Heat shock protein 72 expression in osteosarcomas correlates with good response to neoadjuvant chemotherapy.

Although the therapeutic outcome of osteosarcoma patients has improved dramatically within the last 20 years because of combined neoadjuvant chemotherapy and surgery, the problem of drug resistance remains. Thus far, markers that can predict the response to chemotherapy at the time of biopsy are not available. Heat shock proteins (hsp) 60, 72, and 73 have been shown to play a role in tumor immunity, and our study investigated their expression in human osteosarcomas and nonmalignant bone tumors before neoadjuvant chemotherapy. Immunohistochemical evaluations of hsp expression was performed on paraffin-embedded sections of 45 patients (17 female, 28 male, aged 6.5 to 62 years; mean, 19.4 years) with high-grade osteosarcoma at the time of biopsy, before preoperative chemotherapy. These results were correlated to histological response to chemotherapy, tumor size, age, alkaline phosphatase serum levels, and duration of symptoms. Thirty-four patients (15 male, 19 female, mean age 27 years) with osteoblastoma, osteoid-osteoma, or fibrous dysplasia served as nonmalignant controls. Hsp60 was uniformly found in the cytoplasm of both benign and malignant bone tumors. Nuclear hsp73 expression quantitatively increased in osteosarcoma cells. Hsp72 was significantly overexpressed in osteosarcomas (17 of 45, 38%) compared with nonmalignant bone tumors (1 of 34, 2.9%; P < .001). Hsp72-positive osteosarcomas responded better to neoadjuvant chemotherapy than hsp72-negative cases (P < .001), co-express hsp60, and correlate with higher tumor size (P < .005) and location in the distal femur. No differences were observed relative to age, gender, duration of symptoms, alkaline phosphatase levels, or hsp73 expression between hsp72-positive and hsp72-negative tumors. Hsp72 expression seemed to be a predictive immunohistochemical marker for osteosarcoma, because it is the first marker to prospectively correlate to response to neoadjuvant chemotherapy. It therefore, may be of importance in preoperative therapy regimens for nonresponding high-risk patients.

Evaluation of HLA-DR expression and T-lymphocyte infiltration in osteosarcoma.

Although in recent years the outcome of patients with osteosarcoma has considerably been improved by combining neoadjuvant chemotherapy with radical surgery, there still remains the problem of nonresponse to chemotherapy. T-lymphocytes play a critical role in tumor immunology, and MHC molecules are of central importance in the regulation of the immune response. It is the aim of this study to investigate whether T-lymphocyte infiltration of osteosarcomas and HLA-DR expression on tumor cells and infiltrating immune cells are of predictive or diagnostic value. Expression of CD3, CD8 and HLA-II was evaluated immunohistochemically on paraffin-embedded sections of 35 patients with high-grade osteosarcoma at the time of biopsy before chemotherapy and correlated with histologic response to chemotherapy, tumor size, age, alkaline-phosphatase serum levels and duration of symptoms. Thirty-four patients with osteoblastoma (n = 7), osteoid osteoma (n = 7) or fibrous dysplasia (n = 20) served as controls. Osteosarcomas were infiltrated by CD3+ (33/35, 95%) and CD8+ T-lymphocytes (24/35, 68%), non malignant bone tumors by CD3+ in 91% (31/34) and CD8+ T-lymphocytes in 74% (25/34), respectively. T-lymphocytes were positive for HLA-DR expression in 29% (10/35) in osteosarcomas and in 11% (4/34) in non-malignant controls. Osteosarcoma cells were positive for HLA-DR in 11/35 (31%) and non-malignant tumor cells in only 9% (3/34). Therefore, HLA-DR is overexpressed in osteosarcoma (p < 0.05). HLA-DR expression on osteosarcoma cells showed a positive correlation with HLA-DR expression on lymphocytes (p < 0.001) as well as with duration of symptoms and age (p < 0.05). Response to preoperative chemotherapy, gender, tumor size and serum alkaline-phosphatase levels did not correlate with the expression of the molecules tested. Our results show that HLA-DR is overexpressed in osteosarcoma cells compared to non-malignant bone-tumors. This overexpression, however, fails to serve as a predictive marker for response to neoadjuvant chemotherapy. The same is also true for tumor-infiltrating lymphocytes expressing CD3, CD8 and HLA-DR. Increased HLA-DR expression in osteosarcoma is most likely due to the immune response against the tumor.