bleomycin

Bleomycin is a chemotherapy drug in the cytotoxic antibiotic family, named after Streptomyces verticillus, the bacterium from which it was first isolated. Unlike many chemo agents that are mainly given intravenously, it can be injected into muscle, under the skin, directly into a tumor, or into the pleural space for malignant pleural effusions and pleurodesis.

The way bleomycin works is both elegant and potent. Once inside cells, it binds metal ions, especially iron, and oxygen to generate free radicals. These radicals break DNA strands, which blocks replication and can lead to cell death. It is commonly paired with other agents in regimens for lymphoma, testicular, head-and-neck, and skin squamous cell cancers.

Its principal safety concern is pulmonary toxicity. Bleomycin is inactivated by bleomycin hydrolase, and this enzyme is lower in lungs and skin, allowing the drug to accumulate there and cause inflammation and fibrosis. This can result in progressive shortness of breath and reduced lung function. Risk rises with higher cumulative dose, older age, and oxygen exposure. Providers monitor renal status and lung function throughout treatment, since dose exposure and patient frailty strongly affect toxicity risk.