Gene Therapy for Liver Tumors

Bilobar colorectal liver metastases: a new model for preclinical studies

SUMMARY

This study aimed to develop a new model of colorectal liver metastases (LM) in the rat. Both single macroscopic and multiple bilobar microscopic LM were investigated, as this closely resembled the human situation, before right hepatectomy was performed for 'single' right LM. The single macroscopic LM was elicited by direct injection of DHD/K12 colorectal cancer cells under the capsule of the median liver lobe in immunocompetent BDIX rats. The bilobar micrometastases were elicited by intraportal injection of DHD/K12 cells. A preliminary protocol was conducted to assess the dose of cells required to inject in to the portal vein, using 10(6) , 2 × 10(6) and 3 × 10(6) DHD/K12 cells (n = 15 rats). The resultant protocol for the experimental model used intraportal injection of 10(6) DHD/K12 cells and direct injections of 0.5 × 10(6) , 10(6) and 1.5 × 10(6) DHD/K12 cells (n = 15 rats). For both protocols, BDIX rats were sacrificed at day 30 after injection. The preliminary protocol showed that intraportal injection of 10(6) DHD/K12 cells was associated with bilobar micrometastases of 0.8 mm mean diameter at day 30. The main protocol assessed that direct injection of 0.5 × 10(6) under the liver median lobe capsule and intraportal injection of 10(6) DHD/K12 cells were associated at day 30 with a single macroscopic metastasis confined to a liver lobe and bilobar micrometastases, without peritoneal carcinomatosis or lung metastasis. Thus we have developed a new experimental model of bilobar colorectal LM including both macro- and microscopic colorectal LMs, which mimics the human situation and which will be useful in preclinical studies.

Tumor recurrence after partial hepatectomy for liver metastases in rats: prevention by in vivo injection of irradiated cancer cells expressing GMCSF and IL-12

BACKGROUND

Adjuvant treatment could be helpful in prevent recurrence after partial hepatectomy for liver metastases. The purpose of this study was to assess the benefit of in vivo injection of irradiated autologous cancer cells expressing cytokines after partial hepatectomy in rats.

METHODS

Fifty-four BDIX rats were injected with 3 x 10(6) DHD-K12 cancer cells into the portal vein to induce multiple hepatic metastases. A 70% hepatectomy was carried out 3 days after the injection. The rats were then randomized into three groups of 18 rats each. Rats were given three injections at days 8, 15, and 21 of 5 x 10(6) irradiated DHD-K12 cancer cells expressing either interleukin 12 (IL-12) (group 1), granulocyte monocyte colony stimulating factor (GM-CSF) (group 2), or only saline solution (control group). At day 30, animals of each group were divided into two subgroups: 10 rats of each group were killed for pathological examination and cytofluorimetric analysis and 8 rats of each group were maintained for survival follow-up.

RESULTS

At day 30, mean number of tumors on liver surface was lower in rats treated by irradiated cancer cells expressing IL-12 than those in GM-CSF group or in the control group. Furthermore, peritoneal carcinomatosis was significantly more frequent in the control group: 3/9 (33%) than in pooled IL-12 and GM-CSF groups: 1/19 (5%) (P < 0.05). In the survival study, we observed a significant increased survival in treated rats compared with the control group (P = 0.0008).

CONCLUSION

Our results suggest that vaccination with autologous irradiated cancer cells expressing either IL-12 or GM-CSF induced a systemic immune antitumoral response that may be useful as an adjuvant therapy after surgical resection for liver metastases.

Gene therapy of hepatocarcinoma: a long way from the concept to the therapeutical impact

Hepatocellular carcinoma (HCC), the most prevalent histological form of primary liver cancer is one of the most frequent cancer worldwide. This pathology still requires the development of new therapeutical approaches. Gene therapy strategies focusing on the genetic manipulation of accessory cells involved in the immune reaction against cancer cells, or on the direct transduction of tumor cells with transgenes able to "suicide" cancer cells have been largely developed for more than ten years.

Dr. Gary J. Becker Young Investigator Award: intraarterial adenovirus for metastatic gastrointestinal cancer: activity, radiographic response, and survival

PURPOSE

To determine the antitumoral activity and radiographic response pattern of intraarterial administration of a selective replication-competent adenovirus in patients with hepatic metastases from gastrointestinal carcinomas.

