Three abstracts highlight early clinical data, preclinical evaluation in metastatic models, and combination strategies for PHST001

Pheast Therapeutics, a clinical-stage biotechnology company advancing macrophage-directed immunotherapies for cancer, today announced that it will present three abstracts at the American Association for Cancer Research® (AACR) Annual Meeting 2026, taking place April 17–22 in San Diego.

The presentations include initial data from the ongoing Phase 1 study of PHST001, an IgG4 anti-CD24 macrophage checkpoint inhibitor, in patients with advanced or metastatic solid tumors. Two additional preclinical abstracts evaluate PHST001 in combination with multiple classes of standard-of-care chemotherapy to enhance macrophage-mediated tumor cell clearance, and in metastatic tumor models assessing activity, Fc receptor contribution, and the impact of endogenous IgG competition.

“These presentations reflect the breadth of our work, from first-in-human evaluation to mechanistic and preclinical combination studies,” said Roy Maute, Ph.D., Co-founder and Chief Executive Officer of Pheast Therapeutics. “Together, they provide important context as we advance PHST001 and develop a broad pipeline of macrophage-directed therapies for solid tumors.”

“PHST001 was intentionally designed to balance effective CD24 blockade with controlled immune engagement,” said Raphaël Rousseau, M.D., Ph.D., Chief Medical Officer of Pheast Therapeutics. “At AACR, we will present preliminary Phase 1a clinical data and supporting preclinical studies, as we evaluate PHST001 as a monotherapy and advance to combination settings.”

AACR 2026 Presentation Details for PHST001

Initial Results from a Phase 1 Study of PHST001, a Macrophage Activating anti-CD24 Antibody, in Patients with Advanced/Metastatic Solid Tumors
Session Title: Phase 0 and First-in-Human Phase I Clinical Trials
Date & Time: Monday, April 20, 2PM–5PM PT
Location: Poster Section 51
Poster Board Number: 22
Abstract Presentation Number: CT130

PHST001 combination with standard-of-care chemotherapy enhances macrophage-mediated elimination of tumor cells
Session Title: Combination Immunotherapies
Date & Time: Monday, April 20, 9AM–12PM PT
Location: Poster Section 8
Poster Board Number: 11
Poster Number: 1557

PHST001, a humanized anti-CD24 hIgG4 antibody, is effective against metastatic tumors and retains its anti-tumor activity in the presence of competing IgG
Session Title: Monoclonal Antibodies and Antibody-Cytokine Platforms
Date & Time: Tuesday, April 21, 9AM–12PM PT
Location: Poster Section 9
Poster Board Number: 24
Poster Number: 4353

About CD24

CD24 is a cell surface protein that plays a key role in tumor immune evasion by engaging Siglec-10, an inhibitory receptor on macrophages. This interaction suppresses macrophage-mediated clearance of cancer cells, allowing tumors to escape destruction by the innate immune system. CD24 was identified as a novel macrophage checkpoint through foundational work by Dr. Amira Barkal, principal founder of Pheast. Along with other co-founders, Drs. Irving Weissman, Ravi Majeti, and Roy Maute, Pheast’s research opened the door to therapeutic strategies targeting CD24 to drive innate immune responses against cancer.

About PHST001

PHST001 is an anti-CD24 macrophage checkpoint inhibitor designed to overcome immune suppression in the tumor microenvironment. CD24 is highly expressed by many human cancers and high expression of CD24 is a negative prognostic factor in multiple cancer indications. Pheast has engineered PHST001 to be a potential best-in-class antibody designed to induce macrophages to phagocytose cancer cells and initiate a powerful immune response. PHST001-101 is an open-label, multicenter Phase 1 study in patients with advanced solid tumors (ClinicalTrials.gov Identifier: NCT06840886). Primary objectives include safety, tolerability, and dose optimization, with secondary objectives evaluating pharmacokinetics and preliminary anti-tumor activity.

About Pheast Therapeutics

Pheast is a clinical-stage immuno-oncology company focused on activating the innate immune system in the fight against cancer. Founded as a spinout from Stanford University and led by scientific experts in innate immunity and cancer immunotherapy, Pheast is developing novel therapies for some of the most difficult-to-treat and aggressive cancers. Pheast is backed by leading life sciences investors, Catalio Capital Management and ARCH Venture Partners. For more info, visit Pheast.com and connect on LinkedIn.

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“At AACR, we will present preliminary Phase 1a clinical data supporting preclinical studies, as we evaluate PHST001 as a monotherapy and advance to combination settings," said Raphaël Rousseau, M.D., Ph.D., Chief Medical Officer of Pheast Therapeutics.