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Intraarterial Gene Therapy Infusion
7. Arora K, Pedersen PL. Functional significance of mi~ tochondrial-bound hexokinase in tumor cell metabolism: evidence for preferential phosphorylation of glucose by intramitochondrially generated ATP. J Biol Chern 1988;263,17422-17428. 8. Mathupala SP, Rempel A, Pedersen PL. Glucose catabolism in cancer cells: isolation, sequence, and activity of the promoter for Type II hexokinase. J Bioi Chern 1995;270,16918-16925. 6,00 p.m.
Intraarterial Gene Therapy Infusion Daniel y. Sze, MD, PhD Stanford University Medical Center Statiford, California Learning objectives: upon completion of this course, the attendee should he ahle to, 1) Define gene therapy; 2) List 3 possihle clinical applicatiOns oj gene therapy; 3) List 2 theoretical advantages of intraarterial infUSion of gene therapy agents; 4) Describe how tumor suppressor abnonnalities may aI/ow neoplastic growth; 5) List 2 ways to manipulate tumor suppressor abnormalities to treat cancer. Gene therapy has been touted as the next great revolution of medicine for over a decade. However, there are no currently widely accepted genetic therapies approved for hl.lman subjects. Despite the rapid advancement of the molecular understanding of human pathology, application of bench discoveries to bedside patients has been more difficult than anticipated. Recognition of genetic abnormalities in human diseases turns out to be the easier aspect of molecular medicine-reversing or altering these genetic abnormalities remains the difficult aspect. At the SCVIR annual meeting in 2000, a full-day symposium was dedicated to gene therapy. Unfortunately, just when clinical progress was seeing the first successful human trials, a teenage participant in an ornithine decarbamylase deficiency (ODe) trial suffered severe hepatic toxicity from intraarterial infusion of an adenovirus vector, leading to fulminant hepatic failure, adult respiratory distress syndrome (ARDS), and finally multi-organ failure and death. The Food and Drug Administration (FDA), Recombinant DNA Advisory Committee (RAC), and the whole gene therapy community at large called for a temporary moratorium on human trials while the guidelines and regulatory pathways for human experimentation were re-tooled (1). Last year, in the SCVIR meeting proceedings, the index listed only one abstract under the subject "gene therapy." Now that these guidelines and regulations have been clarified, human trials are again underway, and promise to be a rapidly growing frontier for intervemional oncology. Gene therapy is defined as "alteration or insertion of genetic material into an organism to replace or repair a defect in order to correct or prevent disease." Some diseases are single gene/single enzyme defects, which
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might be curable if corrected. Other diseases have multiple defects, but may exhibit common pathways so that alteration of only one gene may be efficacious (2). Possible applications include reversal of metabolic deficiencies, such as ODe, of coag':!lation factor deficiencies, such as hemophilias, or of vascular diseases such as atherosclerosis and restenosis. Overall, a large majority of the clinical trials in progress address new treatments for malignancies. The spectrum of possible genetic therapy for cancer includes suicide genes, imrnunomodulation such as cytokine induction, tumor vaccines, or surface immunogenicity enhancement, suppression of oncogenes, or restoration of tumor suppressors. In general, cancers demonstrate myriad genetic abnonnalities, but the possibility of selectively killing neoplastiC cells by reversal or exploitation of a genetic Achilles' heel reveals eXciting opportunities. To deliver the genetic payload to the target cells, a vector is used as the vehicle. Most current research is aimed at engineering nature's own TrOjan horses, the viruses, to deliver the genetic therapy (3). Viruses commonly used include adenOVirus, adeno-associated virus, herpes virus, lentivims, retrovinJs, and parvovllus, each with its own characteristics. In addition, non-viral vectors are being investigated, including liposome, lipid, or protein conjugates, and colloidal gold microspheres (gene gun). The highest rates of successful transfection (viral infection and transfer of genetic material) in vitro have been with the adenovinJs, a double-stranded DNA virus capable of infecting all cells regardless of mitotic or DNA-synthetic actiVity. 