Paclitaxel With Encequidar Given by Mouth Shows Higher Response Rate Than Paclitaxel Given by Vein

Results from a new study presented at the San Antonio Breast Cancer Symposium showed the taxane chemotherapy paclitaxel with encequidar, given as pills, resulted in greater response rates and fewer cases of neuropathy in people with metastatic breast cancer.

Background

Taxanes, like paclitaxel, are an important class of chemotherapy medicine used in breast cancer treatment. Like many chemotherapies, these are given by an infusion to the vein, done at a hospital or infusion center.

If a medicine can be made available as a pill, it typically means an easier process for the person taking it, the ability to take the medicine at home, and avoiding reactions that the body sometimes has to infusions.

This study included 360 people with metastatic breast cancer with measurable disease, who had not received a taxane in the last year, and did not have brain metastases. They were randomized to get either

• paclitaxel by vein, given once every 3 weeks as a 3-hour infusion, or
• paclitaxel and encequidar by mouth, given three days in a row, every week

People given paclitaxel by mouth would first take encequidar, a pill used to help the body absorb paclitaxel through the digestive system. About an hour later, they take paclitaxel pills. How many pills depends on personal factors. As an example, a woman who is 5 feet 4 inches and 170 pounds would take 12 pills.

Results

Paclitaxel given by mouth resulted in higher rates of confirmed response and overall survival. It also resulted in fewer people experiencing neuropathy, hair loss, and pain, though more people experienced digestive problems including diarrhea, nausea, and vomiting.

The primary endpoint of the trial was confirmed response rate, or in how many people cancer responded to the treatment. The study found that oral paclitaxel got a response rate 14.8 percentage points higher than paclitaxel given by vein:

• Oral paclitaxel had a confirmed response rate of 40.4 percent.
• Paclitaxel by vein had a confirmed response rate of 25.6 percent.

This difference is statistically significant, meaning it is not likely to have been caused by chance.

Oral paclitaxel also showed a statistically significant improvement in overall survival, with a median overall survival of 27.9 months compared to paclitaxel given by vein, which had a median overall survival of 16.9 months.

Researchers emphasized the lower rate of neuropathy experienced by people taking oral paclitaxel:

• 7.6 percent of people taking oral paclitaxel had neuropathy
• 31.1 percent of people taking paclitaxel by vein had neuropathy

What this means for you

Chemotherapy is infamous for the unpleasant experiences of infusions and negative side effects. Offering paclitaxel by mouth comes with its own challenges, but it can provide an important option for many people with breast cancer.

Some concerns remain about the results. Hope S. Rugo, MD, of University of California, San Francisco, noted in an interview with LBBC on Thursday that giving paclitaxel by vein weekly has been shown to have better outcomes than the schedule used in the study where it is given every 3 weeks. Providers will be interested to see if the pill version provides outcomes that match this updated method.

If approved by the FDA, oral paclitaxel with encequidar would allow some people to avoid infusions and lower their risk of neuropathy and hair loss, even if digestive side effects take their place. Having that choice may be itself important.