Rat Sodium Iodide Symporter for Radioiodide Therapy of Cancer

A NEW HYPOTHESIS IN THE TREATMENT OF RECURRENT GLIOBLASTOMA MULTIFORME (GBM). PART 1: INTRODUCTION

Modern treatment of glioblastoma multiforme (GBM) is based on neurosurgical methods combined with radiotherapy and chemotherapy. The prognosis for patients with GBM is extremely poor. Often, complete removal of the tumor is impossible and it often recurs. Therefore, in addition to standard regimens, modern methods such as modulated electrohyperthermia, monoclonal antibodies and individualised multimodal immunotherapy (IMI) based on vaccines and oncolytic viruses are also used in the treatment of GBM. Radioiodine therapy (RIT) also holds out hope for an effective treatment of this extremely aggressive brain tumor. The expression of the sodium iodide symporter (NIS) gene has been proven to have a positive effect on the treatment of selected cancers. Research confirm the presence of expression of this gene in GBM cells, although only in animal studies. Is it possible and therapeutically effective to treat GBM with RIT without the use of an exogenous NIS gene? The safety of therapy is relevant, as the only more serious adverse effect may be hypothyroidism. The use of RIT requires further clinical studies in patients. Perhaps it is worth revolutionizing GBM therapy to give sufferers a "new life".

Oncolytic viruses as a promising therapeutic strategy for hematological malignancies

The incidence of hematological malignancies such as multiple myeloma, leukemia, and lymphoma has increased over time. Although bone marrow transplantation, immunotherapy and chemotherapy have led to significant improvements in efficacy, poor prognosis in elderly patients, recurrence and high mortality among hematological malignancies remain major challenges, and innovative therapeutic strategies should be explored. Besides directly lyse tumor cells, oncolytic viruses can activate immune responses or be engineered to express therapeutic factors to increase antitumor efficacy, and have gradually been recognized as an appealing approach for fighting cancers. An increasing number of studies have applied oncolytic viruses in hematological malignancies and made progress. In particular, strategies combining immunotherapy and oncolytic virotherapy are emerging. Various phase I clinical trials of oncolytic reovirus with lenalidomide or programmed death 1(PD-1) immune checkpoint inhibitors in multiple myeloma are ongoing. Moreover, preclinical studies of combinations with chimeric antigen receptor T (CAR-T) cells are underway. Thus, oncolytic virotherapy is expected to be a promising approach to cure hematological malignancies. This review summarizes progress in oncolytic virus research in hematological malignancies. After briefly reviewing the development and oncolytic mechanism of oncolytic viruses, we focus on delivery methods of oncolytic viruses, especially systemic delivery that is suitable for hematological tumors. We then discuss the main types of oncolytic viruses applied for hematological malignancies and related clinical trials. In addition, we present several ways to improve the antitumor efficacy of oncolytic viruses. Finally, we discuss current challenges and provide suggestions for future studies.

Radiogenic Therapy: Novel Approaches for Enhancing Tumor Radiosensitivity

Radiotherapy (RT) is a well established modality for treating many forms of cancer. However, despite many improvements in treatment planning and delivery, the total radiation dose is often too low for tumor cure, because of the risk of normal tissue damage. Gene therapy provides a new adjunctive strategy to enhance the effectiveness of RT, offering the potential for preferential killing of cancer cells and sparing of normal tissues. This specificity can be achieved at several levels including restricted vector delivery, transcriptional targeting and specificity of the transgene product. This review will focus on those gene therapy strategies that are currently being evaluated in combination with RT, including the use of radiation sensitive promoters to control the timing and location of gene expression specifically within tumors. Therapeutic transgenes chosen for their radiosensitizing properties will also be reviewed, these include:

gene correction therapy, in which normal copies of genes responsible for radiation-induced apoptosis are transfected to compensate for the deletions or mutated variants in tumor cells (p53 is the most widely studied example). enzymes that synergize the radiation effect, by generation of a toxic species from endogenous precursors ( e.g., inducible nitric oxide synthase) or by activation of non toxic prodrugs to toxic species ( e.g., herpes simplex virus thymidine kinase/ganciclovir) within the target tissue. conditionally replicating oncolytic adenoviruses that synergize the radiation effect. membrane transport proteins ( e.g., sodium iodide symporter) to facilitate uptake of cytotoxic radionuclides.

The evidence indicates that many of these approaches are successful for augmenting radiation induced tumor cell killing with clinical trials currently underway.

Prolonged cardiac allograft survival using iodine 131 after human sodium iodide symporter gene transfer in a rat model

BACKGROUND

Radioiodine is efficiently concentrated by tissues expressing the human sodium iodide symporter (hNIS).

