MedPacto has confirmed the clinical efficacy of its Vactosertib response gene signature (VRGS), a biomarker under development, which can find colon cancer patients who will respond to combined therapy. 

The company’s VRGS can tell who will show a therapeutic response when administered Vactosertib combined with the existing cancer drug, Keytruda.

Colon cancer can be divided into microsatellite instable (MSI) and stable (MSS) status. Although treatment attempts are possible for MSI colon cancer patients, MSS-type patients, which account for 86 percent of all patients, show a low response rate when administered with immune anticancer drugs alone. MedPacto is conducting 1b and 2a parallel clinical studies with MSS colon cancer patients.

The company had selected below 50 VRGS biomarkers after analyzing a total of 2,530 genes collected from tumor tissues before and after providing combined therapy in 24 colon cancer patients with MSS status. The clinical benefit rate (CBR), which combines objective response and progression-free survival rates of all patients, reached 33.3 percent.

However, the CBR of patients who showed high expression to the selected biomarkers was 85.7 percent. These data suggest a new treatment potential for the MSS colon cancer patients, whose objective response rate could not be expected when administered with Keytruda alone.

“MedPacto will conduct follow-up studies for MSS colon cancer patients by applying VRGS, and we will improve the treatment and clinical success rate by selectively administrating drugs to patients using biomarkers in other clinical trials,” a MedPacto official said in a news release on Monday.

MedPacto released the interim results at the annual meeting of the U.S. Society for Immunotherapy of Cancer (SITC) held online from Nov. 9-14.