The combination of the HER2 antibody trastuzumab, the EGFR tyrosine kinase inhibitor gefitinib, and docetaxel as first-line therapy in patients with HER2 overexpressing stage IV breast carcinoma

Abstract

1057 Background: Interference with both HER2 and epidermal growth factor (EGFR) dependent pathways may improve therapeutic efficacy of docetaxel (doc) in pts with HER2 overexpressing (+) BC. Methods: Patients (pts) without prior chemotherapy (Rx) exposure for stage IV HER-2 + BC were enrolled. Prior hormonal or adjuvant Rx inclusive of taxane or trastuzumab (tras) were allowed. A left ventricular ejection fraction of > 45% and ECOG performance status of ≥ 2 were required. Pts were to receive doc 75 m2, tras every 3 weeks, and gefitinib (gef) 250 mg daily. BC samples from 12 pts were analyzed by FISH for HER2 and EGFR amplification (amp), and topoisomerase II (topo II) amp or loss. IHC was to be performed to examine p-Src, p-STAT3, Ki67 and survivin expression. Results: The median age was 49 (range, 34–67) and ECOG performance status 0.5 (0–1). The first 9 patients received gef 250 mg daily; 2 pts received dox 75 mg/m2 and developed grade 3 febrile neutropenia (neu), hence, additional pts received doc at 60 mg/m2: 3 more episodes of grade 3 neu were seen. Gef was held due to grade 3 dermatitis (2 pts) and diarrhea (2 pts). Pts received a median of 6 cycles (3–10). Gef schedule then was changed, and was prescribed on days 2–14, only. Three of the next 9 pts experienced grades 3 or 4 neu, and we observed 3 cases of grade 3 gastrointestinal toxicities; pts were able to receive 11 + (range; 5–25+) cycles on this schedule (p<0.04). There were 4 complete (CR)and 6 partial R (23 % CR, 59 % overall R), and 3 pts had stable disease (SD; all R and SD confirmed); 3 pts progressed at 4, 4, and 5 mos, 1 pt was inevaluable. The median time to progression is 12 + mos. Samples from 3 pts revealed topo II amplification and one pt sample showed loss of one topo II allele; none were amplified for EGFR. Outcome will be correlated with IHC defined signal trasduction status and proliferation rates. Conclusions: The combination of doc, tras, and short course of gef is feasible, with encouraging R and SD rates and time to progression. Further exploration of simultaneous blockage of multiple signal transduction pathways is indicated in combination with chemoRx. Supported by NCI CA33572 and by a grant from AstraZeneca. No significant financial relationships to disclose.