SubscribeAccording to The Cancer Research UK "More than one in three of us will develop cancer at some point. Few of us go through life without coming into contact with the disease in some way." These words only make it too clear that cancer still constitutes one of the major causes of death in our world today.
In particular in the developed countries cancer has emerged as the second most common cause of death (cardiovascular diseases are still the primary cause of deaths). In total there are 1.38 million new cancer cases in North America, 2.8 million in Western Europe and 0.5 million in Japan per year. There are approximately 100 different types of cancer, of which the 25 most common types cause 80% of the new cases and deaths.
The most frequent new cancer cases worldwide include lung (1.2 million), breast (1 million) and colon/Rectum cancer (0.95 million). Unfortunately cancer death rates have not yet been and are not expected to decline significantly during the coming years in contrast to other diseases. In particular Lung Cancer still causes 18% of cancer deaths. Obviously, this constitutes a tremendous unmet medical need.
Currently the industry starts to respond to this need. Large and small pharmaceutical companies change their focus of their R&D programs and devote more of their resources to the battle against cancer. Yet, despite these attempts, novel medication still takes approximately 10 years before it reaches the market and before patients can actually benefit from the developmental efforts.
Cancer Therapeutics
Treatment of cancer nowadays relies on conventional and new therapeutic approaches. Traditional therapies, including Chemotherapy, use Anti-metabolites, Alkalyting agents, topoisomerase and microtubule inhibitors. Hormone therapy is used in certain cancers such as breast and prostate to block the actions of hormones that potentially facilitate tumor growth. The treatment either blocks the reception site for these hormones or prevents their production in the body entirely. Further traditional cancer therapies also include Radiotherapy and surgery. Mostly, however, the different types of treatment are used in combination with each other for more effective cures.
These traditional methods have ruled the market in the past. Mostly they comprise the systematic administration of unguided toxic drugs, which causes a large number of adverse events in patients. However novel therapies benefit from the progression of science and novel discoveries leading to more targeted cancer treatments, which avoid any unwanted effects. Roughly there are five major new technological approaches:
Monoclonal Antibodies: Antibodies, derived from a single B-cell clone that are designed to target specific antigens on tumor cells.
Cell signaling therapy: Certain cell signals inherent in a cells lifecycle are central to cancer pathogenesis and offer highly specific intracellular targets for emerging therapeutics.
Active immunotherapy: Non-specific derivatives of infectious agents are used to trigger the body’s own immune system to treat cancer.
Anti-Angiogenesis: Agents, that block new blood vessel formation to starve growing tumor cells.
Gene-based therapy: Therapeutic approaches either modify gene expression (oncogenes and tumor-suppressor genes), replace oncogenes or direct cytotoxic agents to cancer cells exhibiting specific gene mutations.
What is cancer all about?
Cancer is characterized by an increase of cells that do not fit into the organization of the healthy tissue.
The cellular processes proliferation and apoptosis determine largely the biology of the cancer. It is nowadays accepted that dormant metastases contain proliferating and apoptotic tumor cells. Growing malignant tumors partly consists of apoptotic tumor cells. Cells proliferation normally should equal the rate of cell death, a state which is called tissue homeostasis. With cancer this equilibrium is disturbed resulting in a higher degree of cell proliferation than apoptosis, which in turn leads to tumor growth.
Apoptosis
Apoptosis is a well-organized process of cell suicide which eliminates cells from tissues in a silent and non-provocative manner. It is essential for development and tissue homeostasis of the multicellular organism. In addition, apoptosis plays a role in pathologies such as tumour growth, neurodegeneration, acute myocardial infarction and chronic inflammation.
Apoptosis can be employed as a target for clinical treatment of diseases. For instance, chemo- and radiotherapy are effective in cancer treatment because they induce apoptosis of the tumour cells.
Measurement of apoptosis in vivo thus contributes to our understanding of the role of apoptosis in physiology and pathology. It is also the ultimate drug-screening modality to reveal drug-efficacy in the context of the whole organism if drugs are used to target apoptotic pathways.
Conventional therapies such as chemo- and radiation therapies are effective through inducing apoptosis in the tumor. The process of apoptosis in the cancer lesion results in a permanent level of apoptotic cells. These apoptotic cells are characterized by the cell surface expression of the phospholipid phosphatidylserine (PS). Apoptosis detection can be accomplished with Annexin V, which is a human protein that binds with high affinity to cell surface expressed PS.
Annexin V
One of the founders of PharmaTarget has discovered Annexin V and has identified its ability to bind to apoptotic cells.
Annexin V is a human protein that has the ability to bind to phosphatidylserine (PS) in the presence of Ca2+.
PS is present in the plasma membrane of every cell. If the cell is alive PS is absent in the outer plasma membrane leaflet and predominantly located the plasma membrane leaflet facing the cytosol. Apoptotic cells express actively PS in the outer leaflet of the plasma membrane during execution of apoptosis. PS then functions as an "eat me" signal for phagocytes. The structure-function relationship of Annexin V binding to PS is resolved. Its structural features and its functional characteristics endow this protein with a high potential for diagnostic and therapeutic applications in clinical situations in which apoptosis plays a role.
The research team of PharmaTarget has substantiated the diagnostic potential of Annexin V in vitro and in vivo in animal models and in patients. Currently, PS is a validated marker for detecting apoptotic cells in vitro and in vivo using Annexin V.
Why use Annexin V to detect apoptosis rather than DNA laddering and Tunel assays?
