The Mission
Teaching Macrophages to Feast on Cancer
There is a molecular signal on the surface of many cancer cells - a protein called CD24 - that functions like a "get out of jail free" card. It binds to a receptor called Siglec-10 on macrophages, the immune system's voracious phagocytic cells, and sends a single message: don't eat me. Cancer has been using this trick for decades. Roy Maute and Pheast Therapeutics are working to shut it down.
PHST001, Pheast's lead anti-CD24 monoclonal antibody, is designed to block that interaction - removing the invisibility cloak and letting macrophages do what they evolved to do. In March 2026, Pheast dosed its first patient in Phase 1b combination cohorts. A month later, at AACR 2026 in San Diego, the company presented its initial Phase 1a data: early clinical activity, target engagement, and a signal that the biology works in patients, not just in petri dishes.
Phase 1b
Combination Cohorts Active
FDA
Fast Track (Ovarian Ca.)
For Maute, this is not a first rodeo with checkpoint biology. Before Pheast, he spent two years at Forty Seven Inc. - a company built on the adjacent "don't eat me" signal, CD47. He led the biomarker strategy for magrolimab, the anti-CD47 antibody that became one of biotech's most watched clinical programs. When Gilead acquired Forty Seven for $4.9 billion in 2020, Maute stayed on to lead the biomarkers science team before ultimately deciding it was time to build something new.
CD24 and CD47 work in the same general space - both are macrophage checkpoints on tumor cells - but CD24 has a more tumor-specific expression profile. That specificity matters clinically. And Maute had been watching the CD24 biology for years, including through his Stanford postdoc in Irving Weissman's lab, where the foundational innate checkpoint science was developed.
Clinical Pipeline
What's in the Pheast
PHEAST THERAPEUTICS — PIPELINE STATUS (MAY 2026)
Anti-CD24 IgG4 mAb · Solid tumors (ovarian, breast) · FDA Fast Track
Bispecific ADC · CDH1 x Nectin-4 · Disclosed at PEGS Boston 2026
Career Arc
From Dallas to Weissman's Lab to Clinical Stage
Roy Maute grew up in Dallas, one of four kids in a household where neither parent worked in science. His father is an architect. His mother is an artist. He ended up with a PhD in genetics from Columbia University, studying B-cell lymphoma under Riccardo Dalla-Favera - one of the field's luminaries. The jump from a creative Dallas family to molecular genetics at Columbia, and then to Stanford's Institute for Stem Cell Biology, is a trajectory that reflects the kind of intellectual restlessness that tends to produce founders.
Get the info, take the shot.
Roy Maute - CEO, Pheast Therapeutics
At Stanford, Maute joined Irving Weissman's lab as a postdoctoral fellow. Weissman, who is the godfather of modern stem cell and innate immune biology, is also a scientific co-founder of Pheast Therapeutics. The mentor-to-co-founder pipeline in biotech is common enough - but what makes this one unusual is that Maute credits Weissman's management style as a formative influence on how he leads his own team today. Weissman's approach: give scientists high autonomy, build on trust, and let curiosity run. Maute describes his own philosophy as "trust over control."
In 2015, Maute co-founded Ab Initio Biotherapeutics with Kenneth Lin. The company developed patented antigen technology for targeting multi-transmembrane proteins - GPCRs and similar targets that are notoriously hard to drug. Ligand Pharmaceuticals acquired it in July 2019 for $12 million. Small exit, but clean, and it proved the technology and the founder's ability to take something from idea to transaction.
From there, he moved to Forty Seven Inc., where the work was larger in scale and visibility. Forty Seven's lead program, magrolimab, was an anti-CD47 antibody blocking the same "don't eat me" pathway in a different target - and it was generating serious clinical excitement. Maute led translational research and biomarker strategy. When Gilead swooped in for $4.9 billion in 2020, he continued as a senior research scientist at Gilead before departing to co-found Pheast in 2021.
Context
The CD47-CD24 Connection
CD47 and CD24 are both "don't eat me" signals - proteins that cancer cells overexpress to evade macrophage killing. CD47 works by binding SIRPa on macrophages. CD24 works by binding Siglec-10. Both are innate immune checkpoints analogous to PD-1/PD-L1 in T cells. The key difference: CD24 expression is more restricted to tumors, which may translate into a better therapeutic window.
Maute's career arc from CD47 work at Forty Seven to CD24 at Pheast is not accidental - it reflects a deliberate focus on macrophage checkpoint biology as an underexploited frontier in cancer immunotherapy.
Company Building
$76M, 40 People, and a Bet on Macrophages
Pheast Therapeutics was co-founded in 2020 by Dr. Amira Barkal (principal scientific founder), along with Weissman and Ravi Majeti - both Stanford faculty - and Roy Maute, who came on as CEO. The company's Series A, announced in 2022, was $76 million led by ARCH Venture Partners and Catalio Capital Management, with Alexandria Venture Investments and R2 participating. That's a meaningful Series A for a company with a target - CD24 - that had been well-validated scientifically but not yet tested clinically.
The company now has approximately 40 employees and operates from Redwood City, California - roughly the same zip code as Gilead Sciences. Maute's former employer is practically a neighbor.
"Comfort is the enemy of scientific growth."
Roy Maute
In June 2025, the FDA granted Fast Track Designation to PHST001 for the treatment of ovarian cancer - a signal that the agency sees meaningful unmet need in the indication Pheast is pursuing. Platinum-resistant ovarian cancer, one of the combination cohorts in Phase 1b, is an area where response rates to standard of care remain low and new approaches are urgently needed.
