NEW YORK (Reuters Health) Aug 15 - While very toxic, imatinib may prove useful for treating two rare, usually benign neoplasms, namely, pigmented villonodular synovitis (PVNS) and tenosynovial giant cell tumors (TGCT), according to a report online August 5th in Cancer.
Patients with PVNS and TGCT, which are different clinical presentations of the same disease, commonly over-express colony-stimulating factor 1 (CSF1). Imatinib mesylate is a tyrosine kinase inhibitor that has activity against CSF1 receptor (CSF1R).
Dr. Philippe A. Cassier from Leon Berard Center, Lyon, France and colleagues tested imatinib in 29 patients with PVNS/TGCT. All but one received 400 mg imatinib daily.
The mean age was 41 years. The median follow-up for all patients was 10.8 months.
Fifteen patients discontinued treatment, six of them because of treatment-related side effects.
One patient (4%) had a complete response, four (15%) had partial responses, and 20 (74%) had stable disease, for an overall response rate of 19% and a symptomatic response rate (reduction of pain and/or swelling) of 73%.
Six patients had progressed as of the last follow-up (including three with progression at the first assessment).
All but one patient was still alive at the last follow-up.
"Imatinib may represent an alternative to radiotherapy for patients who have symptomatic TCGT/PVNS that progresses or that is not amenable to surgery," the researchers conclude.
"The benefits of alleviating morbidity in patients with localized PVNS/TGCT must be balanced against the potential toxicity of chronic drug therapy," they add.
"Furthermore," the investigators say, "although our data provide proof of concept for targeting CSF1/CSF1R in TGCT/PVNS, formal studies are needed to confirm the role of imatinib mesylate in this disease. Two international phase II trials using nilotinib, a CSF1R tyrosine kinase inhibitor with potency similar to that of imatinib mesylate, in patients with advanced TGCT or PVNS are currently ongoing."
Patients with PVNS and TGCT, which are different clinical presentations of the same disease, commonly over-express colony-stimulating factor 1 (CSF1). Imatinib mesylate is a tyrosine kinase inhibitor that has activity against CSF1 receptor (CSF1R).
Dr. Philippe A. Cassier from Leon Berard Center, Lyon, France and colleagues tested imatinib in 29 patients with PVNS/TGCT. All but one received 400 mg imatinib daily.
The mean age was 41 years. The median follow-up for all patients was 10.8 months.
Fifteen patients discontinued treatment, six of them because of treatment-related side effects.
One patient (4%) had a complete response, four (15%) had partial responses, and 20 (74%) had stable disease, for an overall response rate of 19% and a symptomatic response rate (reduction of pain and/or swelling) of 73%.
Six patients had progressed as of the last follow-up (including three with progression at the first assessment).
All but one patient was still alive at the last follow-up.
"Imatinib may represent an alternative to radiotherapy for patients who have symptomatic TCGT/PVNS that progresses or that is not amenable to surgery," the researchers conclude.
"The benefits of alleviating morbidity in patients with localized PVNS/TGCT must be balanced against the potential toxicity of chronic drug therapy," they add.
"Furthermore," the investigators say, "although our data provide proof of concept for targeting CSF1/CSF1R in TGCT/PVNS, formal studies are needed to confirm the role of imatinib mesylate in this disease. Two international phase II trials using nilotinib, a CSF1R tyrosine kinase inhibitor with potency similar to that of imatinib mesylate, in patients with advanced TGCT or PVNS are currently ongoing."
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