BIBW 2992, a Novel Irreversible EGFR/HER1 and HER2 Tyrosine Kinase Inhibitor for the Treatment of Patients with HER2-Negative Metastatic Breast Cancer after Failure of No More Than Two Prior Chemotherapies.

Abstract

Abstract Background: BIBW 2992 (Tovok™*) is a novel, oral, irreversible inhibitor of the epidermal growth factor receptor (EGFR)/ human epidermal growth factor receptor (HER)1 and HER2 inhibitor. It has promising preclinical activity in HER2-negative MDA-MB-453 and triple-negative SUM 149-PT cell lines, and showed clinical Phase I activity. First results of a Phase II study of BIBW 2992 in patients with HER2-negative, hormone receptor (HR)-positive or triple-negative breast cancer who have progressed following no more than two prior lines of chemotherapy are presented. The trial was conducted as a multi-institutional, open-label study in Germany and Belgium.Methods: Eligible patients had stage IIIB or IV HER2-negative metastatic breast cancer (MBC), with progression following no more than two prior lines of chemotherapy. No prior EGFR-targeted therapy was allowed and measurable disease, Eastern Cooperative Oncology Group performance status of 0–2 and an adequate organ function were required. Patients received 50 mg BIBW 2992 once-daily until disease progression. Tumor assessment was performed every other treatment course (one course is 28 days). The primary endpoint was objective response rate by Response Evaluation Criteria In Solid Tumors criteria in patients with HR-positive and triple-negative MBC. The latter was changed to clinical benefit, i.e. objective response (OR) or stable disease (SD) on treatment for at least four cycles for patients with triple-negative disease. Safety data were collected and analyses are still ongoing.Results: A total of 56 patients were enrolled with 50 actually starting treatment on the trial, including 29 patients with triple-negative and 21 patients with HER2-negative and HR-positive MBC. No ORs were observed in either cohort. Three patients in the triple-negative cohort had SD for at least 4 treatment cycles, one of them for 12 cycles. The most frequently observed side-effects at snapshot date (on 49 patients) are diarrhea (Common Terminology Criteria for Adverse Events Grade 3 in 18 patients [36.7%]) and Grade 3 skin rash in two patients [4.1%]). These were managed by symptomatic treatments and dose reductions.Conclusion: Long-term oral administration of BIBW 2992 was safe in HER2-negative MBC patients. Side effects mainly affected the skin and gastrointestinal tract, and were manageable. Clinical benefit was achieved in a fraction of triple-negative MBC patients.*Trade name not FDA approved. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5062.