A meta-analysis of phase III trials evaluating the predictive value of HER2 and topoisomerase II alpha in early breast cancer patients treated with CMF or anthracycline-based adjuvant therapy.

Abstract

Abstract Abstract #705 Background: Retrospective studies have suggested that HER2 and topoisomerase II α (TOP2A) might predict sensitivity to anthracyclines (A)
 Methods: Four phase III trials comparing A with CMF in early breast cancer (EBC) patients (pts), and with available primary tumor samples, were identified. HER2 and TOP2A genes were evaluated locally by FISH (amplification if ratio ≥ 2). Data were centralized at the statistical office (IDDI, Belgium). On-site visits were performed to check data quality and laboratory procedures. HER2 and TOP2A local scores were validated by submitting randomly selected samples to a central lab (CL) (University of Tampere – Finland), for a 3 color FISH test (HER2, TOP2A, centromere 17, Abbott Labs, IL, USA). Estrogen (ER), progesterone (PgR) receptors, and grade (G) were evaluated locally (no score validation at the CL).
 Results: We present the results of the planned interim analysis on 1944 pts. Final results (± 3500 pts) will be presented when tumor sample collection for the UK trial is complete. HER2 local scores were validated at the CL in 137 cases (discordance: 8/137, 5.8%). TOP2A local scores were validated in 123 cases (discordance 38/123, 30.8%). Half of the TOP2A discordant cases were locally deleted-centrally normal or vice versa.
 
 A planned exploratory analysis evaluated the TOP2A predictivity in 4 biologically homogeneous groups: highly or moderately hormone sensitive, HER2+ and ER/PgR negative, triple negative (TN). This analysis did not enhance the TOP2A predictivity in any of the 4 groups. In the TN group (294 pts), the DFS HR was 0.77 (0.54-1.09), suggesting that benefit from A might not be confined to HER2+ pts.
 Conclusions: The interim analysis shows that HER2 and TOP2A have a clinically modest and a statistically borderline predictive value. In triple negative disease A may be superior to CMF.
 Acknowledgments: Abbott Laboratories, Belgian Federation Against Cancer, Cancer Research UK, Les Amis de l'Institut Bordet, Pfizer, Scottish BC trials group. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 705.