mRNA expression profiles of primary high-grade central osteosarcoma are preserved in cell lines and xenografts.

BACKGROUND: Conventional high-grade osteosarcoma is a primary malignant bone tumor, which is most prevalent in adolescence. Survival rates of osteosarcoma patients have not improved significantly in the last 25 years. Aiming to increase this survival rate, a variety of model systems are used to study osteosarcomagenesis and to test new therapeutic agents. Such model systems are typically generated from an osteosarcoma primary tumor, but undergo many changes due to culturing or interactions with a different host species, which may result in differences in gene expression between primary tumor cells, and tumor cells from the model system. We aimed to investigate whether gene expression profiles of osteosarcoma cell lines and xenografts are still comparable to those of the primary tumor. METHODS: We performed genome-wide mRNA expression profiling on osteosarcoma biopsies (n = 76), cell lines (n = 13), and xenografts (n = 18). Osteosarcoma can be subdivided into several histological subtypes, of which osteoblastic, chondroblastic, and fibroblastic osteosarcoma are the most frequent ones. Using nearest shrunken centroids classification, we generated an expression signature that can predict the histological subtype of osteosarcoma biopsies. RESULTS: The expression signature, which consisted of 24 probes encoding for 22 genes, predicted the histological subtype of osteosarcoma biopsies with a misclassification error of 15%. Histological subtypes of the two osteosarcoma model systems, i.e. osteosarcoma cell lines and xenografts, were predicted with similar misclassification error rates (15% and 11%, respectively). CONCLUSIONS: Based on the preservation of mRNA expression profiles that are characteristic for the histological subtype we propose that these model systems are representative for the primary tumor from which they are derived.

Improvement in histologic response but not survival in osteosarcoma patients treated with intensified chemotherapy: a randomized phase III trial of the European Osteosarcoma Intergroup.

BACKGROUND: Previous randomized controlled trials that used the two-drug chemotherapy regimen of cisplatin and doxorubicin as the conventional arm showed no evidence of benefit from an increase in the number of agents or the length of treatment. It was then proposed that survival could be improved by increasing the planned dose intensity of cisplatin and doxorubicin. METHODS: Previously untreated patients with nonmetastatic, high-grade, central osteosarcoma of an extremity were randomly assigned to Regimen-C (conventional treatment with six 3-week cycles of cisplatin [100 mg/m2 by 24-hour infusion] and doxorubicin [25 mg/m2/day by 4-hour infusion for 3 days]) or to Regimen-DI (intensified treatment with identical total doses of cisplatin and doxorubicin, planned as six 2-week cycles supported by granulocyte colony stimulating factor (G-CSF). Surgery was scheduled for week 6 in both arms. Primary and secondary outcome measures were overall and progression-free survival, respectively. Intention-to-treat analyses were performed using standard survival analysis methods. Landmark analyses were performed in patients with known surgical details and centrally reviewed histologic response. All statistical tests were two-sided. RESULTS: Between May 1993 and September 2002, treatment was randomly allocated to 497 eligible patients. Six cycles of chemotherapy were completed by 78% of patients in Regimen-C and 80% of patients in Regimen-DI. The delivered preoperative median dose intensity of cisplatin was 86% in Regimen-C and 111% in Regimen-DI (as the percentage of that planned for the conventional regimen). Postoperative median dose intensity of cisplatin was 82% in Regimen-C and 110% in Regimen-DI (the corresponding figures for doxorubicin dose intensity were similar). Regimen-DI was associated with lower risks of severe leucopenia and neutropenia and higher risks of thrombocytopenia and mucositis. Good histologic response (>90% tumor necrosis) was observed in 36% of Regimen-C patients and 50% of Regimen-DI patients (P = .003, chi2 test). There was no evidence of a difference in overall survival (hazard ratio [HR] = 0.94, 95% CI = 0.71 to 1.24; P = .64) or progression-free survival (HR = 0.98, 95% CI = 0.77 to 1.24; P = .83). Landmark analyses showed similar results. CONCLUSIONS: Planned intensification of chemotherapy with cisplatin and doxorubicin increased received dose intensity and resulted in a statistically significant increase in favorable histologic response rate, but not in increased progression-free or overall survival. Our results call into question the use of histologic response as a surrogate outcome measure in trials of this disease.

Desmoplastic fibroma of bone: an immunohistochemical study including beta-catenin expression and mutational analysis for beta-catenin.

Desmoplastic fibroma of bone is a very rare primary bone tumor morphologically resembling desmoid-type fibromatosis, its much more common counterpart of soft tissue. The aim of this study is to investigate the immunohistochemical profile and the involvement of the beta-catenin pathway in desmoplastic fibroma as it is known in desmoid-type fibromatosis. Immunohistochemistry was performed on 13 cases of desmoplastic fibroma for muscle-specific markers, estrogen and progesterone receptors, CD117, beta-catenin, and the potential downstream target of beta-catenin, namely, cyclin D1. In all 13 cases, DNA sequencing was performed for the detection of activating beta-catenin gene mutations. There was no immunoreactivity of CD117, estrogen, and progesterone receptors. Seven cases were immunoreactive for one or more muscle-specific markers. In 6 cases, there was overexpression of beta-catenin in the cytoplasm; in one of these cases, there was also accumulation of beta-catenin in the nucleus. In 6 cases in which DNA sequencing was successful, no beta-catenin mutations were detected. Search in a national database showed that not a single case over a frame of 23 years was associated with occurrence of colon cancer in the same patient. The epidemiological, histological, and immunohistochemical findings in desmoplastic fibroma are suggestive of desmoplastic fibroma being the bony counterpart of the more common desmoid-type fibromatosis of soft tissue. However, the beta-catenin pathway does not seem to have the same essential role in the tumorigenesis of desmoplastic fibroma, as it has in desmoid-type fibromatosis.