Despite aggressive
therapy, many
nervous system neoplasms, including
malignant gliomas,
medulloblastomas,
malignant meningiomas, and
neurofibrosarcomas, maintain high mortality rates. The authors recently utilized a
thymidine kinase-negative herpes simplex-1 mutant virus, dlsptk, with reduced neurovirulence, for the effective treatment of malignant human
gliomas in cell culture and in nude mouse in vivo models. The range of human
nervous system tumors that might be responsive to viral
therapy is now expanded. Three
medulloblastoma, four malignant or atypical
meningioma, and five
neurofibrosarcoma cell lines or early-passage
tumors were treated with the dlsptk virus in cell culture. A cell death rate of at least 99% was evident in every
tumor tested for at least one multiplicity of
infection within 14 days
after treatment. Control
tumor cell cultures remained viable. To test dlsptk
therapy in vivo, the authors treated human
medulloblastoma subcutaneous xenografts with two doses of dlsptk. Mean growth ratios were significantly inhibited in the treated group when compared to control
tumors, and there was a significant number of
tumor regressions in the treated animals. Similar results were seen with human malignant
meningioma xenografts in a subrenal
capsule study. These results encourage the further investigation of viral
therapy in the treatment of a broad spectrum of
nervous system tumors refractory to conventional treatment methods.