gdvmarch conference notes

ENZO’S JANUARY 2000 TO JANUARY 2004 PRESS RELEASE STATEMENTS ON HGTV-43: A Word-for-Word Compilation by GDVMARCH

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[NOTE TO READERS: If you’re like me, I’m tired of hearing what ENZO BIOCHEM, INC. is alleged to have either reported or failed to report about its HGTV-43 (HIV) clinical trials. So, SUPPLIED BELOW are dates and titles of WRITTEN PRESS RELEASES published by ENZO BIOCHEM, INC., starting at the Annual Shareholders’ Meeting in January 2000 through the Annual Shareholders’ Meeting held in January 2004. Now readers can readily verify EXACTLY WHEN and WHAT Enzo PUBLISHED on the topic. The copy-pasted press release excerpts below are dated and titled for easy comparison with the relevant full release. They are available at several Internet sites, including that of the Company at http://www.enzobio.com.]

Date: 1/12/2000
Title: Annual Meeting Told Of Plans For Expanding Clinical Trials For Enzo Biochem's -Therapeutic Products

<<Therapeutic Trials -- Barry Weiner, President of Enzo said that the Company's Phase 1 clinical trial, testing Enzo's proprietary therapeutic treatment for HIV-1 infection, was proceeding satisfactorily and on schedule. The trial is being conducted at the University of California, San Francisco.

Mr. Weiner reported that with the Enzo procedure, antisense RNA was detected in circulating cells a number of months post treatment, indicating that the gene medicine was functioning and producing antisense RNA. Enzo said it was unaware of any other adult study that produced similar results.

In addition, Mr. Weiner said that HGTV43, Enzo's gene transfer vector was able to achieve levels of stable gene transfer (transduction) to the patients non-growing blood stem cells greater than 30%, a technical breakthrough in the development of commercially viable gene medicine.

Mr. Weiner also said that during the trial Enzo scientists have been able to substantially reduce the time period required for successful transduction to 18 hours, as compared to previous transduction times of up to three months. This was accomplished because HGTV43 was shown to transduce non-growing cell populations. "This short transduction period," said Mr. Weiner "has many advantages, most of all, the stem cells will not differentiate to a great degree and thus, the patient will have a greater chance of receiving true stem cells."

"We are encouraged by these findings," said Mr. Weiner. However, he cautioned that the Phase 1 trial, which is designed primarily to determine safety and toxicity in patients, was not yet completed, and that further evaluation of treated individuals and treatment of additional patients was needed to fully document efficacy*.>>

Date: 3/16/2000
Title: Enzo Biochem Reports Record Second Quarter Operating Results

<<In the area of gene-based therapeutics, Enzo scientists and collaborators reported at the Retroviruses and Opportunistic Infections Conference, held in February in San Francisco, that Enzo's HGTV43 vector has successfully delivered antisense genes efficiently and quickly to non-growing blood stem cells outside the human body and, following transduction, these genetically engineered cells survived in circulation and continued to produce antisense RNA. Enzo views this as a critical first step forward in the development of a gene medicine for the treatment of HIV-1 infection. Latest observations continue to support the initial findings.>>

Date: 4/13/2000
Title: Enzo Biochem Says Outlook Remains Highly Favorable For Company's Growth Proprietary Technology and New Products Progress Significantly

<<Enzo's clinical study at the University of California, San Francisco for HIV-1 infected patients is moving towards its final stages. Enzo has reported that HGTV43, the Company's proprietary medicine, has successfully delivered - and continues to deliver - antisense genes effectively and quickly to blood stem cells outside the human body. Following transduction and infusion into the patients, these genetically engineered cells continue to survive in circulation and continue to produce antisense RNA over many months.

