ACTR-44. AUTOPSY STUDY ON THE EFFECTS OF TUMOR TREATMENT FIELDS IN RECURRENT GLIOBLASTOMA: PRELIMINARY RESULTS AND TRIAL DESIGN

Abstract

BACKGROUND

Optune therapy with tumor treatment fields (TTFields) is approved for the treatment of recurrent glioblastoma due to a recent clinical trial that showed better quality of life and comparable overall survival to conventional therapy. In the newly diagnosed setting, the addition of TTFields to standard therapy consisting of surgery, radiation and temozolomide has also been shown to prolong tumor progression and improve overall survival. TTFields are low-intensity, alternating frequency electric fields that have been shown to disrupt cell division and subsequently tumor growth. Apoptosis and cell cycle arrest have been seen in vitro, and shown in mice and rabbit tumor models. Though preclinical studies are ongoing, glioblastoma patients who have undergone TTFields therapy have not yet been assessed at autopsy to determine both the pathological signature of TTFields therapy, and the pattern of failure.

METHODS

Whole brain samples were acquired and analyzed pathologically from two recurrent GBM patients at autopsy. One patient served as a control and one considered a test patient who had undergone TTFields therapy. Tissue samples were acquired from regions suspicious of tumor and treatment effects. Samples were paraffin embedded and hematoxylin and eosin (H&E) stained, and pathologically reviewed by a board certified pathologist. Samples were then compared.

RESULTS

The patient who underwent TTFields therapy showed regions of necrosis and increased cellular debris compared to the control patient who had pseudo-palisading and radiation necrosis.

CONCLUSION

These findings suggest there is increased apoptosis in patients treated with TTFields compared to those on chemoradiation alone. Recruitment is ongoing for expansion of this study to include 10 patients treated with TTFields at recurrence and 10 at treated at initial diagnosis. Patients will be recruited from brain donation. Pathology will be compared to control patients naïve of TTFields therapy.