News News cer cells will render them susceptible to the antiviral drug gancyclovir. Irradiated ovarian cancer cells with the added gene will be injected into the peritoneum to deliver the gene to the ovarian tumor. Gancyclovir will thus be expected to kill the cancer cells receiving the gene.
—ByJMWaalen
Gene Therapy for ADA Takes Next Step The Recombinant DNA Advisory Committee has approved an amended gene therapy protocol for two children who have already benefited from their pioneering gene treatments for an extremely rare, inherited immune system disorder, adenosine deaminase (ADA) deficiency. "We are exceptionally pleased with our patients' progress so far," Michael Blaese, M.D., of the National Cancer Institute, told members of the RAC, citing significant improvements in lymphocyte counts and immune responses since (he initial gene therapy studies began in 1990 and 1991. However, supplemental therapy is needed, Blaese said, because there are still "holes" in the children's immune repertoire that leave them vulnerable to potentially life-threatening infections. According to both Blaese and W. French Anderson, M.D., of the National Heart, Lung, and Blood Institute, the amended gene therapy protocol is designed to plug up these holes by inserting a healthy ADA gene into a population of blood stem cells, which are far more primitive than the T cells now being used, and from which, in theory, the missing ADA enzyme would be churned out indefinitely. By adding a gene to these early stem cells (CD 34+ cells) - the parent cells of T lymphocytes - "the benefit could be profound," Anderson said. "Basically, we're talking about a cure... on the basis of a minute risk." Some RAC members were not convinced. Although the proposed study won approval by an 1 l-to-3 margin (with 2 abstentions), several RAC members felt the use of a new target cell system as well as a new retroviral vector went far beyond the original protocol, and required a review from scratch. Others were concerned about the proposed treatment's anticipated efficacy, given the lack of a good animal model for ADA, and the safety risks associated with an increasing number of potentially mutagenic events. Finally, there were ethical reservations about simultaneously initiating a second gene therapy protocol in children who are reportedly "doing so well" on their present therapy. Anderson told the RAC that no matter how well the children are doing, there is uncertainty about how long their immunologic protection may last, and the investigators see stem cell therapy as the best hope for a normal life. But Anderson stressed the protocol would not be limited solely to these patients and will be made available to other ADA children "as they come along." —By Susan Jenks
382
Researchers Struggle To Get Fetal Tissue For Cancer Research While the federal ban on the use of fetal tissue from induced abortions in human therapeutic transplants continues, cancer researchers are using fetal tissue in laboratory systems to study oncogenes, cancer formation, and immune system development. Many are uncomfortable talking about their work with fetal tissue because of misconceptions about the extent of the ban. Some say they could not do their research without it. Others have developed alternative systems, rather than deal with difficulties in obtaining fetal tissue and the stigma surrounding its use. 'This research is continuing because it's important," although some people are mistakenly concerned that it's not allowable, according to Faye Austin, Ph.D., associate director for the extramural research program in NCI's Division of Cancer Biology, Diagnosis, and Centers. "Many don't understand that the ban is just on transplantation [of fetal tissue] to patients for therapeutic purposes," Austin said. "The ban is very restricted." Since the ban, many NCI grantees have stopped using fetal tissue or significantly dropped the percentage of their grants that cover fetal tissue work, according to Harry Canter, chief of NCI's Research Analysis Evaluation Branch.
Access Not Easy "We have extraordinary trouble getting [fetal tissue]," said Dennis J. Slamon, M.D., Ph.D., associate professor of medicine at the University of California at Los Angeles. He uses tissue collected 5 or 6 years ago, before the ban. Slamon is using fetal tissue to study oncogenes and tumor suppressor genes.
Journal of the National Cancer Institute
Downloaded from http://jnci.oxfordjournals.org/ at University of Birmingham on August 22, 2015
and the plasmid incorporated into the cell's genome, ultimately resulting in expression of HLA-B7. In perhaps the most exotic gene therapy trial approved by the RAC to date, Scott Freeman, M.D., and colleagues at the University of Rochester have devised a protocol for ovarian cancer in which a gene added to ovarian can-
News News marrow works, a lot of people will switch because it's so much easier to get," he said.