An abstract has been accepted for an oral presentation and will be given at the American Society of Gene Therapy in June. The Company has stated that it knows of no other system that has achieved these levels in unablated adult patients (patients in which the blood cells have not been destroyed) and that this proprietary system has application to the entire field of gene medicine. The Company also said it views this achievement as a critical first step forward in development of a gene medicine for the treatment of HIV-1 infection,>>

Date: 6/2/2000
Title: Enzo Biochem Says Data Shows Significant Progress In Human HIV Gene Medicine Trial Results Include Long-Term Survival In Humans Of Engineered Cells And Development Of CD4+ Cells Containing Anti-H

<<FARMINGDALE, NY, June 2, 2000 -Enzo Biochem, Inc. (NYSE:ENZ) announced today preliminary results of a Phase 1 clinical trial of its anti HIV-1 antisense gene therapy product, HGTV-43. These results show an unprecedented eight-month survival of the engineered cells in an HIV-infected individual among the group studied and the development of CD4+ cells expressing the HIV-1 antisense RNA within the cell. Such antisense genes have previously been shown to provide resistance to the virus. These results indicate that the engineered stem cells have replicated and differentiated within participants in the trial.

"Our ultimate goal is to achieve for HIV-1 infected individuals a long-term, lifelong immune responsiveness in a disease characterized by progressive loss of this defensive mechanism. Based on the results thus far we believe we have made significant progress towards this goal," said Dean Engelhardt, Ph.D., a Senior Vice President of Enzo.

"Those of us treating severely ill patients desperately need new therapies that approach this disease from a new paradigm, and we are immensely encouraged that with Enzo¹s treatment we have for the first time successfully modified the progenerator stem cells in HIV infected patients and demonstrated that those cells have been successfully recolonized in these patients," commented Marcus Conant, M.D. of San Francisco, CA, principal clinical investigator for the trial. "It represents a major advance towards creating an immune system in AIDS patients which can resist the destruction of the critical CD4+ cells."

The results will be reported in a paper to be delivered today by Dr. Engelhardt at the annual meeting of the American Society of Gene Therapy, in Denver Colorado. An Enzo spokesperson said that based on the Phase I trial results Enzo is preparing an application for a Phase 2 study involving patients with frank AIDS."

Dr. Engelhardt reported that to date the Company's procedure is being tolerated well by all the patients. "We are fulfilling our Phase I goals, namely achieving safety milestones and the long-term survival and differentiation of the engineered stem cells," he stated.

Dr. Engelhardt reported data on the three initial patients in the study, at three, six and eight months, that demonstrated that the engineered cells have continued in circulation. The survival of the engineered cells for eight months in the first patient, he pointed out, was well in excess of anything thus far achieved by other researchers using blood stem cells from adult human subjects without first ablating the patient, a process in which blood cells are destroyed. Additionally, Dr. Engelhardt reported that the engineered cells containing the HIV antisense were present among the individuals' CD4+ cells at six and eight months.

Enzo's Phase I human clinical trial uses HGTV-43, its proprietary genetic antisense based therapeutic product, developed to protect human immune cells against infection by a broad spectrum of strains of HIV-1 including its mutational variants. Enzo's HGTV-43 medicine incorporates two proprietary technologies. One involves the insertion of a new type of genetic material into blood cells in order to inhibit the growth of HIV-1. This technology, known as genetic antisense, utilizes a "mirror image" of a gene, called an antisense molecule, to block the virus.

The second technology is based on a novel vector designed to deliver the antisense molecule to the cell. This vector is employed to insert new genes into target cells with the objective of integrating the gene into the chromosome of the cell, in a process known as transduction. Enzo stated previously that it has achieved high levels of transduction within 18 hours, thus limiting inconvenience to the patient, and in achieving levels of stable gene transfer to target cells greater than 30%. The cells containing these new genes, when transferred to the patient, replicate and provide the patient with the newly inserted biological function. The Company believes that its proprietary vector system constitutes a technological breakthrough in the development of commercially viable gene medicine.

"We believe that our HGTV-43 medicine has now passed an important milestone with the preliminary data provided by our Phase I trial," said Elazar Rabbani, Ph.D., Chairman and CEO of Enzo. "We will now take our work to the next stage, where our expectations for similar successful results are very high." >>

Date: 6/15/2000
Title: Enzo Biochem Reports Increased Third Quarter Operating Results

<<Preliminary data from the Company's Phase I trial of HGTV43, its proprietary anti HIV-1 antisense gene therapy product, was recently presented at the annual meeting of the American Society of Gene Therapy. These data demonstrated that the engineered cells have continued in circulation for an unprecedented eight months in the first patient. In addition, engineered cells expressing the HIV-1 antisense RNA were present among the individuals' CD4+ cells at six and eight months. CD4+ cells have been shown to provide resistance to HIV*. Enzo also indicated it was proposing Phase II studies of HGTV-43, and would include patients at varying stages of the disease in the expanded test.>>

