Oral Paclitaxel Confers Improved Response Rate, Survival Trends in Patients With Metastatic Breast Cancer

By Cameron Kelsall, /alert Contributor
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Treatment with an oral formulation of the chemotherapy agent paclitaxel resulted in improved response and survival outcomes when compared with the drug in its intravenous (IV) form for women with metastatic breast cancer, according to data from a phase 3 study presented at the 2019 San Antonio Breast Cancer Symposium.

Patients who received oral paclitaxel also experienced less neuropathy than those who received IV paclitaxel, results showed.


Photo by © MedMeetingImages/Todd Buchanan 2019

IV paclitaxel is a standard of care for patients with breast cancer. However, it requires patients to receive infusions at designated treatment centers.

“Oral administration of cancer chemotherapy is very important for cancer patients, especially in areas where patients have difficulty accessing infusion clinics regularly,” said Gerardo Antonio Umanzor Funez, MD, medical oncologist at Centro Oncologico Integral (San Pedro Sula, Honduras), in a press release. 

Funez and colleagues enrolled 402 patients with metastatic breast cancer, whom they randomly assigned to 205 mg/m2 oral paclitaxel (n = 265), in combination with the p-glycoprotein pump inhibitor encequidar, for 3 days a week; or 175 mg/m2 IV paclitaxel (n = 137) every 3 weeks.

In total, 28% of the oral paclitaxel arm and 31% of the IV paclitaxel arm received prior taxane therapy.

Radiologically confirmed tumor response rate at two consecutive time points served as the study’s primary endpoint. Progression-free survival (PFS) and overall survival (OS) served as secondary endpoints.

Results showed that tumor response rates significantly favored oral paclitaxel, with a confirmed tumor response rate of 35.8%, compared with 23.4% for IV paclitaxel (P = .0011).

In a modified subgroup of patients who either did not have target tumors that could be evaluated by a central radiologist, or who did not receive sufficient treatment, the response rate still favored oral paclitaxel (40.4% vs. 25.5%; P = .005).

Fifty-one percent of patients assigned to oral paclitaxel experienced a confirmed response lasting more than 150 days, as did 38% of patients assigned IV paclitaxel.

At the study’s endpoint, 51 patients (19%) assigned oral paclitaxel continued to receive treatment, compared with 18 patients (13%) assigned IV paclitaxel.

The PFS analysis remains ongoing, with a trend in favor of oral paclitaxel (median, 8.5 months vs. 6.9 months). A similar OS trend was observed in favor of oral paclitaxel (median, 27.9 months vs. 16.5 months; P = .02).

Oral paclitaxel conferred a lower incidence of alopecia than IV paclitaxel, as well as a lower severity of neuropathic adverse events at week 23 of treatment (17% vs. 57%). Grade 3 neuropathy was observed in 1% of patients assigned oral paclitaxel and 8% of patients assigned IV paclitaxel.

The adverse event profile of oral paclitaxel was similar to the known safety profile of IV paclitaxel, although patients in the oral treatment group had higher rates of neutropenia, infection and gastrointestinal adverse events.

The highest risk of serious adverse events were seen in patients with evidence of pretreatment hepatic impairment, regardless of treatment arm.

“This oral form of paclitaxel provides a new therapeutic option for patients, in particular for those who cannot easily travel,” said Funez. “While blood counts still need to be monitored, oral administration allows patients to remain home during therapy, and avoid spending significant time in the chemotherapy unit.”

 

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