Recommandations pour la pratique clinique : Standards, Options et Recommandations pour la prise en charge par radiothérapie des patients atteints d'ostéosarcome

Overexpression of SENP1 reduces the stemness capacity of osteosarcoma stem cells and increases their sensitivity to HSVtk/GCV

Osteosarcoma stem cells are able to escape treatment with conventional chemotherapeutic drugs, as the majority of them are in a quiescent state. Recent reports have suggested that small ubiquitin-like modifiers (SUMOs) serve important roles in the maintenance of cancer stem cell stemness. Therefore, a potential strategy to increase the effectiveness of chemotherapeutic agents is to interfere with SUMO modification of proteins associated with the maintenance of stemness in osteosarcoma stem cells. The present study revealed a significant decrease in the expression of SUMO1 specific peptidase 1 (SENP1) in osteosarcoma tissues and osteosarcoma cell lines, and SENP1 expression was much lower in osteosarcoma stem cells than in non-cancer stem cells. Further experiments indicated that the low levels of SENP1 were essential for maintenance of stemness in osteosarcoma stem cells. Overexpression of SENP1 resulted in a marked decrease in the maintenance of stemness, but only slightly induced apoptosis of osteosarcoma cells, which is crucial to reduce the side effects of drugs on normal precursor cells. Finally, SENP1 overexpression led to a significant increase in the sensitivity of osteosarcoma stem cells to the herpes simplex virus 1 thymidine kinase gene in combination with ganciclovir in vitro and in vivo. In conclusion, the present study described a novel method to increase the sensitivity of osteosarcoma stem cells to chemotherapeutic drugs. Notably, this approach may significantly reduce the required dose of conventional chemotherapeutic drugs and reduce side effects.

Childhood osteosarcoma: multimodal therapy in a single-institution Turkish series

Between January 1990 and December 2006, 123 patients<or=16 years with the histopathologic diagnosis of osteosarcoma were treated with a chemotherapy regimen comprising epirubicin, cisplatin, and ifosfamide. The mean follow-up time was 36 months (range 2-219 months). Among the 94 patients analyzed, 68 patients (72.3%) were alive at the time of the analysis. A total of 26 patients (13 each with nonmetastatic and metastatic disease) died; 20 of these (9 with nonmetastatic disease and 11 with metastatic disease) died of disease; 5, of chemotherapy toxicity, and 1, of nonmetastatic disease from acute nonlymphoid leukemia 13 months following the cessation of osteosarcoma therapy. The estimated 5- and 10-year Overall Survival (OS) rates for all patients were 64.7% (95% confidence interval [95% CI] 74.8-52.94%) and 62.2% (95% CI 74.6-49.9%), respectively. The Event Free Survival (EFS) rate for all patients was 51.8% (95% CI 40.2-63.4%) at both 5 and 10 years. The estimated 5- and 10-year Overall Survival (OS) rates for patients with nonmetastatic disease were 78.3% (95% CI 66.9-89.7%) and 75.1 (95% CI 62.6-87.6%), respectively; this 5-year rate was significantly superior to that of patients with metastatic disease, 13.5% (95% CI 0-30.8%) (p<0.001). The estimated EFS rate for patients with nonmetastatic disease was 62.4% (95% CI 49.9-79.9%) at both 5 and 10 years and was significantly better than the 5-year EFS of 6.9% (95% CI 0-19.9%) in patients with metastatic disease (p<0.001). Progression during preoperative chemotherapy was encountered in 18 patients (19.1%), 11 of whom had metastatic disease at diagnosis. Four patients (three with nonmetastatic disease and one with metastatic disease) underwent salvage treatment consisting of early surgical intervention and preoperative radiation. The estimated 5- and 10-year OS rates were 13% (95% CI 0-29.7%) for patients who had progression during treatment; this rate was significantly inferior to both the 5- and 10-year OS rates for patients without progressive disease, which were 78.2% (95% CI 66.1-90.4%) and 75% (95% CI 61.9-83.1%), respectively (p<0.001). A total of 33 patients experienced relapse and/or progression at a median time of 9 months (range 0-40 months). Histologic response (<90% necrosis vs. >or=90%) was significantly correlated with the 5-year EFS (31% vs. 67.6%, respectively, p=0.023) but not with OS (57.7% vs. 76.5%, respectively, p=0.13). The presence of metastases at diagnosis was found to be the most significant single characteristic influencing the outcome. The rate of histologically good response to preoperative chemotherapy was 64.5%, which is comparable with the 28-85% response rates given in the literature. Our results demonstrate that the combination of epirubicin, cisplatin, and ifosfamide is an active and reasonably well-tolerated regimen for childhood osteosarcoma.

Multimodality treatment of osteosarcoma: radiation in a high-risk cohort

PURPOSE

Chemotherapy during radiation and/or bone-seeking radioisotope therapy (153-samarium; 1 mCi/kg) during radiation may improve osteosarcoma cancer control.

PATIENTS AND METHODS

We analyzed our preliminary radiation experience in high-risk, metastatic, and/or recurrent patients during a consecutive period of 20 months (May 2005-December 2006).

RESULTS

Thirty-nine high-risk osteosarcoma patients had radiotherapy; 119 sites were irradiated. A median four sites were irradiated per patient (range 1-14). The median radiation dose and number of fractions of radiation was 30 Gy in 10 fractions (range 10-70 Gy in 4-35 fractions). Chemotherapy, most commonly ifosfamide or methotrexate, was used in 80% (100/119) radiotherapy courses. Of 38 painful sites, 29 had improvement (76%), 4 had no change (10%), and 5 had more pain (13%). Objective and potentially durable responses were documented using PET-CT and bone scans with persistent and sustained reduction of standard uptake values (SUVs; initial SUV of indication lesion 9.5 became <4 at all subsequent time points) and serial bone scans [improvement in 29/39 (72%); stable 10/39 (25%), worse 1/39 (3%)]. The actuarial 4-year survival from development of metastasis was 39%.

CONCLUSIONS

Our early results suggest that the use of multimodality therapy including chemotherapy with radiation in unresectable osteosarcoma may be beneficial.

Impact of radiation therapy on healing and stability of vascularized bone grafts in a dog model

The purpose of the study was to observe the impact of radiation therapy on healing and biomechanical properties of vascularized bone grafts, and thus to establish an appropriate large animal model. Ten male beagles were divided into two experimental groups: radiation (R) and control (C). The left 5th to 7th ribs of the animals of group R were irradiated 3 and 2 weeks preoperatively, using a dose of 8 Gy each time. Each animal of both groups underwent the following operative procedures. The 5th and 7th ribs were removed, and the 5th rib was replaced by a vascularized pedicle transfer of the 4th rib. The 7th rib was reconstructed using a pedicle transplant of the 8th rib. The 5th and 7th ribs were used as nonvascularized bone grafts to replace the donor sites of the 4th and 8th ribs, respectively. Group R received two further irradiation cycles 2 and 3 weeks postoperatively. The vascularized rib grafts of group R demonstrated a higher number of delayed unions in plain x-rays and avascular bone segments in microangiography than the control group. The presence of vital osteocytes in histology was not significantly different between groups. Biomechanical tests focusing on the durability of vascularized ribs against bending and torsion forces demonstrated a reduction of average maximum bending moments by 56.6% after radiation compared to controls (P < 0.05). Twisting moments were reduced by 47.6% (P < 0.05). The data demonstrate a significant worsening in bone healing and stability after pre- and postoperative radiation therapy to the wound bed and bone grafts. Thus, a large animal model is established for further determination of different strategies of radiotherapy in combination with vascularized bone transfers.