Thirty-five to forty percent of colorectal cancers contain a mutated KRAS gene. Somewhere in the process of cancer development, the normal gene has changed and now is changing the way signals are communicated inside the cancer cell.
Several large analyses of clinical trials have found that colorectal cancer patients whose tumors have a mutated KRAS gene do not benefit from Erbitux® (cetuximab) or Vectibix™ (panitumumab).
Tumors of patients with mutated KRAS did not shrink (respond) when treated with Erbitux or Vectibix alone. The time until cancer got worse (progression-free survival) was shorter in those patients with mutated KRAS than in those patients whose tumors didn’t have mutated KRAS.
Patients with normal, unchanged KRAS, may benefit from Erbitux or Vectibix. Normal KRAS is called wild-type.
Experts in colorectal cancer treatment are now recommending that patients’ tumors be tested for KRAS mutations before they begin treatment with either Erbitux or Vectibix. Those with mutated KRAS tumors will want to choose a different therapy since they will not benefit, the medicines are an additional expense, and there may be side effects, including a common skin rash.
Where Can You Go for More Information
Fight Colorectal Cancer posts regular updates about KRAS in its Research and Treatment News section.
More information is available about the CRYSTAL, OPUS, and EVEREST clinical trials from presentations at the 2008 American Society of Clinical Oncology meeting is available from the Fight CRC Research and Treatment News with links to the studies.
Information about the Vectibix trial from a presentation at the 2008 GI Symposium is available from the Fight CRC Research and Treatment News.