Activity of chemotherapy in inflammatory myofibroblastic tumor (IMT): A retrospective analysis within the Italian Rare Tumours Network (RTR)

e22545 Background: IMT is a rare soft tissue tumour often curable with surgical resection. Nonetheless, in advanced cases a medical therapy is needed. Few data are available on the role of conventional chemotherapy. We report on a retrospective study on the activity of cytotoxic chemotherapy in pts with IMT treated within the RTR. Methods: Patients (pts) of any age with a centrally confirmed diagnosis of IMT treated with anthracycline-based or methotrexate (MTX) and vinorelbine/vinblastine-based regimens between 2008 and 2018 were reviewed. ALK status was evaluated by immunohistochemistry and FISH. Response was assessed by RECIST 1.1. Results: Twenty pts were retrospectively identified (ALK positive = 12, under assessment = 8); median age at the time of treatment start = 38, range = 5-77; disease extent: local disease = 2, locally advanced = 9, metastatic disease = 9. Thirteen pts (65%) received an anthracycline-based regimen, 7 (35%) MTX and vinorelbine/vinblastine. In the anthracycline-based group, 6 (46%) and 7 (54%) pts were treated for localized and advanced disease, respectively. Twelve pts were evaluable for response. Best responses were: 1 CR (8%), 6 PR (50%), 2 SD (17%), 3 PD (25%), for an ORR = 58%. 8 pts received a complete surgical resection at the end of the medical treatment and 6 are disease free. At 39 mos median follow-up, mPFS for 7 pts treated for advanced disease was 5.4 mos (IQR: 1.9-18.8). In the MTX and vinorelbine/vinblastine group, 2 (28%) and 5 (72%) pts were treated for localized disease and advanced disease, respectively. All pts were evaluable for response. Best responses were: 5 PR (50%), 3 SD (30%), 2 PD (20%), for an ORR = 50%. Two pts received a complete surgical resection after the end of chemotherapy and both are disease free. At 56.4 mos median follow-up, mPFS for pts with advanced disease was not reached, with disease progression reported only in 1 pt. Conclusions: Chemotherapy is an option in localised IMT when tumour shrinkage is needed as well as for tumour control in advanced disease. Clearly, its efficacy should be compared with ALK inhibitors, although of course both groups of agents may be resorted to stepwisely in advanced cases in need for medical therapy.