Dr. Dennis J. Slamon
Jen-Fu Chiu, Ph.D., professor of biochemistry at the University of Vermont College of Medicine in Burlington, no longer uses fetal tissue. But when he did, he got his supply from his collaborators at the Shanghai Institute of Biochemistry. It is still possible for him to get tissue from that institution, he said, but he no longer receives funding for his study using fetal liver tissue to evaluate messenger RNA of different oncogenes. "It's not a problem of money. We just can't get it, period," said A. Julian Garvin, M.D., Ph.D., professor of pathology at the Medical University of South Carolina in Charleston. He is confined to using fetal tissue from spontaneous abortions. "Fetal tissue is a big part of what I'm working on. There's no other option to work with," he added. Likewise, at the Scripps Research Institute in La Jolla, Calif., researchers can only use fetal tissue from spontaneous abortions, according to Ralph A. Reisfeld, Ph.D., of Scripps' Department of Immunology. His group is working on the SCID-hu mouse model. Reisfeld said researchers are trying to replace the role of fetal tissue with human bone marrow from volunteer donors or from human cadavers. "For SCID-hu, I have a hunch that if bone
Vol. 84, No. 6, March 18, 1992
In Pennsylvania, researchers have an easier time getting fetal tissue. Brian J. Wigdahl, Ph.D., associate professor of microbiology and immunology at the Pennsylvania State University College of Medicine, Hershey, said he has arrangements with four or five clinics that provide tissue under informed consent and approved protocols. "It's not easy to develop this access and maintain it," he said. "It depends on your state. "One thing Pennsylvania decided to do at the urging of all seven medical schools was adopt the NIH guidelines on using fetal tissue," he said. "They follow them 'to a T' and the fetal tissue is made available." At first, the legislature thought the researchers should use only tissue from spontaneous abortions. They were soon educated that "only a small fraction of all
Downloaded from http://jnci.oxfordjournals.org/ at University of Birmingham on August 22, 2015
State Support
abortions are spontaneous, and of those, only a minute fraction would provide material that would be usable for anything," Wigdahl said. "Once the state legislators realized the constraints that would put on experiments, they pulled back from that [restriction]." "In cancer, it's critical to be able to look at [fetal] tissue to see the role genes have in normal growth and development," UCLA's Slamon said. "There's really no substitute for that kind of tissue."
Her-2/neu Slamon has looked at levels of the Her-2/neu gene product in fetal tissue to compare normal distribution of the product to the abnormal distribution in tumor tissue. Her-2/neu is used as an indicator of tumor aggressiveness and may also drive growth in breast and ovarian cancers. Fetal tissue expresses high levels of Her-2/neu only in the kidney. This suggests that the gene product plays a role in growth of epithelial cells, according to Slamon. He is now looking at distribution of tumor suppressor genes like those for retinoblastoma.
SCID-hu Mouse
Dr. Brian J. Wigdahl
Researchers are using human fetal tissue in the immunodeficient SCID-hu mouse to grow human stem cells, as well as to test drugs. By transplanting fetal bone, liver, thymus, and lymph nodes into the SCIDhu mouse, scientists have constructed a human tissue microenvironment for observation. "Using that model, we've shown you can study development of human blood cells and some aspects of the human immune system," said Irving Weissman, M.D., professor of pathology and developmental biology and a member of the Howard Hughes Medical Institute at
NEWS
383
News News when cultured in vitro, Wigdahl said. Wilms' tumor is a condition in which the fetal tissue fails to differentiate and subsequently develops into a malignant tumor. South Carolina's Garvin is trying to grow Wilms' tumor cells in culture along with their fetal benign counterparts to discover and compare what controls their growth and differentiation. Dr. Timothy J. O'Brien "Cancer cells are very much His group is using fetal pathology like fetal cells," Garvin said. They are specimens to demonstrate that the tumor morphologically the same and have antigen is highly expressed during early many of the same surface antigens. He development. is trying to find surface antigens that are unique to the tumor cells and O'Brien made clear that his group is develop monoclonal antibodies to these "not really using fetal tissue." It is using antigens. ectopic pregnancy specimens that are removed and fixed in paraffin. "Getting One antigen expressed at high levels frozen tissue is more difficult," he said. in early development is CA125. Its role "Frozen tissues have the potential to be in the developmental process may be sigthawed out and reused," which is more nificant, according to Timothy J. O'Brien, controversial. "We're fortunate that the Ph.D., professor of obstetrics and gyneantibodies we've developed work well cology, biochemistry, and molecular with fixed tissues," O'Brien added. biology at the University of Arkansas for Medical Sciences, Little Rock. —By Cori Vanchieri
