title: Appraising iniparib, the PARP inhibitor that never was--what must we learn?
abstract: Several drugs targeting poly(ADP-ribose) polymerase (PARP) enzymes are under development. Responses have been observed in patients with germline mutations in BRCA1 and BRCA2, with further data supporting antitumour activity of PARP inhibitors in sporadic ovarian cancer. Strategies to identify other predictive biomarkers remain under investigation. Iniparib was purported to be a PARP inhibitor that showed promising results in randomized phase II trials in patients with triple-negative breast cancer. Negative results from a phase III study in this disease setting, however, tempered enthusiasm for this agent. Recently, data from in vitro experiments suggest that iniparib is not only structurally distinct from other described PARP inhibitors, but is also a poor inhibitor of PARP activity. In this context, the negative iniparib phase III data might have erroneously promulgated the notion that PARP inhibition is not an effective therapeutic strategy. Here, we scrutinize the development of iniparib from preclinical studies to registration trials, and identify and discuss the pitfalls in the development of anticancer drugs to prevent future late-stage trial failures.
authors.affiliation: Drug Development Unit, Division of Cancer Therapeutics and Division of Clinical Studies, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Downs Road, Sutton, Surrey SM2 5PT, UK.
authors.forename: Joaquin
authors.initials: J
authors.lastname: Mateo
authors.forename: Michael
authors.initials: M
authors.lastname: Ong
authors.forename: David S P
authors.initials: DS
authors.lastname: Tan
authors.forename: Michael A
authors.initials: MA
authors.lastname: Gonzalez
authors.forename: Johann S
authors.initials: JS
authors.lastname: de Bono
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001549:Benzamides / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy*; D002986:Clinical Trials as Topic; D005260:Female; D006801:Humans; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D012107:Research Design
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; C090712:iniparib