(Alliance News) - Daiichi Sankyo Co Ltd on Friday said updated results from a phase 1 trial showed datopotamab deruxtecan continued to show promising responses in patients with breast cancer.

The companies said that datopotamab deruxtecan in combination with Imfinzi demonstrated an overall response rate of 74% in patients with previously untreated, unresectable, locally advanced or metastatic triple negative breast cancer.

Dato-DXd is a specifically engineered antibody drug conjugate being jointly developed by the Tokyo-based pharmaceutical company and AstraZeneca PLC.

Daiichi said the trial with Cambridge, England-based pharmaceutical company showed Dato-DXd continued to demonstrate encouraging responses in patients with heavily pretreated metastatic triple negative breast cancer.

In the study of 44 patients, Dato-DXd demonstrated an objective response rate of 32% including one complete response, 13 partial responses and 18 cases of stable disease, as assessed by a blinded independent central review.

In a subgroup of 27 patients who had not previously been treated with topoisomerase I inhibitor-based antibody drug conjugates, the objective response rate was 44% including one complete response, 11 partial responses and 10 cases of standard disease.

The median duration of response was 16.8 months across patient groups.

"The median duration of response of nearly 17 months seen in the trial in these

patients reinforces the potential of datopotamab deruxtecan to treat this persistent disease,” said Cristian Massacesi, chief medical officer and oncology chief development officer at AstraZeneca.

"These results, along with the promising clinical response in combination with durvalumab seen in the BEGONIA trial, underscore the potential role of this TROP2 directed antibody drug conjugate for patients with triple negative breast cancer as both a monotherapy and in combinations."

Approximately 15% of breast cancers are considered triple negative and are associated with higher disease recurrence and more severe prognosis than other subtypes. It is estimated that only 12% of

patients with metastatic TNBC survive five years after diagnosis, while median overall survival is between 12 to 18 months.

Shares in Daiichi closed down 0.3% to JPY4,405.00 in Tokyo on Friday, while shares in AstraZeneca were up 0.5% to 11,374.00 pence in London on Friday afternoon.

By Greg Rosenvinge, Alliance News reporter

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