Abstract S02-03: SARS-CoV-2 induces inflammatory cytokine release, which may be exacerbated by immune checkpoint blockade
Authors: Weatherford Layne , Lehn Maria , Crist McKenzie , Wendling Chelsea , Hudock Kristin , Takiar Vinita , Wise-Draper Trisha 
Published: December 2020

Cancer patients infected with the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have a higher mortality rate compared to non-cancer patients. Recent anticancer treatment, including immunotherapy, is associated with severe infection including development of acute respiratory distress syndrome (ARDS) and high levels of cytokine release resulting in cytokine storm. Immune checkpoint inhibitors (ICIs) are approved for use in multiple cancer types and function by blocking the interaction between PD-1 and its ligand PD-L1, activating antitumor cytotoxic immune cells. However, ICIs can also increase inflammatory cytokine secretion, which may predispose to the development of cytokine storm. In fact, we have shown via single-cell cytokine secretion analysis that pembrolizumab (anti-PD-1 antibody) increases cytokine secretion by polyfunctional strength index, a measure of the percentage of cells secreting multiple functional cytokines. Therefore, we hypothesize that ICIs may worsen inflammatory cytokine secretion and potentiate cytokine storm and downstream complications in COVID-19 patients. Peripheral blood mononuclear cells (PBMCs) were isolated via Ficoll density gradient centrifugation from healthy donors, head and neck cancer (HNC) patients, and COVID-19-infected cancer patients. Flow cytometry was performed on patient PBMCs, after staining for viability and immune cell markers including CD3, CD8, CD19, and CD45. PBMCs were also activated overnight with low-dose IL-2, cocultured with Cal27 or HN5 cell lines, and subjected to various treatment conditions. For non-COVID-19 patients, PBMCs were exposed to 25 nM SARS-CoV-2 recombinant spike (S) protein, a virulent protein associated with cytokine storm, or control prior to drug treatments. Preliminary flow cytometry analysis showed that a COVID-19-positive patient with thyroid cancer had an increased proportion of CD8+ cells compared with a COVID-negative ovarian cancer patient and healthy donor. Recombinant SARS-CoV-2 S protein caused increased secretion of IL-6, IL-2, perforin, and MIP-1b from PBMCs isolated from both healthy donors and HNC patients, which was measured by IsoLight Codeplex bulk cytokine analysis or ELISA. We have previously shown that metformin, a commonly prescribed antidiabetes drug, decreases the proportion of cells that secrete inflammatory cytokines such as IL-6, which is thought to be an important cytokine for cytokine storm. Interestingly, we observed that metformin treatment resulted in decreased IL-6 secretion from PBMCs isolated from a COVID-19-positive patient. Results from this project suggest that ICIs may potentiate cytokine storm, and ongoing investigation will be informative to oncologists as to whether ICI treatment should be postponed in severe COVID-19 infections. In addition, metformin may be a novel potential treatment for COVID-19 patients to prevent and treat cytokine storm.

Citation Format: Layne Weatherford, Maria Lehn, McKenzie Crist, Chelsea Wendling, Kristin Hudock, Vinita Takiar, Trisha Wise-Draper. SARS-CoV-2 induces inflammatory cytokine release, which may be exacerbated by immune checkpoint blockade [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2020 Jul 20-22. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(18_Suppl):Abstract nr S02-03.