OBJECTIVE

To analyze the effects of iodine 131 on acute cardiac allograft rejection after ex vivo hNIS gene transfer in a rat model of cardiac allotransplantation.

MATERIALS AND METHODS

Hearts from Brown Norway rats were perfused ex vivo either with UW (University of Wisconsin) solution (n = 9) or UW solution containing 1 x 10(9) pfu/mL of adenovirus 5 plus NIS (Ad-NIS) (n = 18). Donor hearts were transplanted heterotopically into the abdomen of Lewis rats, and recipients were treated on postoperative day 3 with either 15,000 microCi of (131)I or saline solution. The hearts were explanted when no longer beating, and were evaluated histologically for evidence of rejection and other changes.

RESULTS

Grafts perfused with the Ad-NIS vector survived significantly longer in recipients injected with (131)I (mean [SD], 11.3 [1.9] days) compared with control animals not treated with (131)I (5.7 [0.65] days) (P < .001). Treatment with (131)I did not prolong graft survival in recipients of hearts that were not perfused with Ad-NIS (5.5 [1.0] vs 5.3 [0.8] days). In Ad-NIS (131)I-treated transplants, the level of myocardial damage on day 6 after surgery, when control hearts were rejected, was significantly lower (60.8 [28.0] vs 99.7 [0.8]; P < .05).

CONCLUSION

Our findings indicate that (131)I, after NIS gene transfer, can effectively prolong cardiac allograft survival. To our knowledge, this is the first report of the use of NIS-targeted (131)I therapy in cardiac transplantation. Further studies are required to determine the mechanism of this effect and its potential for clinical application.

Sodium iodide symporter (hNIS) permits molecular imaging of gene transduction in cardiac transplantation

BACKGROUND

We evaluated the feasibility of noninvasive micro-single photon emission computed tomography (SPECT)/computed tomography (CT) imaging and quantification of cardiac gene expression after sodium iodide symporter (hNIS) gene transfer in cardiac transplantation.

METHODS

Donor rat hearts were perfused ex vivo with adenovirus expressing hNIS (Ad-hNIS), Ad-Null, or University of Wisconsin (UW) solution prior to heterotopic transplantation into syngeneic recipients. In the first group of recipients, imaging of the transplanted hearts with micro-SPECT/CT on day 5 was followed by immediate explant of the organs for ex vivo analyses. Radioactivity counts in the explanted hearts were obtained ex vivo and expressed as a percentage of the injected dose per gram of tissue (%ID/g). Intensities of the SPECT images of the transplanted hearts were quantified and converted to radioactive counts using a standard equation. The second group of recipients was imaged sequentially after injection of I on days 2 to 14 after transplantation.

RESULTS

Higher ex vivo radioiodine counts were noted in the hearts perfused with Ad-hNIS (1.04+/-0.2) compared to either the UW group (0.31+/-0.11, P<0.001) or the Ad-Null group (0.32+/-0.08, P<0.001). Image intensity in the Ad-NIS group (0.9+/-0.2) was also significantly higher than in the UW group (0.4+/-.03, P=0.003) or the Ad-Null group (0.5+/-0.1, P<0.05). Sequential imaging of Ad-NIS-perfused hearts between postoperative days 2 and 14 revealed peak image intensity at day 5. Overall, image intensities correlated with ex vivo counts of radioactivity (rho=0.74, P<0.05).

CONCLUSIONS

These data demonstrate that hNIS gene transfer permits sequential real-time detection and quantification of reporter gene expression in the transplanted heart with micro-SPECT/CT imaging.

Non-invasive radioiodine imaging for accurate quantitation of NIS reporter gene expression in transplanted hearts

OBJECTIVE

We studied the concordance of transgene expression in the transplanted heart using bicistronic adenoviral vector coding for a transgene of interest (human carcinoembryonic antigen: hCEA - beta human chorionic gonadotropin: betahCG) and for a marker imaging transgene (human sodium iodide symporter: hNIS).

METHODS

Inbred Lewis rats were used for syngeneic heterotopic cardiac transplantation. Donor rat hearts were perfused ex vivo for 30 min prior to transplantation with University of Wisconsin (UW) solution (n=3), with 10(9) pfu/ml of adenovirus expressing hNIS (Ad-NIS; n=6), hNIS-hCEA (Ad-NIS-CEA; n=6) and hNIS-betahCG (Ad-NIS-CG; n=6). On postoperative day (POD) 5, 10, 15 all animals underwent micro-single photon emission computed tomography/computed tomography (SPECT/CT) imaging of the donor hearts after tail vein injection of 1000 microCi (123)I and blood sample collection for hCEA and betahCG quantification.