'fhe pharmacokinetics of delivering adenoviruses, though, are complicated by the subjects' natural defense mechanism against the adenovllus, which ordinarily causes the common cold. Targeted regional delivery, similar to the techniques employed for regional chemotherapy delivery, may be a good solution to this problem. The liver has been the proVing ground for regional chemotherapy, and appears to be the emerging proVing ground for regional gene therapy, as weJl. Several routes of delivery are possible, induding direct intra-parenchy· mal or intrabiliary injection, intravenous, imraportal, or intraarterial infusions. Experiments in animal models as well as in human subjects show highest rates of transfecLion when vectors are delivered intraarterially. Angiographic techniques such as balloon occlusion, embolization, organ isolation, infusion with vasoactive drugs may also augment transfection. A number of trials have started attempting to manipulate tumor suppressor function. Most of these attempt to replace a missing or mutant tumor suppressor by re-insertion of the wild type gene using a viral vector (4). However, the largest clinical trial explOiting tumor suppressor abnormalities uses an engineered adenovirus dl-1520, also known as Onyx-OJ 5, not to replace deficient tumor suppressor, but to exploit its absence (5), This virus is incapable of synthesiZing the early gene
product E1B, whose function is to deactivate the p53 tumor suppressor found in normal human cells. In the absence of ElB, Onyx-015 can theoretically only infect p53-deficient cells. Over half of all solid tumors in humans demonstrate mutations in p53, rendering them selectively susceptible to Onyx-015 mediated cell lysis. In addition, Onyx-015 appears to have synergistic interactions with standard chemotherapies and with radiation (5,6). Direct injection of Onyx-015 into refractory head and neck squamous cell carcinoma, in conjunction with intravenous chemotherapy, yielded statistically superior results when compared with chemotherapy alone (7). However, direct injection into pancreatic adenocarcinomas was not clinically effIcacious (8). In a Phase I and 1I trial addressing metastatic gastrointestinal carcinomas metastatic to the liver, Onyx-015 was found to be safe at doses up to lOll pfu (plaque forming units), with no dose-limiting toxicities when administered intraarterially (9). In addition, infection and active replication of virus was documented in treated tumors. Efficacy was documented by normalization of the tumor marker carcinoembryonic antigen (CEA), normalization of liver function tests, and tumor stabilization or shrinkage. Cytokine induction, including of interferon gamma, interleukin 2, 6, and 10, and tumor necrosis factor, was dramatiC, likely contributing to the efficacy (10). Interestingly, despite large increases in antibody titers against adenovirus, the pharmacokinetics of repeat administrations were not significantly different from the first, suggesting that arterial administration effectively saturated the humoral immune response. Median surVival, expected to be approXimately 4 months in the selected end-stage patient population, is approximately 2 years after treatment by Onyx-015 and intravenous 5-fluorouracil and leucovorin. As the safety profiles of gene therapy vectors become better understood, a wider variety of human pathologies will be subjects of clinical trials. Drawing upon the established advantages of regional drug delivery, many of these trials will exploit interventional radiological methods to deliver the genetic agents.
References 1. Miller HI. Gene therapy on trial. Science 2000;287: 591-592. 2. Voss SD, Kruskal JB. Gene therapy: a primer for radiologists. Radiographies 1998;18: 1343-1372. 3. Ferry N, Heard JM. Liver-directed gene transfer vectors. Hum Gene Ther 1998;9:1975-1981. 4. Swisher SG, RothJA, Nemunaitis), et al. Adenovirusmediated p53 gene transfer in advanced non-smallcell lung cancer.) !\atJ Cancer Inst 1999;91:763-771. 5. Kim D. Clinical research results with d11520 (Onyx015), a replication-selective adenovirus for the treatment of cancer: what have we learned? Gene Ther 2001 ;8:89-98.
