Pharmacokinetics of Gemcitabine Combined with Trastuzumab in Patients with Advanced Breast Cancer

Pharmacokinetic drug-drug interaction potentials for therapeutic monoclonal antibodies: reality check

A formal assessment of the drug-drug interaction potential of any investigational drug product often requires multiple metabolic and pharmacokinetic evaluations. In contrast to a small-molecule drug, investigating the drug-drug interaction potential of a monoclonal antibody is inherently complicated. High molecular weight monoclonal antibodies are often genetically engineered to demonstrate strong specificity for a particular human antigen target. Consequently, monoclonal antibodies usually have few clinically relevant animal models--other than nonhuman primates--in which to conduct appropriate nonclinical studies. Likewise, clinical drug-drug interaction studies of monoclonal antibodies with long elimination half-lives pose definite operational challenges as conventional crossover studies with adequate washout periods are difficult to conduct. Furthermore, the current regulatory guidance on the design and conduct of in vitro and in vivo drug-drug interaction studies applies more readily to small-molecule drugs than protein-based biologics. Nevertheless, a certain amount of clinically useful information has begun to emerge from the published literature on drug-drug interaction potentials of therapeutic monoclonal antibodies. This article provides a systematic review of the current literature and offers some practical considerations for the design and conduct of pharmacokinetic drug-drug interaction assessments involving novel monoclonal antibodies. Ideally, these evaluations should be performed throughout all stages of drug development. In particular, pharmacokinetic interaction studies with any marketed drugs that are likely to be coadministered with the monoclonal antibody will yield the most clinically useful information for practitioners and patients alike.

Trastuzumab: a review of its use in the management of HER2-positive metastatic and early-stage breast cancer

Trastuzumab (Herceptin) is a humanised monoclonal antibody used in the treatment of breast cancer that overexpresses human epidermal growth factor receptor 2 (HER2), which is associated with clinically aggressive disease and a poor prognosis. The addition of intravenous trastuzumab to first-line chemotherapy improved the time to disease progression, objective response rate, duration of response, and overall survival in randomised, multicentre trials in women with HER2-positive metastatic breast cancer. As such, trastuzumab has become the standard of care in this setting, despite its high acquisition cost and potential for cardiac events, and is licensed for use in combination with paclitaxel (Europe and the US) or docetaxel (Europe). In addition, trastuzumab monotherapy is approved for use in patients with HER2-positive metastatic breast cancer who have previously received chemotherapy for their metastatic disease. Recent data from large phase III trials with trastuzumab in the adjuvant setting revealed significant improvements in disease-free and overall survival. Thus, trastuzumab is also rapidly becoming a standard component of adjuvant therapy for patients with HER2-positive early-stage breast cancer.