RYZ101

Dosing from the Literature

Published for neuroendocrine tumors: trial doses into a vein, measured as radioactivity: 120 kilobecquerels (kBq) per kg of body weight every 8 weeks in the Phase 1b, and a fixed 10.2 megabecquerels (MBq; 275 microcuries, µCi) every 8 weeks, for up to 4 doses, in the Phase 3 (Strosberg et al., 2025; Hope et al., 2023). Not published: any figure from the Phase 3’s results, or an approved dose.

No dose of RYZ101 is approved. The rows are the doses its trials gave, as the documents report them; they are not recommendations. A radiopharmaceutical’s dose is its radioactivity, as Lutathera’s is: 7.4 GBq, that is 7,400 MBq, every 8 weeks for 4 doses, for adults and children 12 and older with somatostatin receptor-positive GEP-NETs (Lutathera label). RYZ101 was “administered intravenously every 8 wk for 1–4 cycles” in ACTION-1’s Phase 1b (Sgouros et al., 2026).

What It Is

RYZ101 is a radiopharmaceutical: a drug that carries a radioactive atom to a target in the body. Bristol Myers Squibb calls it “an investigational, targeted radiopharmaceutical therapy comprised of DOTATATE bound to Actinium-225 (225Ac), a highly potent alpha-emitting radioisotope” (Bristol Myers Squibb, October 12, 2026). DOTATATE is the peptide part: octreotate, a somatostatin analog, with the chelator DOTA that holds the metal (Han et al., 2023). Octreotate is a chain of eight amino acids, six of them closed into a ring by a disulfide bond between its two cysteines, as Lutathera’s label spells out for its own drug, the same peptide and chelator carrying lutetium-177, approved in 2018 (Lutathera label).

RayzeBio, of San Diego, developed it. Bristol Myers Squibb announced on December 26, 2023 that it would buy RayzeBio for $62.50 a share in cash, a total equity value of about $4.1 billion (Bristol Myers Squibb, December 26, 2023), and completed the purchase on February 26, 2024 (RayzeBio, February 26, 2024). RayzeBio is still the sponsor of record of its Phase 3 (ClinicalTrials.gov NCT05477576).

That trial, ACTION-1, compares RYZ101 with the investigator’s choice of everolimus, sunitinib, octreotide or lanreotide, in people whose tumors grew after lutetium-177 treatment (ClinicalTrials.gov NCT05477576). FDA designated RYZ101 an orphan drug for gastroenteropancreatic neuroendocrine tumors on August 26, 2026; its record reads “Not FDA Approved for Orphan Indication” (FDA, August 26, 2026). On October 17, 2026, PubMed returned 3 records naming RYZ101, and a search for actinium-225 DOTATATE under its other names returned 54, and ClinicalTrials.gov listed 5 RYZ101 studies (searches of October 17, 2026).

Mechanism of Action

Receptor and physics terms below are the cited papers’ own. The binding data come from cells and a non-radioactive stand-in for the drug; the radiation figures from physics and from patients’ scans.

