The Food and Drug Administration has approved aminolevulinic acid hydrochloride (Gleolan) to help visualize gliomas during surgery and allow for more complete resection.

Aminolevulinic acid hydrochloride lights up the tumor so surgeons can distinguish it from healthy tissue. Patients take the drug orally – 20 mg/kg – approximately 3 hours before anesthesia. Glioma cells take it up and convert it to the fluorescent chemical protoporphyrin IX. When illuminated under blue light, protoporphyrin in the tumor glows an intense red, while normal brain tissue appears blue, enabling “the surgeon to see the tumor more clearly during brain surgery and to remove it more accurately, sparing healthy brain tissue,” according to information from NX Development Corp, which markets Gleolan.

The drug must be used with a standard surgical operating microscope adapted with a blue light emitting light source, and neurosurgeons should complete a training program on use of fluorescence in surgery beforehand, FDA labeling notes.

In a phase III trial of 349 patients with suspected malignant glioma amenable to complete resection, a contrast-enhanced tumor was resected in 64% of patients in the aminolevulinic acid (ALA) arm, versus 38 % of patients in the control-group, who had conventional resection under white light (P less than .001); 20.5 % of ALA patients versus 11 % patients in the control arm were alive at 6 months without progression.

FDA officials noted that there’s a risk of false negatives and positives with ALA, and that “an increase in the extent of resection might increase the risk of serious neurologic deficits in the short term.”

Side effects in preapproval studies included fever, hypotension, nausea, and vomiting in more than 1% percent of patients within a week of surgery. Adverse events included chills, abnormal liver function tests, and diarrhea in less than 1% of patients within 6 weeks of surgery.