ESMO: New Agent, MGN1703, for Metastatic Colorectal Cancer Effective as Maintenance Therapy

Maintenance therapy with a new immunomodulator agent called MGN1703 improves progression-free survival over placebo in patients with metastatic colorectal cancer, according to a new study presented at the European Society for Medical Oncology (ESMO) congress in Vienna.

Dirk Arnold, MD, discussing the trial results at the ESMO 2012 Congress; © All rights reserved by European Society for Medical Oncology

Researchers led by Dirk Arnold, MD, of the University Cancer Center Hamburg in Germany, presented results of an interim analysis of the phase II/III IMPACT trial. The analysis included 55 patients with metastatic colorectal cancer; all patients showed disease control-complete response, partial response, or stable disease-after 4.5 to 6 months of standard induction chemotherapy with FOLFOX/XELOX or FOLFIRI with or without bevacizumab (Avastin) regimens.

The median progression-free survival was 5.8 months for patients receiving MGN1703 and 2.7 months for those who received placebo in a predefined target population (46 patients), for a hazard ratio (HR) for progression of 0.39 (P = 0.013). In an intent-to-treat population including all 55 patients, the HR was 0.53 (P = 0.062) in favor of the study drug.

Progression-free survival rates after 3 months of treatment also significantly favored MGN1703, at 43% vs 8% for placebo (P < 0.001). The 6- and 9-month rates of progression-free survival were also better in the MGN1703 group, at 34% vs 8% (P = 0.011) and 22% vs 0% (P = 0.010), respectively. The apparent success of the maintenance therapy led to a discontinuation of randomization in the study.

“These surprisingly positive results are equally highly innovative and clinically relevant in two ways: on the one hand, it is with MGN1703, a DNA immunomodulator, that the first representative of a whole new class of substances in colorectal cancer has been tested as efficacious in a randomized study, “ Dr. Arnold said, according to a press release. “And on the other hand, this is the second study ever which has tested the value of a proprietary maintenance therapy after another induction therapy.”

Drug-related adverse events included fever in three patients, as well as atypical pneumonia, muscle aching, arthralgia, fatigue, paresthesia, rash, and others.

Researchers are planning a further clinical study to confirm the efficacy of MGN1703 in patients with metastatic colorectal cancer. The drug is an agonist of toll-like receptor 9 (TLR9), selectively attacking tumor cells and tumor-associated antigens following chemotherapy and radiation therapy. The company says its universal mechanism of action makes it a strong candidate against a number of different types of cancers. Research is also ongoing with MGN1703 against advanced non–small-cell lung cancer.