Indium In-111 satumomab pendetide
Also known as: 111In-satumomab pendetide, CYT-103, In-111 satumomab pendetide, OncoScint, OncoScint CR/OV, Satumomab pendetide
Source Indium In-111 satumomab pendetide at Peptiology
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Summary
Indium-111 satumomab pendetide (OncoScint) is a radiolabeled antibody fragment used for immunoscintigraphic imaging of solid tumours, principally colorectal and ovarian adenocarcinomas. The agent combines a murine Fab' fragment that binds the tumour-associated antigen TAG‑72 with the gamma‑emitting isotope indium‑111, allowing whole‑body scintigraphy to locate primary, recurrent or occult disease.
Mechanism of Action
Satumomab pendetide is the Fab' fragment of the murine monoclonal antibody B72.3, which recognises TAG‑72, a glycoprotein expressed on most adenocarcinomas. The fragment is chemically linked via the chelator pendetide to indium‑111. After intravenous injection, the Fab' fragment circulates, binds TAG‑72‑positive cells, and the attached radioisotope emits gamma photons that are detected by a gamma camera, producing a visual map of tumour localisation.
What the Research Shows
Early clinical work demonstrated that 111In‑satumomab pendetide could reveal extra‑hepatic disease in patients with recurrent colorectal cancer, especially when conventional imaging was equivocal. A multicentre trial of 103 colorectal cancer patients reported a 73% sensitivity for confirmed tumours and a 44% impact on medical or surgical decision‑making, with occult disease identified in 18 patients. No acute adverse reactions were observed after a 1 mg dose labelled with ~5 mCi 111In, although 30% of participants later developed human anti‑mouse antibodies. Review articles highlighted its utility for staging, surveillance, and detection of disease in colorectal, ovarian, and, experimentally, prostate cancers. The agent was FDA‑approved for colorectal and ovarian imaging but has since been withdrawn from the market.
Reported Benefits
Evidence suggests the agent can detect tumour sites that are missed by CT, MRI or ultrasound, particularly extra‑hepatic abdominal and pelvic lesions and occult metastases. In patients with rising carcinoembryonic antigen but negative conventional work‑up, imaging provided clinically relevant information. The technique has been reported to alter management in roughly half of examined patients, aiding decisions about surgery or further therapy.
Limitations of the Evidence
Liver imaging is limited by high nonspecific uptake, reducing sensitivity for hepatic metastases. Development of human anti‑mouse antibodies in about one‑third of recipients may affect repeat imaging. Data are confined to relatively small, non‑randomised studies from the early 1990s, and no contemporary comparative trials exist. The product has been withdrawn, restricting current clinical availability.
Safety Considerations
Acute infusion reactions were not reported in the studied cohorts, indicating good immediate tolerability. However, 30% of patients developed human anti‑mouse antibodies, which could cause hypersensitivity on subsequent exposures or interfere with assay results. As a radiopharmaceutical, it delivers a modest radiation dose, warranting standard radiation safety precautions. Caution is advised in patients with known murine antibody sensitivity.
How It Is Administered
The radiopharmaceutical is prepared by labeling 1 mg of satumomab pendetide with approximately 5 mCi of indium‑111. It is administered intravenously as a single injection, after which planar or SPECT gamma‑camera imaging is performed at prescribed time points to visualise tumour uptake.
Routes of Administration
Goals & Uses
- Staging and restaging of adenocarcinomasOncology DiagnosticsLow
- Tumor imagingDiagnosticHigh
- Detection of ovarian carcinomaDiagnostic ImagingModerate
- Detection of extrahepatic colorectal carcinomaDiagnostic ImagingModerate
Contraindications
- Hypersensitivity to murine proteins or prior murine antibody exposureAllergy / ImmunologicHigh
- Known hypersensitivity to murine antibodiesImmuneModerate
- PregnancyPopulationHighPotential fetal risk or insufficient safety data
- BreastfeedingPopulationHighPotential transfer into breast milk or insufficient safety data
Adverse Effects
- Radiation exposureRadiologicalCommon
- Human anti-mouse antibody (HAMA) formationImmunologicCommon
- Hypersensitivity / allergic reactionsImmunologicUncommon
- Fever and chillsConstitutionalUncommon
- Infusion reactionImmuneCommon
- NauseaGastrointestinalUncommonFeeling of sickness or urge to vomit
- Radiation‑related transient leukopeniaHematologicRare
Drug Interactions
- Other murine antibody-based agentsHigh
- Concurrent radiopharmaceuticalsModerate
- ImmunosuppressantsLowPotential interaction with immune pathways or infection risk
Population Constraints
- Renal impairmentOrgan ImpairmentRelative
- Pediatric patientsAgeRelative
- Patients with prior murine antibody therapyImmunologic HistoryRelative
Regulatory Status
- European UnionUnapprovedNever marketed in EU.