MATERIALS AND METHODS

Thirty-five patients were treated, seven in the dose-escalation phase and 28 at high doses. Inclusion criteria allowed mild laboratory value and performance status abnormalities and as much as 50% replacement of hepatic volume by tumor. An attenuated adenovirus that selectively replicates in p53-deficient cells (Onyx-015) was administered by hepatic arterial infusion at doses as high as 2 x 10(12) particles for two cycles. Subsequent cycles (maximum of eight total) were administered in combination with intravenous 5-fluorouracil (5-FU) and leucovorin.

RESULTS

Tumor responses were demonstrated in combination with chemotherapy, even in 5-FU-resistant patients. The 15 patients who responded radiographically showed a pattern of acute tumor enlargement despite normalization of laboratory and clinical parameters, followed by very slow regression of tumor size. Radiographic response did not correlate with p53 status. Median survival of radiographic responders (475 days) was significantly longer than that of nonresponders (143 days).

CONCLUSIONS

Hepatic arterial infusion of the replication-selective adenovirus Onyx-015 in combination with chemotherapy resulted in tumor regressions in select patients, including some in whom previous chemotherapy had failed. A biphasic radiographic response pattern was demonstrated. The mechanism of action appears to be more complex than that seen in vitro.

Intra-arterial delivery of a recombinant adenovirus does not increase gene transfer to tumor cells in a rat model of metastatic colorectal carcinoma

Hepatic artery infusion of adenoviral vectors has been shown to increase transduction of certain hepatocellular malignancies in preclinical studies. In addition, clinical trials have begun evaluating the efficacy of gene transfer of cytotoxic genes to metastatic colorectal tumors through hepatic artery infusion. Here we evaluate the extent of gene expression and therapeutic effect following various routes of administration of recombinant adenovirus in a rat model of metastatic colorectal carcinoma. We administered adenovirus (AdCMVlacZ) to rats with established colorectal metastases through infusion into the hepatic artery, intravenous infusion, or direct injection into a tumor. Intravenous administration resulted in transduction of hepatocytes, but not tumor cells. Hepatic arterial administration failed to substantially increase transduction of tumor cells. In addition, ligation of the hepatic artery following infusion of adenovirus or the addition of lipiodol infusion had no effect on the transduction of tumor cells. We administered AdCMVp53 by direct injection into tumors, intravenous administration, or hepatic artery infusion to evaluate the delivery of a therapeutic gene. Direct injection of AdCMVp53 into established hepatic colorectal metastases resulted in a therapeutic response in comparison with both hepatic arterial and intravenous infusion of vector. These preclinical studies fail to support a strategy of infusion through the hepatic artery of recombinant adenovirus targeting tumor cells in the treatment of colorectal cancer liver metastases.

Risk-based management of solid tumors in children

BACKGROUND

During the past 25 years significant improvements in survival (56% to 75%) have been observed for children with malignant solid tumors. Multidisciplinary cooperative studies using combined therapy (surgery, chemotherapy, and irradiation) have played a major role. This report describes how recognition of biologic and genetic factors has permitted risk categorization and resulted in new treatment protocols that individualize care.

METHODS

Genetic alterations and biologic factors concerning the multiple endocrine neoplasia syndromes, Wilms' tumor, and neuroblastoma are described.

RESULTS

Using the these data new treatment protocols are designed according to whether a patient is categorized as having a low-, intermediate-, or high-risk tumor, which determines the intensity and type of treatment required.

CONCLUSIONS

Identification of biologic markers and specific gene alterations may be critical in establishing the behavior of tumors (low versus high-risk). Risk-based management permits individualized care for each patient, maximizes survival, minimizes morbidity, and improves the quality of life.

Risk-based management: current concepts of treating malignant solid tumors of childhood

BACKGROUND

Improved survival with pediatric malignancies has been positively influenced by multidisciplinary cooperative studies using surgery, chemotherapy, and radiation therapy, but one-third of all children with cancer succumb to their condition. The identification of biologic and genetic characteristics as risk factors for the various tumors has led to changes in treatment using risk-based management as the template for care.

STUDY DESIGN

The purpose of this report is fourfold: (1) to review survival data concerning three solid malignant tumors of childhood (Wilms' tumor, rhabdomyosarcoma, and neuroblastoma), (2) to describe important prognostic genetic and biologic risk factors for each tumor, (3) to update changes in staging criteria, and (4) to familiarize the reader with the concept of risk-based management, which individualizes treatment in an attempt to maximize survival and minimize longterm morbidity.

