{"entity":{"id":"iniparib","kind":"drug","name":"Iniparib","aka":[],"tldr":"Billed as the first PARP inhibitor for triple-negative breast cancer, it failed its phase 3 in 2011. It turned out not to inhibit PARP at all.","summary":"A randomised phase 2 (O'Shaughnessy, NEJM 2011) in metastatic TNBC showed improved response, PFS, and OS when iniparib was added to gemcitabine-carboplatin. The phase 3 (n=519) missed both co-primary endpoints. Subsequent biochemistry showed iniparib does not trap or inhibit PARP1/2 at clinically relevant concentrations; it acts as a non-specific thiol-reactive compound. Sanofi (which had bought BiPar for up to $500M) discontinued it after a negative phase 3 in squamous NSCLC (2013).\n\nLesson: mechanism claims should be verified before a class label is attached; the true PARP inhibitors (olaparib, talazoparib) later succeeded in BRCA-mutant breast cancer.","status":"negative","asOf":"2026-09-06","wikipedia":"https://en.wikipedia.org/wiki/Iniparib","links":[{"label":"Iniparib is not a PARP inhibitor (Clin Cancer Res 2012)","url":"https://aacrjournals.org/clincancerres/article/18/2/510/76892/A-Deep-Look-at-the-PARP-Inhibitor-Iniparib"}],"tags":["failure","lesson:wrong-drug"],"related":[],"cancers":["tnbc","nsclc"],"sections":[],"technologies":["parp-inhibitor"],"targets":["parp"],"drugs":["olaparib","talazoparib"],"companies":["sanofi"],"institutions":[],"pathways":[],"terms":[],"trials":["nct00938652","nct01045304","nct01204125"],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"code":"BSI-201, SAR240550","modality":"Small molecule (claimed PARP inhibitor)","mechanism":"Originally described as a PARP1 inhibitor; later shown to be a non-selective cysteine-modifying agent without PARP inhibition.","approvals":[],"mechanismSteps":[],"toxicity":[],"access":[],"regulatoryEvents":[]},"route":"/drugs/iniparib/","neighbours":{"cancer":[{"id":"nsclc","kind":"cancer","name":"Non-small-cell lung cancer","route":"/cancers/nsclc/"},{"id":"tnbc","kind":"cancer","name":"Triple-negative breast cancer (TNBC)","route":"/cancers/tnbc/"}],"technology":[{"id":"parp-inhibitor","kind":"technology","name":"PARP inhibitors","route":"/technologies/parp-inhibitor/"}],"target":[{"id":"parp","kind":"target","name":"PARP","route":"/targets/parp/"}],"drug":[{"id":"olaparib","kind":"drug","name":"Olaparib","route":"/drugs/olaparib/"},{"id":"talazoparib","kind":"drug","name":"Talazoparib","route":"/drugs/talazoparib/"}],"company":[{"id":"sanofi","kind":"company","name":"Sanofi","route":"/companies/sanofi/"}],"trial":[{"id":"nct00938652","kind":"trial","name":"A Phase 3, Multi-Center Study of Gemcitabine/Carboplatin, With or Without BSI-201, in Patients With ER-, PR-, and Her2-Negative Metastatic Breast Cancer","route":"/trials/nct00938652/"},{"id":"nct01045304","kind":"trial","name":"Study of SAR240550 (BSI-201) in Combination With Gemcitabine/Carboplatin, in Patients With Metastatic Triple Negative Breast Cancer","route":"/trials/nct01045304/"},{"id":"nct01204125","kind":"trial","name":"Two Regimens of SAR240550/Weekly Paclitaxel and Paclitaxel Alone as Neoadjuvant Therapy in Triple Negative Breast Cancer Patients","route":"/trials/nct01204125/"}],"bottleneck":[{"id":"b-negative-results","kind":"bottleneck","name":"Failures are hidden","route":"/bottlenecks/b-negative-results/"}]}}