396 - Efficacy of trastuzumab containing retreatment after progression on lapatinib therapy in Japanese patients with HER2-positive metastatic breast cancer

Date 28 September 2012
Event ESMO Congress 2012
Session Publication Only
Topics Anti-Cancer Agents & Biologic Therapy
Breast Cancer, Metastatic
Presenter Masaya Hattori
Authors M. Hattori1, H. Iwata1, T. Fujita1, M. Sawaki1, N. Kondo1, A. Horio1, K. Muro2
  • 1Breast Oncology, Aichi Cancer Center, 464-8681 - Nagoya/JP
  • 2Clinical Oncology, Aichi Cancer Center Hospital, JP-464-8681 - Nagoya/JP

Abstract

Background

Lapatinib has been approved for HER2 positive metastatic breast cancer patients with refractory to trastuzumab (T) therapy in Japan. Currently, it has been proposed that lapatinib can resensitize trastuzumab–mediated antibody-dependent cellular cytotoxicity (ADCC). Recent clinical data suggest the efficacy of T containing retreatment after progression on lapatinib therapy in patients with HER2-positive metastatic breast cancer. Here, we present a retrospective review of data from 25 patients who received T containing retreatment after progression on lapatinib therapy.

Methods

We reviewed the data of 50 patients with HER2-positive metastatic breast cancer who received lapatinib therapy in our institution from August 2004 through March 2012. Of these, 25 patients received T containing retreatment after progression on lapatinib therapy. We retrospectively assessed the clinical benefit of this treatment regimen in these patients.

Results

Luminal-HER2 and HER2-enriched subtypes were identified in 13 (52%) and 12 (48%) of these cases, respectively. The median duration of lapatinib therapy was 5.9 months (range, 1.8-20.2 months). The median number of preceding regimens was 3 (range, 2-8) in metastatic setting. Seven patients (31.8%) responded to T containing retreatment; all 7 patients achieved PR and none achieved CR. There were no significant differences in subtype, number of preceding regimens and brain metastases; however, responders achieved higher clinical response from lapatinib therapy than non-responders (response rate of 84% versus 13%, respectively). The median time to progression of T containing retreatment was 3.0 months (95% CI, 2.4-3.5 months). Among seven responders to T containing retreatment, one patient responded to refractory T containing regimen. All patients tolerated T containing retreatment with no occurrence of Grade 3/4 toxicities.

Conclusion

T containing retreatment could be a favorable treatment regimen which can achieve clinical response in patients with HER2-positive metastatic breast cancer who experienced progression on prior trastuzumab and following lapatinib therapy.

Disclosure

All authors have declared no conflicts of interest.