• SSTR2 (the target) — In a cell-based binding test, a lanthanum stand-in for RYZ101 bound human somatostatin receptor 2 with a Ki of 0.057 nmol/L (a measure of how tightly it binds; lower is tighter) and more than 600-fold selectivity over the other subtypes, and was taken up efficiently into SSTR2-positive cells (Han et al., 2023). No document read for this page measured the actinium-225 molecule itself binding the receptor in people.
• Alpha particles (the payload) — Actinium-225 has a half-life of 9.9 days and “emits four α-particles per decay chain” (Leupe et al., 2025). Alpha particles travel 40–100 µm in tissue and leave 80–100 keV of energy per µm of their path, their linear energy transfer (LET), against about 0.2 keV per µm for beta particles; that higher LET “results in more complex and severe cell damage than low-LET damage, such as DNA double-strand breaks” (Leupe et al., 2025).
• Daughter atoms — An atom that gives off an alpha particle recoils, so its daughter atoms “may not remain conjugated to the molecular carrier”; bismuth-213, one of actinium-225’s daughters, “concentrates in the kidneys” (Sgouros et al., 2010). In scans of 9 ACTION-1 patients, bismuth-213 “mostly remained with DOTATATE in the tumors; a minor fraction went to the kidneys” (Sgouros et al., 2026).
• Kidney protection — Lutathera’s label calls for an amino acid solution before, during and after each dose “to decrease the reabsorption of lutetium Lu 177 dotatate through the proximal tubules and decrease the radiation dose to the kidneys” (Lutathera label). In ACTION-1’s Phase 1b, lysine and arginine “were coinfused with each [225Ac]Ac-DOTATATE administration for kidney protection” (Sgouros et al., 2026).
• Absorbed doses (dosimetry) — From the scans of 9 patients, the authors estimate that the Phase 3 regimen, 10.2 MBq every 8 weeks for up to 4 doses, gives the kidneys 22.3 Gy and the bone marrow 1.1 Gy, weighted by a factor of 5 for alpha particles’ greater biological effect (their relative biological effectiveness, RBE), against 19.4 Gy and 1.0 Gy expected from Lutathera’s 4 doses; they write that there is “substantial uncertainty regarding the most appropriate RBE for α-particle emission in radiopharmaceuticals” (Sgouros et al., 2026).

What the Research Shows

RayzeBio’s lab and animal work first, then what other groups’ actinium-225 DOTATATE has done in people; RYZ101’s own trials are under Human Data.

• Small cell lung cancer in animal models — In several SSTR2-expressing small cell lung cancer xenograft models (human tumor cells grown in animals), one intravenous dose “significantly inhibited tumor growth,” with deeper responses where the tumors carried more SSTR2, and more effect when given with carboplatin and etoposide. All the authors are at RayzeBio (Han et al., 2023).
• After lutetium-177, in New Delhi — 32 patients whose gut or pancreas tumors were stable or progressing on lutetium-177 DOTATATE were given actinium-225 DOTATATE at the All India Institute of Medical Sciences, 100 kBq/kg every 8 weeks: of 24 assessed, 15 had a partial remission and 9 stable disease, with no progression or deaths over a median follow-up of 8 months (Ballal et al., 2020).
• With capecitabine, in New Delhi — 91 adults, 57 of them treated before with lutetium-177, were given 100–120 kBq/kg with capecitabine, a drug given to make tumors more sensitive to radiation (a radiosensitizer), in every cycle: at a median follow-up of 24 months, the probability of being alive at 24 months was 70.8% and of being free of progression 67.5%; of 79 with assessable disease, 2 had a complete and 38 a partial response (Ballal et al., 2023). Because every patient also had capecitabine, the results are the combination’s.
• Istanbul — In a retrospective series of 11 patients with tumors from several sites, all but one refractory to lutetium-177 DOTATATE, 4 of 9 had a partial response, median progression-free survival was 12 months, and no grade 3–4 toxicity was reported (Demirci et al., 2023).
• Against lutetium-177 again, in Mumbai — In an observational comparison of 20 patients given actinium-225 DOTATATE and 20 given lutetium-177 DOTATATE again, after progression on a first course of lutetium-177, the response rate was 35% against 10%; progression-free survival (10 against 12 months) and overall survival did not differ significantly. Patients were not randomized: which treatment they got depended on the radionuclide’s availability, their choice and cost (Agrawal et al., 2026).
• Two meta-analyses — Both pooled the same five studies, 153 patients, three of them from the New Delhi group, both series above among them; they found a response in about 52% and disease control in 88% (Rizzo et al., 2025; Ma et al., 2025), with hematological toxicity in 2%, grade I–II kidney toxicity in two patients and no grade III–IV toxicity (Ma et al., 2025). The first concludes that “results from multicenter randomized controlled trials are needed” (Rizzo et al., 2025).

