BCIRG 006: AC vs Taxane Survival Benefit Comparable

SAN ANTONIO–A second interimefficacy analysis of BCIRG 006 indicatessimilar survival benefit but significantlyless toxicity with a regimen oftrastuzumab (Herceptin) plus docetaxel(Taxotere), compared with trastuzumabplus doxorubicin (abstract 52). DennisJ. Slamon, MD, PhD, discussed the findings.The international study randomized3,222 HER2-positive women, withor without lymph node involvement(high-risk node-negative), to three treatmentarms: The control group (A)received 4 cycles of doxorubicin andcyclophosphamide (AC) followed by 4cycles of docetaxel (T). Group B receivedthe group A regimen, plus trastuzumab(AC > TH). Group C received 6 cycles ofdocetaxel with carboplatin andtrastuzumab (TCH). The three groupswere well balanced for known cardiovascularrisk factors. One-third of thewomen had 4 or more positive nodes.

The current analysis, with a medianfollow-up of 3 years, found bothtrastuzumab-containing groups weresignificantly superior to the control groupin terms of reduced mortality and improved disease-free survival (DFS). However,the efficacy differences between theanthracycline- vs taxane-containing experimentalregimens were not statisticallysignificant, with a 6% DFS benefitfor AC > TH and a 5% benefit for TCHvs AC > T. Cardiac and leukemia adverseevents were higher in patients on theanthracycline-containing regimens (seeTable 1).

Dr. Slamon said the latest BCIRG 006efficacy analysis shows that "the differencein the number of DFS events andbreast cancer deaths in favor of AC > TH[over TCH], neither of which are statisticallysignificant, is now exceeded bythe number of critical adverse events" inpatients who received the anthracycline,with sustained loss of LVEF (> 10% decline)in 18% of patients on the AC > THarm (vs 8.6% on the TCH arm, P < .0001). The results, he said, warrant carefulconsideration of the future role ofanthracyclines in adjuvant treatment ofbreast cancer.