{"entity":{"id":"pb-212","kind":"isotope","name":"Lead-212","aka":["212Pb","Pb-212"],"tldr":"A radioactive metal that, once inside the body, turns itself into a much more damaging particle-emitter over the following hours. It is being explored as a way to deliver strong, short-range radiation without needing the rarer isotopes used in similar treatments.","summary":"Lead-212 is itself a beta emitter, but it functions in practice as an in vivo generator of alpha radiation: it decays (half-life 10.64 hours) to bismuth-212 (half-life about 61 minutes), which then decays either directly by alpha emission (to thallium-208) or by a further beta decay to the pure alpha emitter polonium-212. A member of the thorium-232/232U decay series, 212Pb is drawn from generators loaded with its longer-lived parents radium-224 (half-life 3.63 days) or thorium-228 (half-life about 1.9 years).\n\nIts 10.6-hour half-life is long enough to synthesise and ship a labelled radiopharmaceutical but short enough to limit prolonged radiation exposure, and it uses conventional chelation chemistry (unlike some other alpha emitters). 212Pb-DOTAMTATE (AlphaMedix) and other 212Pb-labelled somatostatin and PSMA-targeting agents are in early clinical trials.\n\nUnlike actinium-225, the feedstock chain for 212Pb (natural thorium-232/uranium-232 decay) is not considered scarce: Perspective Therapeutics states its proprietary 224Ra/212Pb generator system and a long-term US DOE supply contract for 228Th could support over 100,000 doses per year, and Orano Med, RadioMedix/Thor Medical and others are commercialising 228Th-based 212Pb generators. Some reviews describe 212Pb supply as having moved from a major constraint to a largely solved production problem, though clinical-scale, GMP-qualified generator throughput is still being industrialised.","status":"phase-2","asOf":"2026-09-22","links":[{"label":"212Pb: Production Approaches and Targeted Therapy Applications (Pharmaceuticals, 2022)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC8777968/"},{"label":"Perspective Therapeutics: Manufacturing & Logistics (VMT-α-GEN Pb-212 generator)","url":"https://perspectivetherapeutics.com/technology/manufacturing-logistics"},{"label":"DOE Isotope Program: Availability of radium-224/lead-212 generators","url":"https://www.isotopes.gov/node/123"},{"label":"Lead radionuclides for theranostic applications in nuclear medicine (PMC, 2026)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC12775822/"}],"tags":["therapy","alpha emitter","in vivo generator"],"related":["alphamedix","alphamedix-02","targeted-alpha-therapy","ra-224","bi-213","idea-reg-alpha-emitter-portfolio","perspective-therapeutics"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"212Pb","element":"Lead","massNumber":212,"halfLife":"10.64 hours","emissions":["β− 0.57 MeV (to 212Bi)","in vivo daughter 212Bi decays 35.9% by α to 208Tl, 64.1% by β− to 212Po","212Po α 8.78 MeV (from 212Bi decay)"],"emissionClass":"mixed","use":"therapy","tissueRange":"Sub-millimetre (alpha range from in-vivo-generated 212Bi/212Po)","production":"Generator: eluted from 224Ra or 228Th sources (228Th itself recovered from decaying 232U stocks), via 220Rn emanation or column separation.","supply":"emerging","supplyNote":"Feedstock (natural thorium-232/232U decay) is not scarce. Perspective Therapeutics reports a long-term DOE supply contract for 228Th and generator capacity aimed at over 100,000 doses/year; Orano Med, Telix and RadioMedix/Thor Medical are also commercialising 228Th/224Ra-based 212Pb generators, but clinical-scale GMP throughput is still being built out.","chelators":["DOTAM","DOTAMTATE-type macrocycles"],"pairedWith":["ga-68"]},"route":"/isotopes/pb-212/","neighbours":{"drug":[{"id":"alphamedix","kind":"drug","name":"212Pb-DOTAMTATE","route":"/drugs/alphamedix/"},{"id":"pb-212-psv359","kind":"drug","name":"Lead-212 