Interstitial photodynamic therapy for newly diagnosed glioblastoma

Abstract

Purpose Innovative, efficient treatments are desperately needed for people with glioblastoma (GBM). Methods Sixteen patients (median age 65.8 years) with newly diagnosed, small-sized, not safely resectable supratentorial GBM underwent interstitial photodynamic therapy (iPDT) as upfront eradicating local therapy followed by standard chemoradiation. 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX was used as the photosensitizer. The tumors were irradiated with light at 635 nm wavelength via stereotactically implanted cylindrical diffuser fibers. Outcome after iPDT was retrospectively compared with a positively-selected in-house patient cohort (n = 110) who underwent complete tumor resection followed by chemoradiation. Results Median progression-free survival (PFS) was 16.4 months, and median overall survival (OS) was 28.0 months. Seven patients (43.8%) experienced long-term PFS > 24 months. Median follow-up was 113.9 months for the survivors. Univariate regression revealed MGMT-promoter methylation but not age as a prognostic factor for both OS (p = 0.04 and p = 0.07) and PFS (p = 0.04 and p = 0.67). Permanent iPDT-associated morbidity was seen in one iPDT patient (6.3%). Patients treated with iPDT experienced superior PFS and OS compared to patients who underwent complete tumor removal (p < 0.01 and p = 0.01, respectively). The rate of long-term PFS was higher in iPDT-treated patients (43.8% vs. 8.9%, p < 0.01). Conclusion iPDT is a feasible treatment concept and might be associated with long-term PFS in a subgroup of GBM patients, potentially via induction of so far unknown immunological tumor-controlling processes.

Interstitial Photodynamic Therapy of Glioblastomas: A Long-Term Follow-up Analysis of Survival and Volumetric MRI Data

“…The retrospectively analyzed cohort consisted of 16 patients who underwent 5-ALAmediated iPDT [17]. This procedure was offered to patients suffering from biopsy-proven de novo glioblastomas for whom an SOC treatment was impossible due to the location of the tumor or other contraindications.…”

“…This procedure was offered to patients suffering from biopsy-proven de novo glioblastomas for whom an SOC treatment was impossible due to the location of the tumor or other contraindications. Instead of definitive chemoradiation [10], iPDT combined with a fractionated 60 Gy radiation therapy and temozolomide (according to Stupp [2]) was offered as salvage treatment [17].…”

“…Further clinical aspects regarding these patients can be found in Quach et al [17]. Details about tumor characteristics and the applied adjuvant therapy are summarized in Table 2.…”

“…Among these approaches, 5-aminolevulinic acid (5-ALA)-mediated interstitial photodynamic therapy (iPDT) was identified as a promising option building on standard stereotactic procedures [14][15][16][17]. Patients receive 5-ALA as a prodrug to achieve the intracellular synthesis of a photosensitizing molecule (protoporphyrin IX, PpIX).…”

“…Another advantage is that the healthy tissue is preserved due to the tumor-selective accumulation of PpIX [18]. After iPDT, prolonged median OS (≥24 months) has been observed [14,17,23], although the reasons for this encouraging observation are not yet fully understood.…”