Bisplatinates, a New Class of Platinum-Based Anti-Tumor Drugs, Demonstrates Potent Anti-Tumor Activity and Ability to Overcome Resistance to Currently Available Platinum-Based Agents

Seattle-based Cell Therapeutics, Inc, a biopharmaceutical company committed to developing an integrated portfolio of oncology products, today announced that its new class of platinum-based anti-tumor compounds, termed bis-platinates, demonstrated a stronger anti-tumor potency and activity compared to currently available platinum-based compounds as well as the ability to overcome cisplatin-resistance in cancer cell lines.

The results were presented in a paper titled "Novel Bis-platinum Complexes Endowed with an Improved Pharmacological Profile," by Laura Gatti et al. that was published in the online edition of the journal Molecular Pharmaceutics. Platinum-based compounds, such as cisplatin and oxaliplatin, are the cornerstone in the treatment of testicular, ovarian, colorectal, lung and other cancers but their effectiveness is limited by the relatively low therapeutic ratio, the ratio of the maximally tolerated dose of the drug to the effective dose, and the frequent occurrence of drug resistance leading to cancer recurrence. The novel bis-platinum compounds represent a completely new class of platinum-based drugs called bisplatinates.

The bis-platinum based compounds, unlike the currently approved platinum-based compounds, contain two platinum atoms and work by binding to and damaging both strands of DNA making it much more difficult for cancer cells to repair the damage. The research demonstrated through cancer cell assays and animal tumor models that the bis-platinum complexes exhibited greater cytotoxic potency and anti-tumor effect compared to cisplatin and oxaliplatin.

There was more than a 200-fold increase in percent accumulation in tumor cells of the bisplatinum compounds compared to cisplatin and oxaliplatin. The bisplatinates were substantially more active against human tumors grown in an immunodeficient preclinical model than the standard palatinate compounds, oxaliplatin, carboplatin and cisplatin. Furthermore, the bis-platinum compounds demonstrated the ability to overcome tumor resistance to cisplatin mediated by DNA mismatch repair defects. The complexes showed marked anti-tumor efficacy in platinum refractory tumors, with significant activity in terms of tumor growth inhibition and tumor growth delay.

"Platinum-based compounds are cornerstone agents in the treatment of very common cancers such as cancers of the lung, colon, and ovary and are also widely used in other gynecological-tumors, testicular cancers, and cancers of the esophagus, head and neck. They are increasingly being used for salvage therapy in lymphoma. However, resistance to palatinate compounds is common. The current results are encouraging as they demonstrate that the bisplatinates are not only more effective in human tumor models than the current agents, but also capable of overcoming some forms of palatinate resistance," said Jack Singer, M.D., Chief Medical Officer of CTI.

For more information:
Gatti L, Perego P, Leone R, Apostoli P, Carenini N, et al. Novel Bis-platinum Complexes Endowed with an Improved Pharmacological Profile. Mol Pharm. 2009 Nov 17. [Epub ahead of print]

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Bisplatinates, a New Class of Platinum-Based Anti-Tumor Drugs, Demonstrates Potent Anti-Tumor Activity