Iniparib (4-iodo-3-nitrobenzamide) is a drug that acts as an irreversible inhibitor of PARP1

PARP1

Poly [ADP-ribose] polymerase 1 also known as NAD+ ADP-ribosyltransferase 1 or poly[ADP-ribose] synthase 1 is an enzyme that in humans is encoded by the PARP1 gene.- Function :PARP1 works:...

 (hence, it is a PARP inhibitor

PARP inhibitor

PARP inhibitors are a group of pharmacological inhibitors of the enzyme poly ADP ribose polymerase . They are developed for multiple indications; the most important is the treatment of cancer...

) and possibly other enzymes through covalent modification

Covalent bond

A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding....

. It is undergoing clinical trial

Clinical trial

Clinical trials are a set of procedures in medical research and drug development that are conducted to allow safety and efficacy data to be collected for health interventions...

s for treatment of some types of breast cancer

Breast cancer

Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...

.

It is the first PARP inhibitor to commence phase III clinical trials. The first was for breast cancer,
another has started for squamous cell lung cancer

Lung cancer

Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue and, eventually, into other parts of the body. Most cancers that start in lung, known as primary...

.

Preliminary results in June 2009 on triple-negative breast cancer were promising.
Later results showed increased median survival of triple negative breast cancer

Triple Negative Breast Cancer

Triple-negative breast cancer refers to any breast cancer that does not express the genes for estrogen receptor , progesterone receptor or Her2/neu. Triple negative is sometimes used as a surrogate term for basal-like, however more detailed classification is possible providing better guidance for...

 patients from 7.7 to 12.2 months. However, Phase III results disclosed in January 2011 were disappointing.

Since December 2009, the FDA have been fast-tracking

FDA Fast Track Development Program

The FDA Fast Track Development Program is a designation of the United States Food and Drug Administration that accelerates the approval of investigational new drugs undergoing clinical trials with the goal review time of 60 days...

 the New Drug Application

New drug application

The New Drug Application is the vehicle in the United States through which drug sponsors formally propose that the Food and Drug Administration approve a new pharmaceutical for sale and marketing...

of iniparib for triple-negative breast cancer.