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Newcastle, UK, 20 October 2025: Iksuda Therapeutics (Iksuda), the developer of class leading, antibody drug conjugates (ADCs), today announces the presentation of new data from its Phase 1 study of IKS014, a human epidermal growth factor receptor 2 (HER2)-directed ADC, in patients with advanced HER2+ solid tumours. The data was presented at the European Society for Medical Oncology (ESMO) Congress in Berlin, Germany.

The Phase 1 study (NCT05872295) is a non-randomised, open-label, multicentre trial evaluating IKS014 in patients with locally advanced or metastatic solid tumours that express HER2. Part I, the dose escalation portion, is being conducted in sites in Australia and is designed to establish the maximum tolerated dose (MTD) and/or the recommended Phase 2 dose (RP2D) for IKS014 and provide initial safety, tolerability, efficacy, pharmacokinetic, pharmacodynamic and immunogenicity characteristics. Part II dose expansion studies will assess IKS014 in HER2+ breast cancer in patients who have previously received Enhertu, HER2-low breast cancer, HER2+-gastric/ GEJ cancers and other HER2+ tumours and mutated HER2-NSCLC. Dose expansion studies will be conducted in sites in the US, Australia, New Zealand and Singapore.

At the data cut-off date (31 July 2025), a total of 62 patients were enrolled in the study, with 55 patients evaluable for efficacy as measured by Response Evaluation Criteria in Solid Tumours (RECIST 1.1). Anti-tumour activity was observed across all dose levels, with partial responses and unconfirmed partial responses observed in various tumour indications including breast, lung, oesophageal, ovarian, gastric, gallbladder and gastroesophageal junction cancers and in both HER2+ and HER2-low tumours.

Amongst 11 participants with breast cancer treated at doses >90mg/m2, seven responses were seen (objective response rate (ORR) 64%), including partial responses in all four patients with HER2+ disease. Three of these patients had previously received Enhertu. Additionally, amongst 10 patients with pre-treated, HER2+ oesophageal cancer that were enrolled across all dose levels, five achieved a response, including complete regression in one patient with non-measurable disease.

Treatment with IKS014 was generally well-tolerated at doses up to 120mg/m2 (~3.2 mg/kg), with anticipated adverse events including ocular surface AEs, pneumonitis and hypokalaemia, all of which were predominately Grade 1 and Grade 2. 

An MTD was not reached per the study protocol. Dose selection for further evaluation in the expansion cohorts will be based on preliminary activity, safety, pharmacokinetic, pharmacodynamic profile and overall benefit-risk assessment from the dose escalation. The Phase 1 trial is expected to complete in H2 2026.

This data follows positive data from Phase 1 clinical trials through Fosun Pharma, which is now progressing FS-1502 (IKS014) through Phase 3 trials in China. [1]

Dr. Dave Simpson, Chief Executive Officer, Iksuda Therapeutics, commented: “We are hugely encouraged by these data, which illustrates the potential of IKS014 to improve outcomes and address the clinical unmet need across various HER-2 positive cancers, including treatment of those patients which are refractory to prior therapy options.”

[1] Li, Q., Cheng, Y., Tong, Z. et al. HER2-targeting antibody drug conjugate FS-1502 in HER2-expressing metastatic breast cancer: a phase 1a/1b trial. Nat Commun 15, 5158 (2024) https://doi.org/10.1038/s41467-024-48798-w