Tamoxifen (brand name Nolvadex), is selective estrogen receptor modulators (SERM) with tissue-specific activities for the treatment and prevention of estrogen receptor positive breast cancer. Tamoxifen itself is a prodrug, having relatively little affinity for its target protein, the estrogen receptor (ER). It is metabolized in the liver by the cytochrome P450 isoform CYP2D6 and CYP3A4 into active metabolites such as 4-hydroxytamoxifen (4-OHT) (afimoxifene) and N-desmethyl-4-hydroxytamoxifen (endoxifen) which have 30–100 times more affinity with the ER than tamoxifen itself. These active metabolites compete with estrogen in the body for binding to the ER. In breast tissue, 4-OHT acts as an ER antagonist so that transcription of estrogen-responsive genes is inhibited. Tamoxifen has 7% and 6% of the affinity of estradiol for the ERα and ERβ, respectively, whereas 4-OHT has 178% and 338% of the affinity of estradiol for the ERα and ERβ. The prolonged binding of tamoxifen to the nuclear chromatin of these results in reduced DNA polymerase activity, impaired thymidine utilization, blockade of estradiol uptake, and decreased estrogen response. It is likely that tamoxifen interacts with other coactivators or corepressors in the tissue and binds with different estrogen receptors, ER-alpha or ER-beta, producing both estrogenic and antiestrogenic effects. Tamoxifen is currently used for the treatment of both early and advanced estrogen receptor (ER)-positive (ER+) breast cancer in pre- and post-menopausal women. Additionally, it is the most common hormone treatment for male breast cancer. Patients with variant forms of the gene CYP2D6 (also called simply 2D6) may not receive full benefit from tamoxifen because of too slow metabolism of the tamoxifen prodrug into its active metabolites. Tamoxifen is used as a research tool to trigger tissue-specific gene expression in many conditional expression constructs in genetically modified animals including a version of the Cre-Lox recombination technique. Tamoxifen has been shown to be effective in the treatment of mania in patients with bipolar disorder by blocking protein kinase C (PKC), an enzyme that regulates neuron activity in the brain. Researchers believe PKC is over-active during the mania in bipolar patients.

Lomustine is used in the treatment of certain neoplastic diseases. Although it is generally agreed that lomustine alkylates DNA and RNA, it is not cross resistant with other alkylators. As with other nitrosoureas, it may also inhibit several key enzymatic processes by carbamoylation of amino acids in proteins. Common adverse reactions include delayed myelosupression, nausea, vomiting, stomatitis, and alopecia.

Mitotane is an oral chemotherapeutic agent indicated in the treatment of inoperable adrenal cortical carcinoma of both functional and nonfunctional types. Mitotane can best be described as an adrenal cytotoxic agent, although it can cause adrenal inhibition, apparently without cellular destruction. The administration of Mitotane alters the extra-adrenal metabolism of cortisol in man; leading to a reduction in measurable 17-hydroxy corticosteroids, even though plasma levels of corticosteroids do not fall. The drug apparently causes increased formation of 6-B-hydroxyl cortisol. Its biochemical mechanism of action is unknown, although data are available to suggest that the drug modifies the peripheral metabolism of steroids as well as directly suppressing the adrenal cortex. Mitotane is used for treatment of inoperable adrenocortical tumours; Cushing's syndrome

Dactinomycin (actinomycin D) was isolated from Streptomyces by Selman Waksman in 1940s. The antibiotic shows anti-cancer activity; it was approved by FDA for the treatment of different cancer conditions among which are Ewing's sarcoma, Wilm's tumor, gestational trophoblastic disease, etc. Dactinomycin exerts its action by binding to DNA (preferably to GC motif) and thus inhibiting transcription.

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.

Cyclophosphamide (the generic name for Cytoxan, Neosar, Revimmune), also known as cytophosphane, is a nitrogen mustard alkylating agent, from the oxazophorines group. It is used to treat various types of cancer and some autoimmune disorders. It is a "prodrug"; it is converted in the liver to active forms that have chemotherapeutic activity

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.

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.

Estramustine is an antineoplastic agent indicated in the palliative treatment of patients with metastatic and/or progressive carcinoma of the prostate. Estramustine is a combination of estradiol with nitrogen mustard. In vivo, the nitrogen-mustard moiety becomes active and participates in alkylation of DNA or other cellular components. This causes DNA damage in rapidly dividing cancerous cells leading to cell death and ideally, tumor shrinkage. Also, due to the drugs estrogen component, it can bind more selectively to active estrogen receptors. Used for the palliative treatment of patients with metastatic and/or progressive carcinoma of the prostate.

Plicamycin (INN, also known as mithramycin; trade name Mithracin) is an antineoplastic antibiotic produced by Streptomyces plicatus. Plicamycin belongs to the group of medicines known as antineoplastics. It may be used to treat certain types of cancer. It is also used to treat hypercalcemia or hypercalciuria (too much calcium in the blood or urine) that may occur with some types of cancer. Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although this use is not included in product labeling, plicamycin is used in certain patients with the following medical condition:Paget's disease of the bone. The manufacturer discontinued plicamycin in 2000. Several different structures are currently reported in different places all with the same chromomycin core, but with different stereochemistry in the glycoside chain, a 1999 study has re-investigated the compound and proposed a revised structure. Although the exact mechanism by which Mithracin (plicamycin) causes tumor inhibition is not yet known, studies have indicated that this compound forms a complex with deoxyribonucleic acid (DNA) and inhibits cellular ribonucleic acid (RNA) and enzymic RNA synthesis. The binding of Mithracin (plicamycin) to DNA in the presence of Mg + + (or other divalent cations) is responsible for the inhibition of DNA-dependent or DNA-directed RNA synthesis. This action presumably accounts for the biological properties of Mithracin (plicamycin). Plicamycin may also lower calcium serum levels by inhibiting the effect of parathyroid hormone upon osteoclasts or by blocking the hypercalcemic action of pharmacologic doses of vitamin D.