Healx, the Cambridge, UK-based AI-native rare-disease biotech, has dosed the first patient in a Phase 1/2 dose-escalation and dose-confirmation clinical trial of HLX-4310 — an investigational oral combination of a class I selective HDAC inhibitor (domatinostat) and the mTOR inhibitor sirolimus — in adolescents and adults with relapsed, refractory sarcoma, focused on osteosarcoma. The July 22, 2026 milestone is Healx's first clinical proof point for a broader rare-oncology strategy built around preventing metastatic recurrence, and it is being run with the National Pediatric Cancer Foundation's flagship Sunshine Project consortium.
The Unmet Need Behind The Trial
Osteosarcoma is the most common bone cancer in children and teenagers, and the past 40 years have brought virtually no improvement in survival for metastatic disease — the five-year survival rate for patients whose sarcoma recurs remains under 30%. HLX-4310's design targets the biology that lets micro-metastatic tumor cells survive at distant sites and re-emerge months or years after remission. Rather than shrinking overt tumors, the combination aims to disrupt the epigenetic and metabolic programs that maintain that hidden reservoir.
An AI-Native Discovery Approach Reaches The Clinic
Healx used its Intelligent Rare Disease Engine and agentic AI platform to identify the domatinostat-plus-sirolimus pairing, then ran rapid iterative lab testing and translational validation before advancing the combination into human dosing. "We believe HLX-4310 provides a novel and differentiated approach focused on the unique biology hypothesized to drive cancer recurrence," said David Warshawsky, Healx's Global Head of Metastatic Prevention. The trial's principal investigator, Dr. Amy Armstrong, said the study will "evaluate the safety and tolerability of HLX-4310 and assess efficacy, including its potential to reduce cancer recurrence risk."
The Sunshine Project Partnership
The trial is running through the National Pediatric Cancer Foundation's Sunshine Project — a research consortium spanning more than 30 leading U.S. pediatric hospitals. "Our consortium brings together leading pediatric cancer centers to accelerate promising science into clinical studies," said NPCF President David Frazer. "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."
Healx's Wider AI Oncology Push
HLX-4310 sits alongside HLX-1502, Healx's Phase 2 candidate for Neurofibromatosis Type 1 that dosed its first patient in 2025. Together they mark the transition of Healx from a rare-disease repurposing platform into a clinical-stage rare oncology company — one of a small set of AI-native biotechs whose in-silico designs are now generating human dose-escalation data. The company has raised more than $100 million to date and continues to expand into oncology use cases alongside real-time AI platforms in the operating room and newly FDA-cleared surgical robotics. Additional trial sites and eligibility criteria will be posted to ClinicalTrials.gov as they open.
Reporting based on coverage from BioSpace, GlobeNewswire, Healx and the National Pediatric Cancer Foundation.