suppress tumor invasion and metastasis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5323.