Unlike antibiotics used to treat infections, "Antitumor Antibiotics" are derived from Streptomyces bacteria and are specifically designed to interfere with DNA. The most famous sub-class is the Anthracyclines (e.g., Doxorubicin). These drugs work through multiple mechanisms: they intercalate between DNA base pairs, inhibit the enzyme topoisomerase II, and generate free radicals that damage cell membranes.

While anthracyclines are highly potent against breast cancer and lymphomas, they carry a "Lifetime Dose Limit" due to their potential for "Cardiotoxicity" (permanent heart muscle damage). For an overview of the cardiac monitoring requirements and the use of liposomal delivery systems to mitigate these risks, the Chemotherapy Market documentation offers a breakdown. Liposomal encapsulation allows the drug to circulate longer and penetrate tumor tissues more effectively while shielding the heart from high peak concentrations.

Topoisomerase Inhibitors (e.g., Irinotecan, Etoposide) work by preventing the DNA from "unknotting" during replication. By stabilizing the DNA-enzyme complex, they cause permanent breaks in the DNA strand. These agents are vital in the treatment of small-cell lung cancer and ovarian cancer. Clinical management of these drugs often involves pre-treating patients to prevent "cholinergic syndrome" or severe diarrhea, which are common side effects of this specific drug class.