Paclitaxel ( Taxol ) is one of the most commonly used chemotherapies in breast cancer. Therefore, the evaluation of Lapatinib ( Tykerb ) in combination with this treatment is of high importance.

A large, randomized, multicenter, prospective trial evaluated a total of 580 patients either negative or untested for HER2 overexpression.

While the combination therapy did not demonstrate an incremental benefit for patients with HER2-negative disease, an analysis of 91 patients who were retrospectively identified as having HER2-positive disease showed that Lapatinib plus Paclitaxel increased progression-free survival in patients with HER2-positive breast cancer not previously treated with Trastuzumab ( Herceptin ).

Results as follows represent the combination of Lapatinib plus Paclitaxel ( n=52 ) versus Paclitaxel alone ( n=39 ), respectively, in patients with HER2-positive disease:

- median progression-free survival was 7.9 months versus 5.2 months ( p=0.007 );

- median duration of response was 7.4 months versus 5.5 months.

Complete or partial response occurred in 60 percent of patients versus 36 percent ( p = 0.027 ).
There was a trend towards improvement in overall survival after 39 deaths had been reported.
Data presently available indicate a median survival of 24 months versus 19 months ( p=0.160 ), but data are not yet fully mature

Data from this trial of Lapatinib plus Paclitaxel versus Paclitaxel alone as first-line treatment in patients with newly diagnosed metastatic breast cancer have provided the first evidence of activity in the HER2-positive subgroup that the combination significantly improves progression-free survival of the disease compared with the chemotherapy alone.

The most common adverse events included rash, diarrhoea, nausea, vomiting, neutropenia and mucositis.
The addition of Lapatinib to Paclitaxel resulted in an increase in diarrhoea and rash. Serious adverse events-related deaths were higher in the combination arm ( 2.7% vs 0.6% ).

Source: American Society of Clinical Oncology ( ASCO ) – Annual Meeting, 2007


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