Abstract CytoAgents is developing CTO1681 for the prevention and treatment of cytokine release syndrome (CRS) associated with chimeric antigen receptor (CAR) T-cell therapy. CAR T-cell therapy has emerged as a very promising treatment option for patients with relapsed or refractory (R/R) hematologic malignancies. However, CAR T-cell therapy can also result in a high incidence of severe and potentially life-threatening immune-mediated toxicity, including CRS and immune effector cell-associated neurotoxicity syndrome (ICANS). CRS is a systemic inflammatory response that has been reported as one of the most frequent and dangerous adverse events following CD19-directed CAR T-cell therapy. CRS is thought to be mediated by an initial release of proinflammatory cytokines, which activate bystander immune cells and endothelial cells, which in turn activate more immune cells, culminating in a cytokine storm. Because CytoAgents’ novel approach is focused on reducing the transcription of multiple proinflammatory cytokines, its compound is expected to mitigate, and in some cases even prevent, CRS. CTO1681 is an orally available, stable compound identical to beraprost sodium-314d (BPS-314d), the stereoisomer of the racemate beraprost sodium (BPS) that accounts for nearly all of BPS’s pharmacological activity. Because BPS can modulate the release of cytokines from human peripheral blood mononuclear cells, CytoAgents has investigated the use of BPS and its active isomer CTO1681 as a treatment for moderate virus-induced CRS, specifically influenza and COVID-19. All of the results to date indicate that CTO1681 has strong potential to reduce the CRS response, leading to better patient outcomes regardless of CRS etiology. Overall, BPS, BPS-314d, and CTO1681 formulations have been found to be well tolerated and to not completely suppress cytokine levels in healthy volunteers with normal serum levels. CytoAgents is currently expanding clinical investigation of CTO1681 to the treatment of CAR T-cell therapy-induced CRS. CytoAgents’ Phase 1b trial of CTO1681, a multicenter, open-label, dose-escalating safety and pharmacokinetic (PK) MAD study in patients with diffuse large B cell lymphoma (DLBCL) receiving CD19-directed CAR T-cell therapy, is scheduled to begin in the coming months. This Direct to Phase II project will support expansion to a Phase 2a cohort once the recommended Phase 2 dose (RP2D) has been determined. The company will undertake three specific aims: 1) determining preliminary efficacy of CTO1681 in preventing or reducing CRS or ICANS vs. historical or placebo treatment, 2) determining the expanded safety profile of CTO1681 in patients with DLCBL receiving CAR T-cell therapy, and 3) investigating the potential impact of CTO1681 on antitumor activity of CAR T-cell therapy compared to historical data and placebo. This project will help support clinical assessment of CTO1681 in CAR T-cell therapy recipients, advancing a novel treatment with the potential to reduce hospitalization, intensity of supportive care, and mortality and to improve patients’ quality of life. Moreover, this therapeutic may allow more patients with R/R hematologic malignancies to have access to potentially life-saving CAR T-cell treatment.

Narrative Chimeric antigen receptor (CAR) T-cell therapy has emerged as a very promising treatment option for patients with relapsed or refractory hematologic malignancies, but it can also result in a high incidence of severe and potentially life-threatening immune-mediated toxicity, particularly cytokine release syndrome (CRS). The compound CTO1681, which has strong potential to reduce the CRS response by modulating the release of cytokines from human peripheral blood mononuclear cells, has shown promise as a treatment for moderate virus-induced CRS. This project will support the expansion of the clinical investigation of CTO1681 for the treatment of CAR T-cell therapy-induced CRS.