Lymphoseek (Technetium Tc-99m tilmanocept) is a radiopharmaceutical agent that binds to cell-surface receptors present on macrophages. It can be used with or without scintigraphic imaging for lymphatic system mapping.

Lymphoseek (Technetium Tc-99m tilmanocept) Uses:

• Diagnostic imaging:

  • This radioactive diagnostic agent indicated with or without scintigraphic imaging (using a handheld gamma counter) for:
    • It is used in lymphatic mapping to locate lymph nodes draining a primary tumor site in patients with solid tumors for which this procedure is a component of intraoperative management.
    • It is also used for guiding sentinel lymph node biopsy in patients with clinically node-negative squamous cell carcinoma of the oral cavity, breast cancer, or melanoma.

Lymphoseek (Technetium Tc-99m tilmanocept) Dose in Adults

It is important to note that the route of administration, number of injections, and total injection volume per patient is variable depending on cancer and planned injection technique.

Lymphoseek (Technetium Tc-99m tilmanocept) Dose in Breast cancer lymphatic mapping:

• Intradermal, SubQ, subareolar, or peritumoral: 18.5 MBq (0.5 mCi) as radioactivity dose and 50 mcg as a mass dose at least 15 minutes before intraoperative lymphatic mapping.

Lymphoseek (Technetium Tc-99m tilmanocept) Dose in Melanoma lymphatic mapping:

• Intradermal or SubQ: 18.5 MBq (0.5 mCi) as radioactivity dose and 50 mcg as a mass dose at least 15 minutes before intraoperative lymphatic mapping

Lymphoseek (Technetium Tc-99m tilmanocept) Dose in Oral cavity squamous cell carcinoma sentinel lymph node biopsy:

• Peritumoral: 18.5 MBq (0.5 mCi) as radioactivity dose and 50 mcg as a mass dose at least 15 minutes before intraoperative sentinel node biopsy

Use in Children:

Not indicated.

Pregnancy Risk Category: C

• Technetium unbound crosses the placenta. Technetium Tc99m can be found in fetal tissue. 
• The amount of Technetium Tc 99m depends on the formulation used, the route taken and the stage of pregnancy.
• The likelihood of a radiopharmaceutical causing harm to the foetus is dependent on how much the baby ingests and what trimester it is in.
• Radiopharmaceuticals used in therapeutic procedures at high doses are more likely than to cause fetal harm.
• Modifying a medically-approved diagnostic procedure to reduce fetal risk is possible.
• It is best to delay elective diagnostic procedures until after delivery.
• It is important to rule out pregnancy before administering it to women with childbearing potential.

Use of Technetium Tc99m tilmanocept during breastfeeding

• Breast milk contains technetium Tc99m. Technetium 99m tilmanocept information has not been fully studied.
• Before administering breastfeeding, it is important to know the status of your baby.
• Women with a stable milk supply should continue to breastfeed after the administration of radiopharmaceuticals.
• Technetium Tc99m secretion into colostrum is variable and poorly studied. It is therefore not possible to make recommendations regarding early breastfeeding.
• According to these guidelines, it is recommended that breastfeeding be stopped for 24 hours following the administration of radiopharmaceuticals.
• To minimize radiation exposure to breastfed children, the manufacturer suggests that breastmilk be pumped and then discarded for at least 24 hours.

Dose in Kidney Disease:

No dose adjustments are required in renal disease according to the literature.

Dose in Liver disease:

There are no dosage adjustments provided in the literature.

Side effects of Lymphoseek (Technetium Tc-99m tilmanocept):

• Hypersensitivity reactions
• Pain and irritation at the site of the injection
• Bluish discoloration of the skin.

Contraindications to Lymphoseek (Technetium Tc-99m tilmanocept):

There have not been any specific contraindications studied

Warnings and precautions

• Hypersensitivity

  • Technetium Tc99m tilmanocept may cause hypersensitivity reactions. This is due to the chemical similarity with dextran.
  • Clinical trials did not show any cases of severe hypersensitivity. However, hypersensitivity medications and equipment should be readily available for administration.

• Malignancy

  • It can significantly increase the chance of malignancy in children.

Monitoring Parameters:

Observe for hypersensitivity reactions.

How to administer Lymphoseek (Technetium Tc-99m tilmanocept)?

• The route of administration (intradermal, subcutaneous, subareolar, or peritumoral) is determined by the type of malignancy and planned injection technique.
• The recommended can be administered as a single injection or as multiple injections.

Breast cancer lymphatic mapping:

• It can be administered by intradermal, subQ, subareolar, or peritumoral injection.

Melanoma lymphatic mapping:

• It can be administered by intradermal or subQ injection.

Oral cavity squamous cell carcinoma sentinel lymph node biopsy:

• May be administered by peritumoral injection.

Administer at least 15 minutes prior to intraoperative lymphatic mapping and sentinel lymph node biopsy; do not delay mapping or sentinel node biopsy more than 15 hours beyond administration. Use a handheld gamma counter to identify radioactivity concentrated within lymph nodes. Avoid injections into biopsy wound areas with evidence of edema or inflammation.

Radiopharmaceutical:

• The use of appropriate precautions and tools for handling and disposal is recommended.
• Use waterproof gloves and effective radiation shielding when handling the product.

Mechanism of action of Lymphoseek (Technetium Tc-99m tilmanocept):

It is a radioactive diagnostic drug that accumulates in lymphatic tissue.

The beginning of action:

• Within 10 minutes, it is detected in lymph nodes. Before mapping, wait at least 15 minutes.

Time:

• It can be detected up to 30 hours following administration. It should be completed within 15 hours of administration.

Distribution:

• Radioactivity also distributes to the liver, kidney, and bladder with accumulated radioactive dose reached a maximum at 1 hour after administration and was approximately 1% to 2% of injected dose in each tissue.

Half-life elimination at injection site:

• 1.8-3.1 hours

International Brand Names of Technetium Tc-99m tilmanocept:

• Lymphoseek

Technetium Tc-99m tilmanocept Brand Names in Pakistan:

It is available in certain specialized centers in Pakistan.