For patients with HER2-negative metastatic breast cancer, first line chemotherapy with cabazitaxel (Jevtana) every 3 weeks offers efficacy comparable to that of once-weekly paclitaxel, but with lower risk for peripheral neuropathy and better patient-reported quality of life, investigators in the multicenter CONCERT trial found.
In an open-label clinical trial of 158 patients from 14 hospitals in the United Kingdom, there was no difference in the primary endpoint of progression-free survival (PFS) or a secondary overall survival endpoint between patients randomly assigned to initial chemotherapy with cabazitaxel every 3 weeks or weekly paclitaxel, reported Amit Bahl, MD, of University Hospital Bristol, England, and colleagues.
“Cabazitaxel is safe and well tolerated for metastatic breast cancer and requires fewer hospital visits than weekly paclitaxel, which is very important for patients and health care providers, but more so in the current situation,” he said in an oral abstract session at the American Society of Clinical Oncology annual meeting (Abstract 1008).
Cabazitaxel is currently approved in the United States and Europe in combination with prednisone for treatment of patients with metastatic castration-resistant prostate cancer previously treated with a docetaxel-containing treatment regimen. It is not currently approved for the treatment of metastatic breast cancer, but has been explored for this indication in clinical trials.
“In the metastatic setting, where patients continue on treatment pretty much indefinitely until disease progression or unacceptable toxicity, the use of an every-3-week regimen could be attractive, because it means less visits for the patients, and it appears that this drug has lower toxicity in terms of peripheral neuropathy,” said breast cancer specialist Aditya Bardia, MD, MPH, who was not involved in the study.
Dr. Bardia, of Mass General Cancer Center in Boston, commented on the study in an interview.
Although paclitaxel is commonly used as first-line chemotherapy for HER2-negative metastatic breast cancer, it is associated with only modest response rates, ranging from 21.5% to 53.7% and carries significant risk of peripheral neuropathy, Dr. Bahl and colleagues noted.
“There is an unmet need for an alternative first-line cytotoxic chemotherapy agent, and cabazitaxel is a taxoid agent which has showed promising results in phase 2 trial of metastatic breast cancer patients in the second-line setting, even those with taxane resistance,” he said.
Open-label trial
To see whether cabazitaxel could meet those requirements, the investigators conducted a phase 2 randomized trial in which patients with HER2-negative metastatic breast cancer not previously treated with cytotoxic chemotherapy were assigned, 79 in each arm, to receive cabazitaxel 25 mg/m2 every 3 weeks, or paclitaxel 80 mg/m2 weekly.
The median patient age was 56 years in the cabazitaxel group and 61 years in the paclitaxel group. Roughly two-thirds of patients in each arm had Eastern Cooperative Oncology Group performance status 0, and the remainder had ECOG performance status 1.
In each arm, the median time on treatment was 15 weeks, but treatment delays and dose reductions were more common among patients on paclitaxel than cabazitaxel (61% vs. 39%, and 37% vs. 24%, respectively).
There were 149 PFS events at the time of the analysis. The median PFS with cabazitaxel was 6.7 months vs. 5.8 months with paclitaxel. This difference was not statistically significant. Median overall survival was 20.6 months in the cabazitaxel arm, vs. 18.2 months 20.0 months, respectively.
Similarly, there were no significant differences in either the overall response rates (42% vs. 37%), or time to response.
There were no complete responses with cabazitaxel vs. two (2.5%) with paclitaxel. The respective partial response rates were 41.8% vs. 34.2%.
In a subgroup analysis of PFS, there were no significant between-arm differences, except for an improved PFS in patients 65 and older with cabazitaxel (hazard ratio 0.45, 95% confidence interval, 0.25-0.80).