Much of the current research in cancer treatment involves small molecules that are specific inhibitors of cancer pathways.

Antisense Oligonucleotides
Antisense oligonucleotide drugs are one of the newer areas of drug development. This technology offers researchers the ability to target almost any cellular process with complete specificity. If a protein is helping a cancer cell to grow, then the appropriate antisense oligonucleotide could be used to prevent that protein from ever being made. Because antisense oligonucleotides are so specific, it is unlikely that any other protein in the body would be affected. This specificity should result in a reduction of the side effects often seen with conventional cancer treatments.
Our genes consist of long strings of nucleotides along the DNA in our chromosomes. When there is a requirement for any particular gene to be expressed, the process of transcription leads to the production of an mRNA message from that gene. Unlike the double-stranded structure of DNA, messenger RNA molecules are single-stranded. Like DNA molecules, these single-stranded RNA molecules are capable of binding to complementary nucleic acid strands. Therefore, if another single stranded string of nucleic acid bases with a sequence complementary to the sequence of a given mRNA (the antisense sequence) enters the cell, it will bind to that specific mRNA and inactivate it. The bound mRNA is not suitable for translation and is degraded.
The full mechanism of this inactivation is not entirely understood, but it may be related to the fact that double stranded RNA occurs only rarely in normal cells. Since the instructions to make each protein are carried by a unique mRNA, these messages can be individually inactivated or "knocked out" by these complementary sequences.

Drugs that Affect Molecular Receptors
Our cells constantly monitor their surroundings for the presence (or sometimes an absence) of regulatory molecules in the environment. These signals control decisions regarding cell division, movement and even death. One way in which the external environment is monitored is through receptor molecules located in the membrane of the cell. Upon binding of a signal molecule, the receptor molecules transmit information to other molecules within the cytoplasm and nucleus resulting in an appropriate response. Many different diseases, including cancer, can be traced back to dysfunctional signalling pathways. In cancer these malfunctions may lead to unregulated cell division and the development of tumors. Particular signalling pathways are often affected in a given type of cancer. Drugs designed to inhibit these specific signalling pathways promise to inhibit cancer growth without harming normal cells. Blockage of the receptors for key molecules is a current area of clinical investigation.

Angiogenesis Inhibitors: Angiostatin and Endostatin
Like all cells, cancer cells require a constant supply of nutrients and oxygen in order to grow and divide. Without an adequate blood supply tumors will not grow. Tumors produce factors that stimulate the formation of blood vessels to provide them with the food and oxygen they need. More details on this process. The process of blood vessel formation is termed angiogenesis.This process is a very active area of research in cancer treatment for several reasons. 1. The treatments should have low toxicity. Angiogenesis occurs at high levels during fetal development, the menstrual cycle and in wound healing. The treatments might be expected to interfere with these processes but should not harm most normal dividing cells. 2.The treatments are not designed to directly attack the cancer cells. The targets of several of these treatments are normal processes controlled by normal cells (such as the cells that form blood vessels), not the tumor cells themselves. The high mutation rates of cancer cells that often render chemotherapy ineffective will not interfere with these drugs.
Angiostatin
This drug is actually a naturally occuring protein that is derived from the cleavage of a larger protein, plasminogen. Angiostatin inhibits the growth of blood vessels in tumors and has been shown to inhibit metastasis of tumors in animal models. This drug is in clinical trials for the treatment of lung cancer in combination with other cancer fighting drugs. Search for current clinical trials involving Angiostatin.
Endostatin
Like angiostatin, this drug is a naturally occuring protein. Endostatin is derived from a form of collagen, a structural protein found in connective tissue. In early trials, endostatin has been shown to be safe and exhibits low toxicity. Further studies will determine its effectiveness both as a single agent and as part of a multi-agent regime. One particular area of study will be the potential use of Endostatin in neuroendocrine cancers.