Evaluating the effectiveness and safety of oral paclitaxel plus encequidar versus intravenous paclitaxel in patients with metastatic breast cancer.

This study evaluated the effectiveness and safety of oral paclitaxel (Taxol) plus encequidar (HM 30181) versus intravenous (IV) paclitaxel in patients with metastatic breast cancer (BC). This study concluded that oral paclitaxel plus encequidar was more effective than IV paclitaxel with manageable side effects in these patients.

Metastatic BC has spread from the original site into neighboring tissue and lymph nodes and/or distant organs of the body. There are limited treatment options for these patients. Chemotherapy is usually used in patients with advanced BC to kill cancer cells.

Taxanes are a type of chemotherapy often used in the treatment of BC. Paclitaxel is a taxane that usually requires IV (into the vein) administration. One side effect of IV administration is peripheral neuropathy (PN). PN involves damage to the nerves in the limbs that can cause weakness, numbness, tingling, and pain in the hands and feet. Oral administration of paclitaxel might be a useful alternative as it does not need IV access, can be administered at home, and does not require previous medications to prevent hypersensitivity-type reactions.

Paclitaxel is poorly absorbed orally. Encequidar is a new P-glycoprotein pump inhibitor that allows oral absorption. However, the effectiveness and safety of oral paclitaxel plus encequidar versus IV paclitaxel in patients with metastatic BC are still unknown.

This study involved 402 patients with metastatic BC. Patients were randomly assigned into two groups. Group 1 included 265 patients who received oral paclitaxel plus encequidar. Group 2 included 137 patients who received IV paclitaxel.

Overall, 36% of the patients in group 1 responded to treatment versus 23% of the patients in group 2.

The average survival without cancer worsening was 8.4 months in group 1 versus 7.4 months in group 2. Patients in group 1 were 23.2% more likely to survive without cancer worsening than patients in group 2.

The average overall survival was 22.7 months in group 1 versus 16.5 months in group 2. Patients in group 1 were 20.6% more likely to have a better survival than patients in group 2.

Serious side effects were observed in 55% of the patients in group 1 compared to 53% of the patients in group 2. The rate of PN was lower in group 1 (2%) than in group 2 (15%). The rate of hair loss was lower in group 1 (49%) than in group 2 (62%). Patients in group 1 experienced more side effects like nausea, vomiting, diarrhea, and low white blood cell counts than patients in group 2.

This study concluded that oral paclitaxel plus encequidar was more effective than IV paclitaxel with manageable side effects in patients with metastatic BC.

This study only included patients from Latin America. Patients knew which treatment they were getting which might affect the conclusions. This study was sponsored by Athenex, Inc., the manufacturer of encequidar.