Adenoviral-mediated gene transfer of a constitutively active retinoblastoma gene inhibits human pancreatic tumor cell proliferation

Generation of a focused poly(amino ether) library: polymer-mediated transgene delivery and gold-nanorod based theranostic systems

A focused library of twenty-one cationic poly(amino ethers) was synthesized following ring-opening polymerization of two diglycidyl ethers by different oligoamines. The polymers were screened in parallel for plasmid DNA (pDNA) delivery, and transgene expression efficacies of individual polymers were compared to those of 25 kDa polyethylenimine (PEI), a current standard for polymer-mediated transgene delivery. Seven lead polymers that demonstrated higher transgene expression than PEI in pancreatic and prostate cancer cells lines were identified from the screen. All seven lead polymers showed highest transgene expression at a polymer:pDNA weight ratio of 5:1 in the MIA PaCa-2 pancreatic cancer cell line. Among the conditions studied, transgene expression efficacy correlated with minimal polymer cytotoxicity but not polyplex sizes. In addition, this study indicated that methylene spacing between amine centers in the monomers, amine content, and molecular weight of the polymers are all significant factors and should be considered when designing polymers for transgene delivery. A lead effective polymer was employed for coating gold nanorods, leading to theranostic nanoassemblies that possess combined transgene delivery and optical imaging capabilities, leading to potential theranostic systems.

Adenoviral p53 gene transfer and gemcitabine in three patients with liver metastases due to advanced pancreatic carcinoma

BACKGROUND

Current therapies for adenocarcinoma of the pancreas do not improve the life expectancy of patients.

METHODS

In a non-randomized pilot trail we tested whether a local therapy based upon an adenoviral gene transfer of wild type p53 in combination with gemcitabine administration would be safe in patients with liver metastases due to pancreatic carcinoma. We report on the clinical course of three patients with respect to safety, tolerability and tumor response.

RESULTS

Transient grade III toxicities occurred with fever, leucopenia, elevation of AP, ALT, AST, GGT, while grade IV toxicity occurred for bilirubin only. Laboratory tests suggested disseminated intravascular coagulation in all three patients, but fine needle biopsies of liver did not show any histological evidence of thrombus or clot formation. Progression of liver metastases was documented in one and stable disease in another patient two months after treatment. However, a major improvement with regression of the indexed lesion by 80% occurred in a third patient after a single administration of 7.5 x 10(12) viral particles, and time to progression was extended to six months.

CONCLUSION

The combination therapy of viral gene transfer and chemotherapy temporarily controls and diminishes tumor burden. Improvement of the toxicity profile is necessary. Further trials are warranted to improve treatment and life expectancy of patients suffering from fatal diseases such as pancreatic carcinoma.

Strategies for cancer gene therapy

Gene therapy offers new opportunities for cancer treatment and prevention through the use of targeted, relatively nontoxic treatments that can identify, disable, and destroy malignant cells. This article reviews the principles behind oncogene inactivation, tumor suppressor gene replacement, inhibition of angiogenesis, immunopotentiation, molecular chemotherapy, and addition of drug resistance genes. The adcantages and limitations of viral and nonviral vectors for delivery of the therapeutic genes are presented.

Intraperitoneal injection of adenovirus-mediated NK4 gene suppresses peritoneal dissemination of pancreatic cancer cell line AsPC-1 in nude mice

NK4, composed of the N-terminal hairpin and subsequent four-kringle domains of hepatocyte growth factor (HGF), acts not only as a competitive antagonist for HGF but also as a potent angiogenesis inhibitor. This study was designed to assess a therapeutic potential of adenovirus-mediated NK4 gene transfer for disseminated pancreatic cancer cells in the peritoneal lavage of nude mice. We constructed a recombinant adenovirus NK4 (Ad-NK4), which encodes a secretable form of human NK4. In vitro migration of AsPC-1 (human pancreatic cancer cell line) was stimulated by HGF, and it was completely inhibited by Ad-NK4 transfection. Weekly intraperitoneal injections of Ad-NK4 could suppress the development of tumor nodules in a nude mouse peritoneal dissemination model. NK4 expression was detected in the disseminated nodules, liver, pancreas, spleen, and mesenterium. Immunohistochemical study of the disseminated tumors showed a remarkable decrease in microvessel density and an increase in number of apoptotic tumor cells in the Ad-NK4-treated mice. Survival of the Ad-NK4-treated mice was significantly improved. This study indicates that the intraperitoneal transduction of adenovirus-mediated NK4 gene may be a useful therapeutic modality to prevent the development of peritoneal dissemination of pancreatic cancer.