Human Data

RYZ101’s own human data are from two trials: ACTION-1, its Phase 1b in meeting abstracts and slides, a dosimetry study inside it in a journal, and its Phase 3 in a press release; and a Phase 1b in small cell lung cancer, its safety in 15 patients in a meeting abstract and slides (Mansfield et al., 2025). ClinicalTrials.gov listed 5 RYZ101 studies on October 17, 2026, none with posted results (searches of October 17, 2026).

• ACTION-1 Phase 1b (Strosberg et al., 2025; ClinicalTrials.gov NCT05477576) — 17 adults whose grade 1 or 2 SSTR2-positive GEP-NETs had progressed after lutetium-177 therapy (Sgouros et al., 2026) were given 120 kBq/kg every 8 weeks; 15 had 4 doses and 2 had 2. At the December 14, 2023 cut-off: the most frequent adverse events were anemia (58.8%), nausea (58.8%) and fatigue (52.9%); serious adverse events occurred in 6 (35.3%), none judged treatment-related; grade 3 or higher events (severe or worse) occurred in 9, 5 of them treatment-related; none led to stopping treatment; one patient died of liver failure judged unrelated to the drug. The confirmed response rate was 29.4% (5 of 17: 1 complete, 4 partial), assessed locally, and median progression-free survival could not yet be estimated. The slides add that a sixth response was confirmed after the cut-off, 35.3%, and that the death was attributed to prior non-alcoholic steatohepatitis and liver cirrhosis (Morris et al., 2024). One arm, no comparison group, run by the sponsor.
• Dosimetry (Sgouros et al., 2026) — 9 of the 17, each through 4 doses, had scans after the first and fourth: “The estimated absorbed doses to kidneys and red bone marrow were 22.3 and 1.1 Gy, respectively,” for the Phase 3 regimen, and selected tumors received 488 to 8,775 mGy per MBq given, with the same weighting by 5. The study “was supported by RayzeBio,” and the authors write that alpha-emitter imaging “is not yet ready for routine patient implementation.” Published online June 4, 2026.
• ACTION-1 Phase 3 (Bristol Myers Squibb, October 12, 2026; ClinicalTrials.gov NCT05477576) — Randomized and open-label: RYZ101 at a fixed 10.2 MBq every 8 weeks for up to 4 doses, against the investigator’s choice of everolimus, sunitinib, or octreotide or lanreotide at a high dose or high frequency (ClinicalTrials.gov NCT05477576; Bristol Myers Squibb, October 12, 2026; Hope et al., 2023). Its primary endpoint is progression-free survival as judged by blinded independent central review, analyzed “after the target number of 143 PFS events have occurred”; the record lists 343 people enrolled across the study’s parts, a start on March 24, 2022, and primary completion estimated for December 2026. On October 12, 2026, Bristol Myers Squibb announced that the planned interim analysis of ACTION-1 (NCT05477576), the Phase 3, met its primary endpoint with “a statistically significant and clinically meaningful improvement in progression-free survival by blinded independent central review, and safety results consistent with the known RYZ101 safety profile.” The release gives no hazard ratio, median or p-value, and says: “Detailed results are expected to be presented at a future medical meeting.” Patients on the comparison drugs may switch to RYZ101 when their disease progresses (Hope et al., 2023), and participants “will be followed for overall survival” (Bristol Myers Squibb, October 12, 2026).
• “The first Phase 3 results” — The release quotes the trial’s principal investigator on radiopharmaceutical therapy (RPT): “ACTION-1 provides the first Phase 3 results for an alpha-based targeted RPT.” Radium-223, an alpha emitter that “selectively targets bone metastases,” reported a Phase 3 survival benefit in prostate cancer (Parker et al., 2013) and was approved by FDA in May 2013 (Sgouros et al., 2020). RayzeBio’s chief medical officer, quoted in the same release, words it for actinium-225: “the first results from a Phase 3 trial of an alpha-isotope based targeted RPT (225Ac) in any indication” (Bristol Myers Squibb, October 12, 2026).
• Other RYZ101 trials — With carboplatin, etoposide and atezolizumab in extensive-stage small cell lung cancer, Phase 1b, 21 enrolled, active but not recruiting; TRACY-1, in ER-positive, HER2-negative breast cancer, Phase 1b/2, recruiting, 64 planned; in progressive or recurrent intracranial meningioma, Phase 1/2, sponsored by an investigator, recruiting, 30 planned; and a Phase 1 in multiple myeloma at the Jules Bordet Institute, withdrawn with no one enrolled (ClinicalTrials.gov NCT05595460, NCT06590857, NCT07150806, NCT06411301). None has posted results. The small cell lung cancer trial reported its safety in 15 patients in September 2025 and set its dose for further study at 10.2 MBq (Mansfield et al., 2025).

