New data has confirmed the biological action of the drug MGN1703 and suggests that it may be possible to identify which patients with gastrointestinal cancer will benefit most from the treatment. MGN1703 is an emerging treatment that aims to fight colorectal cancer by stimulating the immune system. The study was presented at the ESMO 15th World Congress on Gastrointestinal Cancer, which was held in Barcelona, Spain, July 3-6, 2013.

MGN1703 is a small DNA molecule recognized by toll-like receptor 9, which is a receptor that is expressed in certain immune cells. The drug is designed to broadly activate all components of the innate immune system to stimulate the destruction of cancer cells.

The new data come from the final analysis of the phase II IMPACT study, which investigated MGN1703 in 59 patients with metastatic colorectal cancer. The IMPACT study was an international, randomized, double-blind trial that was conducted in patients who had achieved disease control after 4.5 to 6 months of chemotherapy.

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Standard chemotherapy for patients with metastatic colorectal cancer who respond to treatment is often completely or partially discontinued until the disease progresses. The new drug was administered during this maintenance phase of treatment.

Though the study had intended to test the drug in 129 patients, difficulties in recruiting patients meant the trial was closed after 59 patients had been randomly assigned to receive either MGN1703 (43 patients) or placebo (16 patients).

“After a median follow-up of 17.3 months, MGN1703 prolonged profession-free survival from the start of induction as well as start of maintenance therapy, including four patients with sustained progression-free survival who are still on treatment,” said Professor Hans-Joachim Schmoll of Martin Luther University in Halle, Germany.

Schmoll explained that a preplanned analysis of immune cell populations showed that activation of natural killer T cells, which are a subset of immune cells, appeared to potentially predict which patients might benefit. He said, “We saw a significant increase of CD14+CD169+ monocytes in all but one of the MGN1703-treated patients but none of the placebo patients, which indicates the drug is having a biological effect.”

Treatment with MGN1703 is more likely to benefit patients who have a lower tumor burden and a response to prior chemotherapy.