Researchers at Dana-Farber Cancer Institute have showed that a new drug can help patients with metastatic GIST tumors. They conducted a worldwide clinical trial, which showed that the oral drug regorafenib may prolong survival by about four months in patients who do not respond to Gleevec and Sutent treatment.
GIST means gastrointestinal stromal tumor and is the most common gastrointestinal mesenchymal tumor. These tumors can be located anywhere in the digestive tract: esophagus, stomach, duodenum, small intestine and colon or rectum, but most are in the stomach. It is important to note that GIST is a non-epithelial tumor. So far studies show that these tumors arise from intertstitial Cajal cells, that is cell of the autonomic nervous system, and that the proliferation of this tumour is linked to a transmembrane receptor tyrosine kinase Kit (CD117). Over 90% of GIST tumors express this marker (CD117 ) but others are also present, such as CD34 or desmin or vimentin.
These tumors have nonspecific symptoms: abdominal discomfort, abdominal pain, bleeding, anemia. It may happen that tumors are discovered incidentally on routine examination by palpation of abdominal masses. In terms of diagnosis, imaging can be used (computed tomography, ultrasound, etc.), but the final diagnosis is given by biopsy. Basic treatment consists of surgical excision and cure rate depends on tumor stage, tumor size and the presence of metastases.
Tumours up to 2 cm in size and with low mitotic rate have good prognosis and surgical cure seems to be sufficient, but larger tumors need adjuvant treatment with imatinib and sunitinib. These two drugs have significantly improved the survival of patients with advanced disease. However 85% of patients become resistant to these treatments after several years and the prognosis gets worse.
According to the study led by researchers at Dana-Farber Cancer Institute, the oral drug regorafenib can prolong survival in patients in which the current treatment has no effect. George Demetri, MD, of Dana-Farber, principal investigator of this clinical trial, said the study results showed that the drug significantly improves overall survival in patients in which other therapies failed.
The study, whose results were published in the Lancet, was conducted on 199 treatment-resistant GIST patients at 57 hospitals in 176 countries. Of these, 133 received regorafenib for three weeks and the rest received placebo. It should be noted that the drug did not result in tumor reduction, it only prolonged the survival. In addition, there have been reported a number of adverse effects such as hypertension, fatigue, diarrhea, redness, peeling of the skin.