Akeso’s HER3 ADC AK138D1 in combination with Ivonescimab phase 1/2 Breast cancer trial enrolls first patient

CAR-T Digest - August 2020

Weekly Digest - June 2026

15 June 2026: Akeso’s HER3 ADC AK138D1 in combination with Ivonescimab phase 1/2 Breast cancer trial enrolls first patient

Akeso has announced the enrollment of the first patient in the phase 1/2 AK138D1-202 study evaluating its next-generation HER3-targeted antibody-drug conjugate AK138D1 as monotherapy or in combination with Ivonescimab for advanced breast cancer, advancing the company’s “IO2.0 + ADC2.0” strategy in one of the largest oncology markets
This trial is designed to evaluate AK138D1 across multiple treatment lines in patients with HR+/HER2− and Triple-negative breast cancer, including both treatment-naive and heavily pretreated populations, addressing substantial unmet needs across major breast cancer subtypes
The study builds on encouraging early clinical data from China and Australia, where AK138D1 demonstrated robust anti-tumor activity and a favorable safety profile, including low hematologic toxicity and no reported interstitial lung disease, supporting its potential to overcome limitations associated with earlier HER3-targeted ADCs
AK138D1 is a HER3-directed ADC comprising a fully humanized anti-HER3 antibody linked to a DXd topoisomerase I inhibitor payload via a cleavable linker, and is specifically engineered to reduce uptake in normal tissues, minimize off-target toxicity, and improve tumor penetration by overcoming the binding-site barrier commonly observed with conventional ADCs
Strategically, the first-patient dosing strengthens Akeso’s ambition to establish leadership in next-generation ADC and bispecific antibody combinations, while positioning AK138D1 as a differentiated HER3-targeted asset that could complement ivonescimab and further validate the company’s broader IO2.0 + ADC2.0 platform strategy in breast cancer and other solid tumors