Pentixather
Radiation carried to CXCR4, used to clear diseased bone marrow before a stem cell transplant
Pentixather is a small ring-shaped peptide that binds CXCR4, a receptor many blood cancers carry. It is the treatment twin of the scan tracer pentixafor: where pentixafor carries a weak isotope to show the cancer, pentixather carries lutetium-177 or yttrium-90 to irradiate it. Because normal bone marrow also carries CXCR4, it is given only before a stem cell transplant, in specialist centres, and is not approved anywhere.
Used in human trials: 200 MBq lutetium-177 pentixather, Single injection, Intravenous (Study: pretherapeutic dosimetry, 19 patients) Details ↓
Recommended Dosing
Used in human trials
No manufacturer dose exists for this use: these are amounts given in published trials, not recommendations.
What is it?
Radioligand therapy carries radiation to a tumour by attaching a radioactive atom to a molecule that binds a receptor on the cancer cells. Lutetium-177 DOTATATE does this for neuroendocrine tumours and vipivotide tetraxetan (Pluvicto) for prostate cancer. Pentixather applies the idea to CXCR4, a chemokine receptor that helps cells home to and stay in the bone marrow, and that many blood cancers carry in large amounts.
It is a modified analogue of pentixafor, a gallium-68 PET tracer for CXCR4, developed to carry therapeutic isotopes. The two make a theranostic pair: a pentixafor scan shows whether a patient's disease carries enough CXCR4, and pentixather then treats it. A 2017 preclinical study found that lutetium-177 pentixather bound human CXCR4 tightly and selectively, stayed intact in the body, and was held in tumours for days, with the kidneys as the organ most at risk.
CXCR4 is also on the blood-forming stem cells of normal marrow, so pentixather does not spare the marrow. Clinicians turned this into a use: for people with advanced myeloma, lymphoma or leukaemia who were going on to high-dose chemotherapy and a stem cell transplant anyway, pentixather adds targeted radiation to both the cancer and the marrow it lives in. The first three patients, heavily pretreated with myeloma inside and outside the bone, were treated in 2016, and two showed a marked response on FDG PET.
Larger series followed. In 22 patients treated before transplantation, every patient developed low blood counts, as intended, while kidney and liver toxicity was low; one had kidney failure from rapid tumour breakdown. A 2022 dosimetry analysis of 19 patients measured the radiation dose to each organ: kidneys, liver, spleen and marrow took up the most, and tumours received far more per unit of activity than normal organs. In seven people with acute myeloid leukaemia that had failed three to seven treatments, pentixather combined with total body irradiation and chemotherapy before a donor transplant gave a response in six, and six engrafted.
Gallium-68 pentixather has also been compared directly with gallium-68 pentixafor as a scan. In 19 people with newly diagnosed myeloma it found at least as many bone lesions in almost every patient and showed higher uptake, so it may serve as an imaging agent too. In mice, lead-212 pentixather, an alpha emitter, lengthened survival in small cell lung cancer, a tumour that often carries CXCR4.
Pentixather is not approved by FDA or the EMA. The published treatments were given case by case under ethics approval, and phase 1/2 trials in acute leukaemia and central nervous system lymphoma are registered. A version with a different chelator, labelled with fluorine-18, is a different molecule and is not covered here.
Mechanism of Action
Pentixather binds the chemokine receptor CXCR4 and carries lutetium-177 or yttrium-90 into cells that display it, irradiating CXCR4-rich cancer and, by design, the bone marrow around it.
CXCR4 binding
Binds human CXCR4 with high affinity and selectivity and is held in CXCR4-rich tumours for days (preclinical study).
Beta radiation
Lutetium-177 and yttrium-90 emit beta particles; per GBq, yttrium-90 gave each organ about two to four times the absorbed dose of lutetium-177.
Marrow ablation
Blood-forming marrow carries CXCR4, so treatment clears it; patients then receive stem cells to restore blood counts.
Kidneys limit the dose
Kidneys, liver, spleen and marrow take up the most; the kidneys were the dose-limiting organ in dosimetry.
Published Research
Studies whose titles name pentixather, read from their PubMed abstracts on October 29, 2026. The fluorine-18 version built on a different chelator is a different molecule and is not included; two treatment series titled for CXCR4 therapy, and an editorial without an abstract, are listed under References.
