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Desmoplastic small round cell tumor (DSRCT) is a highly fatal, mainly peritoneal cell origin cancer which predominantly affects young adult males. This predilection in young males led us to examine the role of androgen receptors (AR), testosterone, and growth factors in the biology of DSRCT.Slides were prepared from 27 multi-institutional patients all with end-stage DSRCT. Slides were stained for AR, c-Kit, various growth factors, and drug resistance-associated proteins. Immunohistochemical (IHC) expression was scored semi-quantitatively. Western blot and MTT studies were performed to validate the IHC findings of over-expression of the AR and its functional status by stimulation of growth by dihydrotestosterone, respectively. Six patients with positive AR status were treated solely with combined androgen blockade (CAB) as used for prostate cancer.Twenty-two patients were male (81%) and five were female (19%) with a median age at diagnosis of 23. All patients had failed at least two prior multi-agent chemotherapy regimens and 44% had progressed after autologous stem cell transplant. DSRCT samples from 10 of 27 patients wereor=2+ IHC positive for AR (37%,P=0.0045) and 7 of 20 patients wereor=2+ IHC positive for c-Kit (35%, P=0.018). We found elevated IHC expression of GST-pi, MRP and thymidylate synthase in smaller subsets of patients. In vitro studies for AR by Western blot and stimulation of growth by dihydrotestosterone in MTT assays suggest that the AR in DSRCT cells is functional. Six patients with positive AR status were treated with CAB alone and three of six attained clinical benefit (1-PR, 1-MR, 1-SD) in a range of 3-4 months. The three patients who responded to CAB had normal testosterone levels before CAB, while the three who did not respond to CAB had baseline castrate levels of testosterone.DSRCT has significant IHC expression of AR and c-Kit in heavily pre-treated patients. The presence of significant AR expression in 37% suggests that these patients could possibly respond to CAB. The significance of c-Kit expression in 35% of DSRCT patients is unknown and warrants further investigation.

Purpose: Tumor resistance to alkylating agents such as carmustine (BCNU) has been found to be associated with intracellular expression of O 6 -methylguanine-DNA methyltransferase (MGMT). Administration of O 6-benzylguanine (O 6-BG), a substrate that inactivates MGMT, may help overcome chemotherapy resistance. We performed a phase II study to explore the activity of O 6-BG in combination with BCNU in patients with advanced soft tissue sarcoma. Experimental design: Informed consent was obtained from patients with metastatic soft tissue sarcoma naive to systemic chemotherapy (adjuvant chemotherapy allowed). Patients received O 6 -BG 120 mg/m2 I.V. followed by BCNU 40 mg/m2 I.V. Treatment was repeated every 6 weeks until disease progression or development of unacceptable toxicity. Results: No objective responses were observed in 12 enrolled patients. Four patients exhibited stable disease lasting 11–25+ weeks. The median overall survival was 16.9 months (95% CI, 2.9–NR). The most common grade 3–4 toxicities were neutropenia, thrombocytopenia, and anemia. Depletion of MGMT activity was demonstrated in peripheral blood mononuclear cells. Immunohistochemical estimation of MGMT expression from archival tissue ranged from 20 to 99% positive staining cells. Conclusions: Observed toxicities were consistent with previous studies of O 6-BG plus BCNU. The degree of MGMT expression was variable in this small sample of heterogeneous sarcomas. Further development of this regimen and dose for the treatment of soft tissue sarcoma is not warranted due to the lack of objective responses.

Vascular toxicity following the use of vinblastine, bleomycin, and cisplatin (VBP) combination chemotherapy has been described. This report gives details of 5 patients who suffered acute life-threatening vascular events following such a chemotherapy regimen for germ cell tumors. In 3 of the cases no evidence of tumor was found at autopsy. Both an acute and a long-term vascular toxicity were seen. Large artery vascular disease may result from synergistic toxicity of the drugs comprising the regimen. These cases, with an additional 16 collected from the literature, suggest that major vascular disease is a significant side-effect of the VBP regimen.