Tykerb and tamoxifen – pro
Tykerb/Xeloda is now FDA approved. TYKERB is indicated in combination with Xeloda® (capecitabine) for the treatment of patients with advanced or metastatic breast cancer whose tumors overexpress HER2 and who have received prior therapy including an anthracycline, a taxane, and Herceptin® (trastuzumab).
Another way to give Tykerb is with Femara. The addition of lapatinib to letrozole is well tolerated and leads to a significantly greater PFS time, ORR, and CBR than with letrozole alone in women with MBC who coexpress HR and HER-2. On January 29 2010, Tykerb had received FDA approval for use as a first-line breast cancer therapy in combination with the letrozole for the treatment of hormone-receptor positive metastatic breast cancer, in patients whose tumours overexpress the HER2/ErbB2 receptor and for whom hormonal therapy is indicated.
There is not much information on combining lapatinib wit h amoxifen.1 In long-term (treatment over 77 days) in vivo studies with human breast cancer xenografts in athymic mice, lapatinib produces a significant and sustained reduction in xenograft volume versus untreated controls. In murine mammary xenografts of estrogen receptor (ER)-positive, tamoxifen-resistant breast tumors, lapatinib is also able to restore tamoxifen sensitivity. The combination of lapatinib and tamoxifen leads to a more rapid and profound antiproliferative effect than with either of the drugs on their own 4.
There was a study of laptinib and tamoxifen but its was never published “.clinicaltrials.gov says that “The main limitation in this study was poor enrollment. The small number of cases makes the interpretation of results difficult.”
1. Beverly Moy and Paul E. Gos, sLapatinib: Current Status and Future Directions in Breast Cancer. The Oncologist November 2006 vol. 11 no. 10 1047-1057
2. Angelo Di Leo, Henry L. Gomez, Zeba Aziz, Zanete Zvirbule, Jose Bines, Michael C. Arbushites, Stephanie F. Guerrera, Maria Koehler, Cristina Oliva, Steven H. Stein, Lisa S. Williams, Judy Dering, Richard S. Finn, Michael F.Phase III, Double-Blind, Randomized Study Comparing Lapatinib Plus Paclitaxel With Placebo Plus Paclitaxel As First-Line Treatment for Metastatic Breast Cancer Journal of Clinical Oncology, Vol 26, No 34 (December 1), 2008: pp. 5544-5552
3. Schwartzberg, Lee S. , Franco, Sandra X. , Florance, Allison , O’Rourke, Lisa , Maltzman, Julie , Johnston, Stephen Lapatinib plus Letrozole as First-Line Therapy for HER-2+ Hormone Receptor-Positive Metastatic Breast Cancer
Oncologist 2010 15: 122-129;
4. Fumoleau P et al, A phase I pharmacokinetics study of lapatinib and tamoxifen in metastatic breast cancer (EORTC 10053 Lapatam study).Breast. 2014 Oct;23(5):663-9.
5. https://clinicaltrials.gov/ct2/show/results/NCT00118157?term=lapatinib+tamoxifen&cond=Breast+Cancer&cntry1=NA%3AUS&rank=1, 2017
6. NCCN, Breast Cancer 2017