{"entity":{"id":"i-131-tositumomab","kind":"drug","name":"Iodine-131 tositumomab","aka":["Bexxar","tositumomab and I-131 tositumomab"],"tldr":"A cancer-targeting antibody carrying a radioactive form of iodine was used, as a single course, to treat a type of blood cancer called non-Hodgkin lymphoma. The manufacturer stopped selling it in 2014 because too few patients were using it.","summary":"The Bexxar therapeutic regimen combined tositumomab, an anti-CD20 murine IgG2a monoclonal antibody, with the same antibody radiolabelled with iodine-131. It was approved by the FDA in 2003 (and in Canada in 2005) for CD20-positive relapsed or refractory low-grade, follicular or transformed non-Hodgkin lymphoma in patients who had progressed during or after rituximab therapy, including rituximab-refractory disease. It was given as a single course only, comprising an unlabelled predose followed by a dosimetric and then a therapeutic dose of 131I-tositumomab, with activity individualised to deliver a specified total-body radiation dose.\n\nBexxar competed with the similar CD20-targeted radioimmunotherapy ibritumomab tiuxetan (Zevalin, labelled with yttrium-90). Despite comparable efficacy, Bexxar's use declined steadily after a 2006 peak: by 2012 only about 75 US patients received it in a year. GlaxoSmithKline announced in August 2013 that it would discontinue manufacture and sale of the regimen, citing projected declining sales and the availability of alternative therapies; marketing was formally withdrawn on 20 February 2014.\n\nBexxar is a useful cautionary example in the graph: an approved, effective radiopharmaceutical regimen withdrawn for commercial rather than safety reasons, illustrating how logistics (dosimetry visits, hospital nuclear-medicine capacity, competition from simpler agents) can end a therapy's market life even when clinical data support it.","status":"withdrawn","asOf":"2026-09-22","links":[{"label":"GSK: announcement of discontinuation, 6 August 2013","url":"https://pipelinereview.com/gsk-to-discontinue-manufacture-and-sale-of-the-bexxar-therapeutic-regimen-tositumomab-and-iodine-i-131-tositumomab/"},{"label":"JAMA Internal Medicine: Withdrawal of drugs for commercial reasons - tositumomab, 2014","url":"https://static1.squarespace.com/static/55550f38e4b0884d8d80118e/t/5565d1aae4b0660ba5b932e2/1432736170326/2014+-+Nov+-+JAMA+IM+-+Withdrawal+of+Drugs+for+Commercial+Reasons+-+Tositumomab.pdf"},{"label":"The rise and fall of iodine-131 tositumomab: Bexxar's story","url":"https://openmedscience.com/the-rise-and-fall-of-iodine-131-tositumomab-bexxars-story/"}],"tags":["radioimmunotherapy","lymphoma","withdrawn","beta and gamma emitter"],"related":["ibritumomab-tiuxetan","rituximab","i-131","y-90"],"indications":["follicular-lymphoma"],"sections":[],"technologies":["radioimmunotherapy"],"targets":["cd20"],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"brand":"Bexxar","modality":"radioimmunotherapy","mechanism":"An unlabelled anti-CD20 murine monoclonal antibody (tositumomab) dosing step to saturate normal B-cell sinks, followed by the same antibody labelled with iodine-131, which delivers combined beta and gamma radiation directly to CD20-expressing lymphoma cells as well as an antibody-dependent immune effect.","approvals":[{"region":"US","year":2003,"indication":"CD20-positive relapsed or refractory, low-grade, follicular, or transformed non-Hodgkin lymphoma progressing during or after rituximab therapy"},{"region":"CA","year":2005,"indication":"Same indication as the US approval"}],"mechanismSteps":[],"toxicity":[],"access":[],"regulatoryEvents":[{"date":"2013-08-06","type":"withdrawal","region":"US/CA","note":"GlaxoSmithKline announced it would discontinue manufacture and sale of the Bexxar regimen, citing declining use (about 75 US patients in 2012) and available alternative therapies.","source":"https://pipelinereview.com/gsk-to-discontinue-manufacture-and-sale-of-the-bexxar-therapeutic-regimen-tositumomab-and-iodine-i-131-tositumomab/"},{"date":"2014-02-20","type":"withdrawal","region":"US/CA","note":"Marketing of the Bexxar therapeutic regimen formally discontinued.","source":"https://openmedscience.com/the-rise-and-fall-of-iodine-131-tositumomab-bexxars-story/"}]},"route":"/drugs/i-131-tositumomab/","neighbours":{"drug":[{"id":"ibritumomab-tiuxetan","kind":"drug","name":"Ibritumomab tiuxetan","route":"/drugs/ibritumomab-tiuxetan/"},{"id":"rituximab","kind":"drug","name":"Rituximab","route":"/drugs/rituximab/"}],"isotope":[{"id":"i-131","kind":"isotope","name":"Iodine-131","route":"/isotopes/i-131/"},{"id":"y-90","kind":"isotope","name":"Yttrium-90","route":"/isotopes/y-90/"}],"indication":[{"id":"follicular-lymphoma","kind":"indication","name":"Follicular lymphoma","route":"/indications/follicular-lymphoma/"}],"technology":[{"id":"radioimmunotherapy","kind":"technology","name":"Radio-antibody & radio-ADC","route":"/technologies/radioimmunotherapy/"}],"target":[{"id":"cd20","kind":"target","name":"CD20","route":"/targets/cd20/"}]}}