6. Rogulski KR, Freytag SO, Zhang K, et al. In vivo antitumor activity of ONYX-015 is influenced by p53 status and is augmented by radiotherapy. Cancer Res 2000;60: 1193-1196. 7. Khuri FR, Nemunaitis J, Ganly 1, et al. a controlled trial of intratumoral ONYX-015, a selectively-replicating adenovillJs, in combination with cisplatin and 5-fluorouracil in patients with recurrent head and neck cancer. Nat Med 2000;6:879-885. 8. Mulvihill S, Warren R, Venook A, et at. Safety and feasibility of injection with an ElB-55 kDa genedeleted, replication-selective adenovirus (ONYX015) into primaly carcinomas of the pancreas: a phase I trial. Gene Ther 2001;8:308-315. 9. Sze DY, Kim D, Reid TR. Intraarterial treatment of metastatic gastrointestinal cancer using an E1B-deleted adenovirus. ) Vasc Intervent Radiol 2001;12(1 part 2):s6. 10. Reid T, Galanis E, Abbruzzese J, et al. A phase II trial of hepatic artery infusion with a replication-selective adenovirus (d11520) plus intravenous 5-fluorouracil in patients with colorectal carcinoma metastatic to the liver. ) Clin Oncol 2001 On press).
6:10 p.m. Intratumoral Gene Therapy Marshall Hicks, MD University of Texas M.D. Anderson Cancer Center Houston, Texas Learning objectives: upon completion of th'is course, the attendee should be able to: 1) List strategies involved with cancer gene based therapies; 2) Give examples of techniques and limitations ofdirect in vivo intratumoral gene therapy; 3) List ongOing clinical Mal applications of intratumoral gene therapy. There are more than 500,000 cancer deaths annually. in the United States, including a 50% mortality rate from solid tumors. Given these facts, it is probably not surprising that more than half of the Phase One trials for gene therapy in the ·s are cancer related. Gene-based therapies may provide more effective means of treating or preventing cancers than preViOUS, and more conventional, types of therapy such as surgery, radiation, or drug therapies. Existing strategies involve tumor suppression, antiangiogenesis, inhibition of oncogen expression, induction of drug sensitivity Onclurung suicide genes), increased immune response (via cytokines and activation oft-lymphocytes), and protection of the host from other cancer therapies with associated toxicities. Direct in vivo inlratumoral therapy is one means of veCtor delivery. Imaged based direct intratumoral vector delivery provides advantages similar to other imaged based therapies-maximized effIciency of tumor therapy, and documentation of physieal pOSition. IntervcntionaI radiology can playa critical role in the develop-
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Intraarterial Gene Therapy Infusion Daniel y. Sze, MD, PhD Stanford University Medical Center Statiford, California Learning objectives: upon completion of this course, the attendee should he ahle to, 1) Define gene therapy; 2) List 3 possihle clinical applicatiOns oj gene therapy; 3) List 2 theoretical advantages of intraarterial infUSion of gene therapy agents; 4) Describe how tumor suppressor abnonnalities may aI/ow neoplastic growth; 5) List 2 ways to manipulate tumor suppressor abnormalities to treat cancer. Gene therapy has been touted as the next great revolution of medicine for over a decade. However, there are no currently widely accepted genetic therapies approved for hl.lman subjects. Despite the rapid advancement of the molecular understanding of human pathology, application of bench discoveries to bedside patients has been more difficult than anticipated. Recognition of genetic abnormalities in human diseases turns out to be the easier aspect of molecular medicine-reversing or altering these genetic abnormalities remains the difficult aspect. At the SCVIR annual meeting in 2000, a full-day symposium was dedicated to gene therapy. Unfortunately, just when clinical progress was seeing the first successful human trials, a teenage participant in an ornithine decarbamylase deficiency (ODe) trial suffered severe hepatic toxicity from intraarterial infusion of an adenovirus vector, leading to fulminant hepatic failure, adult respiratory distress syndrome (ARDS), and finally multi-organ failure and death. The Food and Drug Administration (FDA), Recombinant DNA Advisory Committee (RAC), and the whole gene therapy community at large called for a temporary moratorium on human trials while the guidelines and regulatory pathways for human experimentation were re-tooled (1). Last year, in the SCVIR meeting proceedings, the index listed only one abstract under the subject "gene therapy." Now that these guidelines and regulations have been clarified, human trials are again underway, and promise to be a rapidly growing frontier for intervemional oncology. Gene therapy is defined as "alteration or insertion of genetic material into an organism to replace or repair a defect in order to correct or prevent disease." Some diseases are single gene/single enzyme defects, which
P314