Date: 10/2/2000
Title: Enzo Biochem Reports New Data On Phase I HIV Test Shows Engraftment Of Engineered Cells In Bone Marrow Company Says Development Is Major Biotech Milestone Treatment Producing New Enzo Engineered

<<FARMINGDALE, NY, October 2, 2000 - Enzo Biochem, Inc. (NYSE:ENZ) reported today that new data on the first individual treated in the Phase 1 clinical trial of HGTV-43, the Company's HIV-1 gene medicine product, show that after nine-and-one-half-months Enzo engineered cells have successfully engrafted in the patient's bone marrow and were spawning new differentiated CD4+ cells designed to fight the virus.

"This is a dramatic result, one that underscores, in the light of the other achievements we have recorded in this trial, that our gene medicine and technology designed to counter the HIV virus is on the right track," said Dean L. Engelhardt, Executive Vice President of Enzo. "It is also, we believe, a scientific milestone since to our knowledge no other technology has been successful in engrafting cells expressing a cloned gene in the bone marrow of adult subjects without first ablating the patient, a process in which blood cells are destroyed."

Enzo is currently compiling and analyzing data from the remaining five patients in the trial. The Company said that while the data is limited and must await further study, it is highly encouraged. "We believe that Enzo has taken an important step to reconstituting an individual's immune system with resistant cells, an exceptional achievement," said Dr. Engelhardt.

"These findings are very exciting. This novel approach may be one of the new treatment platforms we desperately need to confront the problem of resistance to the anti-viral cocktails," said Marcus A. Conant, MD, a leading physician in the management of HIV-1 infected patients and one of the principal investigators of the trial.

The Company said that it is focusing on preparations for a Phase II trial, and that pending submissions to the FDA, it had already begun negotiations with several hospitals at which the broader study would be conducted.

Enzo said that all the patients tolerated the procedure well. The new data that show that the progeny CD4+ cells are now in circulation indicate that it is possible to effectively reintroduce engineered cells into a patient, have them reestablish themselves and, importantly, reproduce progeny cells having the same engineered characteristics.

HGTV-43, the Company's proprietary gene medicine product, was developed to protect human immune cells against infection by a broad spectrum of strains of HIV-1 including its mutational variants. This medicine incorporates two proprietary technologies, plus additional techniques, all of which were successfully implemented during the trial. One involves insertion of a new type of genetic material into blood cells that has been shown to inhibit the growth of HIV-1. This technology, known as genetic antisense, utilizes a "mirror image" of a gene, called an antisense molecule, to block the virus.

Effectively, Enzo has succeeded in developing and utilizing its proprietary vector for delivery of its HIV gene medicine into the patient's blood cells. With this vector, Enzo succeeded in achieving high levels of stable gene transfer within one day, as compared to previous procedures that required two or more weeks. These cells have been shown to persist in patients and to produce differentiated CD4+ immune cells. The engraftment of these blood cells expressing Enzo's anti-HIV-1 transgene brings the goal of reconstituting the immune system with virus resistant cells considerably closer to completion.>>

Date: 10/30/2000
Title: Enzo Biochem Reports Record Fiscal 2000 Operating Results

<<Enzo's therapeutic program also made important strides. Preliminary results from the Phase I clinical trial of the Company's HGTV-43 genetic medicine for HIV-1 infection showed that all patients tolerated the procedure; anti-HIV-1 antisense RNA was detected in the circulation of patients tested, the first patient for as long as nine months, to date; and CD4+ immune cells purified from circulation showed the presence of antisense RNA. In addition, CD34+ stem cells from the bone marrow of the first patient were shown to contain antisense RNA, more than nine months after infusion. The data from the remaining patients are being processed and analyzed.>>

Date: 1/11/2001
Title: Enzo Biochem Reports Successful Results Of Phase I Clinical Trial Of HGTV43 HIV-1 Gene Medicine Product

<<FARMlNGDALE, NY, January 11, 2001 --Enzo Biochem, Inc., (NYSE: ENZ), a leading biotechnology company specializing in gene identification and gene regulation technologies for diagnostic and therapeutic applications, announced today that it has achieved successful results in its Phase 1 clinical trial of HGTV43, Enzo's HIV-1 gene medicine product. The Company is planning to extend the study to two additional sites and has begun the transition to Phase II.

