Daiichi Sankyo has started dosing patients in a Phase II clinical trial of patritumab deruxtecan (U3-1402) for the treatment of advanced or metastatic colorectal cancer.

Patritumab deruxtecan is a HER3 directed DXd antibody drug conjugate (ADC) that is meant to target and deliver chemotherapy to cancer cells expressing HER3 on the surface of tumour cells.

The multi-centre, open-label, two-cohort, two-part, Phase II trial will assess the safety and efficacy of the drug candidate in patients who are resistant, refractory or intolerant to at least two previous lines of systemic therapy.

Previous therapies must include chemotherapy, an anti-EGFR agent if clinically indicated, and an anti-VEGF agent, except when contraindicated.

Daiichi Sankyo Oncology R&D oncology development global head Gilles Gallant said: “The prognosis of patients with advanced or metastatic colorectal cancer remains poor, and there is a need to develop new treatment strategies, including targeting HER3.

“In this study, we are exploring whether the targeted delivery of cytotoxic chemotherapy with patritumab deruxtecan to cancer cells with varying levels of HER3 expression may be a potential treatment option for previously treated advanced or metastatic colorectal cancer.”

The Phase II trial’s first part will enrol two cohorts of patients with different levels of HER3 expression. One cohort will involve patients with HER3 high expression, while the second cohort will include those with HER3 low/HER3 negative expression.

Based on preliminary data, more participants may be recruited for a second part of the trial to evaluate patritumab deruxtecan in patients with HER3 high expression or both HER3 high and low expression.

The trial may enrol up to about 80 patients across the US, Europe and Japan.

The primary objective is the anti-tumour activity of the drug and will assess the objective response rate (ORR).

Secondary objectives include the anti-tumour activity based on the duration of response, investigator-assessed ORR, disease control rate, time to response, progression-free survival, overall survival, and safety and tolerability.

Last month, Daiichi Sankyo partnered with AstraZeneca to assess patritumab deruxtecan in combination with Tagrisso for advanced or metastatic non-small cell lung cancer (NSCLC).