might be curable if corrected. Other diseases have multiple defects, but may exhibit common pathways so that alteration of only one gene may be efficacious (2). Possible applications include reversal of metabolic deficiencies, such as ODe, of coag':!lation factor deficiencies, such as hemophilias, or of vascular diseases such as atherosclerosis and restenosis. Overall, a large majority of the clinical trials in progress address new treatments for malignancies. The spectrum of possible genetic therapy for cancer includes suicide genes, imrnunomodulation such as cytokine induction, tumor vaccines, or surface immunogenicity enhancement, suppression of oncogenes, or restoration of tumor suppressors. In general, cancers demonstrate myriad genetic abnonnalities, but the possibility of selectively killing neoplastiC cells by reversal or exploitation of a genetic Achilles' heel reveals eXciting opportunities. To deliver the genetic payload to the target cells, a vector is used as the vehicle. Most current research is aimed at engineering nature's own TrOjan horses, the viruses, to deliver the genetic therapy (3). Viruses commonly used include adenOVirus, adeno-associated virus, herpes virus, lentivims, retrovinJs, and parvovllus, each with its own characteristics. In addition, non-viral vectors are being investigated, including liposome, lipid, or protein conjugates, and colloidal gold microspheres (gene gun). The highest rates of successful transfection (viral infection and transfer of genetic material) in vitro have been with the adenovinJs, a double-stranded DNA virus capable of infecting all cells regardless of mitotic or DNA-synthetic actiVity. 'fhe pharmacokinetics of delivering adenoviruses, though, are complicated by the subjects' natural defense mechanism against the adenovllus, which ordinarily causes the common cold. Targeted regional delivery, similar to the techniques employed for regional chemotherapy delivery, may be a good solution to this problem. The liver has been the proVing ground for regional chemotherapy, and appears to be the emerging proVing ground for regional gene therapy, as weJl. Several routes of delivery are possible, induding direct intra-parenchy· mal or intrabiliary injection, intravenous, imraportal, or intraarterial infusions. Experiments in animal models as well as in human subjects show highest rates of transfecLion when vectors are delivered intraarterially. Angiographic techniques such as balloon occlusion, embolization, organ isolation, infusion with vasoactive drugs may also augment transfection. A number of trials have started attempting to manipulate tumor suppressor function. Most of these attempt to replace a missing or mutant tumor suppressor by re-insertion of the wild type gene using a viral vector (4). However, the largest clinical trial explOiting tumor suppressor abnormalities uses an engineered adenovirus dl-1520, also known as Onyx-OJ 5, not to replace deficient tumor suppressor, but to exploit its absence (5), This virus is incapable of synthesiZing the early gene
product E1B, whose function is to deactivate the p53 tumor suppressor found in normal human cells. In the absence of ElB, Onyx-015 can theoretically only infect p53-deficient cells. Over half of all solid tumors in humans demonstrate mutations in p53, rendering them selectively susceptible to Onyx-015 mediated cell lysis. In addition, Onyx-015 appears to have synergistic interactions with standard chemotherapies and with radiation (5,6). Direct injection of Onyx-015 into refractory head and neck squamous cell carcinoma, in conjunction with intravenous chemotherapy, yielded statistically superior results when compared with chemotherapy alone (7). However, direct injection into pancreatic adenocarcinomas was not clinically effIcacious (8). In a Phase I and 1I trial addressing metastatic gastrointestinal carcinomas metastatic to the liver, Onyx-015 was found to be safe at doses up to lOll pfu (plaque forming units), with no dose-limiting toxicities when administered intraarterially (9). In addition, infection and active replication of virus was documented in treated tumors. Efficacy was documented by normalization of the tumor marker carcinoembryonic antigen (CEA), normalization of liver function tests, and tumor stabilization or shrinkage. Cytokine induction, including of interferon gamma, interleukin 2, 6, and 10, and tumor necrosis factor, was dramatiC, likely contributing to the efficacy (10). Interestingly, despite large increases in antibody titers against adenovirus, the pharmacokinetics of repeat administrations were not significantly different from the first, suggesting that arterial administration effectively saturated the humoral immune response. Median surVival, expected to be approXimately 4 months in the selected end-stage patient population, is approximately 2 years after treatment by Onyx-015 and intravenous 5-fluorouracil and leucovorin. As the safety profiles of gene therapy vectors become better understood, a wider variety of human pathologies will be subjects of clinical trials. Drawing upon the established advantages of regional drug delivery, many of these trials will exploit interventional radiological methods to deliver the genetic agents.