Enzo said that each of the five HIV-1-infected patients currently enrolled in the study tolerated the procedure well, and that in each case the transduced cells engrafted, propagated and were producing new differentiated CD4+ cells to fight the virus. The results will be presented at the annual Retroviruses and Opportunistic Infections Conference, scheduled to take place in early February in Chicago, IL.

The Phase I trial was conducted at the University of California San Francisco, where Morton J. Cowan, MD, a noted expert in the management of immune compromised patients, and Marcus A. Conant, MD, a leading physician in the management of HIV-I infected patients, were the principal investigators. In the study, three antisense genes designed to interfere with the growth of HIV-1 were put into blood stem cells, the cells that are present in blood, spleen and bone marrow, where they serve as a reservoir of progenitor cells that divide and develop into CD4+ immune cells, the cells predominantly infected by HIV-1. The study demonstrated that the anti-HIV-1 genes could be successfully put into stem cells and that these engineered stem cells survived, grew, and developed into CD4+cells.

All five patients met the trial end point of six months after infusion of the engineered stem cells. During that time antisense RNA was shown to be present in the circulating immune cells, indicating that the gene therapy had worked and that the anti-HIV-1 genes were present and functioning in the cells. Samples are continuing to be measured with results to date demonstrating that antisense RNA has been detected for as long as one year after the initial infusion of the engineered stem cells. In addition, six months after infusion, antisense RNA was present in CD4+ cells, a subset of the immune cells and the target cells that are infected with the HIV-1. CD4+ cells are the cells that are depleted with time and that are associated with the progressive loss of immune functioning with time that defines the major pathogenesis of AIDS. Finally, the presence of the anti HIV-1 antisense RNA was found in the bone marrow of 4 of the 5 patients. While the fifth patient had antisense RNA in both his circulating immune cells and CD4+ cells, his bone marrow produced an insufficient number of stem cells for a valid assay

In addition to the routine tests, including chemistries, blood work, physical exams, HIV-1 viral load and CD4+ cell counts done for each patient on a monthly basis, it was necessary for Enzo to develop a pioneering genetic analysis protocol to identify the fate of the engineered cells in the patient at each time point. These cells were identified and monitored by measuring the presence of the anti-HIV-1 antisense RNA. Each single assay to identify and measure the antisense RNA for a single patient at a single time point required the performance of at least 300 individual tests using reverse transcriptase, DNA polymerase, DNA gel analysis, and restriction enzyme analysis. More than 6000 independent genetic analyses were performed in order to demonstrate the success of this gene therapy trial.

Dr. Conant, who has cared for AIDS patients since 1981 and who has followed these five patients throughout this clinical trial said, "The results of this phase I trial are very exciting and very encouraging. We may now have the ability to restore the immune systems of HIV-infected patients. This is the first time that this exciting strategy has been successful."

"We are anxious to begin the next phase of the trial in which we will try to give these protected CD4+ cells a survival advantage over HIV infected CD4+ cells that are not protected," continued Dr. Conant. " This research is so important because we have numerous patients who have become resistant to their highly active anti-retroviral therapies or who cannot take the new therapies because of drug-drug interactions or serious side effects. This technology, if successful, should lead to an entirely new approach for treating severely ill HIV infected patients."

Enzo said that the study had met the goals established at its initiation. This Phase I trial of HGTV43 marked the first time gene therapy has been successful in non-ablated adults, i.e., those who have not had cells clinically destroyed by chemotherapy or other means. "We believe," said Dean Engelhardt, Ph.D., Executive Vice President of Enzo, "based on what we have been able to accomplish with non-ablated adult patients, that Enzo is the leading company in gene therapy. To our knowledge no one else has been able to achieve what we have accomplished in the Phase I study, i.e. , that the engineered cells have continued to divide and differentiate in circulation and that the anti-HIV antisense gene continues to function. These are very exciting results."