Wide Applications Penn State's Wigdahl is using fetal tissue to look at viral and cellular mechanisms in maintaining virus latency. He has set up model systems for herpes simplex virus, HIV, and HTLV-I. According to Wigdahl, fetal tissue is the closest cell type available to find the cells that play a role in pediatric AIDS. It is much easier to cultivate fetal human neurons than adult human neurons. And fetal tissue lasts longer than adult tissue
384
Dr.MftcMcCwM
Journal of the National Cancer Institute
Downloaded from http://jnci.oxfordjournals.org/ at University of Birmingham on August 22, 2015
Stanford University Medical School, Palo Alto, Calif. The system has proven effective in isolating human stem cells, the precursors of all the blood-forming and immune cells of the body. Now that theresearchersunderstand how to isolate stem cells, they can try it in humans. A clinical trial should begin this year toremovestem cells from patients, treat the patient with chemotherapy or radiation, and reinfuse purified stem cells into the patient, according to Mike McCune, M.D., Ph.D., vice president of the New Enterprise Research Division at Systemix in Palo Alto, Calif. Ideally, these autologous stem cell transplants will be an improvement over whole bone marrow transplants because stem cells do not contain the metastatic tumor cells that remain in whole bone marrow. Therefore, reintroduction of tumor cells should not occur. The California researchers also are working with the SCID-hu mouse to test drugs and evaluate vaccines, McCune said. They are studying pediatric HIV infections and are developing a model system to study human papillomavirus types 16 and 18. In related research, they also hope to study metastatic cervical cancer. "We use the SCID-hu mouse as a surrogate model to address important medical problems for which there are now no effective therapies . . . and no other ways to study easily," he said.
—ByJMWaalen
Gene Therapy for ADA Takes Next Step The Recombinant DNA Advisory Committee has approved an amended gene therapy protocol for two children who have already benefited from their pioneering gene treatments for an extremely rare, inherited immune system disorder, adenosine deaminase (ADA) deficiency. "We are exceptionally pleased with our patients' progress so far," Michael Blaese, M.D., of the National Cancer Institute, told members of the RAC, citing significant improvements in lymphocyte counts and immune responses since (he initial gene therapy studies began in 1990 and 1991. However, supplemental therapy is needed, Blaese said, because there are still "holes" in the children's immune repertoire that leave them vulnerable to potentially life-threatening infections. According to both Blaese and W. French Anderson, M.D., of the National Heart, Lung, and Blood Institute, the amended gene therapy protocol is designed to plug up these holes by inserting a healthy ADA gene into a population of blood stem cells, which are far more primitive than the T cells now being used, and from which, in theory, the missing ADA enzyme would be churned out indefinitely. By adding a gene to these early stem cells (CD 34+ cells) - the parent cells of T lymphocytes - "the benefit could be profound," Anderson said. "Basically, we're talking about a cure... on the basis of a minute risk." Some RAC members were not convinced. Although the proposed study won approval by an 1 l-to-3 margin (with 2 abstentions), several RAC members felt the use of a new target cell system as well as a new retroviral vector went far beyond the original protocol, and required a review from scratch. Others were concerned about the proposed treatment's anticipated efficacy, given the lack of a good animal model for ADA, and the safety risks associated with an increasing number of potentially mutagenic events. Finally, there were ethical reservations about simultaneously initiating a second gene therapy protocol in children who are reportedly "doing so well" on their present therapy. Anderson told the RAC that no matter how well the children are doing, there is uncertainty about how long their immunologic protection may last, and the investigators see stem cell therapy as the best hope for a normal life. But Anderson stressed the protocol would not be limited solely to these patients and will be made available to other ADA children "as they come along." —By Susan Jenks
382
Researchers Struggle To Get Fetal Tissue For Cancer Research While the federal ban on the use of fetal tissue from induced abortions in human therapeutic transplants continues, cancer researchers are using fetal tissue in laboratory systems to study oncogenes, cancer formation, and immune system development. Many are uncomfortable talking about their work with fetal tissue because of misconceptions about the extent of the ban. Some say they could not do their research without it. Others have developed alternative systems, rather than deal with difficulties in obtaining fetal tissue and the stigma surrounding its use. 'This research is continuing because it's important," although some people are mistakenly concerned that it's not allowable, according to Faye Austin, Ph.D., associate director for the extramural research program in NCI's Division of Cancer Biology, Diagnosis, and Centers. "Many don't understand that the ban is just on transplantation [of fetal tissue] to patients for therapeutic purposes," Austin said. "The ban is very restricted." Since the ban, many NCI grantees have stopped using fetal tissue or significantly dropped the percentage of their grants that cover fetal tissue work, according to Harry Canter, chief of NCI's Research Analysis Evaluation Branch.