References 1. Miller HI. Gene therapy on trial. Science 2000;287: 591-592. 2. Voss SD, Kruskal JB. Gene therapy: a primer for radiologists. Radiographies 1998;18: 1343-1372. 3. Ferry N, Heard JM. Liver-directed gene transfer vectors. Hum Gene Ther 1998;9:1975-1981. 4. Swisher SG, RothJA, Nemunaitis), et al. Adenovirusmediated p53 gene transfer in advanced non-smallcell lung cancer.) !\atJ Cancer Inst 1999;91:763-771. 5. Kim D. Clinical research results with d11520 (Onyx015), a replication-selective adenovirus for the treatment of cancer: what have we learned? Gene Ther 2001 ;8:89-98.
6. Rogulski KR, Freytag SO, Zhang K, et al. In vivo antitumor activity of ONYX-015 is influenced by p53 status and is augmented by radiotherapy. Cancer Res 2000;60: 1193-1196. 7. Khuri FR, Nemunaitis J, Ganly 1, et al. a controlled trial of intratumoral ONYX-015, a selectively-replicating adenovillJs, in combination with cisplatin and 5-fluorouracil in patients with recurrent head and neck cancer. Nat Med 2000;6:879-885. 8. Mulvihill S, Warren R, Venook A, et at. Safety and feasibility of injection with an ElB-55 kDa genedeleted, replication-selective adenovirus (ONYX015) into primaly carcinomas of the pancreas: a phase I trial. Gene Ther 2001;8:308-315. 9. Sze DY, Kim D, Reid TR. Intraarterial treatment of metastatic gastrointestinal cancer using an E1B-deleted adenovirus. ) Vasc Intervent Radiol 2001;12(1 part 2):s6. 10. Reid T, Galanis E, Abbruzzese J, et al. A phase II trial of hepatic artery infusion with a replication-selective adenovirus (d11520) plus intravenous 5-fluorouracil in patients with colorectal carcinoma metastatic to the liver. ) Clin Oncol 2001 On press).
6:10 p.m. Intratumoral Gene Therapy Marshall Hicks, MD University of Texas M.D. Anderson Cancer Center Houston, Texas Learning objectives: upon completion of th'is course, the attendee should be able to: 1) List strategies involved with cancer gene based therapies; 2) Give examples of techniques and limitations ofdirect in vivo intratumoral gene therapy; 3) List ongOing clinical Mal applications of intratumoral gene therapy. There are more than 500,000 cancer deaths annually. in the United States, including a 50% mortality rate from solid tumors. Given these facts, it is probably not surprising that more than half of the Phase One trials for gene therapy in the ·s are cancer related. Gene-based therapies may provide more effective means of treating or preventing cancers than preViOUS, and more conventional, types of therapy such as surgery, radiation, or drug therapies. Existing strategies involve tumor suppression, antiangiogenesis, inhibition of oncogen expression, induction of drug sensitivity Onclurung suicide genes), increased immune response (via cytokines and activation oft-lymphocytes), and protection of the host from other cancer therapies with associated toxicities. Direct in vivo inlratumoral therapy is one means of veCtor delivery. Imaged based direct intratumoral vector delivery provides advantages similar to other imaged based therapies-maximized effIciency of tumor therapy, and documentation of physieal pOSition. IntervcntionaI radiology can playa critical role in the develop-
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