This technology involves the transduction of primary HSCs with specific genes (or proteins, which are gene products) and their subsequent expansion in culture.  The expanded HSCs are fully functional stem cells, as demonstrated by their ability to repopulate bone-marrow depleted mice with functional cells of all hematopoietic lineages. Taiga’s accomplishment marks the first time that long-term repopulating, self-renewing HSCs have been expanded to such an extent.  Recent attempts in the field by others have succeeded in expanding a more differentiated, short-term HSC. 

Dr. Refaeli is an expert in the genetic manipulation of cells, regulation of gene expression and transformation in hematopoetic lineages. His research interests focus on three broad area: 1) the contribution of antigen receptor signaling to lymphoid neoplasica; 2) the role of role of proto-oncogenes in the regulation of lymphoid tolerance and disease; and 3) the role of MYC in the regulation of stem cell proliferation, survival, self-renewal and differentiation.  Dr. Refaeli is Associate Professor, Charles C. Gates Program in Regenerative Medicine and Stem Cell Biology, Department of Dermatology, University of Colorado Denver School of Medicine.  He received his Ph.D. from Harvard University and his A.B. degree from the University of Pennsylvania.

Brian Turner, Ph.D., M.H.S. – President and Chief Scientific Officer, Co-Founder

Dr.  Turner has extensive experience in the areas of molecular biology and genetics, biochemistry and the genetic manipulation of viruses and various hematopoietic cell types, including stem cells, mature lymphoid and myeloid cells. In addition to his role at Taiga, Dr. Turner is Research Instructor, Charles C. Gates Program in Regenerative Medicine and Stem Cell Biology, Department of Dermatology, University of Colorado Denver School of Medicine.  He received his Ph.D. from the University of Colorado Health Sciences Center, holds a Masters in Public Health from the Johns Hopkins School of Public Health and received his A.B. degree from Cornell University.

Gregory Bird, Ph.D. – Program Leader in Haematology

Dr. Bird is coordinating the basic science and genetic engineering of the blood stem cells used to generate human antibodies.  Prior to joining Taiga Biotechnologies, Dr. Bird spent eight years as a scientist at biotechnology companies Cytokine Sciences and Sangamo BioSciences. He received his Ph.D. from the University of Colorado Health Sciences Center and his B.A. from the University of Colorado, Boulder.

Red blood cell (RBC) transfusion is routinely used for many clinical and surgical applications. On average, 39,000 units of blood are needed every day and data from 2004 indicate that 29 million units of blood were transfused in one year (source http://www.aabb.com).  This procedure has singe-handedly saved many lives over the past 60 years, and demand continues to increase with advances in medical treatments and an aging population.

In spite of the wide range of clinical applications that have benefited from RBC transfusion, the supply has steadily decreased for three main reasons. First, the number of infectious agents that have been shown to be transmitted through blood transfusions have continuously increased, forcing more extensive testing of the donated supply to prevent iatrogenic infections. Second, the chronic use of Erythropoeitin (Epo) has recently been associated with increased risk of developing erythroid leukemias, embolisms as well as cardiac complications. Third, the performance of stabilized and recombinant hemoglobins and oxygen transporters (perflourocarbons) has been disappointing and these approaches will have to overcome important development hurdles before replacing RBC transfusions in the clinic.

Taiga is developing a novel method that uses its conditionally-transformed long-term repopulating hematopoietic stem cells as the source of a continuous and defined supply for the production of RBCs. This technology can either provide mature RBCs for immediate transfusion or RBC progenitors for transfer and short-term reconstitution of the RBC compartment in patients. Furthermore, the enucleation of mature RBCs should alleviate concerns of any genetic modification. One of the company’s ultimate goals for this project is to engineer a RBC product having a sufficiently longer shelf life to enable its distant transport to patients who don’t have access to RBC therapy currently. Ready access to a continuous supply of RBC progenitors that could generate a defined RBC product for transfusion would alter clinical practice and render blood transfusion a safer and more extensively used procedure.

