Background: Calcium electroporation is a novel cancer treatment, which combines temporary cell permeability from electroporation with a high influx of calcium intracellularly resulting in cancer cell necrosis.

Methods: A phase I trial performing calcium electroporation on 6 patients suffering from recurrent head and neck cancer. In general anesthesia, intratumoral calcium injections were followed by electroporation. Safety was monitored by adverse events registration, serum Ca2+, ECG, and pain scores. Tumor response was measured on PET/MRI scans.

Results: Procedures were performed without complications. No serious adverse events, signs of hypercalcemia, or cardiac arrhythmias were observed. Two months post-treatment tumor responses on MRI: three partial responses, one stable disease, and two progression. Responses on PET: one partial metabolic disease, four with stable metabolic disease, and one not evaluable. One patient was without clinical evidence of disease after 12 months of observation.

Conclusion: Calcium electroporation is feasible and safe in head and neck tumors. Clinical responses were observed in three of six patients, warranting further studies.

Level of Evidence: Level 4.