A novel cancer vaccine strategy with combined IL-18 and HSV-TK gene therapy driven by the hTERT promoter in a murine colorectal cancer model.

A therapeutic vaccine against minimal residual cancer cells is needed for the treatment of patients with colorectal cancer. Several gene therapy studies have revealed that the combination of a suicide gene and cytokine gene might induce effective antitumor immunity. In this study, we constructed an interleukin (IL)-18 and herpes simplex virus-thymidine kinase (HSV-TK) expression vector driven by the human telomerase reverse transcriptase (hTERT) promoter to study the efficacy of combination gene therapy with IL-18 and the HSV-TK suicide gene. Low immunogenic colon 26 cells were used for transfection and inoculation into syngeneic BALB/c mice. Large established tumors of colon 26 transfectants expressing IL-18 and HSV-TK driven by the hTERT promoter were completely eradicated after GCV administration in syngeneic BALB/c mice. Immunohistochemical analysis at the tumor rejection sites revealed enormous infiltrations of CD8+ T lymphocytes as well as CD4+ T lymphocytes and CD11b+ monocytes. Moreover, established distant tumors were completely eradicated by vaccination with the IL-18 and HSV-TK transfectants in combination with GCV. These data suggest that the IL-18 and suicide gene therapy can elicit antitumor specific immunity. In conclusion, gene therapy with IL-18 and HSV-TK plasmid vector driven by the hTERT promoter may be useful for cancer vaccination.

Primary pulmonary mucinous (colloid) adenocarcinoma with postoperative bone metastasis.

We describe rare primary pulmonary mucinous (colloid) adenocarcinoma in an 80-year-old man. Chest computed tomography revealed a lobulated, well-defined nodule with a diameter of 3.2 cm in the right middle lobe. Transbronchial biopsy via endobronchial ultrasound with a guide sheath did not uncover malignancy. Right middle lobectomy proceeded because the tumor was located close to the pulmonary hilum. Macroscopically, the cut surface of the nodule comprised a well demarcated area of somewhat transparent granular aggregates and a yellow-white gelatinous substance. Computed tomography findings of a solitary metastatic lesion in the left fifth costal head 28 months thereafter were consistent with those of a mucin-rich tumor, which was effectively treated by radiotherapy.

UDP-glucuronosyltransferase (UGT) 1A1*28 polymorphism-directed phase II study of irinotecan with 5'-deoxy-5-fluorouridine (5'-DFUR) for metastatic colorectal cancer.

AIM: We performed a phase II study of irinotecan with 5'-deoxy-5-fluorouridine (5'-DFUR) for metastatic colorectal cancer based on UDP-glucuronosyltransferase (UGT) 1A1 polymorphism. PATIENTS AND METHODS: A total of 28 patients were enrolled. The dose of irinotecan was 150 mg/m(2) for patients with the *1/*1 wild-type genotype, and 70 mg/m(2) for those with the *1/*28 mutated genotype. The primary end-point was the response rate (RR); secondary end-points were safety, time to treatment failure (TTF), and overall survival (OS). RESULTS: In 28 patients total, genotype was wild-type in 22 and mutated in six. The RR was *1/*1 (22.7%; wild-type) vs. *1/*28 (16.7%; mutated); the median TTF was 5 months vs. 4.5 months, and the median OS was 13 months vs. 17.5 months, respectively. None of these differences were significant. Toxicities of grade 3 or higher were neutropenia (9.0% vs. 0%, respectively) and diarrhea (13.6% vs. 0%, respectively). CONCLUSION: This genotype-oriented therapy was effective and safe, and thus appears useful for patients who have complications or advanced age.

Phase I study of irinotecan and doxifluridine for metastatic colorectal cancer focusing on the UGT1A1*28 polymorphism.

Although individuals carrying the UGT1A1 allele *28 have an increased risk of severe toxicities associated with irinotecan, no phase I study has been conducted based on the polymorphism. This report presents the recommended doses of irinotecan for patients with the respective genotypes. Twenty-seven patients with advanced colorectal cancer were enrolled in this study, and the UGT1A1*28 polymorphism was genotyped before chemotherapy. One course of chemotherapy consisted of irinotecan infused once every 2 weeks at 70, 100, 120, and 150 mg/m(2) at dose levels 1, 2, 3, and 4, respectively, and doxifluridine was administered orally. This treatment continued for at least 12 weeks. The dose-limiting toxicity was determined as grade 3 hematological and non-hematological toxicities for the TA(6)/TA(6) (6/6) and TA(6)/TA(7) (6/7) genotypes. The pharmacokinetics of irinotecan, SN-38, and SN-38 glucuronide, was assessed at dose level 2. Eighteen and nine patients had the 6/6 and 6/7 genotypes, respectively. The maximum tolerated dose (MTD) was not observed up to dose level 4 in patients with the 6/6 genotype. In contrast, MTD was observed at dose level 2 (100 mg/m(2)) in patients with the 6/7 genotype. Patients with the 6/7 genotype had a significantly higher area under the plasma time-concentration curve (0-infinity) SN-38 (P = 0.022) and biliary index (P = 0.030) than those with 6/6. The recommended starting doses of biweekly irinotecan for phase II/III were 150 mg/m(2) for patients with the UGT1A1 6/6 genotype and 70 mg/m(2) for those with the 6/7 genotype, respectively. The gene polymorphism should be considered when determining the precise recommended doses to be administered in phase I studies.

Tumor secreting high levels of IL-15 induces specific immunity to low immunogenic colon adenocarcinoma via CD8+ T cells.

Although interleukin (IL)-15 augments innate and acquired immunities, IL-15 expression is controlled at the levels of transcription, translation and intracellular trafficking. We constructed plasmid vectors encoding the murine mature-IL-15 cDNA linked to an Igkappa leader sequence and full-length murine IL-15 cDNA to evaluate the efficacy of the mature-IL-15 vector. Weakly immunogenic colon 26 cells were transfected with the above-mentioned vectors or with empty vector (mock). Transfectants with mature-IL-15 produced significantly higher levels of IL-15 than did transfectants with full-length IL-15. When injected into syngeneic BALB/c mice, transfectants secreting high levels of IL-15 were rejected completely. Depletion of natural killer cells or CD4+ T cells did not affect the growth of transfectants. In contrast, transfectants treated with anti-CD8 antibody re-grew 1 month later after implantation. These findings indicate that CD8+ T cells are required for complete rejection of the tumor. Gene therapy with transfectants expressing mature-IL-15 containing the Igkappa leader sequence may be useful as a tumor vaccine.