Types of Chemotherapy Drugs

Paul Ehrlich originated the term chemotherapy in 1914; Ehrlich is credited with the idea of a “magic bullet” which would attack a disease and leave the healthy parts of the body unaffected. The development of anti-cancer agents has been by trial and error, serendipity or empiricism. Over a hundred medicines are now employed in cancer treatment; these agents are classified according to their chemical structure, similarity to other compounds, derivation, and biochemical mechanism.  Therapies take advantage of the fact that malignant cells have different metabolic functions from normal cells.  Conventional chemotherapy agents function by inhibiting mitosis (cell reproduction) and inducing apoptosis (cell death).  Engineered anti-cancer agents (designer drugs) such as monoclonal antibodies, cytokines, gene therapy vectors, antisense, and peptide molecules have only been developed recently.  No medicines work by affecting the underlying mutations that cause cancer.

We organize chemotherapy drugs by category:

Alkylating Agents

Kinase Inhibitors

Vinca Alkaloids

Anthracyclines

Antimetabolites

Aromatase Inhibitors

Topoisomerase Inhibitors

mTor Inhibitors

Retinoids

Half of patients who develop cancer get some form of chemotherapy treatment. Most chemotherapy drugs kill cancer cells outright, or stop their reproduction and spread by inhibiting metabolic functions of the cancer cell. These drugs are called cytotoxic. They can also act on healthy cells (because they also divide) which is the basis for side effects and unwanted complications of therapy.

Some chemotherapy agents work in specific parts of the cell’s reproductive cycle.  You see agents that are described as inhibiting the S-Phase or the M-Phase.  Others are non-phase specific.

Cell Cycle



Other drugs are not explicitly cytotoxic, but instead work by disrupting the ability of the tumor to stay intact. This is the method of action that most targeted therapies use.

Chemotherapy is an individual treatment plan designed specifically for each patient in which a drug or group of drugs is administered by oral or intravenous injection (or other less commonly used routes such as intrathecal injection) at a precise dose, based on patient weight, and given over a finite and defined time period. Adjuvant therapy is chemotherapy given to high risk patients after other definitive local therapy (radiation or surgery) has removed the tumor. It is established therapy for breast, colorectal, osteosarcoma, Wilm’s tumor, and some stages of gastric, non-small lung cell cancers and some melanomas. In contrast, neoadjuvant therapy is given before other localized therapy (such as surgery or radiation) is used. It may be beneficial in treatment of advanced but limited breast tumors, laryngeal, esophageal, bladder, anal cancers and some sarcomas.

Ways to administer chemotherapy

Cancer Mutations and Personalized Therapy

Growing Industry

A forecast by the management consulting firm McKinsey in 2016 stated:

“Oncology is a key driver of growth for the pharmaceutical industry. It is expected to account for about 30 percent of its product pipeline and 25 percent of pharmaceutical-industry revenue by 2020.”

A large part of this revenue growth is expected to be due to biologics – first introduced in the 1990s and now a large part of the oncology treatment arsenal.  Other technologies such as cancer vaccines and antibody delivery systems have the potential to take off.