AstraZeneca, Daiichi Sankyo's drug shows promise in heavily pretreated breast cancer patients in trial
Roland Magnusson

AstraZeneca (NASDAQ:AZN) and Daiichi Sankyo (OTCPK:DSKYF) (OTCPK:DSNKY) said on Thursday that their medicine datopotamab deruxtecan (Dato-DXd) showed durable efficacy in patients with a type of breast cancer in an early stage study.
The two-part, phase 1 trial, dubbed TROPION-PanTumor01, is evaluating datopotamab deruxtecan in patients with advanced solid tumors which have relapsed or are refractory to standard treatment or for which no standard treatment is available. The dose expansion part is enrolling different groups with several types of cancer.
The companies said the drug showed encouraging and durable efficacy in patients with heavily pretreated hormone receptor (HR)-positive, HER2-low (immunohistochemistry [IHC] 1+ or IHC 2+/in-situ hybridisation (ISH) negative) or HER2-negative (IHC 0) unresectable or metastatic breast cancer.
In this group (n=41), Dato-DXd showed an objective response rate (ORR) of 27%. All responses were partial (n=11) and 56% of patients achieved stable disease (n=23), the companies added.
The disease control rate (DCR) was 85% and median progression-free survival (PFS) was 8.3 months.
PFS is the length of time during/after treatment a patient lives with the disease without it getting worse.
In addition, the companies said that with median follow-up of 13.7 months, the median duration of response (DoR) and the median overall survival (OS) had not been reached with 59% of patients alive for more than one year.
One case of Grade 3 interstitial lung disease was adjudicated as treatment-related, the companies added.
The most common Grade 3 or higher treatment-emergent adverse events (TEAEs) were decreased lymphocyte count (15%), sore mouth (10%), anemia (7%), dyspnoea (difficulty in breathing) (2%).
The companies noted that serious TEAEs were seen in six patients, including one death due to dyspnoea which was not considered treatment-related.
"These promising results with datopotamab deruxtecan in such a heavily pretreated patient population support our strong belief that this TROP2-directed antibody drug conjugate has the potential to improve outcomes for patients with HR-positive, HER2-low or negative breast cancer in this, and possibly earlier settings," said Cristian Massacesi, chief medical officer and oncology chief development officer, AstraZeneca.