Australian-based clinical-stage biopharmaceutical company Racura Oncology Limited (ASX:RAC) announced on Thursday that the first patient has been dosed with RC220 in HARNESS-1, a Phase 1a/b clinical trial evaluating RC220 in combination with osimertinib in patients with epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC).

The first patient received RC220 at 50 mg/m2 by intravenous infusion. No adverse events were observed.

HARNESS-1 is designed to test whether RC220, Racura's proprietary formulation of (E,E)-bisantrene, can be safely combined with osimertinib (AstraZeneca's Tagrisso), a third-generation EGFR tyrosine kinase inhibitor (TKI) and standard-of-care therapy for EGFR-mutant NSCLC to delay or prevent TKI treatment resistance.

RC220 is being developed to target the non-canonical G-quadruplex DNA and RNA structures enriched in oncogenic regulatory regions, including promoters, untranslated regions and highly transcribed loci. Stabilisation of these structures can disrupt transcriptional and post-transcriptional control networks that sustain malignant proliferation, including silencing the c-MYC-regulated growth and survival pathways.

HARNESS-1 will evaluate the safety and tolerability of RC220 with continued osimertinib-mediated EGFR suppression, while generating pharmacokinetic, pharmacodynamic, molecular response and translational biomarker data.

The multi-centre Phase 1a/b clinical study in patients with EGFR-mutant NSCLC receiving osimertinib includes an observational screening stage using ctDNA to help identify eligible patients and characterise tumour molecular status before treatment.