Oral Paclitaxel, Encequidar Combo Associated with Improved Efficacy, Lower Neuropathy Rates in mBC

According to additional safety data from the KX-ORAX-001 trial, treatment with the combination of oral paclitaxel and encequidar (oPac+E) was found to be associated with greater efficacy in patients with metastatic breast cancer, as well as lower rates of chemotherapy-induced peripheral neuropathy, compared to intravenous paclitaxel (IVPac).

With this treatment combination, patients experienced lower rates of treatment-emergent neuropathy, compared with those who received the IVPac (22% vs 64%, respectively). Additionally, grade 3 neuropathy was reported less frequently in the oPac+E arm (2% vs. 15%).

The open-label, multinational phase 3 KX-ORAX-001 trial compared oral versus intravenous paclitaxel, both in combination with encequidar, to determine tumor responses, as well as to evaluate duration of response to therapy, progression-free survival (PFS) and overall survival (OS).

Patients either received oPac+E (n = 265) or IVPac (n = 137).

At the 2019 San Antonio Breast Cancer Symposium, complete results from the study showed a significantly higher tumor response rate in patients who were treated with oPac+E (35.8%), compared to those who received IVPac (23.4%).

At this year’s symposium, Hope S. Rugo, MD, professor in the Department of Medicine, Hematology/Oncology, and director of Breast Oncology and Clinical Trials Education at the University of California San Francisco, Helen Diller Family Comprehensive Cancer Center, presented a poster that examined the neuropathy benefits to treating patients with oPac+E.

The cumulative risk of neuropathy with oPac+E was slow to grow and remained steady by week 88 of the study, which was at 50% in the IVPac group during the same time frame.

Neuropathy-induced dose reductions were reported in 8% and 2% of patients treated with IVPac or oPac+E, respectively, and 8% of patients in the IVPac arm discontinued treatment, compared with no patients in the oPac+E arm. Of note, 12% of patients on the oPac+E regimen needed medication to treat neuropathic symptoms, such as gabapentin or pregabalin (Lyrica), compared with 40% of patients treated with the intravenous formulation.

“(oPac+E) was associated with less neuropathy, a later onset, and lower severity compared to intravenous paclitaxel in patients with metastatic breast cancer,” Rugo said in her presentation of the data.

Reference:

Rugo HS, Umanzor G, Barrios FJ, et al. Lower rates of neuropathy with oral paclitaxel and encequidar (oPac+E) compared to IV paclitaxel (IVPac) in treatment of metastatic breast cancer (mBC): Study KX-ORAX-001. Presented at: 2020 San Antonio Breast Cancer Symposium; December 8-11; 2020; Virtual. Poster S13-06.