RESULTS

The overall survival rates for Wilms' tumor, rhabdomyosarcoma, and neuroblastoma are currently 90%, 70%, and 40%, respectively. Most patients with Wilms' tumor have favorable histology and survive after nephrectomy and chemotherapy, but 10% have poor prognostic variables, including unfavorable (anaplastic) histology, chromosomal loss on 1p and 16q, and diploidy. Instances of lung or liver metastases, major tumor spillage during resection, remote lymph node involvement, and bilateral tumors have worse outcomes. Rhabdomyosarcoma is associated with chromosomal translocation of t(2:13) in alveolar types, the p53 tumor suppressor gene, and 11p15. Survival is dependent on the tumor site and pretreatment clinical group. Orbit, paratesticular, vulvar, and vaginal tumors have a good prognosis, but other genitourinary tumors, extremity and trunk lesions, and parameningeal head and neck tumors have a worse prognosis. Survival rates by clinical group are stage I, 93%; II, 81%; III, 73%; and IV, 30%. Resectability, lymph node involvement, DNA ploidy, and pretreatment TNM staging affect outcomes. Neuroblastoma is an embryonal tumor with bizarre behavior and can regress, mature, or rapidly progress. Most patients have advanced disease at diagnosis. Neuroblastoma is associated with loss of heterozygosity on chromosome 1p36 and occasionally deletions on 14q and 17q. Survival is affected by age and stage (at less than 1 year, stages I [95% to 100%], II [85% to 90%], and IV-S [more than 80%] do better) and other risk factors. Patients with advanced disease (older than 1 year, stage III [70%], and stage IV [12%]) often have amplification of the N-myc oncogene, diploid tumors, 1p36 deletion, and unfavorable histology and fare worse.

CONCLUSIONS

On the basis of these data, children with solid tumors are currently categorized into low-, intermediate-, and high-risk groups. Newer protocols individualize treatment using risk factors as predictors of outcomes. Risk-based management allows the clinician to weigh the risks and benefits of treatment for each patient to maximize survival, minimize longterm morbidity, and improve the quality of life.

Cancer gene therapy using a replication-competent herpes simplex virus type 1 vector

OBJECTIVE

The authors investigate the efficacy of hrR3, a viral vector derived from herpes simplex virus type 1 (HSV 1), in destroying colon carcinoma cells in vitro and in vivo. The effect of adding the prodrug ganciclovir in combination with hrR3 infection also is assessed.

SUMMARY BACKGROUND DATA

Most cancer gene therapy strategies use viral vectors that are incapable of replication. The HSV 1 vector hrR3 is capable of replication, and its replication is cytotoxic to cells. hrR3 also possesses the HSV-thymidine kinase gene, which converts ganciclovir into a toxic metabolite. Thus, the addition of ganciclovir to hrR3-infected cells may enhance the ability of hrR3 to destroy tumor cells. To increase specificity for tumor cells, hrR3 has a mutated ribonucleotide reductase gene and replicates selectively in cells with high levels of endogenous rbonucleotide reductase. Actively dividing cells such as tumor cells have high levels of endogenous ribonucleotide reductase for synthesis of DNA precursors. The authors are interested in the use of HSV 1 vectors to treat liver metastases from colorectal cancer.

METHODS

Ribonucleotide reductase expression in several colon carcinoma cell lines and in primary cultures of human hepatocytes was determined by Western blot analysis. hrR3-mediated cytotoxicity in the colon carcinoma cell lines was determined using an in vitro assay. The human colon carcinoma cell line HT29 was injected into the flanks of nude mice followed by intratumoral injection of hrR3. Tumor growth rate was assessed with and without the addition of intraperitoneal ganciclovir.

RESULTS

Ribonucleotide reductase levels in colon carcinoma cell lines are much higher than in primary cultures of human hepatocytes. hrR3 efficiently destroys colon carcinoma cell lines in vitro. A single intratumoral injection of hrR3 into HT29 flank tumors significantly reduces tumor growth rate, and the administration of ganciclovir has no additive effect.

CONCLUSIONS

The inherent cytotoxicity of hrR3 replication effectively destroys colon carcinoma cells in vitro and in vivo. This cytotoxicity is not enhanced in vivo by the addition of ganciclovir. In the future, more efficacious and selective HSV 1 vectors may be useful in the treatment of cancer.