gms | German Medical Science

Objective: We analyzed whether neoadjuvant treatment prior to tumor resection, which is an established principle in oncology for some types of cancer, is also a valid concept for improving the therapy of malignant brain tumors. In GBM, debulking surgery is regularly being performed as initial step to decrease symptomatic intracranial pressure. In a previous study, we found that local injection of radiolabelled substance P into NK1-receptor expressing recurrent malignant gliomas was well tolerated and led to functional improvement. From a surgical point of view, resectability was facilitated due to improved demarcation and the radiation-induced anti-angiogenic effect.

Methods: In a phase I study, we treated 10 glioblastoma (GBM) patients by locally injecting the radiolabelled peptidic vector [⁹⁰Yttrium]-DOTAGA-Substance P prior to tumor resection. Chemical synthesis, the radiolabelling protocol and local injection of the vector have been described previously.

Results: Neoadjuvant injection of [⁹⁰Yttrium]-DOTAGA-substance P was found to be feasible without signs of decompensating intracranial pressure. The prolonged application of corticosteroids in the current study protocol was identified as the main risk factor for potential side effects. Nine out of ten patients stabilized or improved in their functional status. Neoadjuvant intratumoral irradiation made it possible to achieve an extent of resection between 90% and 100% (mean 96%), which may be of prognostic importance.

Conclusions: Neoadjuvant therapy of GBM using locally injected radiopeptides is feasible and of low-toxicity. It should be further assessed as a first line option in the therapeutic cascade of GBM treatments. The high extent of resection and the concomitant irradiation of tumor margins may be prognostically relevant.