Abstract 4772: A novel agonist antibody to human death receptor 4, AY4, induces apoptotic cell death in head and neck cancer through ROS generation: in vitro and in vivo

Background : The proapoptotic tumor necrosis factor-related apoptosis inducing ligand (TRAIL) receptors death receptor (DR) 4 and DR5 are attractive targets to develop the receptorspecific agonistic monoclonal antibodies (mAb) as anticancer agents because of their tumor-selective cell death-inducing activity. Here, we describe the characterization of a novel agonistic mAb (AY4) against human DR4 and apoptosis through reactive oxygen species (ROS) production in head and neck cancer model.

Methods : The effects of AY4 in head and neck cell lines (KB, SNU899, HN9, FaDu) was studied on apoptosis using MTT assy, TUNEL, Annexin V assay and western blotting and was examed on the production of reactive oxygen species with DCFDA staining, intracellular signaling and animal model. In addition, we analyzed the anticancer effect of AY4 in nude mice xenograft model. In addition, drug toxicity (embryotoxicity and neurotoxicity) of AY4 were investigated in vivo zebrafish model.

Results: The DR4 was expressed in head and neck cancer cell lines by Flow cytometry (FACS) and western blotting. AY4 inhibited cell growth in KB and HN9 excluding SNU899 and FaDu and caused cell death via caspase-dependent apoptosis. The apoptotic cell death by AY4 decreased by N-acetylcysteine (NAC), an antioxidant, suggesting ROS generation involved in the cell death. Moreover, NAC and AY4 cotreatment augmented the reduced expression of antiapoptotic molecules, Bcl-XL and XIAP. In vivo administration of AY4 significantly inhibited tumor growth of head and neck cancer preestablished in athymic nude mice. In addition, in a zebrafish model used for toxicity testing, a considerable dose of AY4 did not result in embryotoxicity or neurotoxicity.

Conclusion : Our results demonstrates the effect of AY4 on apoptosis and tumor inhibition via ROS production and provide potential use of AY4 as an anticancer therapeutic agent in head and neck cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4772. doi:10.1158/1538-7445.AM2011-4772

Clinical results of 24 pituitary macroadenomas with linac-based stereotactic radiosurgery

PURPOSE

To determine the impact of stereotactic radiosurgery (SRS) on the clinical course, hormonal status, and follow-up CT/MRI scan of pituitary macroadenomas.

METHODS AND MATERIALS

From July 1988 to March 1996, 24 pituitary macroadenomas had been treated using 6 MV linear accelerator based SRS. They consisted of 11 (45.8%) prolactinomas, 2 (8.3%) growth hormone (GH)-secreting tumors, 1 (4.2%) Cushing's disease, 8 (33.3%) nonsecreting (nonfunctioning: NF) tumors, and 2 (8.3%) mixed prolactin-growth hormone (PRL-GH)-secreting tumors (M:F = 12:12; aged 21-61 years). Postoperative irradiation was performed in all cases except for the instance of Cushing's disease. The prescribed dose to tumor center varied from 10 to 27 Gy (mean 21.1 Gy) using a collimator size of 0.5 to 2.5 cm. The follow-up duration ranged from 13 to 89 months (mean 49.2 months). Results from these patients were compared to our results using conventional radiation.

RESULTS

Visual acuity and field defect were improved or became normal in 19 (79.2%) cases. Four (16.7%) remained unchanged after the treatment. One (4.1%) progressed 6 years after SRS and subsequently had repeat surgery with conventional boost irradiation. Of the 13 (46.4%) prolactinomas, including two mixed PRL-GH secreting tumors, 11 (84.1%) revealed normal hormonal levels within 1 year after SRS. In contrast, it took 2 years to become normal after conventional radiation therapy. In four GH-secreting tumors including two mixed PRL-GH secreting tumors, SRS and conventional methods showed similar responses. On follow-up imagings of the 21 patients, the mass was completely resolved in 4 (16.7%), including 3 PRLs and one NF, decreased in 11 (45.8%), and unchanged in 5 (16.7%) with central necrosis or cysts. One (4.2%) progressed and was reoperated 6 years after treatment. The complications related to SRS were comparable to those from conventional method.

CONCLUSION

Radiosurgery can be used effectively in patients with pituitary adenoma. In this study, a more rapid hormonal and clinical response was achieved with radiosurgery than with conventional pituitary irradiation treatment.