In the trial, blood stem cells were removed from HIV-1 infected human subjects, and subjected to the process of transduction (introducing genes into the cells) in a rapid procedure developed by Enzo. The transduced stem cells containing the anti-HIV-1 antisense genes were infused back into the subject the next day. An unusual property of the transduced cells is that they have persisted in circulation for the duration of the trial to date.

Enzo said that the Company is in the process of expanding the trial with the purpose of increasing the dosage of engineered cells within the body. Additional clinical sites have been identified. The Company said that the new proposed protocols would involve patients with advanced immunological illnesses, including AIDS, resulting from the HIV-1 infection. Enzo said that if everything continues according to schedule, enrollment could begin within the next several months. The study is designed to continue for six to twelve months.

"We are very encouraged by the results of the Phase I clinical trial of HGTV43, our proprietary gene medicine," said Dr. Engelhardt. "The new, expanded studies are designed to confirm our preliminary findings and to enhance the capacity of the anti-HIV-1 antisense RNA to block the growth of the virus. The additional medical researchers with whom we will be involved with in the expanded trials are all recognized and highly regarded practitioners who have a broad range of experience and expertise that will be invaluable as our research moves ahead.">>

Date: 2/6/2001
Title: Enzo Biochem, In Report To Medical Conference, Says It Has Accomplished First Successful Stem Cell Gene Therapy In Adults Presentation Details Enzo's Successful Phase I Clinical Trial To Treat H

<<CHICAGO, IL, February 6, 2001 - Enzo Biochem, Inc. (NYSE:ENZ) has achieved the first successful autologous stem cell gene therapy conducted in HIV-infected adults, Dean L. Engelhardt, Ph.D., Executive Vice President, today reported at the 8th Conference on Retroviruses and Opportunistic Infections, in Chicago, IL. His comment was made in a presentation detailing the Company's Phase I clinical trial of HGTV43, Enzo's HIV-1 gene medicine product.

Dr. Engelhardt reported successful engraftment of autologous transduced CD34+ cells and continued expression of the anti-HIV-1-antisense gene in HIV-1 infected individuals. The Phase 1 trial was designed to test the safety of the procedure and to test for engraftment and differentiation of the transduced cells, as well as to determine whether multiple infusions of transduced cells led to a higher extent of engraftment when compared with a single infusion.

"While much remains to be done, the results of this study are highly encouraging," said Dr. Engelhardt. "Until now no one has been able to achieve successful autologous gene therapy in an unablated individual. We believe our accomplishment opens the way for Enzo to initiate the next phase of our clinical program, which will be to demonstrate effectiveness in controlling the viral infection and its consequences."

Marcus A. Conant, MD, one of the two principal investigators who conducted the Phase 1 trial at the University of California San Francisco, noted that the results of the trial represent the first time that this strategy has been successful and commented that he expects it could provide clinicians for the first time with "the ability to restore the immune systems of HIV-infected patients."

The results from the phase 1 clinical protocol demonstrated long-term (6-12 months post-infusion) survival and functioning of antisense RNA in bone marrow stem cells as well as in their progeny cells in the peripheral blood mononuclear cell (PBMC) fraction and the CD4+ fraction. The fact that the number of transduced PBMC remained approximately constant over a number of months supports the conclusion that stable engraftment of the antisense RNA-producing blood cells has occurred. Bone marrow samples from four of the five subjects involved in the trial showed similar conclusions (the fifth patient did not yield enough bone marrow CD34+ cells to enable the assay to be performed). The five patients enrolled in the study all tolerated the procedure well, and without any significant procedure-related side effects.

The study was undertaken to test HGTV43, Enzo's gene medicine for

HIV-1. The medicine contains three Enzo-developed antisense genes designed to interfere with the functioning of two HIV-1 genes essential for virus growth in human cells. The genes were put into blood stem cells removed from the patients. These cells are present in blood, spleen and bone marrow where they serve as a reservoir of progenitor cells that divide and develop into CD4+ cells, the cell type infected by HIV-1. The trial demonstrated that the anti-HIV-1 genes could be successfully put into the stem cells and that the stem cells themselves survived, grew and developed into CD4+ cells for the minimum six months established as an end point of the trial. Dr. Engelhardt noted that sample collection and analysis are ongoing, anti-HIV-1 antisense RNA has been detected in all patients after six months and has been detected in two of the five patients to date for periods longer than six months, including more than 12 months for the first enrolled patient.

