SAN ANTONIOIn first-line hormonal therapy for advanced breast cancer,
elevated levels of HER-2/neu predict lower response rates and shorter time
to disease progression, compared with normal HER-2 levels, according to a
large international study.
Allan Lipton, MD, professor of medicine and oncology, Pennsylvania State
University, Hershey, presented the findings at the 24th Annual San Antonio
Breast Cancer Symposium (abstract 6).
The study was part of a phase III study comparing the aromatase inhibitor
letrozole (Femara) with tamoxifen (Nolvadex) as first-line therapy in 907
postmenopausal women with advanced breast cancer. That study found a
significant benefit for letrozole.
The companion study reported by Dr. Lipton used the Bayer Immuno 1
automated assay to determine HER-2 levels in pretreatment serum samples from
566 of the 907 participants.
The objective response rate according to HER-2 status, irrespective of
treatment, was significantly higher in HER-2-negative than in HER-2-positive
patients. Overall response rate was 31% vs 15%; clinical benefit rate
(complete and partial responses plus stable disease for 24 weeks) was 50% vs
29%; and time to progression was 9.4 vs 5.6 months for HER-2-negative vs
positive patients, respectively. These differences were all significant (P
< .0001), Dr. Lipton said.
Multivariate analysis revealed elevated serum HER-2 as a negative
predictor of overall response rate, clinical benefit rate, time to
progression, and time to treatment failure, he said.
When HER-2-positive patients were analyzed according to treatment arm,
patients receiving letrozole had numerically higher responses, although the
differences were not significant. For letrozole vs tamoxifen, respectively,
the objective response rate was 17% vs 13%; clinical benefit rate 32% vs
26%; and median time to progression 6.1 months vs 3.3 months.