by Katrina Kahl
On March 13, 2007, the Food and Drug Administration (FDA) approved lapatinib (Tykerb) for patients with advanced or metastatic HER2-positive breast cancers that were previously and unsuccessfully treated with trastuzumab (Herceptin).1 Tykerb, which is manufactured by GlaxoSmithKline, will cost around $2,900 a month.
The approval follows the results of a single Phase III trial of Tykerb in which 399 women were randomized to receive either Tykerb in combination with capecitabine (Xeloda) or Xeloda alone (for more information about the Tykerb trial, see “Tykerb for Treatment of Advanced Breast Cancer” from the BCA Source #95).2 The final results show that adding Tykerb to Xeloda delayed tumor growth (time to progression of disease) by about two months. However, no increase in survival time was reported, so whether women taking Tykerb will live longer than those taking Xeloda alone remains unclear.
Although Tykerb is a new targeted therapy, it is approved only for use in combination with Xeloda, a chemotherapy drug. The promise of targeted therapies—that treatments will be less toxic to patients—can be realized only if targeted therapies are evaluated and approved as single-agent treatments, not as treatments to be combined with systemic chemotherapy.
BCA submitted a letter to the FDA outlining concerns about the approval of Tykerb (available online). While acknowledging that finding better treatments for metastatic breast cancer patients is a critically important field for developing new drugs, BCA questions the Tykerb trial’s use of time to progression of disease as an endpoint in the study rather than looking for a true increase in survival time or improved quality of life. BCA’s letter states, “The FDA should require applicants for drug approval to look at true markers of efficacy so that women can have more meaningful treatment choices.”
Tykerb may be an effective treatment option for women with HER2-positive metastatic breast cancer. But to confirm this, we must have drug trials that study overall survival and quality of life.
1 Food and Drug Administration press release, “FDA Approves Tykerb for Advanced Breast Cancer Patients,” March 13, 2007.
2 Charles E. Geyer, et al., “Lapatinib Plus Capecitabine for Her2-positive Advanced Breast Cancer,” The New England Journal of Medicine 355(26), December 2006, pp. 2733-2743.