Afatinib circumvents multidrug resistance via dually inhibiting ATP binding cassette subfamily G member 2 in vitro and in vivo

A phase I study afatinib/carboplatin/paclitaxel induction chemotherapy followed by standard chemoradiation in HPV-negative or high-risk HPV-positive locally advanced stage III/IVa/IVb head and neck squamous cell carcinoma

INTRODUCTION

Afatinib is an ErbB family receptor inhibitor with efficacy in head and neck squamous cell carcinoma (HNSCC). A phase I trial was conducted to determine the maximally tolerated dose (MTD) of afatinib in combination with carboplatin and paclitaxel as induction chemotherapy (IC).

MATERIAL AND METHODS

Patients with newly diagnosed, locally advanced HPV-negative or HPV-positive HNSCC with a significant smoking history were enrolled. Afatinib alone was given daily for two weeks as lead-in and subsequently given with carboplatin AUC 6mg/mlmin and paclitaxel 175mg/m(2) every 21days as IC. Afatinib was started at a dose of 20mg daily and dose escalated using a modified Fibonacci design. After completion of IC, afatinib was discontinued and patients received concurrent cisplatin 40mg/m(2) weekly and standard radiation. Toxicity was assessed using CTCAE version 4.0.

RESULTS

Seven of nine patients completed afatinib lead-in and IC. Five patients had partial response and two patients had stable disease after IC. Dose level 1 (afatinib 20mg) was well tolerated with one grade 3 (ALT elevation) and one grade 4 (neutropenia) toxicities. However, dose level 2 (afatinib 30mg) was not well tolerated with nine grade 3 (pneumonia, abdominal pain, diarrhea, pancytopenia, and UTI), two grade 4 (sepsis) and one grade 5 (death) toxicities.

CONCLUSIONS

The MTD of afatinib given with carboplatin AUC 6mg/mlmin and paclitaxel 175mg/m(2) is 20mg daily. Combination of afatinib at doses higher than 20mg with carboplatin and paclitaxel should be administered with caution due to the toxicities.

Butorphanol, a synthetic opioid, sensitizes ABCB1-mediated multidrug resistance via inhibition of the efflux function of ABCB1 in leukemia cells

Multidrug resistance (MDR) remains a formidable challenge in the use of chemotherapy and represents a powerful obstacle to the treatment of leukemia. ATP-binding cassette subfamily B member 1 (ABCB1) is a recognized factor which causes MDR and is closely related to poor outcome and relapse in leukemia. Ongoing research concerning the strategy for inhibiting the abnormally high activity of the ABCB1 transporter is critically needed. In the present study, we sought to elucidate the interaction between ABCB1 transporter and butorphanol. Our results showed that butorphanol significantly antagonized ABCB1-mediated drug efflux and increased the intracellular drug concentration by inhibiting the transport activity of ABCB1 in leukemia cells. Mechanistic investigations demonstrated that butorphanol did not alter the protein expression or localization of ABCB1 in HL60/VCR and K562/ADR cells. Furthermore, homology modeling indicated that butorphanol could fit into the large drug-binding cavity of ABCB1 and form a binding conformation. In conclusion, butorphanol reversed the ABCB1-mediated MDR in leukemia cells by directly suppressing the efflux activity of ABCB1.