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.