pRb-expressing adenovirus Ad5-Rb attenuates the p53-induced apoptosis in cervical cancer cell lines

The retinoblastoma protein (pRb), the gene product of the first reported tumour suppressor gene, is functionally inactivated by the E7 protein of high-risk human papillomavirus (HPV) found in most human cervical cancers. We have, in this study, constructed an adenoviral vector expressing wild-type pRb (Ad5-Rb) and used the constructed Ad5-Rb to transfect the osteosarcoma cell line Saos-2, and three cervical cancer cell lines HeLa, SiHa and C-33A. Our results showed that pRb caused G1 arrest in Saos-2 cells after transfection with Ad5-Rb. The number of colonies formed by the Ad5-Rb-transfected Saos-2 cells in soft agar was also found to be significantly lower (P<0.05) than those transfected with the adenoviral control expressing Escherichia coli beta-galactosidase (Ad5-LacZ). The transfection of Ad5-Rb caused an increase in the population of SiHa and C-33A cells in the G1 phase from 53.0 and 52.9% to 72.4 and 64.3%, respectively, but not in the HeLa cells. However, Ad5-Rb did not show any inhibitory effect on the growth of SiHa, HeLa and C-33A cells, and inhibition of colony formation in soft agar was not observed either. In contrast, flow cytometric analysis showed that Ad5-p53, a p53-expressing adenovirus, induced apoptosis, i.e. the appearance of sub-G1 peak, in all three tested cervical cancer cell lines. Nevertheless, the Ad5-p53-induced apoptosis was partially inhibited when Ad5-Rb was added simultaneously. These findings suggested that pRb may not be a good candidate for cervical cancer gene therapy. Our data also showed that the use of full-length pRb in combination with TP53 might not be a suitable strategy for cancer gene therapy.

Evaluation of herpes simplex thymidine kinase mediated gene therapy in experimental pancreatic cancer

BACKGROUND

Despite of recent improvements in the treatment of many malignant diseases, pancreatic ductal adenocarcinoma is still a disease with an extremely poor prognosis with current modes of treatment. Gene therapy has been suggested as a novel approach also against pancreatic cancer. Previous studies have been carried out predominantly with immunodeficient animal models and with tumors growing in environments other than the pancreas. We have attempted to mimic a more clinically relevant situation and investigated suicide gene therapy strategy for experimental pancreatic cancer in animals with an intact immune system.

METHODS

We used herpes simplex virus thymidine kinase (HSV-tk) and ganciclovir (GCV) strategy in both in vitro and in vivo settings.

RESULTS

In vitro studies demonstrated that retro- as well as adenovirally transduced HSV-tk-positive DSL-6A/C1 rat pancreatic carcinoma cells were sensitive to low concentrations of GCV when compared with parental, nontransduced cells. In addition, a strong bystander effect was observed. In in vivo studies, subcutaneously transplanted HSV-tk-positive DSL-6A/C1 cells were killed after GCV treatment, whereas parental, HSV-tk-negative cells continued to grow and developed into ductal adenocarcinomas. In in vivo HSV-tk-transduced pancreatic tumors, GCV treatment caused tumor necrosis and the necrosis volume was significantly more extensive when compared with control groups.

CONCLUSIONS

HSV-tk gene transfer followed by GCV treatment is efficient in killing pancreatic cancer cells in vitro, in a transduced subcutaneous tumor model, as well as in in vivo transduced pancreatic tumors using an immunocompetent animal model. These results highlight the potential of gene therapy to treat experimental pancreatic cancer.

