New immunotherapy for ovarian cancer receives FDA Fast Track status
A new treatment called PHST001 has just received Fast Track designation from the U.S. Food and Drug Administration (FDA). The Fast Track process is designed to accelerate development and review of promising new treatments for diseases like ovarian cancer, where there are limited effective treatment options available.
PHST001 is being developed by Pheast Therapeutics, a biotech company based in California, and aims to unleash the power of the immune system against hard-to-treat cancers including advanced ovarian cancer. This new drug is being tested as a single therapy for patients with advanced platinum-resistant ovarian cancer or in combination with chemotherapy in platinum-sensitive ovarian cancer, alongside other cancer types.
What is PHST001, and how does it work?
The therapy is designed to recognise and attach to a specific marker called CD24, which is often found on the surface of ovarian cancer cells. CD24 helps cancer hide from immune cells called macrophages, which play a role in clearing harmful cells from the body.
By blocking this signal, PHST001 makes it easier for the immune system to recognise and attack tumour cells. Early lab studies have shown that PHST001 encourages macrophages to “eat” cancer cells and slows tumour growth. This immune-boosting approach is also the inspiration behind the name Pheast Therapeutics, informed by the ability of macrophages to “feast” on cancer.
PHST001 is now in a phase 1 clinical trial in the US, where researchers are testing its safety and looking for early signs that it works in people with advanced, treatment-resistant solid cancers including ovarian cancer.
While it’s still early days, the Fast Track status for PHST001 signals promise for a new kind of treatment approach in ovarian cancer. The Ovarian Cancer Research Foundation is excited to see innovation in this space and believes this milestone highlights the importance of continued investment in research.
Key terms:
CD24: A protein found on the surface of many cancer cells, including ovarian cancer. It sends a “don’t eat me” signal to immune cells called macrophages, helping the cancer hide and avoid being destroyed.
Fast Track designation: A special status granted by the U.S. Food and Drug Administration (FDA) allowing drugs to be accelerated through the approvals process due to an unmet need.
Macrophages: A type of immune cell that helps protect the body by finding and destroying harmful cells. They can recognise, engulf (or “eat”), and break down cancer cells, and also signal other immune cells to join the fight.
Platinum-resistant ovarian cancer: A type of ovarian cancer that no longer responds to platinum-based chemotherapy drugs, such as carboplatin.
Platinum-sensitive ovarian cancer: Ovarian cancer that still responds well to platinum-based chemotherapy drugs like carboplatin, often shrinking or stabilising after treatment.
References
- A study of PHST001 in advanced solid tumors. ClinicalTrials.gov. Updated April 29, 2025. Accessed June 18, 2025. https://clinicaltrials.gov/study/NCT06840886.
- FDA Grants Fast Track Status to PHST001 for Ovarian Cancer Treatment. News Article. Cure Today. June 10, 2025. Accessed 12 June 2025. https://www.curetoday.com/view/fda-grants-fast-track-status-to-phst001-for-ovarian-cancer-treatment
- Kahn SA, Brewer R, Sampaio J, et al513 PHST001, a humanized anti-CD24 antibody, induces phagocytosis of human tumor cells in vitro and tumor clearance in vivoJournal for ImmunoTherapy of Cancer 2024;12:doi: 10.1136/jitc-2024-SITC2024.0513
- Pheast Therapeutics receives FDA fast track designation for PHST001 for the treatment of ovarian cancer. News release. Pheast Therapeutics. June 3, 2025. Accessed June 18, 2025.
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