A new type of cancer drug has impressed in early phase colorectal cancer trials.

The drug, called napabucasin, is a type of drug referred to as a ‘stemness inhibitor’ being developed by US-based Boston Biomedical.

The drug targets cancer stem cells which, much like normal stem cells which harness the ability to grow and mature into normal cells, are believed to harness the same properties to instead mature into cancer cells. They are also believed to be highly resistant to conventional cancer therapies.

Napabucasin targets a molecule called STAT3 which has been shown to encourage cancer cell proliferation and discourage cancer cell death.

The phase 1b/2 data, presented at the American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium, suggest the drug to have anti-cancer activity in colorectal cancer (CRC) patients when administered with FOLFIRI (folinic acid, flurouracil and irinotecan) and bevacizumab, and with FOLFIRI alone.

In addition, the data suggested the drug re-sensitised FOLFIRI-resistant CRC patients to FOLFIRI treatment, with and without bevacizumab.

“There remains a significant unmet need for novel treatment advances to ensure greater sustained responses and improve survival for patients with advanced colorectal cancer,” said Johanna Bendell, study investigator and director of GI Cancer Research Program at Sarah Cannon Research Institute. “This underscores that targeting cancer stemness may suppress cancer relapse and metastasis.”

In a second phase 2 study, napabucasin further impressed when combined with panitumumab – an antibody drug used to treat CRC. Napabucasin demonstrated anti-cancer activity in metastatic CRC patients with K-ras mutations (a type of mutation known to greatly reduce the anti-cancer effect of panitumumab) when combined with panitumumab.

The results suggest napabucasin may re-sensitise metastatic CRC to panitumumab treatment.

“Results from these studies for napabucasin in advanced colorectal cancer support the advancement of our clinical development programme for this first-in-class cancer stemness inhibitor into a global, phase 3 trial in combination with standard-of-care chemotherapy,” said Chiang Li, president, CEO and chief medical officer of Boston Biomedical.