The Effect of Calmodulin Inhibitors with Bleomycin on the Treatment of Patients with High Grade Gliomas

Abstract

Glioblastoma multiforme is a fatal malignancy of the central nervous system, demanding new methods of treatment. The combination of a calmodulin antagonist with bleomycin has shown synergistic activity in several preclinical models and has been evaluated in a Phase I clinical trial. Since phenothiazines reach high concentrations in the central nervous system, and bleomycin has been reported to have antitumoral activity as well, we studied this combination in a Phase II clinical trial. In addition, we purified calmodulin from normal brain and malignant gliomas to determine its biochemical and pharmacological characteristics.

Seventeen patients were entered onto this study and all were evaluable. There were no partial or complete responses. There was one case of fatal pulmonary toxicity in a patient showing an objective tumor response. Otherwise, the treatment was well tolerated.

Calmodulin purified from the normal brain and gliomas of patients undergoing resection was identical to each other and to calmodulin prepared from rat cerebrum and glioma These characteristics included elution from a TSK phenyl high pressure liquid chromatography column, migration on 16% sodium dodecyl sulfate gels, amino acid composition, and inhibition by drugs. Therefore, the failure of this combination therapy was not due to a difference in human glioma calmodulin as compared to previously reported studies with calmodulin from murine sources.