First patients treated
Three heavily pretreated patients with multiple myeloma inside and outside the bone, whose disease carried CXCR4 on pentixafor PET, had a lutetium-177 dosimetry scan, then lutetium-177 or yttrium-90 pentixather, followed by chemotherapy and their own stem cells. Two showed a marked fall in FDG uptake.
Dosimetry in 19 patients
After 200 MBq of lutetium-177 pentixather, median absorbed doses per GBq were 0.91 Gy in the kidneys, 0.71 Gy in the liver, 0.58 Gy in the spleen and 0.47 Gy in marrow, and two to four times higher for yttrium-90. Kidney activity fell with a half-life of about 41 hours. Tumour doses reached 1.5 to 18.2 Gy per GBq of yttrium-90, enough to add to high-dose chemotherapy.
Side effects before transplantation
Twenty-two patients with lymphoid or myeloid cancers received 25 treatments with lutetium-177 or yttrium-90 pentixather before conditioning and transplantation. All developed low blood counts, as expected; apart from one grade 3 kidney failure from rapid tumour breakdown, kidney and liver toxicity was low and other serious events resolved or were manageable.
Refractory acute myeloid leukaemia
Seven patients whose AML had failed three to seven lines of treatment received lutetium-177 pentixather with total body irradiation and chemotherapy before a donor transplant. Six responded and six engrafted, and marrow biopsies showed the supporting niche was spared.
Gallium-68 pentixather against pentixafor
In 19 people with newly diagnosed myeloma who had both scans, gallium-68 pentixather was positive in 18 and pentixafor in 15 (not significant). Across 151 matched bone lesions it found as many or more in 13 of 14 patients and showed higher uptake (median SUVmax 16.8 against 13.4), with higher total marrow uptake.
Case: more lesions than pentixafor
In an 83-year-old woman with newly diagnosed myeloma, gallium-68 pentixather PET showed more focal bone lesions, with higher uptake, than gallium-68 pentixafor PET.
Preclinical profile and one patient
Lutetium-177 pentixather bound human CXCR4 with high affinity and selectivity, stayed intact, was over 96% bound to plasma proteins and was held in lymphoma xenografts for a week. In a myeloma patient given 7.8 GBq, tumour received 3.1 times the kidney dose and 6.4 times the liver dose; the kidneys were the dose-limiting organ.
Lung neuroendocrine cancers
In mice with small cell lung cancer xenografts, lutetium-177 pentixather slowed growth and lengthened survival without unacceptable toxicity, and the drug auranofin made it more effective in cells. In human tissue, 84% of 95 samples were CXCR4-positive, and CXCR4 was found in most lung neuroendocrine cancers but none of 25 non-lung tumours.
Lead-212 pentixather in mice
In small cell lung cancer xenografts, lead-203 pentixather imaged CXCR4-dependent uptake and lead-212 pentixather, an alpha emitter, prolonged survival and slowed growth. Mice carrying human marrow developed low blood counts that recovered by about four weeks.
CXCR4 in glioblastoma tissue
Of 191 glioblastomas stained for CXCR4, most showed large variation within and between tumours, 23 were negative and 5 stained strongly; normal brain was negative. The authors suggest patients with high expression on pentixafor PET might be candidates for pentixather.
Review: acute leukaemia
A 2025 review of the pentixafor and pentixather pairing in acute lymphoblastic and myeloid leukaemia, arguing that disrupting CXCR4-mediated contact between leukaemia cells and the marrow niche may help overcome resistance.
Review: pentixafor and pentixather
A 2023 review of CXCR4 imaging with pentixafor across blood cancers, solid tumours and heart and infectious disease, and of pentixather treatment given to patients with myeloma, refractory acute leukaemia and diffuse large B-cell lymphoma.
Dosing Data
Pentixather has no approved label. These are activities given in published human studies; therapy activities are planned for each patient from a dosimetry scan, so they vary widely.
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
What a Buyer Needs to Know
What is sold, how it is mixed, stored and taken, and what is known about its safety, quality and legal status. Each part names its source. Where we have none, it says unknown.
What is sold
Unknown: we hold no regulator's label that says in what form Pentixather is supplied. It is a radioactive drug: the next part says where it is prepared and given.
Mixing a vial: a worked example
Nothing to mix at home, and no syringe units to work out: Pentixather is a radioactive drug, prepared and given in nuclear-medicine departments, and its dose is an amount of radioactivity (MBq or GBq), not a weight.
This page's dosing note: “Pentixather is dosed by radioactivity, planned from a dosimetry scan and given in nuclear-medicine departments before a stem cell transplant.”
