Pentostatin, also known as 2’-deoxycoformycin (DCF) under the trade name Nipent, is a potent inhibitor of the enzyme adenosine deaminase and is isolated from fermentation cultures of Streptomyces antibioticus. It was developed by Parke-Davis (now Pfizer) and the National Cancer Institute in the US. Nipent is indicated as single-agent treatment for both untreated and alpha-interferon-refractory hairy cell leukemia patients with active disease as defined by clinically significant anemia, neutropenia, thrombocytopenia, or disease-related symptoms. Pentostatin is a potent transition state inhibitor of the enzyme adenosine deaminase (ADA). The greatest activity of ADA is found in cells of the lymphoid system with T-cells having higher activity than B-cells, and T-cell malignancies having higher ADA activity than B-cell malignancies. Pentostatin inhibition of ADA, particularly in the presence of adenosine or deoxyadenosine, leads to cytotoxicity, and this is believed to be due to elevated intracellular levels of dATP, which can block DNA synthesis through inhibition of ribonucleotide reductase. Pentostatin can also inhibit RNA synthesis as well as cause increased DNA damage. In addition to elevated dATP, these mechanisms may also contribute to the overall cytotoxic effect of pentostatin. The precise mechanism of pentostatin’s antitumor effect, however, in hairy cell leukemia is not known. In several instances, hepatic toxicity from pentostatin appeared to be somewhat dose related, suggesting that the liver injury is a direct effect of the purine analogue. Because pentostatin is a potent immunosuppressive agent, the possibility exists that some cases of hepatic injury are due to reactivation of hepatitis B or other opportunistic infections. While pentostatin has not been shown to cause reactivation of hepatitis B, there is a strong possibility that it might induce this syndrome, and several cases of hepatic injury during pentostatin therapy were described as due to concurrent hepatitis B.

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.

Cytarabine is a pyrimidine nucleoside analog. Cytarabine or cytosine arabinoside (Cytosar-U or Depocyt) is a chemotherapy agent used mainly in the treatment of cancers of white blood cells such as acute myeloid leukemia (AML) and non-Hodgkin lymphoma. It also has antiviral and immunosuppressant properties. Cytarabine is an antimetabolite antineoplastic agent that inhibits the synthesis of DNA. It is a cell cycle phase-specific, affecting cells only during the S phase of cell division. Intracellularly, cytarabine is converted into cytarabine-5-triphosphate (ara-CTP), which is the active metabolite. The mechanism of action is not completely understood, but it appears that ara-CTP acts primarily through inhibition of DNA polymerase. Incorporation into DNA and RNA may also contribute to cytarabine cytotoxicity. Cytarabine is cytotoxic to a wide variety of proliferating mammalian cells in culture.The drug has a short plasma half-life, low stability and limited bioavailability. Overdosing of patients with continuous infusions may lead to side effects. Thus, various prodrug strategies and delivery systems have been explored extensively to enhance the half-life, stability and delivery of cytarabine. Alternative, delivery systems of cytarabine have emerged for the treatment of different cancers. The liposomal-cytarabine formulation has been approved for the treatment of lymphomatous meningitis.

Melphalan, also known as L-phenylalanine mustard, phenylalanine mustard, L-PAM, or L-sarcolysin, is a phenylalanine derivative of nitrogen mustard. Melphalan is a bifunctional alkylating agent which produces a number of DNA adducts with the DNA interstrand crosslink (ICL) considered to be the critical cytotoxic lesion. Melphalan is used to treat different cancers including myeloma, melanoma and ovarian cancer.

Chlorambucil is a bifunctional 12 alkylating agent of the nitrogen mustard type that has been found active against selected human 13 neoplastic diseases. Chlorambucil alkylates and cross-links DNA during all phases of the cell cycle, inducing DNA damage via three different methods of covalent adduct generation with double-helical DNA. Bone marrow suppression (anemia, neutropenia, thrombocytopenia) is the most commonly occurring side effect of chlorambucil. There are no known drug/drug interactions with chlorambucil.

Methotrexate is an antineoplastic anti-metabolite. Anti-metabolites masquerade as purine or pyrimidine - which become the building blocks of DNA. They prevent these substances becoming incorporated in to DNA during the "S" phase (of the cell cycle), stopping normal development and division. Methotrexate inhibits folic acid reductase which is responsible for the conversion of folic acid to tetrahydrofolic acid. At two stages in the biosynthesis of purines and at one stage in the synthesis of pyrimidines, one-carbon transfer reactions occur which require specific coenzymes synthesized in the cell from tetrahydrofolic acid. Tetrahydrofolic acid itself is synthesized in the cell from folic acid with the help of an enzyme, folic acid reductase. Methotrexate looks a lot like folic acid to the enzyme, so it binds to it quite strongly and inhibits the enzyme. Thus, DNA synthesis cannot proceed because the coenzymes needed for one-carbon transfer reactions are not produced from tetrahydrofolic acid because there is no tetrahydrofolic acid. Methotrexate selectively affects the most rapidly dividing cells (neoplastic and psoriatic cells). Methotrexate is indicated in the treatment of gestational choriocarcinoma, chorioadenoma destruens and hydatidiform mole. In acute lymphocytic leukemia, methotrexate is indicated in the prophylaxis of meningeal leukemia and is used in maintenance therapy in combination with other chemotherapeutic agents. Methotrexate is also indicated in the treatment of meningeal leukemia. Methotrexate is used alone or in combination with other anticancer agents in the treatment of breast cancer, epidermoid cancers of the head and neck, advanced mycosis fungoides (cutaneous T cell lymphoma), and lung cancer, particularly squamous cell and small cell types. Methotrexate is also used in combination with other chemotherapeutic agents in the treatment of advanced stage non-Hodgkin’s lymphomas. Methotrexate is indicated in the symptomatic control of severe, recalcitrant, disabling psoriasis. Methotrexate is indicated in the management of selected adults with severe, active rheumatoid arthritis (ACR criteria), or children with active polyarticular-course juvenile rheumatoid arthritis.

Omacetaxine mepesuccinate (trade name Synribo) formerly named as homoharringtonine or HHT, is a pharmaceutical drug substance that is indicated for treatment of chronic myeloid leukemia (CML). It is a natural ester of the alkaloid cephalotaxine from Cephalotaxus harringtonia, now manufactured by hemi-synthesis. It was approved by the US FDA in October 2012 for the treatment of adult patients with CML with resistance and/or intolerance to two or more tyrosine kinase inhibitors (TKIs). The mechanism of action of omacetaxine mepesuccinate has not been fully elucidated but includes inhibition of protein synthesis and is independent of direct Bcr-Abl binding. Omacetaxine mepesuccinate binds to the A-site cleft in the peptidyl-transferase center of the large ribosomal subunit from a strain of archaeabacteria. In vitro, omacetaxine mepesuccinate reduced protein levels of the Bcr Abl oncoprotein and Mcl-1, an anti-apoptotic Bcl-2 family member. Omacetaxine mepesuccinate showed activity in mouse models of wild-type and T315I mutated Bcr-Abl CML.

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.