Mapatumumab, an antibody targeting TRAIL-R1, in combination with paclitaxel and carboplatin in patients with advanced solid malignancies: results of a phase I and pharmacokinetic study.

PURPOSE: A phase I study assessed the safety, tolerability, pharmacokinetics, and preliminary antitumor effect of mapatumumab, a fully-human agonist monoclonal antibody to the tumor necrosis factor-related apoptosis-inducing ligand receptor 1 (TRAIL-R1, DR4), in combination with paclitaxel and carboplatin. PATIENTS AND METHODS: Patients with advanced solid malignancies received 3, 10, or 20 mg/kg of mapatumumab with standard doses of paclitaxel and carboplatin every 21 days for up to six cycles in the absence of disease progression. Additional cycles of paclitaxel and/or mapatumumab were permissible in selected cases. RESULTS: Twenty-seven patients (21 males), with a median age of 54 years, received mapatumumab in the following three cohorts: 3 mg/kg (n = 4), 10 mg/kg (n = 11), and 20 mg/kg (n = 12). The median number of cycles was four. Dose-limiting toxicities (DLTs) were grade 3 hypersensitivity reaction (n = 1) and neutropenic fever (n = 1), both at 10 mg/kg. Non-DLT treatment-related adverse events occurring in more than 10% of administered doses included alopecia, neutropenia, fatigue, nausea, anemia, thrombocytopenia, anorexia, and neuropathy. Paclitaxel and carboplatin exposures were similar in the presence or absence of mapatumumab. Plasma mapatumumab concentrations seemed similar to data from previous phase I monotherapy studies. Five patients (19%) achieved a confirmed radiologic partial response (including one pathologic complete response), and 12 patients (44%) had stable disease as their best response. CONCLUSION: Mapatumumab is well-tolerated up to 20 mg/kg in combination with paclitaxel and carboplatin. There are no apparent pharmacokinetic interactions among the drugs. Preliminary anticancer activity demonstrated clinical benefit for the majority of these patients.

Phase I pharmacokinetic and biologic correlative study of mapatumumab, a fully human monoclonal antibody with agonist activity to tumor necrosis factor-related apoptosis-inducing ligand receptor-1.

PURPOSE: To assess the safety, pharmacokinetics, and preliminary evidence of antitumor activity of mapatumumab (HGS-ETR1, TRM-1), a fully human agonist monoclonal antibody directed to the tumor necrosis factor-related apoptosis-inducing ligand receptor-1 (TRAIL-R1). PATIENTS AND METHODS: Patients with advanced solid malignancies were treated with escalating doses of mapatumumab intravenously (IV) administered over 30 to 120 minutes, initially as a single dose and then repetitively. Plasma mapatumumab concentrations were measured and serum was assayed to detect human antimapatumumab antibody formation. Archival tumor specimens were collected to detect the presence of TRAIL-R1 by immunohistochemistry. RESULTS: Forty-nine patients received 158 courses at doses ranging from 0.01 to 10 mg/kg IV. Initially, patients received mapatumumab as a single dose, then every 28 days repetitively, and then 10 mg/kg every 14 days. Mild (grade 1 or 2) fatigue, fever, and myalgia were the most frequently reported nonhematologic adverse events related to mapatumumab, whereas hematologic toxicity was not clinically significant. The mean (+/- standard deviation) clearance and terminal elimination half-life values for mapatumumab at 10 mg/kg every 14 days were 3.7 mL/d/kg (+/- 1.5 mL/d/kg) and 18.8 days (+/- 10.1 days), respectively. TRAIL-R1 was documented in 68% of patients' tumors assayed. Nineteen patients had stable disease, with two lasting 9 months. CONCLUSION: Mapatumumab can be administered safely and feasibly at 10 mg/kg IV every 14 days. The absence of severe toxicities and the attainment of plasma mapatumumab concentrations that are active in preclinical models warrant further disease-directed studies of this agent alone and in combination with chemotherapy in a broad array of tumors.