In July 2003, the company completed exclusive license negotiations with M.D. Anderson for a second technology platform, In Situ Hydrogel, which
will be used for local regional chemotherapy and radiotherapy. In comparison
with other hydrogel technologies, In Situ Hydrogel is the only hydrogel
formulation capable of delivering a high yield load of a therapeutic
radionuclide like 188Re directly to the tumor site without leakage
into surrounding tissue. The In Situ Hydrogel forms a polysaccharide matrix
which encapsulates tumor sites for solid tumors and surgically unresectable
tumors. The polymer and cross-linking composition are administered separately
using a dual compartment syringe. The polymeric matrix forms at the tumor site
almost immediately following administration of either the anticancer drug or
radionuclide matrix. The matrix remains in tact for a least 48 hours which is
excellent for administering an anticancer drug like cisplatin or a therapeutic
radionuclide like 188Re with a physical half-life of 17 hours and a 2.1
MeV beta emission. In fact, In Situ Hydrogel is capable of delivering both
therapies at once. The company is aware of hydrogels that can deliver anticancer
drugs, however, all of these hydrogels leak which means they cannot be used for
delivering high yield doses of therapeutic radionuclides. In addition, the other
hydrogel formulations require varying amounts of time to form their matrix which
makes them much less efficient and effective. The polymeric material used for In
Situ Hydrogel is alginic acid which has widespread use and is a non-toxic
substance.
To date, studies on breast
tumor-bearing rats have been performed using In Situ Hydrogel loaded with
cisplatin (3mg/kg). Cisplatin was gradually released into the surrounding tumor
tissue. The tumors were completely suppressed within 16 days following a single
injection. In a second study, In Situ Hydrogel was loaded with 188Re
(1 mCi/rodent) and injected into breast tumor-bearing rats. No post injection
leakage into surrounding tissue was detected. Tumor growth was delayed
substantially compared to free 188Re treated rats. The
188Re studies were completed several months ago and no tumor regrowth
is present. In the next series of studies, an In Situ Hydrogel
cisplatin/188Re cocktail therapy will be administered. All the
studies have used a Siemens m-Cam using a medium energy parallel-hole
collimator. The largest single market for In Situ Hydrogel therapy will likely
be in the treatment of prostate cancer, however, we feel lymphoma will be
significant as well. In prostate cancer, we believe that In Situ Hydrogel will
show more consistent therapeutic results compared to brachytherapy.
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