Access Not Easy "We have extraordinary trouble getting [fetal tissue]," said Dennis J. Slamon, M.D., Ph.D., associate professor of medicine at the University of California at Los Angeles. He uses tissue collected 5 or 6 years ago, before the ban. Slamon is using fetal tissue to study oncogenes and tumor suppressor genes.
Journal of the National Cancer Institute
Downloaded from http://jnci.oxfordjournals.org/ at University of Birmingham on August 22, 2015
and the plasmid incorporated into the cell's genome, ultimately resulting in expression of HLA-B7. In perhaps the most exotic gene therapy trial approved by the RAC to date, Scott Freeman, M.D., and colleagues at the University of Rochester have devised a protocol for ovarian cancer in which a gene added to ovarian can-
News News marrow works, a lot of people will switch because it's so much easier to get," he said.
Dr. Dennis J. Slamon
Jen-Fu Chiu, Ph.D., professor of biochemistry at the University of Vermont College of Medicine in Burlington, no longer uses fetal tissue. But when he did, he got his supply from his collaborators at the Shanghai Institute of Biochemistry. It is still possible for him to get tissue from that institution, he said, but he no longer receives funding for his study using fetal liver tissue to evaluate messenger RNA of different oncogenes. "It's not a problem of money. We just can't get it, period," said A. Julian Garvin, M.D., Ph.D., professor of pathology at the Medical University of South Carolina in Charleston. He is confined to using fetal tissue from spontaneous abortions. "Fetal tissue is a big part of what I'm working on. There's no other option to work with," he added. Likewise, at the Scripps Research Institute in La Jolla, Calif., researchers can only use fetal tissue from spontaneous abortions, according to Ralph A. Reisfeld, Ph.D., of Scripps' Department of Immunology. His group is working on the SCID-hu mouse model. Reisfeld said researchers are trying to replace the role of fetal tissue with human bone marrow from volunteer donors or from human cadavers. "For SCID-hu, I have a hunch that if bone
Vol. 84, No. 6, March 18, 1992
In Pennsylvania, researchers have an easier time getting fetal tissue. Brian J. Wigdahl, Ph.D., associate professor of microbiology and immunology at the Pennsylvania State University College of Medicine, Hershey, said he has arrangements with four or five clinics that provide tissue under informed consent and approved protocols. "It's not easy to develop this access and maintain it," he said. "It depends on your state. "One thing Pennsylvania decided to do at the urging of all seven medical schools was adopt the NIH guidelines on using fetal tissue," he said. "They follow them 'to a T' and the fetal tissue is made available." At first, the legislature thought the researchers should use only tissue from spontaneous abortions. They were soon educated that "only a small fraction of all
Downloaded from http://jnci.oxfordjournals.org/ at University of Birmingham on August 22, 2015
State Support
abortions are spontaneous, and of those, only a minute fraction would provide material that would be usable for anything," Wigdahl said. "Once the state legislators realized the constraints that would put on experiments, they pulled back from that [restriction]." "In cancer, it's critical to be able to look at [fetal] tissue to see the role genes have in normal growth and development," UCLA's Slamon said. "There's really no substitute for that kind of tissue."