An important challenge in vaccine design involves the selection of targets that are readily accessible to the immune system. For antiviral vaccines, a majority of such targets are highly variable and unless a vaccine can overcome this diversity, the virus can simply change its expression patterns, thus limiting vaccine effectiveness. Similarly, in cancers like melanoma, the specific challenges to vaccine design include the selection of antigens that are required for tumor cell maintenance as well as the ability for the immune system to respond to self-antigens expressed by the tumor cells.

Taiga has developed a proprietary molecular antigen TBI4000 that, in animal models, improves the response to antiviral or anti-melanoma vaccines through the simultaneous enhancement of immune function and the transient modulation of self-tolerance. Based on the transient modulation of specific growth gene(s) in lymphoid cells, Taiga’s TBI4000 adjuvant appears to accelerate vaccine responses, generate cross-reactive antibodies, and allow significant (100X) “dose-sparing”.

Taiga’s proprietary stem cell technology has the possibility of overcoming both of the limitations that have been associated with this breakthrough discovery.  We can amplify large amounts of bone-marrow stem cells (overcoming the issue of numbers of cells) and because they are a pure stem cell population, we can overcome the issue of matching donors and recipients (pure stem cell populations can be transplanted across genetic barriers).

One important issue that has recently been raised by possible institutional investors is the regulatory issues associated with the development and approval of cell based products.  Because of the recent setbacks that have been seen in the area of gene-therapy, investors have been reluctant to support programs that include the genetic modification of cells by viral integration.  The scientists at Taiga also recognize the inherent dangers of transducing genes into stem cell populations and have recently developed a method to grow adult stem cells without integrating foreign genes into the cellular DNA by using recombinant proteins.  The pieces appear to be in place for a radical new approach for treating HIV infection to become a reality in our lifetime.

Stem cell transplant

The unmet medical need for stem cell transplantation in each specific hematology indication is presented in Table 1. We have also assumed that the number of transplants per year in the U.S. will remain stable in the next 10 years and will not grow or decline significantly. In fact, if we're successful with our Universal stem cell product, we expect an increase in the number of transplants in these indications due to the future use of transplant in patients who today aren’t eligible due to lack of a matching donor.

Therapeutic Antibodies

The dynamics of the antibody market are highly attractive for innovative small companies such as Taiga. Significant unmet needs remain in infectious disease and nearly all cancer indications; regulatory pathways involving accelerated approval can be achieved for innovative therapeutics that demonstrate meaningful early clinical results; the sales and marketing organizations required to launch and market new therapeutics are small relative to other therapeutic areas and are therefore feasible for small companies to build; and the pricing environment remains very attractive for products that genuinely improve on current standards of care.

The use of antibody therapy for the treatment of disease has drawn approval by the Food and Drug Administration (FDA). Over the past 10 years or so, the US FDA has approved several monoclonal antibodies for the treatment of certain cancers (source: American Cancer Society).

Small molecule therapEutics

As with antibody therapeutics the dynamics of the small molecule therapeutics market are highly attractive to small companies such as Taiga. Major unmet medical needs remain in nearly all blood cancer indications. Accelerated and subsidized regulatory pathways to approval can be achieved for novel therapeutics that demonstrate promising early clinical results. Also, as with antibody therapeutics, the sales and marketing organizations required to launch and market new treatments are feasible for small companies with or without large pharmaceutical partnerships and the pricing environment remains very attractive for products that genuinely improve on current standards of care.

Taiga's initial indication for its three small molecule candidates is AML (Acute Myelogenous Leukemia), which represents an even larger potential market than CML (13,410 new cases of AML are expected to be diagnosed in 2007 in the United States vs. 4,570 new cases of CML-source: Leukemia and Lymphoma Society).

