Healx Announces First Patient Dosed in Phase 1/2 Trial to Evaluate the Effect of HLX-4310 on Metastatic Recurrence and Progression in Sarcomas with a Focus on Osteosarcoma

Cambridge, UK – 22 July, 2026 – Healx, an AI-powered, clinical-stage biotech company dedicated to rare diseases, today announced that the first patient has been dosed in its Phase 1/2 dose-escalation and dose-confirmation clinical trial to evaluate the safety and efficacy of HLX-4310, an investigational oral combination of a class I selective HDAC inhibitor and an mTOR inhibitor, in adolescents and adults with relapsed, refractory sarcoma, with a focus on osteosarcoma.

Osteosarcoma is a rare, aggressive bone cancer that most often affects children, adolescents, and young adults. Patients who develop metastatic disease face particularly poor outcomes, with a five-year survival rate of less than 30% ¹. The past 40 years have brought little improvement in survival outcomes for patients with osteosarcoma, underscoring a critical need for new approaches designed to reduce relapse risk and improve long-term outcomes.

HLX-4310 represents the first clinical proof point for Healx’s broader rare oncology strategy focused on preventing metastatic recurrence, which is responsible for the vast majority of cancer-related deaths. Healx is leveraging its AI-driven discovery capabilities together with rapid iterative laboratory testing and translational validation to advance this initial therapeutic combination and generate new drug combinations designed to explore a new approach to preventing metastatic recurrence in rare oncology settings.

The trial is being advanced in collaboration with the National Pediatric Cancer Foundation’s (NPCF) flagship research program, the Sunshine Project™.

Addressing an Unmet Need in Rare Oncology

“Metastatic osteosarcoma is so difficult to treat because patients can undergo intensive therapy, reach remission, and still relapse within months or within several years,” saidDavid Warshawsky, Ph.D., Global Head of Metastatic Prevention at Healx. “We believe that HLX-4310 provides a novel and differentiated approach focused on the unique biology hypothesized to drive cancer recurrence, and we are delighted to see it advance into trials.”

“I’m excited to see this study begin dosing patients and to evaluate a strategy that is explicitly focused on preventing metastatic recurrence,” said Amy Armstrong, M.D., Principal Investigator for the Phase 1/2 HLX-4310 trial. “This trial will evaluate the safety and tolerability of HLX-4310 and assess efficacy, including its potential to reduce cancer recurrence risk.”

Partnership with NPCF’s Sunshine Project™

“We are proud to support the advancement of HLX-4310 through the Sunshine Project™,” said David Frazer, President of the National Pediatric Cancer Foundation. “Our consortium brings together leading pediatric cancer centers to accelerate promising science into clinical studies. This trial reflects the shared commitment of the Sunshine Project™ and Healx to drive progress for children and young adults facing high-risk cancers like osteosarcoma.”

About HLX-4310
HLX-4310 is a combination approach built around the concept of preventing metastatic recurrence rather than focusing only on overt tumors. The scientific hypothesis behind this novel strategy is based on targeting biological programs that enable micro-metastatic tumors to survive and persist at distant sites and later re-emerge as deadly metastatic disease.

HLX-4310 combines two agents with complementary activity profiles:

• An investigational class I selective histone deacetylase (HDAC) inhibitor being evaluated for its epigenetic modulation of gene expression programs involved in tumor cell survival and in tumor-immune interactions; and
• An mTOR inhibitor, which targets a central pathway involved in cell growth, metabolism, and stress responses.

About Healx
Healx is the first AI-native rare disease pharma company, advancing breakthrough therapies from discovery through clinical development and commercial launch. With 95% of rare diseases still lacking an approved treatment, Healx’s mission is to use AI to change this.
Combining its proprietary Intelligent Rare Disease Engine and agentic platform with deep drug discovery expertise, the company is advancing a growing franchise of breakthrough medicines for patients in need.

Founded in Cambridge, UK, by Tim Guilliams, PhD, from the Chemistry Department at Cambridge University, and Founding Director of the Cambridge Rare Disease Network; and David Brown, PhD, co-inventor of Viagra and former Global Head of Drug Discovery at Roche, Healx has raised more than $100 million to date. For more information, visit https://healx.ai or follow Healx on LinkedIn.

About National Pediatric Cancer Foundation
The National Pediatric Cancer Foundation (founded in 1991) is a national nonprofit organization dedicated to funding research to eliminate childhood cancer. NPCF governs a unique, collaborative research consortium (the Sunshine Project™) consisting of physicians and scientists from over thirty of the top hospitals in the nation. We collaborate to idealize and aggregate the best scientific ideas and fund innovative research. The NPCF has received a perfect 100% score for financial health and transparency and is recognized as the top-rated cancer charity in the U.S. by Charity Navigator. For more information, visit NationalPCF.org.

About the Phase 1/2 HLX-4310 Trial
The Phase 1/2 open-label, cohort sequential dose-escalation and dose-confirmation trial is designed to evaluate the safety and efficacy of HLX-4310, an investigational oral combination of a class I selective HDAC inhibitor and an mTOR inhibitor, in adolescents and adults with relapsed, refractory sarcoma and osteosarcoma. Additional details, including study design, participating sites, and eligibility criteria, will be available at ClinicalTrials.gov once posted.

About Osteosarcoma
Osteosarcoma is an aggressive cancer of the bone and is the most common type of bone cancer in children and teens. Since metastatic recurrence has shared biological mechanisms in many other cancer types, therapies that show promise in osteosarcoma can be developed in parallel for many other cancer types, such as breast, kidney and melanoma. Despite successful control of primary osteosarcoma tumors and follow-up chemotherapy, metastasis continues to be the most common cause of mortality. The last 40 years have brought little improvement in survival outcomes for children with osteosarcoma, despite intensification of therapy. Metastatic osteosarcoma has a dismal 5-year survival rate of less than 30% ¹. Due to the lack of improved outcomes, new approaches to therapy are desperately needed. Furthermore, if targeted therapeutics are found to prevent metastasis in this cancer, a strong biological rationale would exist for the evaluation of such a therapy in other human cancers.

Footnote
¹ Sadykova LR, Ntekim AI, Muyangwa-Semenova M, Rutland CS, Jeyapalan JN, Blatt N, Rizvanov AA. Epidemiology and Risk Factors of Osteosarcoma. Cancers. 2022;14(2):360.https://doi.org/10.3390/cancers14020360

Media Contacts:

Healx	Myrta Barell
Myrta.Barell@Healx.ai
ICR Healthcare	Jessica Hodgson, Namrata Taak
Healx@icrhealthcare.com	+44 (0)20 3709 5700