Proactive Treatment With Rexin-G for Pancreatic Cancer

Despite decades of research, pancreatic cancer still remains an intractable disease. As of 2006, according to the National Cancer Institute, the five-year survival rate for pancreatic cancer was 5.6 percent. Consequently, there's been significant interest among researchers in finding better treatments. Rexin-G is one experimental therapy currently in clinical trials for pancreatic cancer.

Background

• Rexin-G is being developed by a biotech company, Epeius Biotechnologies, headquartered in San Marino, California. The name Rexin-G stands for Retroviral Expression Vectors bearing an Inhibitory Gene. Rexin-G is essentially a gene therapy approach to treating cancer; the idea is to introduce a gene into cancer cells to help to disable or kill them. The vehicle used to insert the gene into the cancer cells is called a vector.

Mechanism of Action

• Retroviruses are viruses that incorporate their own genetic information into the genome of the cells they infect. These properties have made retroviruses a subject of perennial interest for scientists working on gene therapy. Rexin-G uses a retrovirus to insert a defective version of a gene for a protein called cyclin G1 into tumor cells. The retrovirus has been genetically altered so that it can't replicate and infect other cells; it's also been altered to exhibit part of a protein that guides platelets to exposed collagen fibers in wounds. Since cancer cells are growing rapidly, this collagen-binding feature is intended to ensure that the retrovirus targets tumor cells in preference to healthy cells. Once the virus infects the cancer cell, the defective cyclin G1 gene can prevent the tumor cells from proliferating, since cyclin G1 is a protein that helps determine when cells divide.

History

• Epeius Biotch completed a phase I/II clinical trial for pancreatic cancer in August, 2009. Early stage clinical trials are primarily intended to assess drug safety in humans and thus involve a limited number of patients. Epeius has also completed phase I/II clinical trials for two other cancers.

Effects

• The results from the phase I/II pancreatic cancer study, published in the journal "Molecular Therapy" in 2009, seem to have been positive. All the patients in the trial had previously been treated unsuccessfully with a chemotherapy drug called gemcitabine. The trial data suggests that Rexin-G extended the average overall survival for patients treated with the drug, and the adverse effects that were reported were fairly minor (headache and fatigue). However, since the study was a phase I/II clinical trial involving only a limited number of patients it doesn't provide sufficient data by itself to fully evaluate the effectiveness of Rexin-G.

Future

• Rexin-G for pancreatic cancer is still in clinical trials and hasn't yet been approved for use in the United States. It's common knowledge that many drugs and therapies fail in clinical trials; it remains to be seen whether Rexin-G will prove effective against pancreatic cancer and earn FDA approval. If it does, it would help rehabilitate the field of gene therapy, and potentially offer a new alternative for treatment.