Which Patients can benefit from PRRT

PRRT is a short form for Peptide Receptor Radionuclide Therapy. It is also known as molecular therapy or radioisotope therapy. PRRT has been found to be very effective in the treatment on certain cancers called Neuro endocrine tumours or NETs as some of you may know them.

PRRT is an integral part of Nuclear Medicine Therapy and when a PRRT is conducted, the following steps are carefully undertaken and reviewed by trained Nuclear Medicine Physicians.

1. A cell targeting protein or peptide is combined with a Radioactive Material, creating a Radio Peptide. This cell targeting peptide is similar to Somatostatin a naturally occurring hormone in the human body.
2. This radio peptide created with a combination of a Peptide and Radioactive Material is then injected in the patient’s blood stream.
3. This radio peptide has a property to bind with the neuroendocrine tumour cells in the body of a patient. This is achieved because of a cell surface protein (Somatostatin Receptors) present in the tumour cells which have the property to bind to Somatostatin
4. This radio peptide has the capability to deliver high dosage of radiation directly to the cancer cells - this leads to structural changes in the tumour cells and ultimately killing them.
5. There are two types of Somatostatin Receptors – which are made in the labs at our Nuclear Medicine Centre in Gurgaon India – These are DOTATOC and DOTATATE.

This completes the fundamental steps of the PRRT process, now let’s also understand the radioactive chemicals (also called radionuclides) involved – this would help us understand the process a little deeper. So, which are these radionuclides?

Yttrium 90 (Y90) and Lutetium 177 (Lu177) are the most commonly used radionuclides.

What conditions can be treated by PRRT?

PRRT, like we mentioned earlier, is a procedure that is used for treating Neuroendocrine Tumours (NETs) – gastro-entero-pancreatic NETs, which arise from the stomach, gastrointestinal tract, pancreas, islet cell carcinomas of the pancreas (These NETs are included in the US Federal Drug Administration {FDA} approved indication)

PRRT is a recommended option for patients typically with the following conditions:

1. Patients with Advanced Metastatic or progressive NETs which are positive on Somatostatin Receptor Imaging (Ga68-DOTATATE PET CT or other equivalent scans your Doctor may recommend)
2. Patients without options for Surgery
3. Patients who are not responding to other therapies

The objective of PRRT therapy is symptom relief, slow down or stoppage of tumour progression and to improve survival and quality of life.

Now that we know about which patients can benefit from PRRT, let’s go a bit further to understand: 

1. How is PRRT performed?
2. What are the advantages of PRRT?
3. Is PRRT safe?
4. What are the post-therapy guidelines?

How is PRRT Performed?

The most common procedure followed during the PRRT process (as per US FDA and European Medicine Agency Approval) includes a series of 4 cycles of PRRT Treatments with Lu177 DOTATATE approximately 8 weeks apart. The treatment at our Nuclear Medicine Department at Fortis Memorial Research Institute, Gurgaon India can be done on an outpatient basis or may require hospitalisation of a few days. The Nuclear Medicine Physicians at our centre led by Dr. Ishita B Sen and Dr. Vineet Pant decide if a particular patient requires hospitalization or can be discharged the same day from the hospital.

The procedure begins with a discussion with the Patient and the caregiver and proceeds with the patient's scan or review of the medical history and medical reports. The patient is then given appropriate anti-nausea pre-medicines followed by Amino acid solution. The amino acid solution is given intravenously to protect the Patient’s Kidneys from the effects of the treatment. The treatment in total last about 7-8 hours. The patient is then injected with the treatment followed by Amino Acid Solutions again. 

Post the treatment, a Dosimetry Molecular Imaging Scan is done to note where the injected radio-peptide has travelled in the patient’s body.

What are the advantages of PRRT?

PRRT Treatment offers personalized cancer treatment, the radio peptides used (Lu 177 or Y 90) can be tuned to the tumour characteristics and the molecular property of the tumour cells.

PRRT is a selective therapy because the radio peptide cells bind themselves with the tumour cells directly and deliver a high dosage of radiation to kill tumour cells (Targeted Therapy). This also prevents damage to healthy cells in the body by limiting their exposure to radiation. PPRT has been found to be effective in inoperable or metastatic and progressive Neuroendocrine Tumours (NETs)

PRRT is well tolerated and is known to help relieve symptoms, arrest tumour growth, shrink tumour lesions, trials with PRRT have noted improved progression-free survival for the patients.

Is PRRT safe?

PRRT is generally well tolerated but like all other therapies it has its side effects and risks. Nuclear Physicians at our centre will take you through the details of the risks and side effects before the patient opts for this therapy

Side Effects of PRRT may include Nausea, vomiting, long term side effects include suppression of blood counts, permanent renal toxicity, Myelo Dysplastic Syndrome (MDS)

What are the post-therapy guidelines?

• Maintain good bathroom hygiene. 
• Follow radiation safety protocols provided by highly skilled Nuclear Medicine Physicians at our centre. 

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Original Sources: https://nuclearmedicinetherapy.in/blog/which-patients-can-benefit-with-prrt

https://nuclearmedicinetherapy.in/blog/is-prrt-safe-for-you

Also Read: How PRRT Therapy works in Cancer Treatment