131I-81C6 (131I-Monoclonal Antibody 81C6, Neuradiab™) is a radioimmunoconjugate consisting of 81C6, a murine IgG2 anti-tenascin monoclonal antibody labeled with Iodine-131 for diagnosis and therapy. Tenascin is an extracellular matrix protein which is overexpressed in gliomas and other cancers.

As tenascin is mainly overexpressed in gliomas, brain tumor therapy becomes the first target indication. Clinical trials performed so far have mainly included patients with Glioblastoma Multiforme (GBM).

Phase II clinical trials showed encouraging data: the mean overall PFS reached 17.2 months in 19 GBM patients treated with Neuradiab. A Phase III trial was initiated on this basis.

Enrollment for the Neuradiab Phase III trial was initiated in June 2008. Up to 760 patients were supposed to be enrolled across the US. The study was expected to be completed by end of 2013, but was terminated in February 2011, “due to delay in site initiation and funding considerations.” The drug is on hold.

Target/Mechanism: Tenascin

Leading Emitter: beta electrons (β)