Stem-cell therapeutics and red blood cell production for the treatment of hematological malignancies via hematopoietic stem cell transplant or any medical procedure requiring red blood cell transfusion. A stem cell is an extraordinary type of cell that has the ability to self-renew over time and can also give rise to all of the different cell types present in blood. Development and testing of our long-term hematopoietic stem cells has demonstrated the effectiveness of these cells in treatment of a variety of cancers in animal models. Transitioning into the clinical setting, the lead indications for this program include acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), and chronic myeloid leukemia (CML). Taiga is also leveraging its patented stem cell technology to develop a safer and more efficient method to produce large amounts of red blood cells for medical use.

THE HEMATOPOIETIC STEM CELL (HSC) TRANSPLANTATION OPPORTUNITY

HSC transplants have been performed by physicians for decades to treat a variety of deadly diseases, in particular cancer. Patients are initially treated with high dose chemotherapy drugs that ablate existing bone marrow cells, including HSCs. The subsequent treatment of these patients with healthy HSCs restores the patient’s hematopoietic system.

The success of HSC transplant in specific cancers has led to significant use. As described in Table 1, >30,000 HSC transplants were performed in the U.S. in 2006 among leukemia and lymphoma patients alone.

Though HSC transplantation has become a successful approach and is standard of care for many cancers, the technology currently employed in HSC transplantation has not been adapted to address the significant problems associated with the procedure that limit both its effectiveness and the breadth of its use.

The specific technical hurdles limiting the use and the effectiveness of HSC transplant are:

1. Cell numbers. Obtaining a sufficient number of HSCs to ensure successful engraftment of the HSC transplant.
   • Often the optimal number of cells needed for an adult HSC transplant is not available and results in a failure to engraft.
   • Ensuring sufficient cell numbers in HSC transplant for cancer indications has significant clinical benefits, including increased survival, improved bone marrow function, and a lower incidence of subsequent Myelodysplastic Syndrome.
   • Cases that require multiple rounds of bone marrow (HSC) transplantation pose a particularly difficult challenge, in terms of procuring a sufficient number of stem cells.
2. Cell purity. Achieving sufficient cell purity to allow HSC transplant into non-matched transplant recipients.
   • Because HSCs harvested from either bone marrow or peripheral blood are contaminated with donor immune cells, HSC transplants are only successful when the donor and recipient are matched (histocompatible).
   • Obtaining pure HSCs allows the transfer of donor cells into ANY recipient.

TAIGA’S SOLUTION FOR HSC TRANSPLANTATION

Taiga has addressed the technical hurdles associated with HSC transplant by developing patented technologies that allow for the unlimited expansion and purification of undifferentiated HSCs ex vivo. The expanded HSCs are fully functional stem cells, as demonstrated by their ability to repopulate bone-marrow depleted mice with functional cells of all hematopoietic lineages. This is the first time that long-term repopulating, self-renewing HSCs have been expanded to such an extent.

Using these technologies, Taiga’s goal is to develop a single Universal HSC product for broad use in HSC transplant. A universal product would have several critical benefits over current approaches that would make it an attractive therapy for use in the clinic:

• Removes the need for donor / recipient histocompatibility, greatly expanding the population of patients eligible for HSC transplant.
• Creates a single standard for the preparation and transfer of donor HSC cells (current protocols for HSC harvest and preparation vary widely and perform inconsistently in practice).

RED BLOOD CELL DEMAND AND OPPORTUNITY

Transfusion of red blood cells (RBC) is commonly needed in many clinical and surgical practices. On average, 39,000 units of blood are needed every day and data from 2004 indicate that 29 million units of blood were transfused in one year (source http://www.aabb.com). This procedure has singe-handedly saved many lives over the past 60+ years, and demand continues to increase with advances in medical treatments and an aging population, but is increasingly difficult to provide for the following reasons:

• The supply of blood components available from transfusion has steadily decreased over the past number of years, and will continue to do so, with more complex and thorough diagnostic testing for blood borne infectious diseases.
• The performance of stabilized and recombinant hemoglobins and oxygen transporters (perflourocarbons) has been disappointing and these approaches will have to overcome important development hurdles before replacing RBC transfusion in the clinic.
• Increasing reports of potential unwanted side-effects of long-term exposure to recombinant erythropoietin (EPO) suggest that additional studies of this widely used product may be warranted.
• While some initial attempts have been made to derive RBCs from hematopoietic stem cells in vitro (bone marrow, cord blood and peripheral blood), they are expensive and labor intensive, and suffer from the absence of a defined and continuous supply of RBC progenitor cells.