- United StatesWithdrawnApproved: Imaging of TAG‑72‑positive colorectal cancerDiscontinued 2004.
- United KingdomUnapprovedNot authorized.
Approved by the FDA in 1992 for immunoscintigraphy of colorectal and ovarian cancer. Subsequently withdrawn from the US market by the manufacturer (Cytogen Corporation) for commercial reasons, not safety concerns. No longer marketed in the US or EU.
Evidence & Sources
- Journal ArticleLowWeiner GJ, et al.1994-01-01T00:00:00.000000Z
- Journal ArticleModerateCorman ML, et al.1994-01-01T00:00:00.000000Z
- Journal ArticleModerateNeal CE, Meis LC1994-01-01T00:00:00.000000Z
- Journal ArticleModerateMaguire RT, et al.1993-01-01T00:00:00.000000Z
Frequently Asked Questions
What type of cancer is this imaging agent approved for?
The FDA approved 111In‑satumomab pendetide for diagnostic imaging of colorectal and ovarian adenocarcinomas. Clinical investigations have also explored its use in prostate cancer, but it is not approved for that indication.
Can the test replace standard imaging methods like CT or MRI?
No. The agent is intended as a complementary tool. Studies show it can reveal lesions missed by conventional imaging, especially extra‑hepatic disease, but it does not substitute for CT, MRI, or ultrasound.
What are the main safety concerns with this radiopharmaceutical?
Acute reactions are rare, but about 30% of patients develop human anti‑mouse antibodies, which may limit repeat dosing. Radiation exposure is modest but requires standard precautions. Liver uptake is nonspecific, which can affect image interpretation.
Is the product still available for clinical use?
Although it received FDA approval, the compound has been withdrawn from the market, so it is no longer commercially available for routine clinical imaging.
How is the test performed after the injection?
After intravenous administration of the indium‑111‑labeled antibody fragment, gamma‑camera imaging (planar or SPECT) is typically performed at set intervals to capture the distribution of radioactivity and identify TAG‑72‑expressing tumour sites.
What is Indium In-111 satumomab pendetide?
Indium-111 satumomab pendetide (OncoScint) is a radiolabeled antibody fragment used for immunoscintigraphic imaging of solid tumours, principally colorectal and ovarian adenocarcinomas. The agent combines a murine Fab' fragment that binds the tumour-associated antigen TAG‑72 with the gamma‑emitting isotope indium‑111, allowing whole‑body scintigraphy to locate primary, recurrent or occult disease.
What is Indium In-111 satumomab pendetide used for?
Indium In-111 satumomab pendetide is educationally associated with: Staging and restaging of adenocarcinomas, Tumor imaging, Detection of ovarian carcinoma, Detection of extrahepatic colorectal carcinoma. Educational only — not medical advice.
How is Indium In-111 satumomab pendetide administered?
Recorded routes of administration: Intravenous.
What are the potential side effects of Indium In-111 satumomab pendetide?
Reported adverse effects include: Radiation exposure, Human anti-mouse antibody (HAMA) formation, Hypersensitivity / allergic reactions, Fever and chills, Infusion reaction, Nausea, Radiation‑related transient leukopenia. This list is not exhaustive — consult a qualified clinician.
Who should avoid Indium In-111 satumomab pendetide?
Recorded contraindications: Hypersensitivity to murine proteins or prior murine antibody exposure, Known hypersensitivity to murine antibodies, Pregnancy, Breastfeeding. Consult a qualified clinician before use.