Enzo Biochem intends to extend the study and to add additional medical center sites in the next phase of the clinical trials.>>

Date: 6/7/2002
Title: Enzo Biochem Reports Sustained Progress Among HIV Individuals Treated With Its Proprietary Gene Medicine Protocols Reviewed at Gene Therapy Conference

<<BOSTON--(BW HealthWire)--June 7, 2002--Enzo Biochem, Inc. (NYSE:ENZ - News), a leading biotechnology company specializing in gene identification and gene regulation technologies for diagnostic and therapeutic applications, today presented further information that in the follow up phase all five HIV-1-infected individuals treated with the Company's proprietary gene medicine product continue to tolerate the procedure well and that there has been continuing anti-HIV-1 antisense RNA expression in all the subjects.

In addition, Enzo said that thus far only one of the five followed subjects treated has reported an episode of an AIDS defining infection.

The report was presented by Dean L. Engelhardt, Ph.D., Enzo Executive Vice President, at the annual meeting here of The American Society of Gene Therapy. Entitled "Engraftment and Development of HGTV43-Transduced CD34+ PBSC in HIV-1 Seropositive Individuals," the report commented on the latest findings as a result of follow-up investigations of subjects of a Phase 1 study who were treated with HGTV43, Enzo's Stealth Vector(TM). Multiple-site clinical trials involving HGTV43 are planned to develop methods to expedite and enhance engraftment and to determine dosage of the transduced stem cells, in addition to testing for safety and efficacy.

According to Dr. Engelhardt, HIV-1-infected subjects who have undergone one-time ex vivo CD34+ stem cell (PBSC) transduction and transplantation continue to produce cell populations expressing anti-HIV-1 antisense RNA after more than two years post infusion. HGTV43-transduced CD34+ PBSC engrafted in the subject's bone marrow and subsequently replicated and differentiated in vivo into mature CD4+ lymphocytes in HIV-1 seropositive individuals. The CD4+ cells continued to express anti-HIV-1 antisense RNA for 24 months to date, Dr. Engelhardt told the meeting.

"This is the longest reported example of gene expression in CD4+ cells in non-ablated adults," he said. "Moreover, we are highly encouraged because subject to further investigation in the forthcoming trials, the sustained expression of our gene medicine in CD4+ cells strengthens Enzo's belief that gene therapy can be achieved as a once in a lifetime treatment for this antisense protocol."

At UC San Francisco, Marcus A. Conant, MD, one of the principal investigators, commented that "we continue to be extremely enthusiastic about this new approach to the treatment of HIV-1 infection which offers an alternative to patients, more and more of whom are becoming resistant to their anti retroviral cocktail."

In the study, three antisense genes designed to interfere with the growth of HIV-1 were put into blood stem cells, the cells that are present in the blood, spleen and bone marrow, where they serve as a reservoir of progenitor cells that divide and develop into CD4+ immune cells, the cells predominantly infected by HIV-1. The study demonstrated that the anti-HIV-1 genes could be successfully put into stem cells and that these engineered stem cells survived, grew and developed into CD4+ cells. All five patients met the trial end points, and subsequent examinations indicate that antisense RNA was present in the circulating immune cells, indicating that the gene therapy had worked and that the anti-HV-1 genes were present and functioning in the cells. As of the most recent time points at 24 and 18 months, the engineered cells were still present and functioning in all five subjects, all of whom thus far have tolerated the procedure well.

