P01.003 Botulinum toxin therapy to improve Tumor Treating Field (TTF) compliance: A case report

Abstract Background Glioblastoma therapy traditionally consists of maximal surgical debulking and radiation therapy with concomitant chemotherapy. Adjunctive therapy with TTF earned FDA approval in 2015. Transducer arrays are placed on a shaved scalp and emit low intensity (1–2 V/cm), intermediate frequency (200 Hz) wavelengths which interfere with mitotic microtubular assembly in rapidly dividing cancer cells, leading to apoptosis. The TTF must be worn for at least 18 hours/day for optimal results. However, use of this device is associated with local skin irritation. Case 57 year-old left-handed woman presented with left facial numbness and droop, slurred speech, and left hand numbness persisting over one day. Brain MRI demonstrated two ring-enhancing lesions in the right motor strip. The patient underwent a frontal craniotomy near-total resection. Pathology was consistent with glioblastoma (MGMT methylated, IDH1 negative). She underwent radiotherapy (6000 cGy in 30 fx) with concurrent temozolomide followed by 6 cycles of post-radiation chemotherapy. Two months later, she elected to pursue TTF. She developed progressive contact dermatitis/hyperhidrosis of the scalp at the sites of transducer array application. The hyperhidrosis interfered with the contact of the arrays to the scalp and became intolerable. Eleven months into TTF therapy, she began subcutaneous botulinum toxin injections of the scalp and forehead every 3–4 months. Her hyperhidrosis and tolerance of TTF improved significantly. She remains on TTF 22 months after beginning treatment. Conclusion TTF is a novel therapy that may prolong progression-free and overall survival in glioblastoma when used as an adjunct to surgery, radiotherapy, and chemotherapy. However, tolerability may be limited by localized skin toxicity. Botulinum toxin therapy at TTF application site can improve patient comfort and quality of life.