ASTROINTESTINAL STROMAL tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. Gastrointestinal stromal tumors are usually found in the stomach or the small intestine but can occur at any site along the gastrointestinal tract and rarely elsewhere within the abdominal cavity. 1 The median age at presentation is 60 to 65 years, and the annual incidence approximately 10 cases per million. 2-4 Most GISTs (75% to 80%) harbor an activating mutation in the KIT oncogene and 5% to 10% in platelet-derived growth factor receptor-␣ (PDGFRA), which are important for tumor molecular pathogenesis. 5 The ma-For editorial comment see p 1312.

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Introduction: The EUROpean Bone Over 40 Sarcoma Study (EURO-B.O.S.S.) was the first prospective internationalstudy for patients 41-65 years old with high-grade bone sarcoma treated with an intensive chemotherapy regimen derived from protocols for younger patients with high-grade skeletal osteosarcoma. Methods: Chemotherapy based on doxorubicin, cisplatin, ifosfamide, and methotrexate was suggested, but patients treated with other regimens at the investigators' choice were also eligible for the study. Results: The present report focuses on the subgroup of 218 patients with primary high-grade osteosarcoma. With a median follow-up of 47 months, the 5-year probability of overall survival (OS) was 66% in patients with localized disease and 22% in case of synchronous metastases. The 5-year OS in patients with localized disease was 29% in pelvic tumors, and 70% and 73% for extremity or craniofacial locations, respectively. In primary chemotherapy, tumor necrosis ≥90% was reported in 21% of the patients. There were no toxic deaths; however, hematological toxicity was considerable with 32% of patients experiencing 1 or more episodes of neutropenic fever. The incidence of nephrotoxicity and neurotoxicity (mainly peripheral) was 28% and 24%, respectively. After methotrexate, 23% of patients experienced delayed excretion, in 4 cases with nephrotoxicity.

BackgroundRobatumumab (19D12; MK‐7454 otherwise known as SCH717454) is a fully human antibody that binds to and inhibits insulin‐like growth factor receptor‐1 (IGF‐1R). This multiinstitutional study (P04720) determined the safety and clinical efficacy of robatumumab in three separate patient groups with resectable osteosarcoma metastases (Group 1), unresectable osteosarcoma metastases (Group 2), and Ewing sarcoma metastases (Group 3).ProcedureRobatumumab infusions were administered every 2 weeks and were well tolerated with minimal toxicity. Centrally reviewed response data were available for 144 patients.ResultsLow disease burden was important for osteosarcoma response: three of 31 patients had complete response or partial response (PR) by Response Evaluation Criteria in Solid Tumors (RECIST) in resectable patients (Group 1) versus zero of 29 in unresectable patients (Group 2); median overall survival was 20 months in Group 1 versus 8.2 months in Group 2. In centrally reviewed patients with Ewing sarcoma with PET‐CT data (N = 84/115), there were six PR, 23 stable disease, and 55 progression of disease by RECIST at 2 months. Patients with Ewing sarcoma had a median overall survival of 6.9 months. However, responding patients with Ewing sarcoma were allowed to continue on treatment after study closure. A minority of patients with metastatic Ewing sarcoma showed clinical responses and have remained healthy after receiving 25–115 doses of robatumumab with remissions of >4 years duration (N = 6).ConclusionsThese findings show that although the IGF‐1R remains an attractive treatment target, additional research is needed to identify responders and/or means to achieve durable remissions in order to successfully exploit IGF‐1R signal blockade in Ewing sarcoma (clinicaltrials.gov: NCT00617890).

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