The evidence meter on the RYZ101 card reads “Human pilots”: it counts published human data for neuroendocrine tumors, which for RYZ101 are the open-label Phase 1b and the dosimetry study inside it. The Phase 3 result is not published.

Reconstitution & Storage

There is nothing to reconstitute or store outside a trial site. ACTION-1’s record describes RYZ101 as an “Actinium 225 radiolabeled somatostatin analog (SSA) for injection” (ClinicalTrials.gov NCT05477576), and its radioactivity halves every 9.9 days as the actinium-225 decays (Leupe et al., 2025). No document read for this page gives storage conditions or a shelf life for the trial material.

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Side Effects & Risks

• Most common — Anemia (58.8%), nausea (58.8%) and fatigue (52.9%) in ACTION-1’s Phase 1b (Strosberg et al., 2025).
• Blood counts — “The most common grade ≥3 AEs were anemia and lymphopenia,” ACTION-1’s slides say of its Phase 1b (Morris et al., 2024): severe adverse events of low red blood cells and of low lymphocytes, a kind of white blood cell.
• Kidneys — In ACTION-1’s Phase 1b, a fall in creatinine clearance (CrCl), a measure of kidney function, was reported in 6 of 17 patients (35.3%); in two, both with reduced clearance at the start, it reached grade 3 or 4 and was judged treatment-related: “One patient with reduced CrCl at baseline experienced grade 3 decreased CrCl; another with reduced baseline CrCl developed grade 4 decreased CrCl” (Morris et al., 2024). The estimated kidney dose for the Phase 3 regimen, weighted by a factor of 5 for alpha particles, is 22.3 Gy, against 19.4 Gy for Lutathera’s 4 doses (Sgouros et al., 2026). ACTION-1’s registry record now lists an eGFR (estimated glomerular filtration rate, another measure of kidney function) of at least 60 mL/min/1.73 m² to enter (ClinicalTrials.gov NCT05477576); ACTION-1’s Phase 1b asked for a creatinine clearance of at least 50 mL/min (Morris et al., 2024).
• Serious events and the one death in ACTION-1’s Phase 1b — Serious adverse events in 6 of 17 (35.3%), none judged treatment-related, and one grade 5 event, hepatic failure, “deemed unrelated to the study drug” (Strosberg et al., 2025).
• With chemotherapy and atezolizumab — In 15 patients with extensive-stage small cell lung cancer given RYZ101 at 6.5, 8.3 or 10.2 MBq with carboplatin, etoposide and atezolizumab, every patient had a grade 3 or 4 adverse event and 12 (80%) a serious one, from any cause; side effects judged related to RYZ101 occurred in 11 (73.3%) and serious ones in 2 (13.3%: one with vomiting, nausea and anemia, one with loss of appetite and fainting); the only RYZ101-related event above grade 3 was a grade 4 fall in platelets, in one patient, and the related grade 3 events included a fall in creatinine clearance in one patient given 8.3 MBq; there was no dose-limiting toxicity, and no one stopped treatment for a side effect (Mansfield et al., 2025).
• The amino acid infusion — ACTION-1’s slides call the adverse events seen with RYZ101 “consistent with its mechanism of action, concomitant amino acid administration, and the disease under study” (Morris et al., 2024).
• Other groups’ actinium-225 DOTATATE — Hematological toxicity in 2% across 5 studies, two patients with grade I–II kidney toxicity, and no grade III–IV toxicity (Ma et al., 2025).
• Bone marrow cancers (the beta drug) — In Lutathera’s NETTER-1 trial, 2 of 111 patients given lutetium-177 DOTATATE developed myelodysplastic syndrome, one of whom died (Strosberg et al., 2021). No RYZ101 document read for this page reports on it.
• WADA — RYZ101, actinium-225 and DOTATATE are not named on the 2026 Prohibited List. Section S0 prohibits at all times any pharmacological substance not addressed by another section “with no current approval by any governmental regulatory health authority for human therapeutic use (e.g. drugs under pre-clinical or clinical development or discontinued…)” (World Anti-Doping Agency, 2026). RYZ101 is a drug in clinical development, so S0 covers it.
• Identity and purity — No source read for this page shows RYZ101 sold or made outside its trials, so there are no outside copies to describe.

