Combination of temozolomide with immunocytokine F16-IL2 for the treatment of glioblastoma

Background:Glioblastoma patients are still not cured by the treatments available at the moment. We investigated the therapeutic properties of temozolomide in combination with F16-IL2, a clinical-stage immunocytokine consisting of human interleukin (IL)-2 fused to the human antibody F16, specific to the A1 domain of tenascin-C.Methods:We conducted three preclinical therapy studies, using subcutaneous and intracranial U87MG glioblastoma tumours xenografted in BALB/c nude mice. The same therapeutic schedule was used, consisting of five total administrations every third day, of 0.525 mg temozolomide, 20 g F16-IL2, the combination, or the control solution.Results: Immunohistochemical analysis of U87MG xenografts and of human glioblastoma specimens showed selective tumour staining of F16. A quantitative biodistribution confirmed the preferential tumour accumulation of radiolabelled F16-IL2. In the study with subcutaneous xenografts, the combination of F16-IL2 with temozolomide induced complete remission of the animals, which remained tumour free for over 160 days. The same treatment led to a consistent size reduction of intracranial xenografts and to a longer survival of animals. The immunocytokine promoted the recruitment of leukocytes into tumours of both models.Conclusion:The combined use of temozolomide with F16-IL2 deserves clinical investigations, which will be facilitated by the excellent safety profile in cynomolgus monkeys, and by the fact that F16-IL2 is in clinical trials in patients with cancer.