Inflammatory myofibroblastic tumours (IMT) are rare. Complete resection is the therapy of choice but there is no standard treatment for inoperable or recurrent disease. An aggressive subtype, epithelioid inflammatory myofibroblastic sarcoma (IMS), characterized by nuclear or perinuclear ALK staining and an epithelioid morphology has been described. Conventional therapies have been ineffective with most patients dying from progressive disease.
We describe a rapid, early response of an aggressive epithelioid IMS to Crizotinib(PF-02341066). A 14-year old boy presented with weight loss, lethargy, unexplained fever, increasing abdominal discomfort, a microcytic anaemia, thrombocytosis and raised C-reactive protein (CRP). Examination and imaging demonstrated a large localized pelvic mass (6.1x4.3cm) and ascites. Immunohistochemical and cytogenetic studies were consistent with an epithelioid IMS. Prednisolone and celecoxib were ineffective and a complete macroscopic resection was performed. Celecoxib was continued, but a life-threatening multifocal abdominal relapse was detected within one month of resection. There was a rapid clinical deterioration due to tumour progression and respiratory impairment from ascites and pleural effusions, requiring ICU admission. Crizotinib, an inhibitor of the anaplastic lymphoma kinase (ALK) tyrosine kinase, was commenced within 48 hours with evidence of response within 72 hours. Over the next 2 weeks a dramatic clinical improvement occurred with resolution of pleural effusions and ascites, 50% tumour shrinkage, normalization of the CRP and improved thrombocytosis. Three months after commencing Crizotinib, progress scans show remarkable reduction in intra-abdominal disease.
Crizotinib has been well tolerated with mild side effects (transaminitis, leukopaenia, neutropaenia). This case confirms that Crizotinib is effective and can induce a rapid response in patients with life threatening symptoms. We suggest that Crizotinib may be considered as initial therapy for aggressive or inoperable ALK+ve epithelioid IMS however further studies would be warranted in this indication.
We would like to acknowledge Pfizer Oncology, Australia who provided Crizotinib on a compassionate use basis.