Daiichi reports Phase I responses for U3-1402 in HER3-positive breast cancer

Daiichi Sankyo Co. Ltd. (Tokyo:4568) said U3-1402 led to a confirmed overall response rate (ORR) of 47% and a disease control rate of 94% in 32 evaluable patients with HER3-positive metastatic breast cancer who are refractory or intolerant to standard treatment or for whom no standard treatment is available. The preliminary data were from patients who received 1.6-8 mg/kg doses of IV U3-1402 every three weeks in the dose-escalation Phase I portion of Phase I/II trial.

The maximum tolerated dose (MTD) was not reached. The most common adverse events included nausea, thrombocytopenia, reduced appetite, neutropenia, reduced white blood cell count, vomiting, elevated alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, anemia, stomatitis and diarrhea. Dose-limiting toxicities (DLTs) included grade four thrombocytopenia, grade three elevated ALT and grade two elevated AST...