RESULTS

Significantly higher image intensity was noted in the hearts perfused with Ad-NIS (1.1+/-0.2; 0.9+/-0.07), Ad-NIS-CEA (1.2+/-0.3; 0.9+/-0.1) and Ad-NIS-CG (1.1+/-0.1; 0.9+/-0.1) compared to UW group (0.44+/-0.03; 0.47+/-0.06) on POD 5 and 10 (p<0.05). Serum levels of hCEA and betahCG increased in animals showing high cardiac (123)I uptake, but not in those with lower uptake. Above this threshold, image intensities correlated well with serum levels of hCEA and betahCG (R(2)=0.99 and R(2)=0.96, respectively).

CONCLUSIONS

These data demonstrate that hNIS is an excellent reporter gene for the transplanted heart. The expression level of hNIS can be accurately and non-invasively monitored by serial radioisotopic SPECT imaging. High concordance has been demonstrated between imaging and soluble marker peptides at the maximum transgene expression on POD 5.

A Prospective Study of Iodine Status, Thyroid Function, and Prostate Cancer Risk: Follow-up of the First National Health and Nutrition Examination Survey

Few studies have investigated the association between iodine status, thyroid disease, and cancer risk despite evidence that thyroid function impacts many organs, including the prostate. We investigated iodine status and prostate cancer risk prospectively using data from the NHANES I Epidemiologic Follow-up Study. Participants were stratified into tertiles according to the urinary iodine/creatinine ratio, as a marker of iodine exposure. As iodine is an integral constituent of thyroid hormones, we also examined the relationship between thyroid disease and prostate cancer risk. Relative to the group with low urinary iodine, the age-adjusted hazard ratio was higher (although marginally insignificant) in the moderate group, hazard ratio 1.33 (95% confidence interval 1.00-1.78), and significantly lower in the high group, 0.71 (0.51-0.99). Thyroid disease was associated with an increased prostate cancer risk, 2.34 (1.24-4.43). Similarly, > 10 yr since thyroid disease diagnosis was associated with an elevated risk, 3.38 (1.66-6.87). After adjusting for other confounding factors, only a history of thyroid disease, 2.16 (1.13-4.14), and > 10 yr since diagnosis of thyroid disease, 3.17 (1.54-6.51) remained significant. Although the role of dietary iodine remains speculative, a role for thyroid disease and/or factors contributing to thyroid disease as a risk factor for prostate carcinogenesis warrants additional investigation.

Gene manipulation to enhance MIBG-targeted radionuclide therapy

The goal of targeted radionuclide therapy is the deposition in malignant cells of sterilizing doses of radiation without damaging normal tissue. The radiopharmaceutical [(131)I]meta-iodobenzylguanidine ([(131)I]MIBG) is an effective single agent for the treatment of neuroblastoma. However, uptake of the drug in malignant sites is insufficient to cure disease. A growing body of experimental evidence indicates exciting possibilities for the integration of gene transfer with [(131)I]MIBG-targeted radiotherapy.

Rat sodium iodide symporter allows using lower dose of 131I for cancer therapy

Efficient gene delivery is a critical obstacle for gene therapy that must be overcome. Until current limits of gene delivery technology are solved, identification of systems with bystander effects is highly desirable. As an anticancer agent, radioactive iodine (131)I has minimal toxicity. The physical characteristics of (131)I decay allow radiation penetration within a local area causing bystander killing of adjacent cells. Accumulation of (131)I mediated by the sodium iodide symporter (NIS) provides a highly effective treatment for well-differentiated thyroid carcinoma. Other types of cancer could also be treated by NIS-mediated concentration of lethal (131)I radiation in tumor cells. Our group and others previously reported that a significant antitumor effect in mice was achieved after adenoviral delivery of rat or human NIS gene following administration of 3 mCi of (131)I. We have also demonstrated 5-6-fold greater uptake of (125)I by rat NIS over human NIS in human cancer cells. Recently, we reported the capability of the rat NIS and (131)I to effectively induce growth arrest of relatively large tumors (approximately 800 mm(3)) in an animal model. In the present work tumor growth inhibition was achieved using adenoviral delivery of the rat NIS gene and 1 mCi of (131)I (one-third of the dose used in earlier reports). We also demonstrated that a higher concentration of (123)I was accumulated in the NIS-expressing tumors than in the thyroid 20 min after radioiodine administration. The highest intratumoral radioiodine concentration was observed along the needle track; however, the rat NIS-(131)I effectively induced growth arrest of tumor xenografts in mice through its radiological bystander effect. Importantly, the rat NIS allowed reducing the injected radioiodine dose by 70% with the same antitumor efficacy in pre-established tumors. These results suggest that the rat NIS gene may be advantageous compared to the human gene in its ability to enhance intratumoral (131)I uptake.

