On Wednesday 23 June 2010, GlaxoSmithKline (GSK) announced that Tyverb (lapatinib) has been granted approval in the European Union to be used in the extended indication as a first-line breast cancer treatment in combination with an aromatase inhibitor for metastatic breast cancer patients who are hormone-receptor (HR) positive as well as HER2/Erb2 positive. The new indication for Tyverb will provide a new breast cancer treatment option for such patients that will see them benefit in terms of progression-free survival and act to delay treatment with chemotherapy.
Mode of Action for GSK's Tyverb (Lapatinib) as a Breast Cancer Therapy
Tyverb (lapatinib) is a targeted treatment for breast cancer, and therefore acts to kill cancer cells without damaging the body’s normal cells. Tyverb’s mode of action is through inhibition of the tyrosine kinase receptors, epidermal growth factor receptor and human epidermal growth factor receptor2 (HER2/Erb2). These receptors are involved in cell proliferation and cancer progression, as well as the spreading of cancer to other parts of the body (metastases).
Breast Cancer Treatment Indications for Tyverb (Lapatinib)
Tyverb has been available on the European market since mid-2008 as a breast cancer treatment for advanced stage or metastatic breast cancer patients in combination with capecitabine (a chemotherapy agent) following previous treatment with other chemotherapy products. Tyverb was also already approved for use in metastatic breast cancer patients following treatment with trastuzumab (Herceptin), another drug that acts by targeting the HER2 receptor.
Prior to approval of Tyverb in its new indication, the breast cancer treatment could only be used for such patients once these other therapies had been tried and the cancer had stopped responding to the drugs and begun to progress. As such, the new indication for Tyverb will provide a new treatment option for metastatic breast cancer patients that will allow them to delay treatment with cytotoxic chemotherapy, which has many unwanted side effects.
Clinical Trials Studying Tyverb in Combination with Hormone Therapy for Breast Cancer
Approval of Tyverb in the extended indication as a first-line breast cancer therapy in combination with an aromatase inhibitor for metastatic breast cancer patients who are hormone-receptor positive as well as HER2/Erb2 positive is based on a pivotal study, which compared Tyverb (lapatinib) plus letrozole treatment to letrozole treatment alone in postmenopausal hormone-receptor positive breast cancer patients. (Letrozole is an aromatase inhibitor, like exemestane and anastrozole, and this type of hormonal therapy is currently standard-of-care for the treatment of hormone-receptor positive breast cancer patients).
Although the HER2/Erb2 status was not required for patients to enter the clinical trial, a post-study sub-analysis of patients who over-expressed HER2/Erb2 showed that the combination of Tyverb (lapatinib) and letrozole significantly extended the time before the cancer started to progress in this treatment group. Tyverb (lapatinib) plus letrozole combination treatment resulted in a median progression-free survival of 8.2 months compared to 3.0 months for the group of patients who received letrozole alone.
In the study, adverse events for the breast cancer treatment were consistent with previous clinical studies investigating Tyverb’s use in advanced breast cancer. The most commonly reported side effects for the combination were diarrhoea, rash, nausea and fatigue.
Tyverb is also marketed in the USA as Tykerb, which received FDA approval in this extended indication in January 2010. The new indication for Tyverb to be used as a first-line treatment in women with metastatic breast cancer will provide these patients with more treatment choices earlier on, delaying progression of the their breast cancer and increasing their overall survival time.
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BreastScreen Australia Benefits, AIHW Report
Sources:
Bedard et al. 2008, ‘Overcoming endocrine resistance in breast cancer – are signal transduction inhibitors the answer.’ Breast Cancer Res Treat. 2008, vol 108:pp307-317
GSK 2010, ‘GlaxoSmithKline receives EU authorisation for a new therapeutic indication for Tyverb (lapatinib)’, 23 June 2010
Johnston et al. 2009, ‘Lapatinib combined with letrozole vs letrozole and placebo as first-line therapy for postmenopausal hormone receptor-positive metastatic breast cancer.’ J Clin Oncol, 2009, vol. 27:pp5538-5546
Christine Redmond - My interest in science and healthcare has seen me working in the laboratory with tiny cells and DNA to helping set up a cancer clinical ...
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