Bloodwork & Monitoring

No monitoring guidance for RYZ101 has been published outside its trial protocols. What the trial documents measured:

• Kidney function — An eGFR of at least 60 mL/min/1.73 m² to enter ACTION-1, by its registry record now (ClinicalTrials.gov NCT05477576), and a creatinine clearance of at least 50 mL/min in ACTION-1’s Phase 1b (Morris et al., 2024); creatinine clearance fell to grade 3 and grade 4 in two ACTION-1 Phase 1b patients whose clearance was already reduced (Morris et al., 2024).
• Blood counts — Anemia and lymphopenia were the most common grade 3 or higher events in ACTION-1’s Phase 1b (Morris et al., 2024).
• Where the radiation goes — SPECT/CT scans (a nuclear-medicine camera combined with CT) of francium-221 and bismuth-213, actinium-225’s daughters, after the first and fourth doses, in 9 patients; the authors write that alpha-emitter imaging “is not yet ready for routine patient implementation” (Sgouros et al., 2026).
• Tumor response — By RECIST 1.1, the rules trials use to measure tumors on scans, read at each site in the Phase 1b (Strosberg et al., 2025) and by blinded independent central review in the Phase 3 (ClinicalTrials.gov NCT05477576).
• Which tests fit a given person — A question for a licensed healthcare provider. This page can’t answer it.

Commonly Stacked With

In ACTION-1’s Phase 1b, every dose was given with an infusion of the amino acids lysine and arginine to protect the kidneys (Sgouros et al., 2026). Its registered trials give it alone or with cancer treatments: carboplatin, etoposide and atezolizumab in small cell lung cancer (ClinicalTrials.gov NCT05595460), and endocrine therapy in breast cancer (ClinicalTrials.gov NCT06590857). None of these is a compound on this site, and no document read for this page shows RYZ101 given with one (searches of October 17, 2026).

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Legal Status

Related Compounds

Two other compounds on this site that people look up for cancer:

