Epirubicin is an anthracycline cytotoxic agent, is a 4'-epi-isomer of doxorubicin. The compound is marketed by Pfizer under the trade name Ellence in the US. It is indicated as a component of adjuvant therapy in patients with evidence of axillary node tumor involvement following resection of primary breast cancer. Although it is known that anthracyclines can interfere with a number of biochemical and biological functions within eukaryotic cells, the precise mechanisms of epirubicin’s cytotoxic and/or antiproliferative properties have not been completely elucidated. It is known, that epirubicin forms a complex with DNA by intercalation of its planar rings between nucleotide base pairs, with consequent inhibition of nucleic acid (DNA and RNA) and protein synthesis. Such intercalation triggers DNA cleavage by topoisomerase II, resulting in cytocidal activity. Epirubicin also inhibits DNA helicase activity, preventing the enzymatic separation of double-stranded DNA and interfering with replication and transcription. Epirubicin is also involved in oxidation/reduction reactions by generating cytotoxic free radicals.

Irinotecan is an antineoplastic enzyme inhibitor primarily used in the treatment of colorectal cancer. Irinotecan is sold under the brand name Camptosar among others. CAMPTOSAR is a topoisomerase inhibitor indicated for: • First-line therapy in combination with 5-fluorouracil and leucovorin for patients with metastatic carcinoma of the colon or rectum. • Patients with metastatic carcinoma of the colon or rectum whose disease has recurred or progressed following initial fluorouracil-based therapy. Irinotecan is a derivative of camptothecin. Camptothecins interact specifically with the enzyme topoisomerase I, which relieves torsional strain in DNA by inducing reversible single-strand breaks. Irinotecan and its active metabolite SN-38 bind to the topoisomerase I-DNA complex and prevent religation of these single-strand breaks. Current research suggests that the cytotoxicity of irinotecan is due to double-strand DNA damage produced during DNA synthesis when replication enzymes interact with the ternary complex formed by topoisomerase I, DNA, and either irinotecan or SN-38. Mammalian cells cannot efficiently repair these double-strand breaks.

Idarubicin is an antineoplastic in the anthracycline class.Idarubicin hydrochloride is a DNA-intercalating analog of daunorubicin which has an inhibitory effect on nucleic acid synthesis and interacts with the enzyme topoisomerase II. The absence of a methoxy group at position 4 of the anthracycline structure gives the compound a high lipophilicity which results in an increased rate of cellular uptake compared with other anthracyclines.Idarubicin possesses an antitumor effect against a wide spectrum of tumors, either grafted or spontaneous. Idarubicin in combination with other approved antileukemic drugs is indicated for the treatment of acute myeloid leukemia (AML) in adults.

Daunorubicin, also known as daunomycin, is a chemotherapy medication used to treat cancer. Specifically, it is used for acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), chronic myelogenous leukemia (CML), and Kaposi's sarcoma. Similar to doxorubicin, daunorubicin interacts with DNA by intercalation and inhibition of macromolecular biosynthesis. This inhibits the progression of the enzyme topoisomerase II, which relaxes supercoils in DNA for transcription. Daunorubicin stabilizes the topoisomerase II complex after it has broken the DNA chain for replication, preventing the DNA double helix from being resealed and thereby stopping the process of replication. On binding to DNA, daunomycin intercalates, with its daunosamine residue directed toward the minor groove. It has the highest preference for two adjacent G/C base pairs flanked on the 5' side by an A/T base pair. Daunorubicin should only be administered in a rapid intravenous infusion. It should not be administered intramuscularly or subcutaneously, since it may cause extensive tissue necrosis. It should also never be administered intrathecally (into the spinal canal), as this will cause extensive damage to the nervous system and may lead to death.

Aldoxorubicin (INNO-206) is a tumor-targeted doxorubicin conjugate developed by CytRx for treating relapsed and refractory sarcomas, especially L-sarcomas. Aldoxorubicin is a rationally-engineered cytotoxic which delivers a well-established anti-cancer agent, doxorubicin, into the tumor. Currently, in late-stage clinical trials, Aldoxorubicin appears to overcome the key limitations of doxorubicin, including cumulative dose restrictions. Aldoxorubicin utilizes an acid-sensitive linker that selectively binds to albumin, which may allow the cytotoxic payload to preferentially accumulate in the tumor and potentially spare the surrounding healthy tissue. This mechanism leverages the tumor's low pH environment and accompanying dependency upon circulating albumin to fuel growth, to enable the delivery of multifold times the standard dosing of doxorubicin. The preferential uptake of Aldoxorubicin by tumor tissue and the acid sensitive release of doxorubicin allow for Aldoxorubicin to be a very promising anticancer agent. In phase I and II trials, Aldoxorubicin demonstrates superior efficacy over doxorubicin. Although the studies were not powered for OS, Aldoxorubicin shows improved PFS and tumor response in comparison to doxorubicin. The safety profile was also comparable to that of doxorubicin. Similarly, results from the recent phase III study showed a benefit in PFS in the leiomyosarcoma subtypes.

Teniposide is an inhibitor of topoisomerase II with anti-cancer activity. The drug was approved by FDA under the name Vumon for the treatment of children with acute lymphoblastic leukemia.

Etoposide (trade name Etopophos) is a semisynthetic derivative of podophyllotoxin that exhibits antitumor activity. It has been in clinical use for more than two decades and remains one of the most highly prescribed anticancer drugs in the world. The primary cytotoxic target for etoposide is topoisomerase II. This ubiquitous enzyme regulates DNA under- and over winding, and removes knots and tangles from the genome by generating transient double-stranded breaks in the double helix. Etoposide kills cells by stabilizing a covalent enzyme-cleaved DNA complex (known as the cleavage complex) that is a transient intermediate in the catalytic cycle of topoisomerase II. The accumulation of cleavage complexes in treated cells leads to the generation of permanent DNA strand breaks, which trigger recombination/repair pathways, mutagenesis, and chromosomal translocations. If these breaks overwhelm the cell, they can initiate death pathways. Thus, etoposide converts topoisomerase II from an essential enzyme to a potent cellular toxin that fragments the genome. Although the topoisomerase II-DNA cleavage complex is an important target for cancer chemotherapy, there also is evidence that topoisomerase II-mediated DNA strand breaks induced by etoposide and other agents can trigger chromosomal translocations that lead to specific types of leukemia. Etopophos (etoposide phosphate) is indicated in the management of the following neoplasms: Refractory Testicular Tumors-and for Small Cell Lung Cancer. The in vitro cytotoxicity observed for etoposide phosphate is significantly less than that seen with etoposide, which is believed due to the necessity for conversion in vivo to the active moiety, etoposide, by dephosphorylation. The mechanism of action is believed to be the same as that of etoposide.