PHST001 is an IgG4 antibody - a format chosen deliberately. IgG4 antibodies have lower effector function than IgG1, meaning the drug works primarily by blocking the CD24-Siglec10 interaction rather than by recruiting additional immune mechanisms. This design choice reduces the risk of cytokine release while still releasing the macrophage brake. The Phase 1a data presented at AACR 2026 showed early clinical activity and target engagement - meaning the antibody is getting to the tumor and doing what it is supposed to do.
Pipeline Expansion
PHST677: A New Target Goes Public
In May 2026, at the PEGS Boston Summit, Pheast made its first public disclosure of a second program: PHST677, a bispecific antibody-drug conjugate targeting CDH1 (cadherin) and Nectin-4. This was notable - CDH1 as an immune-regulatory ADC target had not previously been disclosed in the literature. The presentation represented Pheast expanding its modality toolkit beyond straight monoclonal antibodies into the ADC space, which has seen intense activity across the oncology drug development landscape.
Two programs, two different modalities, and a clear strategic logic: macrophage checkpoints plus tumor-targeted ADCs, both focused on solid tumors where T cell-based immunotherapy has limited traction.
The Details
Six Things Worth Knowing
01
His parents are an architect and an artist - neither scientist - yet he earned a PhD in genetics from Columbia University.
02
"Pheast" is a wordplay on phagocytosis - the cellular process by which macrophages engulf and digest targets. The name does exactly what a biotech name should do: tell you what the science is.
03
Maute trained under Irving Weissman at Stanford - who is also a scientific co-founder of Pheast Therapeutics. Mentor-to-co-founder, decades later.
04
He was present at two separate major biotech acquisitions: Ligand/Ab Initio (2019, $12M) and Gilead/Forty Seven (2020, $4.9B). Two for two before founding Pheast.
05
Pheast's Redwood City office sits in the same California zip code as Gilead Sciences - Maute's former employer from his Forty Seven days.
06
CD24 is expressed by cancer cells as a message to the immune system. PHST001 is Pheast's reply: an IgG4 antibody that quietly removes the "do not disturb" sign from the tumor.
Timeline
From Bench to Boardroom
UC Berkeley
B.A. in Molecular and Cell Biology - the foundation of a career in innate immunology and cancer biology.
Columbia University
Ph.D. in Genetics under Prof. Riccardo Dalla-Favera, studying genetic rearrangements in B-cell lymphoma.
Stanford University
Postdoctoral fellow in the laboratory of Dr. Irving Weissman, Institute for Stem Cell Biology and Regenerative Medicine - where the foundational CD47/CD24 biology was being developed.
2015
Co-founds Ab Initio Biotherapeutics with Kenneth Lin. Head of Biology. Focus: antigen technology for GPCRs and multi-transmembrane proteins.
2019
Ab Initio Biotherapeutics acquired by Ligand Pharmaceuticals for $12 million. Joins Forty Seven Inc. as Director of Translational Research.
2020
Forty Seven Inc. acquired by Gilead Sciences for $4.9 billion. Continues as Senior Research Scientist at Gilead, leading the Biomarkers Science team for magrolimab and GSI-189 programs.
2021
Co-founds Pheast Therapeutics as CEO and Chief Scientific Officer, alongside Amira Barkal, Irving Weissman, and Ravi Majeti.
2022
Pheast closes $76M Series A led by ARCH Venture Partners and Catalio Capital Management.
Jun 2025
FDA grants Fast Track Designation to PHST001 for treatment of ovarian cancer.
Mar 2026
First patient dosed in Phase 1b combination cohorts, evaluating PHST001 with chemotherapy in ovarian cancer.
Apr 2026
Initial Phase 1a clinical data presented at AACR 2026 - early clinical activity and target engagement confirmed for PHST001.
May 2026
Pheast discloses second program PHST677 (bispecific ADC, CDH1 x Nectin-4) at PEGS Boston Summit - first public disclosure of CDH1 as an ADC target.
Leadership
Trust Over Control
Roy Maute has given a multi-part series on The Biotech Startups Podcast that covers, in unusual detail, how he thinks about building companies and leading scientists. The through-line is a belief that the best scientific environments are high-autonomy ones - that giving scientists room to think produces better results than managing them to milestones.
He traces this view to his time with Irving Weissman, whose laboratory culture at Stanford is famously unstructured. Weissman gives postdocs and students the latitude to follow their curiosity. Maute absorbed this and carried it forward: at Pheast, he describes the culture as trust-based rather than control-based.
He is also candid about the harder parts of biotech leadership - navigating funding cycles, staying focused through volatility, and making resource decisions with incomplete information. His four-part podcast series addresses all of these directly, without the sanitized version most biotech executives prefer to offer.
The "get the info, take the shot" philosophy sounds almost too simple until you consider what it means in a clinical-stage biotech: you never have perfect information before you have to decide whether to dose the next patient cohort, pick the combination partner, or bet on a new mechanism. The willingness to act on incomplete data - deliberately and methodically - is what distinguishes operators from analysts in this industry.
Track Record
What He's Built
- Co-founded Ab Initio Biotherapeutics; sold to Ligand Pharmaceuticals in 2019 for $12M
- Led translational research and biomarker strategy at Forty Seven Inc. ahead of its $4.9B acquisition by Gilead
- Co-founded Pheast Therapeutics; raised $76M Series A from ARCH Venture Partners, Catalio Capital Management, Alexandria Venture Investments, and R2
- Secured FDA Fast Track Designation for PHST001 in ovarian cancer (June 2025)
- Advanced PHST001 into Phase 1b combination cohorts; first patient dosed March 2026
- Presented Phase 1a data at AACR 2026 showing early clinical activity and target engagement
- Disclosed second program PHST677 at PEGS Boston 2026 - CDH1 as a novel immune-regulatory ADC target
- Published peer-reviewed research on PD-1 variants, CD47-SIRPα therapeutics, macrophage checkpoint biology
