title: Treatment of small cell lung cancer with TRA-8 in combination with cisplatin and radiation.
abstract: BACKGROUND
  Limited stage small cell lung cancer (SCLC) represents a minority of SCLC. Despite extensive clinical trials, standard treatment remains cisplatin-based chemotherapy and thoracic irradiation (TI). This study focused on the interaction of cisplatin/radiation with the anti-human DR5 monoclonal antibody TRA-8 in SCLC cells. TRA-8 binds specifically to DR5 and has been shown to activate apoptosis.
  
  
  METHODS
  Four human SCLC cell lines were utilized for experimentation (SCLC-41, SCLC-58, SCLC-68, and SCLC-74). Immunoblot analysis was used to determine relative protein levels of DR5, DR4 and pro-caspase 8 for each cell line. Using a tetrazolium-based assay (XTT), the IC(50) values for cisplatin with or without TRA-8 were determined for the SCLC cell lines. Four SCLC lines were assayed with a combination of TRA-8 (10 μg/ml), 2 Gy radiation and various concentrations of cisplatin. Apoptosis was evaluated using Annexin V-FITC and cleaved caspase immunoblotting. Using a SCLC-58 subcutaneous xenograft model, treatment began 21 d after tumor cell injection. Treatment included weekly cisplatin (4 mg/kg) and radiation of 1 Gy (24 h after cisplatin) and TRA-8 (200 μg) was administered i.p. twice weekly for three weeks.
  
  
  RESULTS
  Immunoblot analysis showed similar levels of DR5 for all cell lines with variable levels of DR4. Various concentrations of TRA-8 antibody (≤ 10 μg/ml) induced no significant cytotoxicity in the SCLC cell lines. The in vitro combination treatment with TRA-8 (10 μg/ml), 1.25 μg/ml cisplatin and 2 Gy radiation showed increased cytotoxicity when compared to combinations without TRA-8. Furthermore, the triple combination demonstrated the greatest amount of apoptosis as measured by Annexin V staining. The in vivo studies showed the combination of 1G y, cisplatin and TRA-8 extended the tumor doubling time to 44 d as compared to any doublet treatment groups that ranged from 12 to 20 d. Analysis of survival data showed 100% of the combination group (RT+cisplatin+TRA-8) were alive 65 d after treatment began whereas all doublet treatment groups showed 50% or less survival.
  
  
  CONCLUSIONS
  These studies showed increased cytotoxicity when TRA-8 was added to radiation/cisplatin in SCLC. This effect was demonstrated in vitro and in vivo. TRA-8 represents a promising new agent in the treatment of SCLC.
authors: Department of Radiation Oncology, The University of Alabama, Birmingham, AL 35249, USA. jabonner@uabmc.edu
authors: James A
authors: JA
authors: Bonner
authors: Christopher D
authors: CD
authors: Willey
authors: Eddy S
authors: ES
authors: Yang
authors: Michael C
authors: MC
authors: Dobelbower
authors: Leisa L
authors: LL
authors: Sanford
authors: Sheila J
authors: SJ
authors: Bright
authors: Donald J
authors: DJ
authors: Buchsbaum
authors: Kevin P
authors: KP
authors: Raisch
mesh_terms: D000818:Animals; D017304:Annexin A5 / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D045744:Cell Line, Tumor / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival; D059248:Chemoradiotherapy; D002945:Cisplatin / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D066298:In Vitro Techniques; D008175:Lung Neoplasms / Q000473:pathology / Q000628:therapy*; D051379:Mice; D008819:Mice, Nude; D011839:Radiation, Ionizing; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000037:antagonists & inhibitors*; D012680:Sensitivity and Specificity; D055752:Small Cell Lung Carcinoma / Q000473:pathology / Q000628:therapy*; D016896:Treatment Outcome
chemical_list: D017304:Annexin A5; D000911:Antibodies, Monoclonal; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; C572208:TRA-8 monoclonal antibody; D002945:Cisplatin