Evaluation of herpes simplex thymidine kinase mediated gene therapy in experimental pancreatic cancer

BACKGROUND

Despite of recent improvements in the treatment of many malignant diseases, pancreatic ductal adenocarcinoma is still a disease with an extremely poor prognosis with current modes of treatment. Gene therapy has been suggested as a novel approach also against pancreatic cancer. Previous studies have been carried out predominantly with immunodeficient animal models and with tumors growing in environments other than the pancreas. We have attempted to mimic a more clinically relevant situation and investigated suicide gene therapy strategy for experimental pancreatic cancer in animals with an intact immune system.

METHODS

We used herpes simplex virus thymidine kinase (HSV-tk) and ganciclovir (GCV) strategy in both in vitro and in vivo settings.

RESULTS

In vitro studies demonstrated that retro- as well as adenovirally transduced HSV-tk-positive DSL-6A/C1 rat pancreatic carcinoma cells were sensitive to low concentrations of GCV when compared with parental, nontransduced cells. In addition, a strong bystander effect was observed. In in vivo studies, subcutaneously transplanted HSV-tk-positive DSL-6A/C1 cells were killed after GCV treatment, whereas parental, HSV-tk-negative cells continued to grow and developed into ductal adenocarcinomas. In in vivo HSV-tk-transduced pancreatic tumors, GCV treatment caused tumor necrosis and the necrosis volume was significantly more extensive when compared with control groups.

CONCLUSIONS

HSV-tk gene transfer followed by GCV treatment is efficient in killing pancreatic cancer cells in vitro, in a transduced subcutaneous tumor model, as well as in in vivo transduced pancreatic tumors using an immunocompetent animal model. These results highlight the potential of gene therapy to treat experimental pancreatic cancer.

Gene therapy for head and neck cancer

OBJECTIVES/HYPOTHESIS

New treatment methods are needed for head and neck cancer to improve survival without increasing morbidity. Gene therapy is a potential method of improving patient outcome. Progress in gene therapy for cancer is reviewed with emphasis on the limitations of vector technology and treatment strategies. Given the current technological vector limitations in transmitting the therapeutic genes, treatments that require the fewest number of cells to be altered by the new gene are optimal. Therefore an immune-based gene therapy strategy was selected in which the tumors were transfected with the gene for an alloantigen, human leukocyte antigen (HLA)-B7, a class I major histocompatibility complex (MHC). This would restore an antigen presentation mechanism in the tumor to induce an antitumor response. This gene therapy strategy was tested in patients with advanced, unresectable head and neck cancer.

STUDY DESIGN

Prospective trial.

METHODS

Twenty patients with advanced head and neck cancer who had failed conventional therapy and did not express HLA-B7 were treated with gene therapy using a lipid vector by direct intratumoral injection. The gene therapy product contained the HLA-B7 gene and the beta2-microglobulin gene, which permits complete expression of the class I MHC at the cell surface. Patients were assessed for any adverse effects, for changes in tumor size, for time to disease progression, and for survival. Biopsy specimens were assessed for pathological response, HLA-B7 expression, apoptosis, cellular proliferation, CD-8 cells, granzyme, and p53 status.

RESULTS

There were no adverse effects from the gene therapy. At 16 weeks after beginning gene therapy, four patients had a partial response and two patients had stable disease. Two of the tumors completely responded clinically, but tumor was still seen on pathological examination. The time to disease progression in the responding patients was 20 to 80 weeks. The median survival in patients who completed gene therapy was 54 weeks, compared with 21 weeks in patients whose tumors progressed after the first cycle of treatment. One patient survived for 106 weeks without any additional therapy. HLA-B7 was demonstrated in the treated tumors, and increased apoptosis was seen in the responding tumors.

CONCLUSION

Significant advances have been made in the field of gene therapy for cancer. Alloantigen gene therapy has had efficacy in the treatment of cancer and can induce tumor responses in head and neck tumors. Alloantigen gene therapy has significant potential as an adjunctive treatment of head and neck cancer.