title: Radiofrequency ablation and immunostimulant OK-432: combination therapy enhances systemic antitumor immunity for treatment of VX2 lung tumors in rabbits.
abstract: OBJECTIVE
  To evaluate whether antitumor immunity is enhanced systemically by combining radiofrequency ablation (RFA) and local injection of an immunostimulant, OK-432.
  
  
  METHODS
  Experiments were approved by the institutional animal care committee. Experimental Japanese rabbits inoculated with VX2 tumors in the lung and the auricle were randomized into four groups of eight: control (supportive care), RFA (RFA of lung tumor), OK-432 (direct injection of OK-432 into lung tumor), and combination therapy (lung RFA and direct OK-432 injection into lung tumor). All procedures were performed 1 week after implantation of VX2 tumors (week 1). In addition, a VX2 tumor rechallenge test was performed in the RFA and combination therapy groups. Survival time was evaluated by means of the Kaplan-Meier method and by using the log-rank test for intergroup comparison. Mean auricle tumor volumes were calculated every week. Specific growth rates (SGRs) were calculated and compared by using the Mann-Whitney test.
  
  
  RESULTS
  The median survival times of the control, RFA, OK-432, and combination therapy groups were 23, 36.5, 46.5, and 105 days, respectively. Survival was significantly prolonged in the combination therapy group when compared with the other three groups (P <.05). The mean auricle tumor volume decreased only in the combination therapy group. The mean auricle tumor volumes of the combination therapy group from week 1 to week 7 were 205, 339, 264, 227, 143, 127, and 115 mm(3). SGR in the combination therapy group became significantly smaller than those in the other three groups (P < .05). In the rechallenge test, the volume of all reimplanted tumors decreased.
  
  
  CONCLUSIONS
  Combining RFA with local injection of immunostimulant OK-432 may lead to indirectly activation of systemic antitumor immunity.
authors: Department of Radiology, Graduate School of Medicine, Osaka City University, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545-8585, Japan.
authors: Shinichi
authors: S
authors: Hamamoto
authors: Tomohisa
authors: T
authors: Okuma
authors: Akira
authors: A
authors: Yamamoto
authors: Ken
authors: K
authors: Kageyama
authors: Toru
authors: T
authors: Takeshita
authors: Yukimasa
authors: Y
authors: Sakai
authors: Norifumi
authors: N
authors: Nishida
authors: Toshiyuki
authors: T
authors: Matsuoka
authors: Yukio
authors: Y
authors: Miki
mesh_terms: D000818:Animals; D017115:Catheter Ablation; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D015552:Injections, Intralesional; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology / Q000601:surgery*; D010844:Picibanil / Q000008:administration & dosage / Q000494:pharmacology*; D016016:Proportional Hazards Models; D011817:Rabbits; D011897:Random Allocation; D018709:Statistics, Nonparametric; D015996:Survival Rate
chemical_list: D010844:Picibanil