He said there had been reports of imatinib's effectiveness in several cases of metastatic DFSP, so he and colleagues at other centres in the USA, Belgium and Switzerland set out to see whether the cellular genetic and kinase profiles in DFSP would correlate with clinical responses to imatinib.
The ten patients were treated with 800mg of imatinib daily. Of the eight with locally advanced disease, two achieved complete response that was pathologically confirmed through resections of the regions where the tumour was present and two achieved complete response confirmed by tumour assessment. Four had partial response followed by surgery to make them free of disease. So, the disease was controlled in all these patients either by imatinib alone or imatinib plus surgery.
Two patients had metastatic DSFP with a more complex genetic profile. One, with a translocation t(17-22) had a partial response to imatinib but the disease progressed after seven months of treatment. The other did not have a translocation and did not respond to imatinib.
Dr. McArthur explained that over 95% of DFSP tumours have t(17-22). "It's difficult to be certain based on only one case, which was very high grade and where there was also the possibility that it may not have been a true DFSP, but our patient without the translocation did not respond to imatinib. Nevertheless, our data support the use of imatinib where t(17-22) is detected, although our findings cannot be used to make any definite statements about tumours with other molecular abnormalities.
"The most important outcome of our study is that molecular analysis of the tumour can be used to predict a patient's response to treatment where the analysis indicates that the pathway targeted by imatinib is activated."
Said Professor Cvitkovic: "These results fit perfectly the FNAB objectives supporting research using tissue sample biopsy
Contact: Margaret Willson
European Organisation for Research and Treatment of Cancer