"The conclusion that the expression is still occurring in CD4+ cells over this extended period is supported by molecular analysis of the anti-HIV-1 antisense RNA expression. It was monitored by RT/PCR amplification of the isolated RNA and characterization of the amplicon using the restriction enzyme digestion," said Dr. Engelhardt. "All in all, the results to date continue to be impressive, with long term survival of the anti HIV-1 antisense genes in the CD4+ cells and no serious side effects from the protocol.">>

Date: 6/17/02
<<On Friday, June 7, 2002, at a meeting of The American Society of Gene Therapy, Enzo presented updated information on the Phase I trial of the Company's proprietary HGTV43 gene medicine for HIV-1 infected individuals. The results indicate that all subjects continue to tolerate the procedure well and that anti-HIV-1 antisense RNA continues to be expressed in all subjects. "The sustained expression of the gene medicine in CD4+ cells strengthens our belief that this gene therapy protocol could function as a once in a lifetime treatment," said Dr. Dean Engelhardt, Executive Vice President of Enzo. "We continue to make progress towards final development of a planned multi-site expanded clinical trial of HGTV43 aimed at expediting and enhancing engraftment, and determining dosage of the engineered cells." >>

Date: 10/29/02

<<“And, as has been noted, data from the subjects in the follow-up phase I of Enzo’s HGTV43™ gene medicine trial for management of HIV infection shows that all tolerated the procedure and that the engineered cells continue to express anti-HIV-1 RNA. Next step is institution of a multi-site Phase I/II study, which is nearing the final stages.>>

Date: 1/15/03

Enzo Biochem Comments on FDA Action

<<FARMINGDALE, N.Y.--(BUSINESS WIRE)--Jan. 15, 2003--Enzo Biochem, Inc. (NYSE: ENZ - News) today commented on the Food and Drug Administration's precautionary measure placing a temporary "clinical hold" on all active gene therapy trials using retroviral vectors to insert genes into blood stem cells.

The FDA said it initiated the action after learning that a second "X-SCID" child, commonly known as "bubble baby syndrome," treated in a French gene therapy trial had developed a leukemia -like condition. The FDA noted, that in its continuing review of adverse event reports from all U.S. studies involving retroviral vectors, it has to date found no evidence of leukemia caused by gene therapy.

Enzo's HGTV43 gene regulation construct, which uses retroviral vectors for its delivery to blood stem cells, differs materially from the construct used in the French gene study. Furthermore, the five subjects treated in Enzo's Phase I HGTV43 trial have been followed for up to three years and to date there has been no treatment-related serious adverse events, including leukemia. It should be noted that HIV continues to be on the rise in the U.S. as well as the rest of the world and that it remains a major problem with limited long-term treatment options. The Company plans to proceed with its goal of management of HIV infection through its gene transfer technology in compliance with FDA guidelines.>>

Date: 1/23/2003
Title: Enzo Biochem Tells Shareholders Meeting It Expects Further Progress in Operating Results and Product Development Plans Announced for Phase II Clinical Study for Crohn's Disease Treatment

<<NEW YORK--(BUSINESS WIRE)--Jan. 23, 2003--Enzo Biochem, Inc. (NYSE: ENZ - News), a leading biotechnology company specializing in gene regulation and immune regulation technologies for diagnostic and therapeutic applications, today reported to shareholders attending the annual meeting here that it . . . . .

Enzo also told shareholders that it is hopeful that the recent action of the U.S. Food & Drug Administration temporarily placing a clinical hold on certain active gene therapy trials would not unduly further delay the Company's HGTV43 HIV medicine. It added that its HGTV43 StealthVector(TM) delivery system differs in material respects from the construct used in the French gene study that prompted the FDA's action. The Company reiterated that none of the subjects in Enzo's HGTV43 Phase I trial in up to three years of follow-up have shown any evidence of treatment-related serious adverse events, including leukemia. Enzo said it is continuing with plans to move forward with its Phase I-II trials of HGTV43.>>

Date: 11/6/2003
Enzo Biochem Gene Vector For HIV Cleared To Begin Phase I/II Clinical Trial At New York Presbyterian Hospital-Weill Medical College Of Cornell University ___________________________________________________________________

<<FARMINGDALE, NY, November 6, 2003 – Enzo Biochem, Inc. (NYSE:ENZ), a leading biotechnology company specializing in gene identification and genetic and immune regulation technologies for diagnostic and therapeutic applications, announced today that Enzo Therapeutics, its wholly owned subsidiary has been cleared to proceed with a Phase I/II study of its Stealth Vector® HGTV43™ gene construct for HIV infection at the New York Presbyterian Hospital-Weill-Medical College of Cornell University, in New York City.

