PSDV » Topics » The BioSilicon Technology System

This excerpt taken from the PSDV 10-K filed Sep 26, 2008.

The BioSilicon Technology System

Our proprietary BioSilicon technology system is based on a nano-porous form of elemental silicon. We believe it has the potential to deliver a wide variety of drugs, including small chemical entities, peptides, proteins and other therapeutics such as P32. The BioSilicon technology involves processing the silicon to create a “honeycomb” structure of pores. BioSilicon has two significant characteristics:

 

   

Biocompatibility. BioSilicon is biocompatible, meaning that it is not injurious and does not cause immunological rejection within the body when it degrades into silicic acid (the non-toxic, dietary form of silicon found in food).

 

   

Biodegradability. BioSilicon is biodegradable both in vivo (in animals and humans) and in vitro (in solution). BioSilicon’s biodegradability can be finely tuned so that it dissolves in suitable environments in days, weeks or months.

As a result, we believe that BioSilicon, like Durasert, can be designed to locally deliver therapeutics to a target site at a controlled release rate for an extended period of time.

The following properties make BioSilicon a potentially effective drug delivery platform:

 

   

high level drug loading (up to 95%) and up to 50% weight/weight;

 

   

ability to improve the dissolution and bioavailability of poorly water soluble drugs and the ability to control drug release;

 

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ability to accommodate different molecular sizes of drugs; and

 

   

ability to serve as a conductor of electrical charge which can be altered to regulate drug delivery rate (in potential future advanced drug delivery systems).

BioSilicon Product Candidate and Potential Applications.

BrachySil for Pancreatic Cancer. Our BrachySil product candidate is designed to treat pancreatic cancer. Brachsyil is injected through a needle directly to the tumor site in an in-office procedure. BrachySil delivers phosphorus-32, or P32, a beta-emitting radioactive isotope that has been shown to shrink tumors. Because this radiation is also harmful to healthy tissue, BrachySil is designed to reduce radiation dispersed beyond the area of the tumor. Existing P32-based products allow the isotope to dissolve, disperse throughout the body and harm healthy tissue in other parts of the body.

We believe BrachySil has a number of potential advantages:

 

   

Short range. P32 isotope has a short active range resulting in less damage to healthy tissue;

 

   

Range of tumors. Fine gauge needle delivery allows potential application to a range of solid tumors;

 

   

Direct delivery. Injection via fine gauge needle minimizes side effects and tissue trauma;

 

   

Distribution. P32 half-life of 14 days allows more logistically convenient distribution to hospitals and application in the patient;

 

   

Immobilization. P32 particles are generally localized in the tumor, significantly reducing risk of leakage or systemic side effects.

We have completed an initial clinical trial, designed as a safety study, of Brachysil for the treatment of pancreatic cancer and have commenced a dose-ranging trial. We are seeking to clarify the regulation of BrachySil as a medical device in the U.S. and the European Union (EU). Generally, obtaining regulatory approval to market a medical device is less expensive and time consuming than the process required for approval of a new drug. Our strategic plan is to secure a development and marketing partner in advance of commencing a pivotal Phase III clinical trial of BrachySil.

Other Potential BioSilicon Applications

We believe BrachySil has the potential to be used to treat other solid tumors, and we intend to investigate other tumor indications, such as liver metastases.

This excerpt taken from the PSDV 8-K filed Jun 20, 2008.

The BioSilicon Technology System

Our proprietary BioSilicon technology system utilizes an elemental silicon, which is processed to create a “honeycomb” structure of pores, to deliver various drugs, including small chemical entities, peptides and proteins. BioSilicon has two significant characteristics:

 

   

Biocompatibility. BioSilicon is biocompatible, meaning that it is not injurious and does not cause immunological rejection within the body when it degrades into silicic acid (the non-toxic, dietary form of silicon found in food).

 

   

Biodegradability. BioSilicon is biodegradable both in vivo (in animals and humans) and in vitro (in solution). BioSilicon’s biodegradability can be finely tuned so that it dissolves in suitable environments in days, weeks or months.

As a result, we believe that BioSilicon, like Durasert, can be designed to provide localized delivery, controlled release rate and extended delivery of therapeutics at a target site.

The following properties make BioSilicon a potentially effective drug delivery platform:

 

   

high level drug loading (up to 95%) and up to 50% weight/weight;

 

   

ability to improve the dissolution and bioavailability of poorly water soluble drugs and the ability to control drug release;

 

   

ability to accommodate different molecular sizes or drugs; and

 

   

ability to serve as a conductor of electrical charge which can be altered to regulate drug delivery rate (in potential future advanced drug delivery systems).

BioSilicon Product Candidate and Potential Applications.