A Preclinical Large Animal Model of Adenovirus-Mediated Expression of the Sodium–Iodide Symporter for Radioiodide Imaging and Therapy of Locally Recurrent Prostate Cancer

The sodium-iodide symporter (NIS) is primarily a thyroid protein, providing for the accumulation of iodide for biosynthesis of thyroid hormones. Native NIS expression has made possible the use of radioactive iodide to image and treat thyroid disease successfully. The current study, using adult male beagle dogs, was carried out in preparation for a Phase I clinical trial of adenovirus-mediated NIS gene (approved symbol SLC5A5) therapy for prostate cancer. Direct intraprostatic injection of virus (Ad5/CMV/NS) was followed by iv injection of 3 mCi 123I and serial image acquisition. The dogs were then given a therapeutic dose of 131I (116 mCi/m2) and observed for 7 days. SPECT/CT fusion imaging revealed clear images of the NIS-transduced prostates. Dosimetry calculations revealed an average absorbed dose to the prostate of 23 +/- 42 cGy/mCi 131I, with acceptably low radiation doses to other organs. This study demonstrated the successful introduction of localized NIS expression in the prostate gland of dogs, with no vector-related toxicity observed. None of the animals experienced any surgical complications, and serum chemistry panels showed no significant change following therapy. The results presented provide further evidence of the safety and efficacy of NIS as a therapeutic gene and support translation of this work into the clinical setting.

Effective Growth Arrest of Human Colon Cancer in Mice, Using Rat Sodium Iodide Symporter and Radioiodine Therapy

We have demonstrated that the rat sodium iodide symporter (rNIS) and 131I can effectively induce growth arrest of human prostate tumor xenografts [Mitrofanova, E., Unfer, R., Vahanian, N., Daniels, W., Roberson, E., Seregina, T., Seth, P., and Link, C. (2004). Rat sodium iodide symporter (rNIS) for radioiodide therapy of cancer. Clin. Cancer Res. 10, 6969-6976]. In that study the average size of tumors established in athymic nude mice was 200 +/- 50 mm3 when treated. Testing under more rigorous and extreme in vitro conditions will better evaluate the ability of an anticancer approach to induce tumor regression or killing capacity in preclinical studies. In this work the ability of the rNIS and 131I system to inhibit the growth of relatively large (about 800 mm3 when treated with 131I) and rapidly growing colon tumors in an animal model was examined. in vitro experiments demonstrated that transduction of human colon cancer cells with Ad-rNIS resulted in a 100- to 150-fold increase in 125I uptake compared with nontransduced cells. Western blot analysis revealed robust expression of rNIS protein in cells 72-120 hr posttransduction with Ad-rNIS. Immunocytochemical analysis demonstrated that intracellular localization of rNIS-specific staining was observed mainly in plasma membranes of cells. in vitro studies revealed an immediate inhibition of growth of rapidly expanding tumors after radioiodine injection in the rNIS and 131I treatment group of mice. Twenty-seven percent of experimental mice survived more than 30 days (p = 0.019), whereas control groups had only 7% survival over 30 days. This is the first report demonstrating that rat NIS and 131I can effectively induce growth arrest of relatively large tumors in an animal model.

In vivo radioiodide imaging and treatment of breast cancer xenografts after MUC1-driven expression of the sodium iodide symporter

PURPOSE

Expression of the sodium iodide symporter (NIS) in the thyroid gland provides for effective imaging and treatment of thyroid cancer using radiolabeled iodide. Transfer of NIS into other tumors would expand the utility of this treatment to tumors of nonthyroid origin. MUC1 is a transmembrane glycoprotein that is overexpressed in many tumor types, including breast, pancreatic, and ovarian. The aim of this study was to create a construct containing NIS under the control of the MUC1 promoter to target expression specifically to MUC1-positive breast cancer cells.

EXPERIMENTAL DESIGN

A replication-deficient adenoviral construct was created containing the MUC1 promoter followed by the human NIS gene. Iodide uptake assays, Western blot, and immunohistochemistry were used to confirm NIS expression and function. Breast cancer xenografts in mice were infected with Ad5/MUC1/NIS and then imaged and treated using radioiodide.

RESULTS

A 58-fold increase in iodide uptake was observed in infected MUC1-positive T47D cells with no significant increase observed in MUC1-negative MDA-MB-231 cells or in cells infected with the control virus. The in vivo study yielded clear images of Ad/MUC1/NIS-infected tumor xenografts using (123)I. Administration of a therapeutic dose of (131)I resulted in an 83% reduction in tumor volume, whereas control tumors continued to increase in size (P < 0.01).

CONCLUSIONS

These results show that the MUC1 promoter is capable of directing efficient and selective expression of the NIS gene in MUC1-positive breast tumor cells. This could potentially have applications for both imaging and therapy in a range of MUC1-positive tumor types.