Her-2/neu Slamon has looked at levels of the Her-2/neu gene product in fetal tissue to compare normal distribution of the product to the abnormal distribution in tumor tissue. Her-2/neu is used as an indicator of tumor aggressiveness and may also drive growth in breast and ovarian cancers. Fetal tissue expresses high levels of Her-2/neu only in the kidney. This suggests that the gene product plays a role in growth of epithelial cells, according to Slamon. He is now looking at distribution of tumor suppressor genes like those for retinoblastoma.
SCID-hu Mouse
Dr. Brian J. Wigdahl
Researchers are using human fetal tissue in the immunodeficient SCID-hu mouse to grow human stem cells, as well as to test drugs. By transplanting fetal bone, liver, thymus, and lymph nodes into the SCIDhu mouse, scientists have constructed a human tissue microenvironment for observation. "Using that model, we've shown you can study development of human blood cells and some aspects of the human immune system," said Irving Weissman, M.D., professor of pathology and developmental biology and a member of the Howard Hughes Medical Institute at
NEWS
383
News News when cultured in vitro, Wigdahl said. Wilms' tumor is a condition in which the fetal tissue fails to differentiate and subsequently develops into a malignant tumor. South Carolina's Garvin is trying to grow Wilms' tumor cells in culture along with their fetal benign counterparts to discover and compare what controls their growth and differentiation. Dr. Timothy J. O'Brien "Cancer cells are very much His group is using fetal pathology like fetal cells," Garvin said. They are specimens to demonstrate that the tumor morphologically the same and have antigen is highly expressed during early many of the same surface antigens. He development. is trying to find surface antigens that are unique to the tumor cells and O'Brien made clear that his group is develop monoclonal antibodies to these "not really using fetal tissue." It is using antigens. ectopic pregnancy specimens that are removed and fixed in paraffin. "Getting One antigen expressed at high levels frozen tissue is more difficult," he said. in early development is CA125. Its role "Frozen tissues have the potential to be in the developmental process may be sigthawed out and reused," which is more nificant, according to Timothy J. O'Brien, controversial. "We're fortunate that the Ph.D., professor of obstetrics and gyneantibodies we've developed work well cology, biochemistry, and molecular with fixed tissues," O'Brien added. biology at the University of Arkansas for Medical Sciences, Little Rock. —By Cori Vanchieri
Wide Applications Penn State's Wigdahl is using fetal tissue to look at viral and cellular mechanisms in maintaining virus latency. He has set up model systems for herpes simplex virus, HIV, and HTLV-I. According to Wigdahl, fetal tissue is the closest cell type available to find the cells that play a role in pediatric AIDS. It is much easier to cultivate fetal human neurons than adult human neurons. And fetal tissue lasts longer than adult tissue
384
Dr.MftcMcCwM
Journal of the National Cancer Institute
Downloaded from http://jnci.oxfordjournals.org/ at University of Birmingham on August 22, 2015
Stanford University Medical School, Palo Alto, Calif. The system has proven effective in isolating human stem cells, the precursors of all the blood-forming and immune cells of the body. Now that theresearchersunderstand how to isolate stem cells, they can try it in humans. A clinical trial should begin this year toremovestem cells from patients, treat the patient with chemotherapy or radiation, and reinfuse purified stem cells into the patient, according to Mike McCune, M.D., Ph.D., vice president of the New Enterprise Research Division at Systemix in Palo Alto, Calif. Ideally, these autologous stem cell transplants will be an improvement over whole bone marrow transplants because stem cells do not contain the metastatic tumor cells that remain in whole bone marrow. Therefore, reintroduction of tumor cells should not occur. The California researchers also are working with the SCID-hu mouse to test drugs and evaluate vaccines, McCune said. They are studying pediatric HIV infections and are developing a model system to study human papillomavirus types 16 and 18. In related research, they also hope to study metastatic cervical cancer. "We use the SCID-hu mouse as a surrogate model to address important medical problems for which there are now no effective therapies . . . and no other ways to study easily," he said.