PSV359","route":"/drugs/pb-212-psv359/"},{"id":"pb-212-vmt-alpha-net","kind":"drug","name":"Lead-212 VMT-alpha-NET","route":"/drugs/pb-212-vmt-alpha-net/"}],"trial":[{"id":"alphamedix-02","kind":"trial","name":"ALPHAMEDIX-02","route":"/trials/alphamedix-02/"},{"id":"nct06710756","kind":"trial","name":"Lead-212 PSV359 Therapy for Patients With Solid Tumors","route":"/trials/nct06710756/"},{"id":"nct05655312","kind":"trial","name":"MC1R-targeted Alpha-particle Monotherapy and Combination Therapy Trial With Nivolumab in Adults With Advanced Melanoma","route":"/trials/nct05655312/"},{"id":"nct07278479","kind":"trial","name":"Study of [212Pb]Pb-DOTAM-MAM279 ([212Pb]Pb-MP0712) in Patients With Small Cell Lung Cancer and Other DLL3 Expressing Solid Tumors","route":"/trials/nct07278479/"},{"id":"nct05636618","kind":"trial","name":"Targeted Alpha-Particle Therapy for Advanced Somatostatin Receptor Type 2 (SSTR2) Positive Tumors","route":"/trials/nct05636618/"}],"technology":[{"id":"actinium-225-supply","kind":"technology","name":"Actinium-225 supply: thorium stocks, accelerators and radium targets","route":"/technologies/actinium-225-supply/"},{"id":"alpha-daughter-redistribution","kind":"technology","name":"Alpha-emitter daughter redistribution ('free daughter' problem)","route":"/technologies/alpha-daughter-redistribution/"},{"id":"macropa-chelation","kind":"technology","name":"Macropa chelation","route":"/technologies/macropa-chelation/"},{"id":"prrt","kind":"technology","name":"Peptide receptor radionuclide therapy (PRRT)","route":"/technologies/prrt/"},{"id":"targeted-alpha-therapy","kind":"technology","name":"Targeted alpha therapy","route":"/technologies/targeted-alpha-therapy/"},{"id":"therapy-isotope-supply-chain","kind":"technology","name":"Therapeutic isotope supply chain (Mo-99, Lu-177, Ac-225)","route":"/technologies/therapy-isotope-supply-chain/"}],"isotope":[{"id":"bi-213","kind":"isotope","name":"Bismuth-213","route":"/isotopes/bi-213/"},{"id":"ra-224","kind":"isotope","name":"Radium-224","route":"/isotopes/ra-224/"}],"idea":[{"id":"idea-reg-alpha-emitter-portfolio","kind":"idea","name":"Fund alpha emitters beyond actinium-225: lead-212, terbium-149 and astatine-211","route":"/ideas/idea-reg-alpha-emitter-portfolio/"}],"company":[{"id":"advancell","kind":"company","name":"AdvanCell","route":"/companies/advancell/"},{"id":"artbio","kind":"company","name":"ARTBIO","route":"/companies/artbio/"},{"id":"orano-med","kind":"company","name":"Orano Med","route":"/companies/orano-med/"},{"id":"perspective-therapeutics","kind":"company","name":"Perspective Therapeutics","route":"/companies/perspective-therapeutics/"},{"id":"radiomedix","kind":"company","name":"RadioMedix","route":"/companies/radiomedix/"}],"indication":[{"id":"neuroendocrine","kind":"indication","name":"Neuroendocrine tumours","route":"/indications/neuroendocrine/"}],"target":[{"id":"sstr2","kind":"target","name":"Somatostatin receptor 2","route":"/targets/sstr2/"}],"term":[{"id":"prrt-term","kind":"term","name":"PRRT (peptide receptor radionuclide therapy)","route":"/terms/prrt-term/"}],"pairing":[{"id":"prrt-then-alpha-net","kind":"pairing","name":"Beta PRRT → alpha PRRT","route":"/pairings/prrt-then-alpha-net/"}],"roadmap":[{"id":"alpha-therapy-roadmap","kind":"roadmap","name":"Alpha-emitter roadmap: radium-223 → 225Ac-PSMA-617 → a phase 3 pipeline","route":"/roadmaps/alpha-therapy-roadmap/"},{"id":"radiopharma-roadmap","kind":"roadmap","name":"Radiopharmaceutical roadmap: iodine → lutetium → actinium","route":"/roadmaps/radiopharma-roadmap/"},{"id":"sstr-theranostics-roadmap","kind":"roadmap","name":"SSTR theranostics roadmap: octreotide scintigraphy → 68Ga-DOTATATE → 177Lu-DOTATATE → alpha","route":"/roadmaps/sstr-theranostics-roadmap/"}]}}