Translating TRAIL-receptor targeting agents to the clinic.

The extrinsic apoptotic pathway can be activated by the endogenous ligand TRAIL (Tumor Necrosis Factor (TNF)-Related Apoptosis-Inducing Ligand) by binding to the death receptors TRAIL-R1 and TRAIL-R2 on the cell surface. This pathway is currently evaluated as an anticancer treatment strategy. Both recombinant human TRAIL and several agonistic antibodies against TRAIL-R1 and R2 have been studied in single agent and combination studies and proved to be safe and well tolerated. In this article, the clinical studies published to date will be reviewed. Also, future perspectives and biomarker studies for selecting patients that will benefit from these agents will be discussed.

Targeting TRAIL towards the clinic.

Tumor necrosis factor-related apoptosis-inducing ligand or Apo2 ligand (TRAIL/Apo2L) is a member of the tumor necrosis factor (TNF) superfamily that induces apoptosis upon binding to its death domain-containing transmembrane receptors. The preferential toxicity of TRAIL to cancer cells and the sparing of normal cells make it an ideal cancer therapeutic agent. TRAIL induces apoptosis via the extrinsic death receptor apoptotic pathway and activates the JNK, ERK, Akt and NF-κB signaling cascades. However, not all cancer cells are sensitive to TRAIL therapy. This may limit its efficacy in the clinic, although ways have already been identified to overcome resistance by combining TRAIL with chemotherapeutic and other biological agents. This review focuses on TRAIL receptor-targeting as anticancer therapy, the apoptotic signaling pathways induced by TRAIL receptors, the prognostic implications of TRAIL receptor expression and modulation by combination therapies. The mechanisms of TRAIL resistance and strategies to overcome drug resistance will also be addressed. Finally, the progress of TRAIL and DR4/DR5-specific agonistic antibodies in clinical trials and the development of new receptor-selective TRAIL variants are discussed including future directions for apoptosis inducing therapy.

Mapatumumab, a fully human agonistic monoclonal antibody that targets TRAIL-R1, in combination with gemcitabine and cisplatin: a phase I study.

PURPOSE: To evaluate the safety, tolerability, pharmacokinetics, and antitumor activity of mapatumumab, a fully human monoclonal antibody targeting tumor necrosis factor-related apoptosis-inducing ligand receptor 1 (TRAIL-R1), in combination with gemcitabine and cisplatin. EXPERIMENTAL DESIGN: Patients with advanced solid tumors received gemcitabine 1,250 mg/m(2) i.v. on days 1 and 8 and cisplatin 80 mg/m(2) i.v. on day 1 of each 21-day cycle. Escalating mapatumumab doses were administered i.v. every 21 days. Toxicity was evaluated and pharmacokinetic analysis of plasma mapatumumab, gemcitabine, 2-difluoro-2-deoxyuridine, and unbound and total platinum was done. TRAIL-R1 tumor expression was determined immunohistochemically. RESULTS: Forty-nine patients received mapatumumab (1 mg/kg, n = 4; 3 mg/kg, n = 7; 10 mg/kg, n = 12; 20 mg/kg, n = 13; or 30 mg/kg, n = 13). A median of six cycles (range, 1-48) was administered. The adverse events most commonly observed reflect the toxicity profile of gemcitabine and cisplatin. Dose-limiting toxicities were seen in 3 of 12 patients at 10 mg/kg, consisting of grade 3 transaminitis, neutropenic fever, and grade 4 thrombocytopenia. At 20 mg/kg, 2 of 12 patients had dose-limiting toxicities, including grade 4 thrombocytopenia and grade 4 fatigue. The maximum tolerated dose was not reached. Pharmacokinetic interactions have not been observed. Twelve patients had a partial response, and 25 patients showed stable disease with a median duration of 6 months. CONCLUSIONS: Mapatumumab in combination with gemcitabine and cisplatin is safe and well tolerated at doses up to 30 mg/kg. Further studies on this combination are warranted.

Sulindac inhibits beta-catenin expression in normal-appearing colon of hereditary nonpolyposis colorectal cancer and familial adenomatous polyposis patients.

Sulindac reduces colorectal cancer risk in genetically susceptible humans and animals. The molecular mechanisms underlying these effects are incompletely understood. Many studies suggest an important role for induction of apoptosis involving the mitochondrial pathway and the death receptor pathway. Alternatively, mechanisms involving the APC-beta-catenin-Wnt pathway have been suggested, possibly mediated by p21. We determined the effects of sulindac on apoptosis and expression of death receptor (DR)-4 and DR5, beta-catenin, and p21 in normal-appearing colorectal epithelium. Biopsies were obtained before and after sulindac treatment during two chemoprevention studies. Patients (n = 18) with hereditary nonpolyposis colorectal cancer (HNPCC) received 150 mg sulindac bd for 4 weeks in a placebo-controlled crossover design. Patients (n = 6) with familial adenomatous polyposis (FAP) received 150 mg sulindac bd for 6 months. Apoptosis was assessed by M30 staining and expression patterns of DR4, DR5, beta-catenin, and p21 were studied immunohistochemically. In HNPCC patients, apoptotic indices were similar following placebo and sulindac. Also in FAP patients, apoptotic indices were not different after sulindac compared with pretreatment values. Expression of DR4 and DR5 was observed in all samples with no consistent differences between placebo/baseline and sulindac. Intensity of membranous beta-catenin staining was lower in HNPCC samples following sulindac compared with placebo (P < 0.001). Similar results were obtained in FAP samples (P < 0.01). p21 expressions before and after sulindac treatment were similar in both patient groups. In conclusion, sulindac inhibits beta-catenin expression in normal colorectal epithelium from HNPCC and FAP patients without affecting apoptotic indices and DR4, DR5, and p21 expression.