What it is
Bleomycin is a glycopeptide antibiotic, sold as a mixture. The label describes it as "a mixture of cytotoxic glycopeptide antibiotics isolated from a strain of Streptomyces verticillus," a soil bacterium. The main component is bleomycin A2; bleomycin B2 is the other named one. A2's formula is C55H84N17O21S3+ and its mass 1,415.6 Da (PubChem CID 5460769) — roughly the mass of a 12- to 13-residue peptide, our comparison, though its structure is not a straight chain of standard amino acids. It is built from amino-acid-derived pieces, carries a disaccharide (the "glyco" part), and ends in a two-ring sulfur-containing tail.
Because it is a mixture, it is measured by activity, not weight: one unit equals the old "milligram activity," which the label calls a misnomer. Vials hold 15 or 30 units.
It shares the "glycopeptide antibiotic" label with the hospital antibiotic vancomycin, but the two are used for different things: vancomycin treats bacterial infections; bleomycin's approved uses are all in cancer.
How it works
The label states the evidence plainly: the exact mechanism "is unknown," but the main mode of action appears to be inhibition of DNA synthesis, with lesser effects on RNA and protein synthesis. Bleomycin causes single and, less often, double-strand breaks in DNA and arrests cells in the G2 phase and in mitosis — in-vitro and in-vivo findings. Dropped into the chest cavity, it acts instead as a sclerosing agent, inflaming the lining so the space closes and fluid cannot collect.
It is absorbed quickly from muscle, under the skin or from the chest cavity, peaking in 30 to 60 minutes; systemic bioavailability is 100% after intramuscular and 70% after subcutaneous injection (label).
What it is approved for
The label frames it as "a palliative treatment" useful alone or "in proven combinations":
- Squamous-cell carcinoma of the head and neck (mouth, tongue, tonsil, nasopharynx, larynx and more), penis, cervix and vulva — with poorer response in previously irradiated head and neck cancer.
- Lymphomas: Hodgkin's disease and non-Hodgkin lymphoma.
- Testicular carcinoma: embryonal cell, choriocarcinoma and teratocarcinoma.
- Malignant pleural effusion: as a sclerosing agent, to treat it and prevent recurrence.
The research record behind these uses is large: PubMed indexes 25,496 records on bleomycin and 812 tagged as randomised controlled trials, most testing it inside combination regimens rather than alone (2026-10-22).
Safety
Lung toxicity defines the drug. The boxed warning calls pulmonary fibrosis "the most severe toxicity." Pulmonary reactions occur in about 10% of treated patients, most often as pneumonitis; in about 1% the pneumonitis progresses to fibrosis and death. Risk is higher over age 70 and above 400 units total dose, but the label stresses that the toxicity "is unpredictable" and has been seen in young patients on low doses. The earliest symptom is breathlessness; the earliest sign is fine crackles on listening to the chest.
A severe idiosyncratic reaction — low blood pressure, confusion, fever, chills and wheezing, similar to anaphylaxis — has been reported in about 1% of lymphoma patients, usually after the first or second dose. Kidney and liver toxicity have been reported. Bleomycin can cause fetal harm and was teratogenic in rats (label). It is given under a physician experienced in cancer chemotherapy, who sets the dose.
Where it stands
- Approved in the US since 1973-07-31, first as Blenoxane (Bristol-Myers Squibb, NDA 050443), now discontinued; generic bleomycin for injection is marketed by Hospira (since 2000), Hikma, Meitheal and Fresenius Kabi, among others (Drugs@FDA, 2026-10-22).
- Research record: PubMed 25,496 records, 812 randomised controlled trials; ClinicalTrials.gov 272 studies (2026-10-22).
Related reading
The library's other glycopeptide antibiotic, the one used against bacteria, is vancomycin, a seven-residue cross-linked glycopeptide; a different class of peptide antibiotic is polymyxin B. For what makes a molecule count as a peptide, see what peptides are.