TAIGA'S SOLUTION FOR RBC PRODUCTION

Taiga is currently developing a novel method that uses our conditionally-transformed long-term repopulating hematopoietic stem cells as the source of a continuous and defined supply for the production of RBCs. This technology can either provide mature RBCs for immediate transfusion, or RBC progenitors for transfer and short-term reconstitution of the RBC compartment in patients. Furthermore, the enucleation of mature RBCs should alleviate concerns of any genetic modification. One of our ultimate goals for this project is to engineer a RBC product that has a longer shelf life that would enable far enough transport to reach patients who don’t have access to red blood cell therapy currently.

Biologics are therapeutics whose mode of action is based on naturally occuring interactions within living animals.

Therapeutic antibodies. Taiga has also developed an innovative method for rapidly generating monoclonal antibodies for treating cancer and infectious disease. Monoclonal antibodies work in the same way natural antibodies work, by identifying and binding to a specific target in the body. They then alert other cells in the immune system to eliminate the antibody bound substance. Development of fully humanized antibodies for the treatment of disease has become a primary focus of Taiga.

THERAPEUTIC ANTIBODY OPPORTUNITY

In recent years, the clinical application of Monoclonal Antibodies (MoAbs) has emerged as a major new source of drugs for cancer therapy. Monoclonal antibodies are naturally occurring proteins of the immune system that attack foreign substances in the body and can be grown and purified in a laboratory setting. As a cancer therapy, once the antibody binds its receptors, it marks the cancer cells as targets of the immune system. Despite the success of antibody therapies in the clinic, the overall approach is limited by the difficulty in generating antibodies to certain protein targets. These limitations include the physiological processes that keep the immune system from making antibodies that recognize proteins from the body (self-proteins), as well as the requirement to be able to fuse an antibody-making cell with a myeloma cell line in order to generate large amounts of the specific antibody. These problems specifically impact on our ability to generate novel antibodies that specifically recognize proteins expressed by tumor cells. We have developed a novel method to generate monoclonal antibodies to any protein we would like, without regard to the limitations involved by tolerance to self-proteins. We have also overcome the need to fuse the antibody-producing cells with a myeloma cell line in order to enable us to produce large amounts of a specific antibody.

Limitations of current technology:

1. Specificity. Traditional methods used to make MoAbs limit the possible target specificity at several stages.
   • The ability to make an antibody against just any target is limited by regulatory mechanisms that prevent antibody formation against the host’s "self" proteins.
   • The process of generating an antibody-producing cell line requires that the antibody cell reside in a specific point of growth to "fuse" with another cell.
   • These two steps are likely to reduce the number of possible target specificities represented at the end of the process by approximately 90%.
2. Time. If an antibody can be generated against a specific target, producing a therapeutic product can take years because:
   • Extensive testing is required to identify the one cell that makes the antibody of interest.
   • The elaborate process of changing a mouse antibody into a human antibody. This is also the main source of unforeseen complications that have derailed several clinical trials.

TAIGA'S SOLUTION FOR THERAPEUTIC ANTIBODY PRODUCTION

We have developed a novel method of generating MoAbs that is able to overcome both obstacles and recognize antigenic specificities that would normally be difficult to generate with current technologies. This can be achieved 3-4 times faster than current technologies, which would also enable us to use this approach for the rapid generation of antibodies for emerging infectious diseases.

