Summary
A prospective six-patient preprint evaluated Hiporfin for fluorescence-guided surgery and cavity photodynamic therapy in recurrent glioblastoma. Fluorescence had moderate specimen-level diagnostic accuracy, with some tumour samples not fluorescing.
A prospective six-patient study evaluated Hiporfin, also called hematoporphyrin derivative (HpD), as a fluorescence guide during surgery for recurrent glioblastoma, while also testing photodynamic therapy (PDT) in the surgical cavity. The medRxiv preprint reports moderate specimen-level accuracy: fluorescent tissue was often tumour, but some tumour samples did not fluoresce.
One drug for surgical guidance and cavity treatment
Each adult received a single intravenous dose of Hiporfin at 5 mg/kg before surgery. Surgeons assessed tissue fluorescence under blue-light excitation to guide resection, then applied cavity PDT at 630 nm. The approach uses the drug both to make tissue fluoresce during surgery and as part of light-based treatment after resection.
The study was a prospective, single-arm series. Histopathology—the examination of tissue under a microscope—served as the reference standard for judging whether samples contained tumour. The researchers assessed 63 specimens from the six patients.
Fluorescence results and feasibility
Of the 63 specimens, 35 were true positives: they fluoresced and contained tumour. Seven were false positives, eight were false negatives, and 13 were true negatives. Using a bivariate random-effects model, the researchers reported pooled sensitivity of 0.751 (95% confidence interval 0.600 to 0.858) and specificity of 0.606 (0.407 to 0.775). The crude positive predictive value was 0.833 (0.694 to 0.917), while the negative predictive value was 0.619 (0.409 to 0.792).
In practical terms, a fluorescent sample was more likely to contain tumour than not, but an absence of fluorescence could not reliably rule tumour out. All seven false-positive samples came from peritumoral tissue; the eight false negatives were tumour samples that did not fluoresce. The authors identify tissue around the treated cavity as the main source of diagnostic error.
The combined fluorescence-guided resection and cavity PDT procedure was completed in all six patients, with no new neurological deficits reported. This supports the feasibility of carrying out the approach in this small series; the study does not compare it with another surgical strategy. The findings are reported in a medRxiv preprint.