Next Steps

References

1. Bristol Myers Squibb. Bristol Myers Squibb Announces Positive Topline Results from the Interim Analysis of Phase 3 ACTION-1 for RYZ101, RayzeBio’s Radiopharmaceutical Therapy, in Patients with GEP-NETs. Press release, October 12, 2026. https://news.bms.com/news/corporate-financial/2026/Bristol-Myers-Squibb-Announces-Positive-Topline-Results-from-the-Interim-Analysis-of-Phase-3-ACTION-1-for-RYZ101-RayzeBios-Radiopharmaceutical-Therapy-in-Patients-with-GEP-NETs/default.aspx. Read October 17, 2026, in the Internet Archive’s copy of October 13, 2026.
2. Han G, Hwang E, Lin F, Clift R, Kim D, Guest M, Bischoff E, Moran S, Li G. RYZ101 (Ac-225 DOTATATE) Opportunity beyond Gastroenteropancreatic Neuroendocrine Tumors: Preclinical Efficacy in Small-Cell Lung Cancer. Mol Cancer Ther. 2023;22(12):1434-1443. PMID: 37616528. DOI: 10.1158/1535-7163.MCT-23-0029.
3. ClinicalTrials.gov. Phase 1b/3 Global, Randomized, Controlled, Open-label Trial Comparing Treatment With RYZ101 to Standard of Care Therapy in Subjects With Inoperable, Advanced, SSTR+, Well-differentiated GEP-NETs That Have Progressed Following Prior 177Lu-SSA Therapy (ACTION-1). NCT05477576. Sponsor: RayzeBio, Inc. Record last updated October 5, 2026. Read October 17, 2026.
4. Strosberg JR, Morris M, Ulaner GA, Halperin DM, Mehr SH, Li D, et al. Phase 1b portion of the ACTION-1 phase 1b/3 trial of RYZ101 in gastroenteropancreatic neuroendocrine tumors (GEP-NET) progressing after 177Lu somatostatin analogue (SSA) therapy: Safety and efficacy findings. J Clin Oncol. 2025;43(4_suppl):661. DOI: 10.1200/JCO.2025.43.4_suppl.661. Meeting abstract; data as of December 14, 2023.
5. Morris M, Ulaner GA, Halperin D, Strosberg J, Mehr S, Li D, et al. Phase 1b portion of the ACTION-1 phase 1b/3 trial of RYZ101 in gastroenteropancreatic neuroendocrine tumors progressing after 177Lu somatostatin analogue therapy: safety and efficacy findings. Presentation slides, data cut-off December 14, 2023, posted by RayzeBio in 2024. https://rayzebio.com/wp-content/uploads/2024/09/RYZ101-301-ASCO-2024-ACTION-1-ORAL-for-SNMMI-03-Jun-2024.pdf. Read October 17, 2026.
6. Hope TA, Halperin D, Strosberg J, Jacene H, Tesselaar MET, Kunz PL, et al. ACTION-1: A randomized Phase Ib/3 trial of RYZ101 compared with SoC in SSTR+ well-differentiated GEP-NET with progression following Lu-177 SSA. Endocr Abstr. 2023;98:T1. DOI: 10.1530/endoabs.98.T1. Meeting abstract.
7. FDA. Search Orphan Drug Designations and Approvals: 225Ac-Dotatate, designated August 26, 2026, for the treatment of gastroenteropancreatic neuroendocrine tumors; sponsor RayzeBio, Inc.; “Not FDA Approved for Orphan Indication.” https://www.accessdata.fda.gov/scripts/opdlisting/oopd/detailedIndex.cfm?cfgridkey=875222. Read October 17, 2026.
8. Sgouros G, Ulaner GA, He B, Ghaly M, Frey E, Kotiah S, et al. Dosimetry Results from the Phase 1b/3 ACTION-1 Trial of [225Ac]Ac-DOTATATE (RYZ101) in Patients with Somatostatin Receptor-Expressing, Well-Differentiated GEP-NETs. J Nucl Med. 2026;67(8):1239-1246. PMID: 42242867. DOI: 10.2967/jnumed.125.270573.
9. Bristol Myers Squibb. Bristol Myers Squibb Adds Premier Radiopharmaceutical Platform with Acquisition of RayzeBio. Press release with RayzeBio, December 26, 2023, filed with the SEC as Exhibit 99.1 to Schedule TO-C. https://www.sec.gov/Archives/edgar/data/1825367/000114036123059406/ny20017436x1_ex99-1.htm. Read October 17, 2026.
