#177lu-psma

[cancerabcs]

Pluvicto is Approved By Health Canada 

The good news for our Canadian patients is that Health Canada has approved Pluvicto (lutetium (177Lu) vipivotide tetraxetan injection) for the treatment of men with prostate-specific membrane antigen (PSMA) positive metastatic castration-resistant prostate cancer (mCRPC) who have received at least one androgen receptor pathway inhibitor (ARPI) and taxane-based chemotherapy.  

  Pluvicto is a precision cancer treatment that combines a targeting compound (ligand) with a therapeutic radioisotope (a radioactive particle). This means that the radioisotope treatment (a radioactive particle) is delivered directly to the cancer cells.

 Now, let's unpack who could qualify to receive this treatment. 

 1- This particular approval only affects men living and being treated in Canada; other countries have already approved Pluvicto.

 2- Men must have confirmed metastatic castrate-resistant prostate cancer (mCRPC). This means that the prostate cancer must have left the prostate gland and spread to a different site other than the prostate gland. In addition, the prostate cancer must have stopped responding to first-line hormone therapy treatments (ADT) like Lupron, Eligard, Trelstar, or Zoladex. 

Treatment nonresponse is measured by a rising prostate-specific antigen (PSA blood test) despite confirming that these medications have dropped the testosterone blood levels to a castrate level.  

 3- Men must also have had and failed (as indicated by a rising PSA blood test) at least one of the second-line or androgen receptor pathway inhibitor (ARPI) medications like Erleada (apalutamide), Nubequa (darolutamide), Xtandi (enzalutamide) or Zytiga (abiraterone).

 4- Men must also have chemotherapy with a taxane-based drug like Taxotere (docetaxel) or Jevtana (cabazitaxel).

 5- The prostate cancer must be confirmed to be PSMA positive, or the tumor must express prostate-specific membrane antigen (PSMA) on the cancer cell's surface. Only about 80% of prostate cancer is PSMA positive. A positive PSMA scan confirms the presence of PSMA. 

 To qualify, men must meet all of the above criteria. 

 Pluvicto is administered into the bloodstream by a specially trained doctor who handles radioactive drugs. Once the drug is administered, the Pluvicto targets (finds) the PSMA being expressed on the prostate cancer cell surfaces, directly delivering the treatment radioisotope to the cancer cell. The radioisotope disrupts the cancer cell's ability to duplicate itself and triggers cell death.  

 The Health Canada approval of Pluvicto is based on the pivotal Phase III VISION trial results. The trial randomized patients with PSMA-positive mCRPC who received 177Lu-PSMA-617 in addition to best supportive/best standard of care (BSC/BSoC) versus patients treated with BSC/BSoC alone.

 The full product monograph for Pluvicto can be found at https://www.adacap.com/our-products/.

[cancerabcs]

Prostate Theranostics - What the Hell?

Theranostics has been around for a while; however, it is a relatively new word in our lexicon for those of us with prostate cancer. 

What is Theranostics other than a cool sounding word and a thing that happens in Germany?

The concept behind Theranostics is pretty simple; it is using the same or similar drugs for both diagnosis and therapy. In prostate cancer, theranostics involves using the same radioisotope to identify or diagnose where the prostate cancer is located and also to use it to treat the disease.  

ASCO recently provided an educational presentation you might be interested in reviewing, which offers a good description of Theranostics (see it here). 

Theranostics has been in medical use in other clinical care areas long before its use in prostate cancer. The treatment of thyroid cancer is one of the oldest examples where the use of the radioisotope radioiodine is common. Radioiodine, which is taken up by the thyroid gland, thus allowing metastases to be visualized in a scan. If you also inject additional radioiodine amounts, it will also be taken up by the thyroid gland, making the thyroid gland “hot” enough to kill the cancer cells.

In prostate cancer, Radium 223, approved in prostate cancer treatment as a treatment known as Xofigo, is a radioisotope that mimics calcium. Like calcium, Xofigo seeks bone, and where there is more bone turnover and remodeling as happens at the site of bone metastases, more Radium 223 accumulates at these sites. 

Radium 223 (Xofigo), landing in bone, specifically at the bone metastases, emits alpha particles that will kill cancer cells. The beauty of Xofigo is that alpha particles have a short reach and kill the cancer cells, but will not penetrate and damage the healthy bone marrow.  

The hottest new Theranostics topic in prostate cancer is 177Lutetium (177Lu). 177Lu is an isotope that, when bound to PSMA, allows both diagnoses (visualization on a scan) because it emits gamma radiation for detection and high energy beta radiation that can kill cancer cells. 

177Lu shows considerable promise for treating prostate cancer, but it is not yet approved for use in most countries. Several completed trials of 177Lu-PSMA have demonstrated that this Theragnostic can increase overall survival in men with progressing castrate-resistant prostate cancer.  

For more details on 177Lu-PSMA treatment, this is an excellent recent review from the European Society of Radiology.

There are some ongoing trials of 177Lu-PSMA, which you can find here.