Stereotactic Photodynamic Therapy of Recurrent Malignant Gliomas

The aim of the study is to assess the effectiveness and safety of stereotactic photodynamic therapy (sPDT) with 5-aminolevulinic acid (5-ALA) in patients with recurrent malignant supratentorial gliomas in functionally relevant brain areas.

In a retrospective single-center study the results of sPDT with 5-ALA in 10 patients (6 of 10 were male), aged 30 to 62 years (median: 51.5 years; 95% CI: 38-59 years) with recurrent malignant brain gliomas after standard therapy who underwent surgery during the period of 2020-2023 were analyzed. sPDT was conducted during 15 min using 5-ALA at a dosage of 20 mg/kg, a diode laser with a wavelength of 635 nm and power of 1 W, and the LFT-02-BIOSPEC unit (BIOSPEC, Russia). Three patients got repeated sPDT after 3, 7, and 15 months due to a relapse. The number of target points and the optimal position for intervention paths were determined according to the data of preoperative stereotactic MRI of the brain with contrast intensification using the CRW Precision stereotactic navigation system (Integra, USA) and intraoperative registration of the area with the highest intensity of protoporphyrin IX fluorescence along the path (according to fluorescence biospectroscopy).

Glioblastoma (grade IV, WHO) was diagnosed in 7 patients, anaplastic astrocytoma (grade III, WHO) - in 3 persons. Genetic studies were performed for 9 patients, 7 of them had tumors without the IDH1 gene mutation. None of the patients had a combined 1p/19q deletion. The median volume of the contrast-enhancing part of the recurrent tumor was 7.95 cm³ (95% CI: 3.3-13.6 cm³). The median time to relapse after sPDT in patients with anaplastic astrocytomas and glioblastomas was 14.5 and 6.5 months, respectively. The median survival time after sPDT in patients with glioblastomas was 15.8 months (95% CI: 0.5-20.1 months), and in patients with anaplastic astrocytomas - 46.3 months (95%, CI not specified). In the early postoperative period, two patients had motor aphasia and hemiparesis, which further regressed.

The results of a small group of patients allow to consider sPDT with 5-ALA as a promising technique to treat patients with recurrent high-grade gliomas in functionally relevant brain areas and require further prospective assessment.