BrachySil for Pancreatic Cancer. Our BrachySil product candidate is designed to treat pancreatic cancer by injection through a needle directly to the tumor site in an in-office procedure. BrachySil delivers phosphorus-32, or 32-P, a beta-emitting radioactive isotope that has been shown to shrink tumors. Because this radiation is also harmful to healthy tissue, BrachySil is designed to reduce radiation beyond the area of the tumor. Existing 32-P-based products allow the isotope to dissolve, disperse throughout the body and harm healthy tissue in other parts of the body.

We believe BrachySil has a number of potential advantages:

 

   

Short range. 32-P isotope has a short active range resulting in less damage to healthy tissue;

 

   

Range of tumors. Fine gauge needle delivery allows potential application to a range of solid tumors;

 

   

Direct delivery. Injection via fine gauge needle minimizes side effects and tissue trauma;

 

   

Distribution. 32-P half-life of 14 days allows more logistically convenient distribution to hospitals and application in the patient;

 

   

Immobilization. 32-P particles are generally localized in the tumor, significantly reducing risk of leakage or systemic side effects.

We recently completed a Phase IIa clinical trial for pancreatic cancer and expect shortly to commence a Phase IIb dose-ranging trial. Although we have to date funded the BrachySil clinical development activities, our strategic plan is to identify a co-development and marketing partner in advance of commencing a pivotal Phase III clinical trial.

We are seeking to clarify the regulation of BrachySil as a medical device in the U.S. and the European Union (“EU”). Generally, obtaining regulatory approval to market a medical device is less expensive and time consuming than the process required for a new drug.

Other Potential BioSilicon Applications

We believe BrachySil has the potential to be used to treat other solid tumors, and we intend to investigate other tumor indications, such as liver metastases. Although our research in the following areas is at a preliminary stage, we also believe that BioSilicon has potential to be used as a biodegradable scaffold for orthopedic tissue engineering to treat bone conditions, to promote bone growth and for other orthopedic applications, as well as for tissue regeneration in the area of wound management.

 

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This excerpt taken from the PSDV 20-F filed Oct 1, 2007.

The BioSilicon Technology System

BioSilicon is composed of elemental silicon, which can be processed to create a “honeycomb” structure of pores. These pores can be formed into a diverse array of shapes and sizes and can be filled with various drugs, including small chemical entities, peptides and proteins. We believe that BioSilicon’s features include:

 

   

Biocompatibility. BioSilicon is biocompatible, meaning that it is not injurious and does not cause immunological rejection within the body. We have assessed the biocompatibility of BioSilicon in

 

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a series of pre-clinical studies, as well as in our ongoing clinical work. BioSilicon degrades in the body into silicic acid, the non-toxic, dietary form of silicon which is found in some common foods.

 

   

Biodegradability. BioSilicon can be made biodegradable in vivo (in animals and humans) and in vitro (in solution). The rate of biodegradation depends on the degree of nanostructure that is imparted on the material. As a result, we believe that BioSilicon can be made to dissolve in suitable environments in days, weeks or months, depending upon the particle size and nature of the BioSilicon implanted. This has been demonstrated in various models, including in vitro buffer and simulated body fluid systems and in pre-clinical in vivo models.

The focus of our internal BioSilicon product development is therapeutic delivery, with an initial emphasis on a product for pancreatic cancer. Other potential BioSilicon drug delivery products include reformulation of generic drugs or formulation of new chemical entities to enhance bioavailability, stability and/or provide controlled release. We have developed commercialization plans for BrachySil, our lead BioSilicon product candidate, bearing in mind market sizes, benefits offered to patients and alternative competitive therapies. The first step in our commercialization strategy for BrachySil was a validation of human safety and efficacy through human clinical trials in primary liver cancer (hepatocellular carcinoma, or HCC). Using the results from the HCC program, we began a Phase IIa safety trial in pancreatic cancer which has now been fully enrolled. We believe pancreatic cancer is a more viable indication to pursue than HCC. We may develop BrachySil for a number of other solid tumor indications in the future, such as liver metastases and breast, brain and lung cancer.

We are also focusing on the application of BioSilicon technology for the formulation of poorly water soluble drugs as well as the development of controlled, slow release drug delivery products. We intend to achieve this primarily through licensing the use of BioSilicon to pharmaceutical and biotechnology companies for delivery of their proprietary drugs.

The following properties make BioSilicon a potentially effective drug delivery platform:

 

   

high level drug loading (up to 95%) and up to 50% weight/weight;

 

   

ability to improve the dissolution and bioavailability of poorly water soluble drugs and the ability to control drug release;

 

   

ability to accommodate different molecular sizes or drugs; and

 

   

ability to serve as a conductor of electrical charge which can be altered to regulate drug delivery rate (in potential future advanced drug delivery systems).

