Breast Cancer Coverage from Every Angle

Oral Paclitaxel Plus Encequidar Versus Intravenous Paclitaxel

By: Julia Fiederlein
Posted: Friday, April 2, 2021

Patients with metastatic breast cancer may benefit from treatment with oral paclitaxel plus encequidar compared with intravenous paclitaxel, according to a multinational phase III study conducted by Gerardo Umanzor, MD, of Liga Contra el Cancer, San Pedro Sula, Honduras, and colleagues. They presented their findings during the virtual edition of the 2021 PER’s Miami Breast Cancer Conference (Abstract 21).

“P-glycoprotein is an adenosine triphosphate–dependent efflux pump that is very efficient in limiting the uptake and distribution of xenobiotics and toxic substances. Inhibiting P-glycoprotein is an effective way of improving the bioavailability of orally administered P-glycoprotein substrates,” the investigators commented. “Encequidar is a highly specific, potent, minimally systemically absorbed inhibitor of P-glycoprotein in the gastrointestinal mucosa.”

A total of 402 patients were enrolled in the intention-to-treat (ITT) population; they were randomly assigned in a 2:1 ratio to receive oral paclitaxel plus encequidar (n = 265) or intravenous paclitaxel (n = 137). The prespecified modified ITT population comprised 360 patients.

In the ITT population, more patients treated with oral paclitaxel plus encequidar had complete or partial responses than those treated with intravenous paclitaxel (36% vs. 23%; P = .011). Complete or partial responses occurred in 40% of patients treated with oral paclitaxel plus encequidar and in 26% of those treated with intravenous paclitaxel in the modified ITT population (P = .005). The duration of response was longer than 180 days in 48% of patients. Progression-free survival benefits were observed with oral paclitaxel plus encequidar versus intravenous paclitaxel in the ITT (8.4 vs. 7.4 months, respectively; P = .046) and modified ITT (8.4 vs. 7.4 months; P = .023) populations. Oral paclitaxel plus encequidar reduced the risk of death by 20.6% and 26.5% in the ITT and modified ITT populations, respectively, compared with intravenous paclitaxel.

Disclosure: No information regarding conflicts of interest was provided.

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