Lapatinib plus paclitaxel
A double-blind, randomized phase III study compared paclitaxel and lapatinib with paclitaxel plus placebo as first-line therapy in patients with metastatic breast cancer. In the intention-to-treat population, no benefit was found with the combination treatment. However, specimens were evaluated retrospectively to determine HER2/neu status. When used in HER2/neu-positive patients, treatment with paclitaxel and lapatinib showed improvement in time to progression, event-free survival, response rate, and clinical benefit rate; OS did not increase. Toxicities, specifically alopecia, diarrhea, and rash were higher in the HER2/neu-positive lapatinib group. A series of AE were low and existed in both arms.[Level of evidence: 1iDiii]
Pertuzumab is a humanized, monoclonal antibody that binds to a different epitope at the HER2 extracellular domain than trastuzumab. The binding of pertuzumab to HER2 prevents dimerization with other ligand-activated HER receptors, most notably HER3. Given their potentially complementary mechanisms of action, the phase III CLEOPATRA [NCT00567190] trial assessed the efficacy and safety of pertuzumab plus trastuzumab plus docetaxel versus placebo plus trastuzumab plus docetaxel, in the first-line HER2+ metastatic setting.[Level of evidence: 1iA]. The median PFS was 12.4 months in the control group versus 18.5 months in the pertuzumab group (HR, 0.62; 95% CI, 0.51–0.75; P < .001). Final OS results are pending. The toxicity profile was similar in both treatment groups with no increase in cardiac toxic effects seen in the pertuzumab combination arm.
Ado-trastuzumab emtansine (T-DM1) is an antibody-drug conjugate that incorporates the HER2–targeted antitumor properties of trastuzumab with the cytotoxic activity of the microtubule-inhibitory agent DM1. T-DM1 allows specific intracellular drug delivery to HER2-overexpressing cells, potentially improving the therapeutic index and minimizing exposure of normal tissue. The phase III EMILIA or TDM4370g (NCT00829166) study was a randomized, open-label trial enrolling 991 patients with HER2-overexpressing, unresectable, locally advanced or metastatic breast cancer who were previously treated with trastuzumab and a taxane.[Level of evidence: 1iiA]
Patients were randomly assigned between T-DM1 versus lapatinib plus capecitabine. Median PFS was 9.6 months with T-DM1 versus 6.4 months with lapatinib plus capecitabine (HR, 0.65; 95% CI, 0.55–0.77; P < .001). Median OS at the second interim analysis crossed the stopping boundary for efficacy (30.9 months vs. 25.1 months; HR, 0.68; 95% CI, 0.55–0.85; P < .001). The incidences of thrombocytopenia and increased serum aminotransferase levels were higher in patients who received T-DM1, whereas the incidences of diarrhea, nausea, vomiting, and palmar–plantar syndrome were higher in patients who received lapatinib plus capecitabine.