10. RayzeBio. Form 8-K, current report of February 26, 2024: completion of the acquisition by Bristol-Myers Squibb Company. https://www.sec.gov/Archives/edgar/data/1825367/000114036124009377/ef20022333_8k.htm. Read October 17, 2026.
11. Advanced Accelerator Applications USA, Inc. LUTATHERA (lutetium Lu 177 dotatate) injection, for intravenous use. Prescribing information. DailyMed set ID 72d1a024-00b7-418a-b36e-b2cb48f2ab55, effective January 15, 2026. Read October 17, 2026.
12. Leupe H, Cauwenbergh M, Cleeren F, Dekervel J, Verslype C, Deroose CM. Clinical Experience with Targeted Alpha-Emitter Peptide Receptor Radionuclide Therapy (α-PRRT) for Somatostatin Receptor-Positive Neuroendocrine Tumors. Pharmaceuticals (Basel). 2025;18(11):1608. PMID: 41304857. DOI: 10.3390/ph18111608.
13. Sgouros G, Roeske JC, McDevitt MR, Palm S, Allen BJ, Fisher DR, et al. MIRD Pamphlet No. 22 (abridged): radiobiology and dosimetry of alpha-particle emitters for targeted radionuclide therapy. J Nucl Med. 2010;51(2):311-328. PMID: 20080889. DOI: 10.2967/jnumed.108.058651.
14. Ballal S, Yadav MP, Bal C, Sahoo RK, Tripathi M. Broadening horizons with 225Ac-DOTATATE targeted alpha therapy for gastroenteropancreatic neuroendocrine tumour patients stable or refractory to 177Lu-DOTATATE PRRT: first clinical experience on the efficacy and safety. Eur J Nucl Med Mol Imaging. 2020;47(4):934-946. PMID: 31707430. DOI: 10.1007/s00259-019-04567-2.
15. Ballal S, Yadav MP, Tripathi M, Sahoo RK, Bal C. Survival Outcomes in Metastatic Gastroenteropancreatic Neuroendocrine Tumor Patients receiving Concomitant 225Ac-DOTATATE–Targeted α-Therapy and Capecitabine: A Real-World-Scenario Management-Based Long-Term Outcome Study. J Nucl Med. 2023;64(2):211-218. PMID: 35863893. DOI: 10.2967/jnumed.122.264043.
16. Demirci E, Alan Selçuk N, Beydağı G, Ocak M, Toklu T, Akçay K, Kabasakal L. Initial Findings on the Use of [225Ac]Ac-DOTATATE Therapy as a Theranostic Application in Patients with Neuroendocrine Tumors. Mol Imaging Radionucl Ther. 2023;32(3):226-232. PMID: 37870290. DOI: 10.4274/mirt.galenos.2023.38258.
17. Agrawal R, Parghane RV, Basu S. Targeted Alpha Therapy With [225Ac]Ac-DOTATATE Versus Salvage Retreatment PRRT With [177Lu]Lu-DOTATATE in Progressive Metastatic Neuroendocrine Tumor Patients After Initial Course of [177Lu]Lu-DOTATATE Treatment: An Observational Study Comparing the Therapeutic Response, Survival, and Clinical Toxicity. Clin Nucl Med. 2026;51(10):e877-e885. PMID: 42302403. DOI: 10.1097/RLU.0000000000006578.
18. Rizzo A, Imperiale A, Annunziata S, Delgado Bolton RC, Albano D, Fiz F, et al. Efficacy and Safety of Radioligand Therapy with Actinium-225 DOTATATE in Patients with Advanced, Metastatic or Inoperable Neuroendocrine Neoplasms: A Systematic Review and Meta-Analysis. Medicina (Kaunas). 2025;61(8):1341. PMID: 40870386. DOI: 10.3390/medicina61081341.
19. Ma J, Ji Y, Yao Z, Yangqing J, Zhang C. The therapeutic efficacy of 225Ac-DOTATATE in neuroendocrine tumors: a preliminary meta-analysis. Front Oncol. 2025;15:1696063. PMID: 41244898. DOI: 10.3389/fonc.2025.1696063.
20. Strosberg JR, Caplin ME, Kunz PL, Ruszniewski PB, Bodei L, Hendifar A, et al. 177Lu-Dotatate plus long-acting octreotide versus high‑dose long-acting octreotide in patients with midgut neuroendocrine tumours (NETTER-1): final overall survival and long-term safety results from an open-label, randomised, controlled, phase 3 trial. Lancet Oncol. 2021;22(12):1752-1763. PMID: 34793718. DOI: 10.1016/S1470-2045(21)00572-6.
