Daiichi Sankyo Presents Updated Phase 1 Data for U3-1402 in Patients with HER3-Expressing Metastatic Breast Cancer at 2018 San Antonio Breast Cancer Symposium (SABCS) - Seite 2

Updated safety results were also reported. With a median exposure to treatment of 7.6 months, U3-1402 showed a manageable safety profile. The most common adverse events (≥30 percent, any grade) included nausea (85.7 percent), thrombocytopenia (71.4 percent), decreased appetite (66.7 percent), neutropenia (64.3 percent), leukopenia (59.5 percent), vomiting (54.8 percent), AST increased (47.6 percent), ALT increased (45.2 percent), anemia (38.1 percent), stomatitis (35.7 percent) and diarrhea (31.0 percent). The most common adverse events Grade ≥3 (>10 percent of patients) were thrombocytopenia (35.7 percent), neutropenia (28.6 percent), leukopenia (21.4 percent), anemia (16.7 percent) and ALT increased (11.9 percent). Fourteen (14) patients (33.3 percent) experienced serious adverse events regardless of causality, and seven (7) patients (16.7 percent) experienced serious adverse events that were treatment-related. One (1) patient experienced an adverse event leading to treatment discontinuation (2.4 percent), and there were no adverse events leading to death.

"We are encouraged by these preliminary findings with U3-1402, particularly because there are no therapies specifically approved for HER3-expressing breast cancer," said Kouichi Akahane, PhD, MBA, Executive Officer, Head of Oncology Function, R&D Division, Daiichi Sankyo. "Additionally, these findings continue to build evidence that supports the portability of Daiichi Sankyo's proprietary DXd and linker ADC technology to other targets such as HER3."

About the Phase 1 Study
In this three-part, open-label global phase 1/2 study, U3-1402 is given as an intravenous infusion every three weeks. The first part of the study (dose escalation) assessed the safety, tolerability and maximum tolerated dose of U3-1402 in HER3-positive (defined as IHC [immunohistochemistry] 2+/3+) metastatic breast cancer patients who are refractory or intolerant to standard treatment or for whom no standard treatment is available. A maximum tolerated dose has not been reached. Based on preliminary results, dose levels of 4.8 mg/kg and 6.4 mg/kg are being further evaluated. The second part of the study (dose finding) is assessing the safety and efficacy of U3-1402 and determining the recommended phase 2 dose in HER3-positive metastatic breast cancer patients who have received six or fewer prior chemotherapy regimens. The third part of the study (phase 2) is assessing the safety and efficacy of the recommended dose of U3-1402 in HER3-positive metastatic breast cancer patients who have received six or fewer prior chemotherapy regimens. The study is currently enrolling patients in Japan and the U.S. For more information about this study, please visit ClinicalTrials.gov.