Antennova announced completion of the first dosing cohort in the Phase I study for the anti-CD24 antibody, ATN-031 (also known as ATG-031). The dose escalation trial is evaluating ATN-031 in patients with advanced solid tumors or B-cell non-Hodgkin's lymphoma (B-NHL), (NCT06028373). The PERFORM trial is being conducted at four cancer centers in the U.S., led by The University of Texas MD Anderson Cancer Center.

A total of five late stage cancer patients have been enrolled based on the Bayesian Optimal Interval (BOIN) design of the trial in the first dosing cohort. To date, no dose-limiting toxicities (DLTs) have been reported among the 5 patients. Tumor shrinkage based on CT scan was observed in one heavily pre-treated patient (7 prior lines of therapy).

Compared to CD47, another "don't eat me" target, CD24, has a more markedly restricted distribution in normal tissues and higher expression in cancerous tissues, especially solid tumors. Importantly, CD24 is differentiated from CD47 because it is not expressed on human red blood cells, allowing for a wider therapeutic window and minimal on-target-off-tumor toxicity. CD24 acts as a novel innate immune checkpoint, orchestrating immune evasion through its interaction with the inhibitory receptor Siglec-10 (sialic-acid-binding Ig-like lectin 10), expressed on tumor-associated macrophages (TAMs).

Preclinical data presented at the American Association for Cancer Research Annual Meeting in 2023 (AACR 2023) and the Society for Immunotherapy in Cancer Annual Meeting in 2022 (SITC 2022) demonstrated that ATN-031 can specifically bind to CD24 with nM affinity and block the interaction of CD24 and Siglec-10. Furthermore, ATN-31 induces efficient phagocytosis with a picomolar EC50 and stimulates the pro-inflammatory cytokines production by macrophages.