Heterogeneous reovirus susceptibility in human glioblastoma stem-like cell cultures.

Glioblastoma (GB) is a devastating disease for which new treatment modalities are needed. Efficacious therapy requires the removal of stem-cell like cells, these cells drive tumor progression because of their ability to self-renew and differentiate. In glioblastoma, the GB stem-like cells (GSC) form a small population of tumor cells and possess high resistance to chemo and radiation therapies. To assess the sensitivity of GSC to reovirus-mediated cytolysis, a panel of GSC cultures was exposed to wild-type reovirus Type 3 Dearing (T3D) and its junction adhesion molecule-A (JAM-A)-independent mutant, jin-1. Several parameters were evaluated, including the fraction of cells expressing the JAM-A reovirus receptor, the fraction of cells synthesizing reovirus proteins, the number of infectious reovirus particles required to reduce cell viability, the amount of infectious progeny reovirus produced and the capacity of the reoviruses to infect the GSC in 3-dimensional (3D) tumor cell spheroids. Our data demonstrate a marked heterogeneity in the susceptibility of the cultures to reovirus-induced cytolysis. While in monolayer cultures the jin-1 reovirus was generally more cytolytic than the wild-type reovirus T3D, in the 3D GSC spheroids, these viruses were equally effective. Despite the variation in reovirus sensitivity between the different GSC cultures, our data support the use of reovirus as an oncolytic agent. It remains to be established whether the variation in the reovirus sensitivity correlates with a patient's response to reovirus therapy. Moreover, our data show that the expression of the JAM-A receptor is not a major determinant of reovirus sensitivity in 3D GSC cultures.

Phase II study on cisplatin and ifosfamide in recurrent high grade gliomas.

27 patients with recurrent high grade glioma following surgery and radiation therapy were treated with 100 mg/m2 cisplatin and 6 g/m2 ifosfamide per cycle, administered on days 1-3 in 4 week cycles, for a maximum of six cycles. Toxicity was assessed after every cycle. Response was assessed following every second cycle, and a 50% decrease of the largest cross-sectional tumour area on contrast enhanced magnetic resonance imaging or computed tomography scan was considered a partial response (PR). A total of 95 cycles was administered; 26 patients were evaluable for response. In 5 patients (19%), a PR was obtained (median time to progression (TTP): 34 weeks). Stable disease was observed in 6 patients (23%, median TTP: 22 weeks). The most frequent toxicity was haematological: 37% of cycles were complicated by a grade 3 or 4 leucopenia. 1 patients died, probably as a consequence of increased cerebral oedema induced by the cisplatin hydration schedule. Determination of the cisplatin concentration in this patient showed a 10-fold increase in the tumour concentration as compared with that in normal brain tissue, demonstrating the absence of a blood-brain barrier in the tumour. In conclusion, generally this schedule was well tolerated, but it is of moderate activity for recurrent glioma.