New First-line Therapy Now Available For Treatment Of Advanced Hormone Receptor Positive, HER2+ Breast Cancer
TykerbTM (lapatinib ditosylate) has received Health Canada approval for use in combination with letrozole (an aromatase inhibitor) for the treatment of post-menopausal women with hormone receptor-positive (HR+) metastatic breast cancer, whose tumours overexpress the HER2 (ErbB2) receptor, and who are suitable for endocrine therapy.
Approval was based on progression-free survival data from a double blind, placebo controlled study (EGF30008) that randomized 1,286 post-menopausal women with HR+ locally advanced or metastatic breast cancer to treatment with lapatinib plus letrozole or to letrozole alone. Progression free survival of women with HR+HER2+ tumors (n=219) treated with Tykerb™ plus letrozole was 35.4 weeks (95%CI: 24.1, 39.4) compared to 13.0 weeks (95% CI: 12.0, 23.7) for women treated with letrozole alone.
The combination of Tykerb™ and letrozole is the first Health Canada approved regimen for postmenopausal women with this type of aggressive breast cancer. The most common adverse events during therapy with Tykerb™ plus letrozole were diarrhea, rash, nausea and fatigue. The safety profile of Tykerb™ was consistent with previously reported results from trials of Tykerb™ in the advanced or metastatic breast cancer population.
TykerbTM is also indicated in combination with an oral chemotherapy – capecitabine – for the treatment of patients with advanced or metastatic breast cancer whose tumours overexpress HER2 (ErbB2) and who have progressed following prior therapies including taxanes, anthracyclines and trastuzumab (Herceptin®).
Letrozole, an aromatase inhibitor (AI), is a recognized therapy for the treatment of HR+ breast cancer. Approximately 70 per cent of all breast cancer cases are HR+[1] and only a third of all HR+ tumours respond to first-line treatment with AIs as a monotherapy. Furthermore, tumours that initially respond to AIs can become resistant, leading to disease progression and ultimately, patient death.[2]
“We’re pleased to see Tykerb and letrozole offered in combination as a first-line oral therapy for women who are HR+ and ErbB2 positive,” said Dr. Kathleen Pritchard, Senior Scientist at Sunnybrook Odette Cancer Centre, and Professor of Medicine at the University of Toronto. “Tykerb’s new indication provides physicians and clinicians with an option for their patients where previously there was none – it’s a step in the right direction.”
About Breast Cancer in Canada
- In 2010, an estimated 23,200 Canadian women will be diagnosed with breast cancer.[3]
- For Canadian women, breast cancer is the second leading cause of cancer mortality.[4]
- Breast cancer is the most common cancer and cause of cancer death in women aged 20 – 59, accounting for 37 per cent of new cases and 22 per cent of deaths.[5]
- One in nine women is expected to develop breast cancer during her lifetime. One in 28 will die of it.[6]
About HER2 Positive Breast Cancer
HER2 (otherwise known as ErbB2) positive breast cancer is an aggressive form of cancer that hits women in their prime. Approximately 20 per cent of women with breast cancer overexpress the HER2 (ErbB2) protein.[7] Since it is a particularly aggressive form of cancer, women with HER2 (ErbB2) positive breast cancer are at a greater risk of disease progression and death compared to women with breast cancer tumors that do not overexpress HER2 (ErbB2).[8] The five-year relative survival rate is significantly lower among women with a more advanced stage (stage III or IV) of cancer at diagnosis at 59% and 26% respectively.[9]
References
[1] Bedard PE, Freedman OC, Howell A, et al. Overcoming endocrine resistance in breast cancer – are signal transduction inhibitors the answer. Breast Cancer Res Treat. 2008;108:307-317.
[2] Prat A and Baselga J. The role of hormonal therapy in the management of hormonal-receptor-positive breast cancer with co-expression of HER2. Nature Clinical Practice Oncology. 2008;5:531-542.
[3] Canadian Cancer Society’s Steering Committee: Canadian Cancer Statistics 2010. Toronto: Canadian Cancer Society, 2010.
[4] Ibid.
[5] Ibid.
[6] Ibid.
[7] Ross JS, Slodkowska EA, Symmans WF, et al. The HER-2 receptor and breast cancer : ten years of targeted anti-HER-2 therapy and personalized medicine. The Oncologist 2009;14:320-368.
[8] Slamon DJ, Clark GM, Wong SG, Levin WJ, Ullrich A, McGuire WL. Human breast cancer: correlation of relapse and survival with amplification of the HER-2/neu oncogene. Science 1987:235:177-87.
[9] Canadian Cancer Statistics 2007. Canadian Cancer Society. Page 84.
Source:
GlaxoSmithKline Inc.