REDWOOD CITY, Calif., July 21, 2026
Pheast Therapeutics announced the publication of peer-reviewed preclinical data in Clinical Cancer Research, an American Association for Cancer Research (AACR) journal, highlighting the anti-tumor potential of its lead investigational therapy PHST001, a novel anti-CD24 monoclonal antibody. The study demonstrated that PHST001 effectively blocks the CD24-Siglec-10 immune checkpoint pathway, activates macrophage-mediated tumor cell destruction, and exhibits broad anti-tumor activity across multiple solid tumor models. The publication also supports the ongoing Phase 1 clinical development of PHST001, with monotherapy dose escalation nearing completion and combination chemotherapy cohorts actively enrolling patients with advanced solid tumors.
Preclinical Study Demonstrates Broad Anti-Tumor Activity
The published research establishes CD24 as a key macrophage immune checkpoint that enables cancer cells to evade immune surveillance through the CD24-Siglec-10 signaling pathway. PHST001, a high-affinity IgG4 anti-CD24 monoclonal antibody, was shown to bind CD24, block inhibitory signaling, and stimulate macrophage phagocytosis of tumor cells. Across six preclinical solid tumor models—including ovarian, breast, endometrial, pancreatic, lung, and cholangiocarcinoma cancers—the therapy demonstrated significant anti-tumor activity. Researchers also observed enhanced therapeutic effects when PHST001 was combined with chemotherapy, radiotherapy, and antibody-drug conjugates, including in treatment-resistant tumor models.
Publication Supports Ongoing Phase 1 Clinical Development
Pheast stated that the findings provide a strong scientific foundation for the ongoing Phase 1 PHST001-101 clinical trial evaluating PHST001 in patients with relapsed or refractory advanced solid tumors. The open-label, multicenter study is assessing safety, tolerability, dose optimization, pharmacokinetics, and preliminary anti-tumor activity. According to the company, monotherapy dose escalation is nearly complete, while combination cohorts evaluating PHST001 alongside chemotherapy are currently underway across several solid tumor indications, including ovarian cancer. Initial clinical data are expected to be presented at an upcoming scientific meeting.
Advertisement
Macrophage Checkpoint Therapy Targets Innate Immunity
PHST001 is designed to activate the innate immune system by inhibiting CD24, a cell surface protein commonly overexpressed in multiple cancers and associated with poor patient outcomes. By disrupting CD24-mediated immune suppression, the therapy aims to restore macrophage function and promote cancer cell elimination. The publication also demonstrated important interactions between activated macrophages and adaptive immune responses, supporting PHST001’s potential as a next-generation macrophage-directed immunotherapy. The investigational therapy previously received FDA Fast Track Designation for ovarian cancer, reinforcing its potential to address significant unmet needs across difficult-to-treat solid tumors.
Source: Pheast Therapeutics press release