BioSilicon functions as a “honeycomb” structure to retain drugs within the ‘pores’ inside of the nanometer scale structure. BioSilicon’s biodegradability can be finely tuned without changing the chemical nature of the material itself. Thus, unlike polymer-based systems, BioSilicon’s composition is identical for all potential products whether they are implants for drug delivery or biodegradable orthopedic devices. The only characteristic that is varied is the level of engineering and shape of the silicon matrix.

Product Candidate: BrachySil

Brachytherapy is a relatively new form of treatment for cancer involving the localized delivery of radioactive agents directly into a tumor. With improved tumor location and mapping, this approach to cancer therapy has grown substantially in recent years allowing the clinician to specifically expose tumor tissue to radioisotopes in a targeted manner.

The market is currently dominated by the use of radioactive ‘seeds’ for the treatment of hormone non-responsive prostate cancer. Current mainline brachytherapy implants are relatively large, causing trauma and hemorrhaging in tumors. Such seeds also carry comparatively long-range gamma emitters that cause normal tissue damage and other quality of life problems to the patient.

 

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Other products in this area such as Yttrium 90 (Y90) ceramic spheres are not generally administered directly into tumors but into the vasculature feeding tumor-bearing organs such as the liver. The latter approach has the potential to cause a significant degree of damage to healthy tissues.

BrachySil consists of an injectable BioSilicon structure that carries phosphorus-32, or 32-P, a beta-emitting radioactive isotope which has been shown to shrink tumors. However, as this radiation is also harmful to healthy tissue, the 32-P and its radiation should be localized to the area of the tumor and not allowed to travel within the body. Existing 32-P-based products do not fully immobilize 32-P, allowing the isotope to dissolve, disperse throughout the body and harm healthy tissue in other parts of the body. We have engineered BrachySil to minimize 32-P leakage from the BioSilicon particle. Therefore, the 32-P is in effect “locked” into BrachySil by producing an alloy of phosphorus and silicon. BrachySil is administered, without surgery, via a fine gauge needle using ultrasound guided endoscopy under a local anesthetic. This allows the clinician to administer a single dose of BrachySil directly into the tumor site. BrachySil offers interventional radiologists a short-range longer life isotope that can be delivered through a fine bore needle making it a more user-friendly and precise product for both patient and physician.

In summary, for this form of treatment, we believe BrachySil has many significant advantages:

 

   

Short range. 32-P isotope has a short active range resulting in less damage to healthy tissue;

 

   

Range of tumors. Fine gauge needle delivery allows potential application to a range of solid tumors;

 

   

Direct delivery. Injection via fine gauge needle minimizes side effects and tissue trauma;

 

   

Distribution. 32-P half-life of 14 days allows more logistically convenient distribution to hospitals and application in the patient;

 

   

Immobilization. 32-P particles are localized in the tumor, significantly reducing risk of leakage or systemic side effects.

Indications

Pancreatic cancer. Using the results of our Phase IIa clinical trials for primary liver cancer, we have been developing BrachySil for the treatment of pancreatic cancer, and a Phase IIa clinical trial is in progress. We believe BrachySil has the potential to be used to treat other solid tumors and we intend to investigate other tumor indications, such as liver metastases.

During 2007, we began a dialogue with the FDA in order to clarify and facilitate the clinical development activities for BrachySil in the U.S. We are pursuing a similar strategy with respect to EU regulatory authorities to qualify for device registration in Europe under the auspices of a CE mark application. Generally speaking, obtaining regulatory approval to market a medical device is less expensive and time consuming than the process required for a new drug.

Other BioSilicon Applications

Orthopedics. We believe that BioSilicon also has potential to be used as a biodegradable scaffold for orthopedic tissue engineering. A porous silicon structure could be deliberately sculpted to provide bone-building cells with a scaffold that the cells can penetrate and to which cells can anchor. As the bone tissue deposits itself onto the scaffold, the silicon would slowly dissolve away, eventually leaving just the new bone. Silicon’s ability to carry an electrical current charge bias may also give BioSilicon an advantage in the treatment of bone conditions, promote bone growth and may have other orthopedic applications. Data gathered to date in preclinical studies indicate that cells will grow and divide in BioSilicon substrates and that certain forms of BioSilicon have the potential to be osteoinductive, promoting bone growth and deposition.

Tissue Regeneration/Wound Healing. We believe that BioSilicon also has potential uses in tissue regeneration as a biodegradable scaffold or framework. For example, a BioSilicon scaffold containing growth factors could be

 

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used to assist with tissue regeneration. We also believe that BioSilicon could be used in the area of wound management products, including the development of potentially novel biodegradable sutures. Our research involving the use of BioSilicon in the area of tissue regeneration is at a preliminary stage.

Food Technology. We are developing applications of our silicon technology in the food industry. Our research in the area of food technology is at a preliminary stage.

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