Copenhagen, Denmark: Eagerly awaited results from the world’s first head to head trial between the anti-cancer drugs docetaxel (Taxotere) and paclitaxel (Taxol) have shown that there was a better overall response rate and longer overall survival among breast cancer patients given docetaxel – although docetaxel was associated with more severe side effects.
The new results were presented for the first time today (Wednesday 24 September) at ECCO 12 – The European Cancer Conference taking place in Copenhagen.
Four hundred and forty nine women with advanced incurable breast cancer who had received previous treatment with an anthracycline-based chemotherapy were randomised into the Phase III trial from multiple centres across the USA between 1994 and 20012. Half were treated with paclitaxel and half were treated with docetaxel.
The trial’s principal investigator, Professor Peter Ravdin, associate professor in the Department of Medicine at the University of Texas Health Science Center in San Antonio, told a news briefing that the women treated with docetaxel survived for a median 15.4 months compared with a median 12.7 months for the women who received paclitaxel.
There was an overall response rate of nearly a third among the docetaxel patients compared with a quarter for the paclitaxel patients. The median time before the breast cancer progressed (TTP) was 5.7 months for the docetaxel patients and 3.6 months for the paclitaxel patients. The results for overall survival and for TTP were statistically significantly superior for docetaxel and the overall response rate in favour of docetaxel approached statistical significance.
However, the women who received docetaxel did experience more severe side effects (grade 3/4 toxicities) with higher incidences of neutropenia (reduction in infection-fighting white blood cells), asthenia (loss of strength), infection, oedema (abnormal accumulation of fluid), mouth ulcers and neuromotor and neurosensory problems.
“This has been an important study with very useful results,” said Prof. Ravdin. “Oncologists have been waiting for the outcome. It is the first time that these two drugs, which are related but which do act in somewhat different ways, have been tested directly against each other. Physicians and their patients now have more definitive information about the relative effectiveness and safety of these two every-3- week chemotherapy treatments.”
“All the endpoints in this trial are important. But, I think that overall survival is in many ways the most important endpoint as it is in some ways a summation of objective response, duration of response and tolerability.
“What is most exciting about the improvement in survival caused by docetaxel is the possible implications for adjuvant therapy. Usually, when a treatment shows superior survival in patients with metastatic disease, this treatment also improves survival in adjuvant therapy of early breast cancer. We are all waiting with great interest for the results of recently completed and ongoing trials, which are evaluating what additional effectiveness docetaxel may bring to adjuvant therapy. ”
Abstract no: 670 (Wednesday 24 September, 10.45 hrs CET, Proffered papers: Breast cancer II)
Taxanes have been one of the most encouraging anti cancer drug developments of the 1990s. Taxotere (docetaxel) and Taxol (paclitaxel) are closely related. Taxol was discovered in the USA by testing many natural compounds while Taxotere was developed in Europe as part of a programme to screen closely related compounds. Both compounds work by interfering with cell division, but there are subtle differences. When tested in tissue culture not all cancer cells are equally sensitive to both agents. There are also differences in they way they are broken down and cleared from the body. So there are reasons to believe they may have different effectiveness as anti-cancer medicines.
This Phase III multi-centre randomised trial was sponsored by Aventis, the pharmaceutical company that manufactures and markets Taxotere.