21. Parker C, Nilsson S, Heinrich D, Helle SI, O’Sullivan JM, Fosså SD, et al. Alpha emitter radium-223 and survival in metastatic prostate cancer. N Engl J Med. 2013;369(3):213-223. PMID: 23863050. DOI: 10.1056/NEJMoa1213755.
22. Sgouros G, Bodei L, McDevitt MR, Nedrow JR. Radiopharmaceutical therapy in cancer: clinical advances and challenges. Nat Rev Drug Discov. 2020;19(9):589-608. PMID: 32728208. DOI: 10.1038/s41573-020-0073-9.
23. Mansfield AS, Parent E, Rivera-Rodriguez N, Hao Z, Bushnell D, Mulvey C, et al. OA13.03 RYZ101 (225Ac-DOTATATE) + Carboplatin + Etoposide + Atezolizumab in Somatostatin Receptor-Expressing Extensive-Stage SCLC. J Thorac Oncol. 2025;20(10):S39. DOI: 10.1016/j.jtho.2025.09.075. Meeting abstract; the figures on this page are from its slides (World Conference on Lung Cancer 2025), posted by RayzeBio: https://rayzebio.com/wp-content/uploads/2025/09/Mansfield-et-al-WCLC-2025-RYZ101-101-Oral_-Final_08Sep2025.pdf. Read October 17, 2026.
24. ClinicalTrials.gov. NCT05595460 (RYZ101 with carboplatin, etoposide and atezolizumab in extensive-stage small cell lung cancer, RayzeBio), NCT06590857 (TRACY-1, ER-positive, HER2-negative breast cancer, RayzeBio), NCT07150806 (progressive or recurrent intracranial meningioma, sponsor-investigator) and NCT06411301 (multiple myeloma, Jules Bordet Institute, withdrawn). Read October 17, 2026.
25. 21 U.S.C. 353a, Pharmacy compounding (section 503A of the Federal Food, Drug, and Cosmetic Act), subsection (d), Application. https://www.govinfo.gov/content/pkg/USCODE-2024-title21/html/USCODE-2024-title21-chap9-subchapV-partA-sec353a.htm. Read October 17, 2026.
26. FDA. Compounding and Repackaging of Radiopharmaceuticals by State-Licensed Nuclear Pharmacies, Federal Facilities, and Certain Other Entities (https://www.fda.gov/media/102615/download), and Compounding and Repackaging of Radiopharmaceuticals by Outsourcing Facilities (https://www.fda.gov/media/102637/download). Guidances for industry, September 2018. Read October 17, 2026.
27. FDA. 503B Bulk Drug Substances List, updated August 21, 2023. https://www.fda.gov/drugs/human-drug-compounding/503b-bulk-drug-substances-list. Read October 17, 2026.
28. FDA. Bulk Drug Substances Nominated for Use in Compounding Under Section 503B of the Federal Food, Drug, and Cosmetic Act (categories 1–3), updated March 21, 2025. https://www.fda.gov/media/94164/download. Read October 17, 2026: no actinium or DOTATATE entry.
29. World Anti-Doping Agency. Prohibited List 2026 (in effect January 1, 2026). S0, Non-approved substances. https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf. Read October 17, 2026: RYZ101, actinium-225, DOTATATE, somatostatin analogs and radiopharmaceuticals are not named.
30. Searches of October 17, 2026: PubMed, “RYZ101” (3 records) and “225Ac-DOTATATE” or its other names, “Ac-225 DOTATATE”, “actinium-225 DOTATATE”, “225Ac DOTATATE” and “[225Ac]Ac-DOTATATE” (54 records); ClinicalTrials.gov, interventions “RYZ101” (5 studies) and expanded-access records naming actinium-225 (none); FDA’s Drugs@FDA data (openFDA, api.fda.gov/drug/drugsfda.json), active ingredient “actinium” (no records) and “dotatate” (five products: Lutathera, NETSPOT, Detectnet, Bexlutry and Bravnetsa).

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