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Imatinib mesylate in chordoma
Paolo G Casali1, Antonella Messina, Silvia Stacchiotti
1Adult Sarcoma Medical Oncology Unit, Department of Cancer Medicine, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milan, Italy. paolo.casal@stitutotumori.mi.it
Background:
To the authors' knowledge, no effective medical therapy currently is available for advanced chordoma. Imatinib mesylate is a tyrosine kinase inhibitor targeting platelet-derived growth factor receptor-beta (PDGFRB), BCR-ABL, and KIT.
Methods:
Six patients with advanced chordoma were treated with imatinib mesylate at a dose of 800 mg daily. In all patients, the tumor was found to be positive for PDGFRB, and in four patients PDGFRB was shown to be phosphorylated/expressed.
Results:
After a treatment period of > or = 1 year, overt tumor liquefaction was evident on computed tomography (CT) scan in the first patient. In previous months, a decrease in contrast enhancement on magnetic resonance imaging (MRI) and a decrease in glucose uptake on positron emission tomography (PET) were detected. Similar signs on MRI and PET were observed in subsequent patients, who had a shorter treatment period. One of these patients initially was removed from therapy and then was readmitted to therapy because of difficulties with regard to tumor response assessment; 1 month after the reinitiation of therapy, an overt decrease in tumor density was visible on CT scan in this patient. In four of five symptomatic patients, a subjective improvement was observed early in the course of treatment. The first patient died after 17 months, with a sizeable, mostly liquefied mass. Another patient died early, apparently of unrelated causes. The remaining patients were on therapy at the time of last follow-up.
Conclusions:
Imatinib mesylate has been found to have antitumor activity in patients with chordoma. This activity might be mediated by inactivation of PDGFRB. Tumor response manifests through patterns that are similar to those observed in patients with gastrointestinal stromal tumors who respond to molecular-targeted therapy, but evolves more slowly. The benefit to the patient entailed by this pattern of tumor response in chordoma needs to be elucidated, but may be limited in the presence of significant local disease.
Insights
Imatinib mesylate shows antitumor activity in advanced chordoma patients by targeting platelet-derived growth factor receptor-beta (PDGFRB). Tumor response, including liquefaction, was observed, but long-term patient benefit requires further study.
Area of Science:
- Oncology
- Medical Therapy
- Molecular Targeted Therapy
Background:
- Advanced chordoma lacks effective medical therapies.
- Imatinib mesylate is a tyrosine kinase inhibitor targeting platelet-derived growth factor receptor-beta (PDGFRB), BCR-ABL, and KIT.
Purpose of the Study:
- To evaluate the efficacy of imatinib mesylate in patients with advanced chordoma.
- To investigate the potential role of PDGFRB in chordoma treatment response.
Main Methods:
- Six patients with advanced chordoma received imatinib mesylate (800 mg daily).
- Tumor PDGFRB expression and phosphorylation were assessed.
- Tumor response was monitored using CT, MRI, and PET scans.
Main Results:
- Tumor liquefaction observed on CT scans after treatment.
- Decreased contrast enhancement on MRI and reduced glucose uptake on PET scans noted.
- Subjective improvement reported in four of five symptomatic patients.
Conclusions:
- Imatinib mesylate demonstrates antitumor activity in chordoma, potentially via PDGFRB inactivation.
- Observed tumor response patterns resemble those in gastrointestinal stromal tumors but evolve more slowly.
- The clinical benefit of this response pattern in chordoma requires further elucidation, especially with significant local disease.