Approval by Cornell’s Institutional Biosafety Committee (IBC) was the last in a series of regulatory actions that included the U.S Food and Drug Administration (FDA), the Recombinant DNA Advisory Committee (RAC) of the National Institutes of Health and Cornell’s Institutional Review Board (IRB), after a comprehensive review of the clinical protocol and safety features of the vector.

The HGTV43™ vector was developed by Enzo to include a proprietary delivery system that overcomes a major challenge in gene medicine – the efficient and safe delivery of the medicine to the appropriate target. The benefits of Enzo’s vector technology are that it achieves efficient delivery of the gene into the patient’s cells, and that it is “silent” and unlikely to trigger an immune response. In addition, during the development of the vector, two critical safety features designed to prevent the possibility of inadvertently turning on deleterious genes in the subject were incorporated into its design.

“The Phase I trial at the University of California San Francisco (UCSF) demonstrated the safety of Enzo’s StealthVector® HGTV43™ gene construct and the ability of the engineered cells to survive and function in vivo,” said Dean L. Engelhardt, Ph.D., Executive Vice President of Enzo. We look forward to this next step, the goal of which is to increase the proportion of immune cells containing anti-HIV-1 antisense genes, and thus increase resistance to HIV.”

“We are excited about this special opportunity to move into the next phase of the trial, building on the success of the Phase I study,” said Jeffrey Laurence, M.D., Professor of Medicine and Director of the Laboratory for AIDS Virus Research at The New York Presbyterian Hospital-Weill Medical College of Cornell University. “Our objective will be to expand the number of engineered cells containing anti-HIV genes in order to achieve a therapeutic effect. This approach could add a much needed option in the treatment of HIV infection.”

Dr. Engelhardt noted that the incidence of HIV infection has begun to grow in the U.S. and continues to grow at an alarming rate worldwide. It remains a major global problem with limited long-term treatment options. Current therapies, including HAART (highly active antiretroviral therapy) cocktails and protease inhibitors have been somewhat effective, but with severe side effects. In addition, an increasing number of patients who have been infected for many years are becoming resistant to these drugs. Enzo’s StealthVector® HGTV43™ gene construct represents a novel strategy for managing patients with AIDS who are resistant to current therapies.”

In the upcoming trial, Enzo’s StealthVector® HGTV43™ gene construct will be used to transfer three antisense genes designed to interfere with the growth of HIV-1 into blood cells, including CD4+ T-cells, which are the main target of infection by HIV-1.The Phase I study that took place at UCSF demonstrated that these anti-HIV-1 genes could successfully be inserted into stem cells and that the engineered stem cells were able to survive and produce CD4+ cell progeny containing functioning antisense genes, for as long as four years to date.

Date: 1/14/2004
Phase I/II Hiv Gene Therapy Trial Initiated Enzo Biochem Tells Annual Meeting. Company Now Focused on Five Therapeutic Platforms. Enzo Life Sciences Building New Direct Sales Group.

NEW YORK, NY, January 14, 2004 – Enzo Biochem, Inc. (NYSE:ENZ), a leading biotechnology company specializing in gene identification and genetic and immune regulation technologies for diagnostic and therapeutic applications, said today that the Phase I/II study of its Stealth Vector® HGTV43™ gene construct for HIV infection has been initiated at New York Presbyterian Hospital-Weill Medical College of Cornell University.

Speaking at the Company’s annual meeting of shareholders, Barry W. Weiner, President, said that the gene therapy trial, while holding important implications in treating individuals infected with HIV, could also be applicable to a broad spectrum of other infectious diseases. The objective of the current trial is to increase the number of engineered cells containing the anti-HIV-1 antisense RNA genes in circulation.

“For the last three years, ever since the Phase I trial demonstrated the safety of the HGTV43™ gene construct and the ability of the engineered cells to survive and function in vivo, Enzo has worked diligently, conducting literally hundreds of additional tests designed to assure the safety of our medicine, to reach this stage,” commented Mr. Weiner. “Now, while we await the results of the current study, we can look back and take great pride that we have advanced to this level of development, something that few others have accomplished. The sustained expression of our HGTV43™ gene construct in circulating CD4+T-cells strengthens our belief that this gene therapy protocol could function as a once in a lifetime treatment.”

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