An experimental therapy using sodium selenite led to complete remission in a patient with advanced lung cancer that had stopped responding to standard treatment, according to a case report published in the journal Oncology and Therapy. Ten years after finishing the therapy, the patient shows no signs of the disease.
The patient had been enrolled in a study examining sodium selenite in people with progressive malignant tumors that were not responding to standard therapy. After the course of treatment, the tumor disappeared entirely, despite a prognosis so poor that doctors had expected the patient to survive only a few months.
During treatment, the researchers also recorded a sharp drop in levels of soluble PD-L1 (sPD-L1), a protein considered a potential biomarker of the body's antitumor immune response.
Possible immune link
The study's authors suggested that sodium selenite may have helped activate the patient's immune system and suppress the tumor's growth, though they said the mechanism behind the effect still needs further investigation.
PD-L1 is a protein that some tumors use to evade attack from the immune system, and drugs that block it, known as checkpoint inhibitors, are already used to treat certain cancers. A fall in the soluble form of the protein is one of the signs researchers look for when trying to gauge whether the immune system has become more active against a tumor.
One case, not a cure
The researchers stressed that their findings are based on a single clinical observation and do not allow any conclusions about how effective the treatment might be more broadly. A larger clinical trial is now being prepared to assess the safety of sodium selenite in patients with advanced forms of cancer.
Selenium is a trace mineral the body needs in small amounts, and sodium selenite is one of the chemical forms in which it can be administered. Scientists have long studied selenium compounds for possible anticancer properties, though none has yet been established as a standard cancer treatment.