Source: this page's own note in Dosing Data below; the amount of each dose row in Dosing Data below.
Storage before and after mixing
Unknown: no label on file says how Pentixather is stored. It is a radioactive drug held by the nuclear-medicine department that prepares and gives it (see the part above); the home rules for a mixed vial in the mixing guide do not apply to it.
How it is taken
As it was given in human studies: Intravenous (Single injection; Study: pretherapeutic dosimetry, 19 patients).
Source: Used in human trials: the route and frequency of each row in Dosing Data below.
What to expect, and when
How long it stays in the body: not established by a measurement cited on this entry.
How long the doses were given: Study: pretherapeutic dosimetry, 19 patients: Whole-body scans over at least 4 days; Study: treatment of one myeloma patient: Followed by stem cell support.
When effects appear: unknown; no source on this page gives a time to effect for Pentixather. Results reported in the studies are under Published Research.
Source: Used in human trials, the duration of each row in Dosing Data below.
Side effects, and when to stop or get help
From the Side Effects section: Low blood counts in every patient, the intended marrow-clearing effect; One grade 3 acute kidney failure from rapid tumour breakdown among 22 patients; Low kidney and liver toxicity otherwise; other serious events were transient or manageable; Radiation to the kidneys, liver, spleen and marrow; the kidneys limit the dose. Full list and cautions ↓
When to stop or get help: unknown; no label or trial on file sets rules for stopping Pentixather. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“From the treatment series above, all in heavily pretreated patients going on to stem cell transplantation”).
Interactions
Unknown: a PubMed search for human interaction studies of Pentixather (reviewed 2026-10-28) found none. Unknown is not the same as safe to combine.
Every peptide's record, with its source: the interaction matrix.
Checking what you bought
Unknown: no published independent test of Pentixather products is in our lab-results database yet, so how products sold under this name measure up is not known.
To read a certificate of analysis, paste it into the COA decoder. Trust & Verification explains what independent testing can and cannot show.
Legal status
US: In Clinical Trials (Not approved: Drugs@FDA and the EMA medicines list hold no record (searched October 29, 2026)). Sport: Prohibited (S0 catch-all).
Country by country ↓ · Regulatory tracker
Source: this entry's approval status and the WADA Prohibited List, as in Legal Status below.
Side Effects & Contraindications
Reported Side Effects
From the treatment series above, all in heavily pretreated patients going on to stem cell transplantation.
Contraindications & Cautions
No approved label exists, so there are no official contraindications. Points from the studies above:
Legal Status
Pentixather is investigational in every jurisdiction checked.
Frequently Asked Questions
?What is pentixather?
A small cyclic peptide that binds the CXCR4 receptor, carrying radioactive lutetium-177 or yttrium-90 to treat cancers that carry the receptor. It is the treatment partner of the PET tracer pentixafor.
?Who receives it?
In the published series, people with advanced multiple myeloma, lymphoma or acute leukaemia who were about to have high-dose chemotherapy and a stem cell transplant.
?Why is a stem cell transplant needed?
Normal blood-forming marrow carries CXCR4 too, so the treatment wipes it out along with the cancer. Every patient in a 22-person series developed low blood counts, and stem cells are given to restore them.
?Is it approved?
No. Drugs@FDA and the EMA have no record of it. Phase 1/2 trials in acute leukaemia and CNS lymphoma are registered.
?How is it different from pentixafor?
Pentixafor carries gallium-68 for a diagnostic PET scan. Pentixather is an analogue developed to carry therapy isotopes. Gallium-68 pentixather has also been used for scans and found slightly more myeloma lesions than pentixafor.
?Which organs are most at risk?
In the 19-patient dosimetry study the kidneys, liver, spleen and marrow received the most radiation; the kidneys were dose-limiting in the preclinical work.
?How does it compare with Lutathera or Pluvicto?
Same principle, different target: Lutathera carries lutetium-177 to somatostatin receptors and Pluvicto to PSMA. Both are approved; pentixather is not.
References
- [registry] ClinicalTrials.gov API v2, read October 29, 2026: NCT06356922 (phase 1/2, lutetium-177 pentixather in relapsed or refractory CXCR4-positive acute leukaemia, 21 participants, active, not recruiting); NCT06132737 (phase 1/2, yttrium-90 pentixather in CNS lymphoma, recruiting); NCT05557708 (early phase 1, lead-212 pentixather, not yet recruiting); NCT05364177 (gallium-68 pentixather and pentixafor PET in multiple myeloma, status unknown).
