Lu PSMA Therapy (Lutetium-177 Prostate-Specific Membrane Antigen Therapy), also known as type-ll membrane-based antigen therapy. Such a classified category of nuclear medicine therapy is becoming a widely prescribed option for men with advanced prostate cancer who have metastatic or treatment-resistant malignancies.
Is PSMA a Protein?
The PSMA protein has a unique 3-part structure:
- A 19-amino-acid internal section,
- A 24-amino-acid transmembrane portion, and
- A 707-amino-acid exterior region.
The PSMA gene is expressed in the short arm of chromosome-11 in a region that is not commonly eliminated in prostate cancer.
PSMA (prostate-specific membrane antigen) is a type II membrane protein that is expressed in all kinds of prostate tissue, including cancer, and it was first recognized using the murine monoclonal antibody (mAb) 7E11-C5. 3.
The chemical element lutetium has the symbol Lu and the atomic number 71. It is a silvery-white metal that is corrosion resistant in dry air but not in humid air. The last element in the lanthanide series, lutetium is traditionally classified as rare earth.
Lutetium is most commonly found in combination with the element yttrium and employed in metal alloys and as a catalyst in a variety of chemical reactions.
What is Lutetium 177?
Lutetium-177 is a radioactive material that emits beta radiation, which is a type of radiation that is slightly harmful to living things. Lutetium-177 is attached to a short peptide that binds to the PSMA receptor on the surface of cancer cells.
When the Lutetium 177 – PSMA complex is coupled to a prostate cancer cell, it produces lethal radiation, causing the cancer cell to die.
The surrounding normal cells are spared due to the low penetration of the released beta particle.
How was Lutetium 177 given?
Lutetium Lu 177 Dotatate is injected into a vein as an infusion. This injection will be given to you once every 8 weeks for a total of 4 doses.
The infusion of this treatment must be done gently, and it can take 30 to 40 minutes to finish.
The patient is admitted to the hospital and will be there for the next 24 hours. Prior to the Lu177 PSMA injection, a MAG3/EC scan is performed for the assessment of kidney function.
Intravenous fluids are normally given to the patient before and after the Lu177 PSMA is given throughout a 24-hour period.
What is PSMA Treatment?
PSMA (prostate-specific membrane antigen) is a microscopic protein located in the prostate gland.
PSMA levels are many times higher in prostate cancer patients than in the general population. PSMA is a good target for treating advanced prostate cancer over this.
Many prostate tumors, specifically those that have progressed or grown resistant to hormone therapy, display a specific receptor termed Prostate-Specific Membrane Antigen on their cell surface (PSMA).
The PSMA receptor is expressed over the locations of metastases when prostate cancer metastasizes or spreads to other regions of the body.
For various reasons, PSMA is a great deal of emphasis for both radionuclide imaging and therapy of prostate cancer:
It can be found in almost all cases of prostate cancer, at any stage of the disease.
It gets upregulated in hormone-refractory or metastatic disease
It is a cell membrane protein that is not released into the bloodstream.
After Antibody Binding, PSMA is internalized (Receptor-mediated Endocytosis).
Mechanism of Action
A radioactive atom is conjugated to a medicinal molecule under this treatment. The medicine is then put into the bloodstream via intravenous or intramuscular, where it can directly connect to cancer cells.
The medication can detect the presence of a chemical called prostate-specific membrane antigen, which can be used to identify these cells (PSMA).
What are the Side-Effects of Lu PSMA Therapy?
Overall, major side effects were minimal in those who received 177Lu-PSMA-617. They included nausea and bone marrow damage, the latter of which constrain blood transfusions in around 13% of patients.
PSMA Lu177 is well tolerated. A little dry mouth, tiredness, and physical fatigue are the most prevalent adverse effects.
About 2–3 weeks following the Lu177 PSMA delivery, there may be a modest drop in white blood cells and platelets as well.
These side effects are usually mild and transitory, and they go away on their own without any active therapy.
Serious or life-threatening consequences are quite unlikely.
Is PSMA PET Scan is Safe?
The radioactive molecule is extremely safe; it is administered in very small doses, and hundreds of thousands of patients who have received PSMA radiotracers have reported no side effects.
After years of clinical investigation, the FDA recently approved it.
What is The Response Rate With Lu PSMA Therapy?
Lu177 PSMA response rates are determined by the tumor biology of prostate cancer, the initial Gleason Score, the degree of illness, and prior therapy responses.
Lu177 PSMA therapy typically results in a drop in PSA and a shrinking of tumors in more than 70% of patients.
By the second dosage of therapy, nearly all patients have experienced a reduction in pain and an improvement in overall health.
The mindset of Doctors while doing this therapy?
Expertise says Lu PSMA Therapy is a particularly precise nuclear medicine therapy that is used to treat metastatic prostate cancer or when other methods of treatment are no longer effective.
According to doctors, patients with advanced castration-resistant metastatic prostate cancer who have shown symptoms of tumor progression are candidates for this treatment. The progression of cancer can take several forms:
PSA levels in the bloodstream are increasing.
CT/MRI or Ga68 PSMA scans show an increase in the size or number of metastatic lesions.
Increased pain or other indications of the disease getting worse
Patients cannot get Lu177 PSMA Therapy if they have any of the following conditions:
- Renal insufficiency is a serious condition that affects the kidneys.
- A serious hematological problem
Treatment Schedules with Lu PSMA Therapy?
The majority of patients receive three to four therapy cycles separated by 8 to 12 weeks. Depending on the response and midterm evaluations, the number of cycles and intermediate time may differ between individuals.
The average dose of Lu PSMA Therapy provided per treatment is between 5.5 and 11 GBq, and the doses are calculated employing pre-treatment dosimetry (Dosimetry is the measurement, calculation, and assessment of the ionizing radiation dose absorbed by the human body).
The patient is admitted to a hospital and placed in a Specialised High Dose Radioisotope Therapy Unit for treatment, monitoring, and radiation protection.
Lutetium-177 therapy is only used on men who have prostate cancer and have exhausted all other treatment options. It has been shown to be a successful treatment for metastatic prostate cancer or prostate cancer that has failed to respond to conventional treatments.