We discovered that we could force mice to generate antibodies to a "self" target (which are called "autoantibodies") by over-expressing a particular gene in our proprietary stem cells. The progeny cells, called B-cells, become activated and produce copious amounts of autoantibody as a result of their ability to overcome the regulatory mechanisms that normally prevent antibody formation against the host's "self" proteins.

Using this technology, Taiga has the opportunity to develop antibodies against any conceivable target for clinical applications in a variety of indications. Our ability to quickly generate specific antibodies without the need, and problems related to, humanizing antibodies makes our approach unique in the field

Small Molecules are naturally occurring or synthetic organic compounds that interfere or augment biological processes.

Small Molecules. Taiga is in the process of identifying novel drugs that selectively inhibit growth or viability of cancer cells while sparing normal cells. Taiga is currently pursuing IND-enabling research on lead candidates that have shown promise in the specific targeting of stem leukemic cells and leukemias, but did not affect normal blood stem cells. Our goal is to reduce the impact of chemotherapy on the patients while undergoing treatment, and greatly increase their quality of life.

SMALL MOLECULE DEVELOPMENT OPPORTUNITY

Small molecules represent a bridging of historical scientific observation and cutting edge chemical synthesis. Historically, the most effective drugs we have had until recently have been natural products – these are all small molecules. We now have the ability to harness combinatorial chemistry to synthesize novel species of small molecules that do not commonly occur in nature. Furthermore, once a candidate is identified, medicinal chemistry allows for the subsequent modification of the small molecule to better suit our therapeutic goals.

Limitations of current small molecule development:

1. Top-down approaches. By focusing on a specific enzymatic function, and targeting a disease later, issues arise regarding delivery in vivo such as solubility, half-life and targeting the malignant cell type.

2. Side effects. If a small molecule can be generated against a specific target, unwanted side effects are often discovered only after several expensive stages of development:

TAIGA'S SOLUTION FOR SMALL MOLECULE DISCOVERY AND VALIDATION

Our cellular products enable these screens – the ability to produce many blood stem cells has been an enabling breakthrough in this setting. Until now, the logistics, expense and resources required for performing such screens have all been rate-limiting steps that have prohibited the identification of such compounds. Our early screening efforts have already identified candidates that are being moved into IND-enabling studies.

Our proprietary screening platform allows us to perform differential screens to identify novel agents that will specifically kill leukemic stem cells, but spare normal blood stem cells. We can also search for novel drugs that can induce differentiation of normal or cancerous blood stem cells in order to curb their ability to reproduce. The drug candidates will then be used to determine the specific molecular mechanism of action. To date, none of the natural products that have been developed were kept out of clinical use for lack of understanding of the molecular mode of action.

We have committed to producing new treatments for blood cancers that are effective and have minimal effects on normal or non-cancerous cells. Our high standards for pre-clinical testing in genetically validated animal models of disease help assure that drugs with serious side effects can be eliminated from consideration for further human use.

Research Assistant Professor, Department of Pediatrics, NJMRC. Cornell University, B.A., Johns Hopkins School of Public Health, M.H.S., University of Colorado Health Sciences Center, Ph.D. NJMRC, Postdoctoral Fellowship.

Yosef Refaeli, Ph.D. Co-founder and Chairman of the Scientific Advisory Board.

Assistant Professor, Charles C. Gates Program in Regenerative Medicine and Stem Cell Biology, Department of Dermatology, University of Colorado Denver School of Medicine. University of Pennsylvania, A.B., Harvard University, Ph.D. University of California San Francisco, Postdoctoral Fellowship.

Gregory Bird, Ph.D. Group Leader in Molecular Biology.

Research Fellow, Department of Pediatrics, NJMRC and UCDHSC. University of Colorado Boulder, B.A., University of Colorado Health Sciences Center, Ph.D. NJMRC/UCHSC, Postdoctoral Fellowship.

Peter Kiener, Ph.D.

David B. Weiner, Ph.D.

Jakub Tolar, M.D.

Jack McGuire