- [pubmed] Herrmann K, et al. "First-in-Human Experience of CXCR4-Directed Endoradiotherapy with 177Lu- and 90Y-Labeled Pentixather in Advanced-Stage Multiple Myeloma with Extensive Intra- and Extramedullary Disease." J Nucl Med, 2016;57(2):248-51. PMID: 26564323.
- [pubmed] Hänscheid H, et al. "Biokinetics and Dosimetry of (177)Lu-Pentixather." J Nucl Med, 2022;63(5):754-760. PMID: 34413147.
- [pubmed] Maurer S, et al. "Side Effects of CXC-Chemokine Receptor 4-Directed Endoradiotherapy with Pentixather Before Hematopoietic Stem Cell Transplantation." J Nucl Med, 2019;60(10):1399-1405. PMID: 30850502.
- [pubmed] Braitsch K, et al. "CXCR4-directed endoradiotherapy with [(177)Lu]Pentixather added to total body irradiation for myeloablative conditioning in patients with relapsed/refractory acute myeloid leukemia." Theranostics, 2025;15(1):19-29. PMID: 39744224.
- [pubmed] Yang Q, et al. "Chemokine Receptor 4-Targeted PET/CT with [(68)Ga]pentixather in Newly Diagnosed Multiple Myeloma: a Comparative Study with [(68)Ga]pentixafor PET/CT." Mol Imaging Biol, 2024;26(6):986-994. PMID: 39304574.
- [pubmed] Yang Q, et al. "Chemokine Receptor 4-Targeted PET/CT With 68 Ga-Pentixather Detects More Lesions Than 68 Ga-Pentixafor PET/CT in Multiple Myeloma." Clin Nucl Med, 2024;49(6):592-593. PMID: 38630995.
- [pubmed] Schottelius M, et al. "[(177)Lu]pentixather: Comprehensive Preclinical Characterization of a First CXCR4-directed Endoradiotherapeutic Agent." Theranostics, 2017;7(9):2350-2362. PMID: 28744319.
- [pubmed] Fath MA, et al. "Chemokine Receptor CXCR4 Radioligand Targeted Therapy Using 177Lutetium-pentixather for Pulmonary Neuroendocrine Cancers." Radiat Res, 2024;201(1):35-47. PMID: 37989124.
- [pubmed] Christensen KA, et al. "Targeting CXCR4 with 212Pb/203Pb-Pentixather Significantly Increases Overall Survival in Small Cell Lung Cancer." Radiat Res, 2025;204(3):173-183. PMID: 40605199.
- [pubmed] Jacobs SM, et al. "CXCR4 expression in glioblastoma tissue and the potential for PET imaging and treatment with [(68)Ga]Ga-Pentixafor /[(177)Lu]Lu-Pentixather." Eur J Nucl Med Mol Imaging, 2022;49(2):481-491. PMID: 33550492.
- [review] Rahimian S, et al. "CXCR4-targeted theranostics in acute leukemia: disrupting leukemic cell-microenvironment interactions with pentixafor and pentixather." Med Oncol, 2025;42(9):402. PMID: 40754635.
- [review] Chen Z, et al. "Nuclear Medicine Application of Pentixafor/Pentixather Targeting CXCR4 for Imaging and Therapy in Related Disease." Mini Rev Med Chem, 2023;23(7):787-803. PMID: 36529918.
- [pubmed] Dreher N, et al. "Myeloablative Radioligand Therapy Targeting C-X-C Motif Chemokine Receptor 4 in Advanced Multiple Myeloma." Clin Nucl Med, 2025;50(6):495-500. PMID: 40323995.
- [pubmed] Dreher N, et al. "C-X-C Motif Chemokine Receptor 4-Targeted Radioligand Therapy in Hematological Malignancies-Myeloablative Effects, Antilymphoma Activity, and Safety Profile." Clin Nucl Med, 2024;49(2):146-151. PMID: 38081189.
- [pubmed] Bauckneht M, et al. "Pentixather: paving the way for radioligand therapy in oncohematology." Expert Rev Anticancer Ther, 2024;24(5):205-209. PMID: 38593347.
Sources & Citations
Studies were read from their PubMed abstracts on October 29, 2026; trial registrations from ClinicalTrials.gov and status from Drugs@FDA and the EMA medicines list, read the same days. Grey Peptides sells nothing and links to no vendor.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.