Therapy of metastatic prostate tumors with Lu-177-PSMA-DKFZ-617

Lu-177 PSMA therapy is applicable to patients with tumors with sufficient expression of PSMA on the cell surface who no longer respond to other treatments (hormone therapy, external radiation therapy or chemotherapy). Before a Lu-177-PSMA-DKFZ-617 therapy can be carried out, the PSMA status and the indication for carrying out the therapy must first be checked using a Ga-68-PSMA ligand PET/CT (standard at the University Hospital of Munich). In addition to other prerequisites, which the treating physicians check individually in detail before Lu-177 PSMA therapy, the patient must above all still have good kidney and bone marrow function. As a rule, further preliminary examinations (e.g. renal function scintigraphy, laboratory tests and others) are necessary, all of which can be carried out at the Department of Nuclear Medicine at LMU Munich.

The therapy takes place at our therapy station K0 and lasts approx. 15 minutes (infusion of the radioactive preparation). Due to the storage of Lu-177 PSMA in the salivary glands, patients should be given cold packs 30 minutes before and up to 4 hours after the therapy to cool the salivary glands and thus reduce blood flow. This is expected to reduce the accumulation of radioactivity in the salivary glands. In order to reduce damage to the kidneys, fluid infusions are administered via the vein directly before, during and in the days following the therapy. In addition, sufficient fluid intake is recommended on the day of therapy and the following days, as this can reduce the radiation load on the kidneys and the rest of the body.

In the days following therapy, whole-body scintigraphic images and blood samples are taken to monitor the storage of Lu-177 in the tumor cells and the degradation of the therapeutic substance. After therapy, the patient must not leave the therapy ward for 48 hours. The treated patient can leave the hospital again after an observation period of approx. 3 days. After discharge from hospital, a laboratory check of the blood, liver and kidney values is necessary after approx. 2 and 6 weeks. This can be carried out close to home by the family doctor, urologist or oncologist.

As a rule, at least three treatments are carried out at intervals of 8 weeks. Follow-up examinations (e.g. PET/CT, kidney scintigraphy) are also carried out at certain intervals to check the response to therapy as well as side effects and complications. In the event of a good response or stabilization of the disease and continued good storage in the Ga-68-PSMA ligand PET/CT, further therapy cycles can often be carried out if the blood count and kidney function allow this.

The results to date show that no serious, acute complications are to be feared. However, despite the greatest care, Lu-177 PSMA therapy can lead to side effects and complications. As the therapy is an individual treatment trial with an unapproved drug, previously unknown risks, side effects and complications cannot be ruled out.

The following side effects and complications are currently known:

General side effects and complications:

• Fever following therapy
• Theoretically, allergic reactions may occur during the administration of the therapeutic substance, including allergic shock
• (this has not yet been observed in any case with this therapy)
• Nausea, vomiting and loss of appetite
• Occasionally slight hair loss in the weeks following therapy
• In rare cases, changes in taste have been described after RLT
• Tiredness and fatigue (can last up to a few weeks after RLT)

Specific side effects and complications:

• The number of red blood cells (erythrocytes), platelets (thrombocytes) and white blood cells (leukocytes) may decrease after therapy. The blood count must therefore be checked 2 and 6 weeks after therapy. In individual cases, repeated therapy can lead to a long-term, in rare cases even life-threatening reduction in bone marrow function with the need for a blood transfusion.
• Repeated therapy can lead to a reduction in kidney function, which is why this is examined before each therapy. In individual cases, repeated therapy may lead to a permanent loss of kidney function with the need for external blood washing (dialysis).
• Repeated therapy can lead to a reduction in saliva production with dry mouth. This can lead to an increased incidence of tooth decay. Changes in taste may also occur as a result.
• In rare cases (despite cortisone therapy), the temporary swelling of large, extensive metastases in the spinal cord area can lead to symptoms of incarceration in the first 72 hours after therapy.
• In principle, radiation exposure is associated with the risk of secondary malignancies, but these occur, if at all, with a delay of years to decades.
• Since long-term experience is not available, side effects may occur that are not yet known.

Important behavior for patients:

• On the day of therapy, several liters of fluid should be drunk in order to keep the burden on the kidneys and the radiation load on the rest of the body as low as possible (accelerated excretion).
• Approximately 30 minutes before and up to 4 hours after the therapy, the salivary glands should be cooled using cold packs in order to reduce blood flow. This is expected to reduce the accumulation of radioactivity in the salivary glands.
• During your inpatient stay, you are unfortunately not allowed to receive visitors in the K0 therapy ward. Only in exceptional cases and after prior consultation with your doctor will you be allowed to leave the ward in the first 48 hours after therapy.
• After your discharge, you do not pose a radiation risk to your relatives.
• Please inform your doctor immediately if you experience any symptoms of any kind or severity after the therapy.