The United States Patent and Trademark Office (USPTO) has issued a key patent No. 8,450,280 “Activation of Peptide Prodrugs by HK2” to GenSpera, Inc. The key patent covers the composition of a series of prodrugs activated by HK2 to deliver a thapsigargin derivative selectively to prostate cancers.

HK2 is an enzyme secreted by prostate cancer cells. A derivative of thapsigargin, 12ADT, is the active component of G-202, GenSpera’s lead drug candidate in Phase II clinical trials for liver cancer after sorafenib (Nexavar) therapy.

“The issuance of this patent further strengthens our intellectual property position for targeted anti-cancer prodrugs and recognizes their unique applicability in treating prostate cancer,” commented GenSpera CEO, Craig Dionne, Ph.D. “It is important that we continue to expand and defend our thapsigargin prodrug research and development in areas of high unmet medical needs and commercial opportunities.”

GenSpera’s technology platform combines a powerful, plant-derived cytotoxin (thapsigargin) with a prodrug delivery system that provides for the targeted release of drug candidates within a tumor. Unlike typical chemotherapeutic agents, thapsigargin results in cell death irrespective of the rate of cell division, which may provide an effective approach to kill both fast- and slow-growing cancers. GenSpera’s lead drug candidate, G-202, is activated by the enzyme PSMA which is found at high levels in liver and prostate cancer and in the vasculature of almost all other solid tumors and is therefore expected to have efficacy in a wide variety of tumour types.

Data from the G-202 phase Ib programme in solid tumour patients demonstrated that G-202 is well-tolerated with prolonged disease stabilization observed in several hepatocellular carcinoma (liver cancer) patients whose disease had previously worsened on standard therapy. A phase II clinical trial in patients with hepatocellular carcinoma is currently underway.