The answer is simple. Annexin V is very easy to use in vivo as well as in vitro. Information is provided on a per cell basis. It is based on the key processes in programmed cell death, i.e. the expression of PS on the outer leaflet of the cell membrane. This phenomenon happens at a very early stage of the apoptosis process, when the cell membrane is still intact. Annexin V is a protein which binds with high affinity to PS, which is expressed on the surface of the apoptotic cells. The simplicity of the Annexin V method provides rapid, real-time results. Consequently, the screening of a number of compounds by means of in vivo experiments becomes less time consuming because Annexin V detects dying cells very quickly.
Other methods to detect apoptosis such as DNA and TUNEL rely on the destruction of this membrane integrity and actually the destruction of the cells, leading to the shrinkage of the tumor. The drawback with TUNEL assays is the fact that the testing includes a number of steps that can lead to a certain amount of variation of result. DNA laddering is a time-consuming and complex method as well and provides information only on a population of cells.
Since Annexin V plays a key role in apoptosis detection, PharmaTarget has decided to implement in house manufacturing of this essential protein. This 2nd generation Annexin V product meets the highest standard of quality. The use of Annexin V is increasingly recognized as a rapid and accurate way of detecting apoptosis. Therefore the company offers labeled Annexin V products to research institutes and companies.
Due to the extensive knowledge on conjugation of labels to Annexin-A5, these products can be tailor made to meet the needs of individual customers. PharmaTarget delivers products based on Annexin V, mainly tagged with fluorescent labels such as Oregon-Green, Alexa-red and FITC. An Annexin V based magnetic bead assay is developed for the detection of anti bodies against Annexin-A5, as has been required by FDA. All these products are distributed to research institutes and biotech or pharmaceutical companies by PharmaTarget.
Imaging
Following from the discovery of Annexin V, the company developed a Molecular Imaging Platform, intended to visualize the process of Apoptosis.
Molecular Imaging is an emerging field for studying animal models. Optical imaging is particularly suited for molecular imaging as fluorescent probes are safe, sensitive and can be specifically conjugated to small molecules, monoclonal antibodies and proteins. It is designed for monitoring physiological changes in living animals rather than only pathological changes. The research team of PharmaTarget has optimized procedures to couple Annexin V to a wide range of reporters without impairing its PS binding ability.
The Annexin V conjugates retain the power to detect apoptotic cells in vitro and in vivo. Furthermore, PharmaTarget has developed a Molecular Imaging Platform to measure apoptosis in tissues of the living animal in real-time and on a per cell basis using fluorescently labeled Annexin V. This Platform creates the possibility to study the efficacy of pro- as well as anti-apoptotic drugs real-time in the complexity of the whole organism.
Molecular Imaging Platform
Our two medical and biochemical experts have combined their expertise to develop the unique Molecular Imaging Platform which can test in vivo new drug candidates in real time. The analysis is conducted by means of tailored mouse models. Furthermore, the assessment with regard to drug efficacy centres on the Annexin V technology. Annexin V is a protein that binds with cells in apoptosis, undergoing programmed cell death.
The Molecular Imaging Platform can visualize the level of apoptosis within special animal models that are treated with your developed compound. Depending on whether your drug candidate should hamper or promote apoptosis, the gathered results very quickly reveal the effectiveness of the drug at hand. Possible tests include kinetic studies and studies regarding the compound’s efficacy of the drug at hand.
Your Advantages:
- Quick Results: Testing your new compound with PharmaTarget’s Molecular Imaging Platform accelerates your preclinical R&D Program in general. Due to in vivo testing, the results immediately reveal the effects of your compound in the target tissue of the living animal. It circumvents lengthy experiments to identify your leads. Traditional approaches mostly used tumor size index as an endpoints in their efficacy studies of their compounds.
- Lower Costs: Due to PharmaTarget’s unique approach to testing compounds, test results are produced much quicker than using classical methods. You save scarce financial resources and require fewer test animals.
- Fewer Test Animals: Compared to classic in vitro studies the tests are conducted with one animal instead of several per sequence of time. Therefore biological variation leading to biased test results can be effectively diminished.
An example
Our Molecular Imaging Platform allows for the evaluation of compounds in a variety of animal models. In this example a novel anti-tumor compound is evaluated in a mouse tumor model. Tumor bearing animals are injected with either placebo or the experimental compound. Subsequently the mice receive fluorescently labeled Annexin V. The molecular imaging equipment registers Annecin-A5 uptake by the tumor real-time in the living animal.
The speed and the extent of the uptake reflect the efficacy of the experimental compound. In the example the experimental compound is a chemo-therapeutic small chemical entity. The experimental compound causes an increased uptake of Annexin V. by the tumor because the drug killed the tumor cells through programmed cell death. The placebo does not enhance the uptake of Annexin V by the tumor.
There are five different animal models of disease, covering the therapeutic areas of oncology in particular lung, breast and colon rectal cancer. Furthermore, drugs treating Ischemia of the Heart, Thrombosis, Artherosclerosal Vascular Injury and Angiogenesis can be tested as well. The majorities of compounds induce or inhibit Apoptosis.
Conclusion
Cancer still constitutes a major threat to today’s society. More than one in three individuals will probably experience the disease at some point. Current drug development time is too lengthy. It comprises several selective stages in which one lead compound has to be identified out of a number of candidate drugs. Furthermore, long lasting tests exhaust valuable resources. There is the need for sound and efficient development in the shortest time possible.
The concept of Annexin V as a tool for rapid apoptosis detection has a huge potential to offer a solution to the above mentioned difficulties. Using this protein for in vitro and in vivo research can significantly speed up current drug development and more specifically current screening activities during the preclinical phase. Compounds can be tested on their efficacy in vivo by using molecular imaging, revealing real time results within days instead of weeks.
PharmaTarget aims to accelerate the development process for novel drug candidates based on the unique Molecular Imaging Platform and the Annexin V technology. With these tools offered commercially for the first time, PharmaTarget hopes to make a difference and to speed up R&D.