PSMA expression: As part of the... - Advanced Prostate...

Advanced Prostate Cancer

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PSMA expression

spw1 profile image
spw1
23 Replies

As part of the screening for the Crescendo/Potentia trial, my husband was given a GaPSMA PET scan. We have not seen images of it but the written report talks of multiple sites of PSMA expression, most of which are 10-11 SUV range. They did not do an FDG PET scan. The comparison was made with an MRI and a CT scan. We very much would like to look into Lu177 as a treatment if it is not contraindicated. I have seen higher numbers of SUV than 10-11 when other members have talked about their PSMA scans. Is there any significance to this number if one is considering whether Lu177 treatment will work or not? Thank you

23 Replies
Seasid profile image
Seasid

How many mets do you have?

If you don't have too many on the PSMA PET scan visible mets maybe you could just SBRT them with the MRI Linac in your hospital.

If you do Lutetium PSMA therapy for 2 or 3 mets than you will kill of the PSMA positive cancer and you will not have a means to monitor the progression of the prostate cancer with the PSMA PET scan anymore.

Also the expression of the PSMA with SUV max value of 10 to 11 is not very high if we are talking about the SUV max values of the mets here?

spw1 profile image
spw1 in reply to Seasid

They did not count the mets. There are multiple according to the report. The scan was done to see if there is any PSMA positivity for the phase 1 trial rather than treatment.

Seasid profile image
Seasid in reply to spw1

I personally will not take part in any trial under this condition.

I just finished radiation of my prostate.

I think clinical trials are too stressful. Especially if they don't want to share the data.

spw1 profile image
spw1 in reply to Seasid

Personally, I would be of the same opinion but if my husband decides to go ahead with one, I will support him.

Seasid profile image
Seasid in reply to spw1

Was it a SUV max value between 10 and 11 for all the mets?

What was the SUV mean value? If it is above 10 than it is possible to use Lutetium PSMA therapy but if you have only few visible mets positioned so that they can safely SBRT them than I would rather use the linear accelerator to irradiate them.

Cooolone profile image
Cooolone in reply to Seasid

Just curious...

You posted:

you will not have a means to monitor the progression of the prostate cancer with the PSMA PET scan anymore

Although this makes sense, I've not read or come across this anywhere. The LU agent doesn't clear from the body? I'll have to read up some more, but that's interesting if fact. Because my recent RO consult had discussed LU-177 but didn't mention the downside of excluding thereafter any PSMA scanning.

Interesting...

Seasid profile image
Seasid in reply to Cooolone

tango65GeorgeGlass4 days ago

Still on ADT.

My PSA was 4 when the mets were diagnosed. We were chasing the mets with Pylarify PET/CTs since the PSA was 0.4.

The actual cancer has a low PSMA expression (max SUV was 7).

Since I had previous Lu 177 PSMA treatment, we speculate the mets have to get to a volume large enough to be detected since each cell may be expressing little PSMA. The lymph nodes grew from 0.5 to 1.1 cm before the mets were detected.

Last edited by tango65

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anony2020 profile imageanony2020tango65

4 days ago

How did you detect the lymph node in 0.5 mm? Just wondering if you can detect it, cant you eradicate it then?

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tango65 profile imagetango65anony2020

4 days ago

My mistake cm no mm

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anony2020 profile imageanony2020tango65

4 days ago

Mistake is mine. Same question tough. If you can detect it why didnt they treat it?

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tango65 profile imagetango65anony2020

4 days ago

The CT scan detects size, no cancer.

It is judgement call from the radiologists and ROs to decide an enlarged node is cancerous. In general they wait until the node is 15 mm or larger and there is clear evidence of size progression.

With PSMA PET/CTs, if the nodes are PSMA positive, there is cancer independently from the size of the node.

My nodes were PSMA negative until they got to be 10-12 mm. In about 5 months they jump from sub centimeter nodes to larger nodes and become PSMA positive.

In a PSMA PET/CT , the detection depend on the machine and the node has to irradiate enough gamma radiation to be pickup by the machine. If the cells have a low PSMA expression more cells are needed to produce enough radiation to be seen by the machine.

Seasid profile image
Seasid in reply to Cooolone

Lutetium kills the PSMA positive cancer.

MateoBeach profile image
MateoBeach in reply to Cooolone

The logic on this is , well, not logical. If one has predominantly PSMA expressing cancer, then saying not to treat it with a PSMA targeting treatment just because that will be gone (to whatever degree) and will no longer light up on PSMA PET scans makes no sense. You can still use periodic PSMA scans to monitor for progression, along with, PSA and other non-PSMA imaging technologies.

And yes, Lu177 is cleared from the body rather rapidly, predominantly via the kidneys for Pluvicto. It is gone within a few weeks, even for any small residual and will not interfere with PSMA PET scan results.

Cooolone profile image
Cooolone in reply to MateoBeach

I thought I had read that somewhere, clearance via kidneys but didn't remember the actual data, and also considering half life even if radioactive... Knew it didn't make sense to preclude PSMA from being effective at a later time.

And yes, though it kills what's there at the time, doesn't mean it won't come back, etc.

I think, like most things PCa, "timing" is completely relevant and import when considering where you are, what you can do, and where it might take you ;)

Tall_Allen profile image
Tall_Allen

SUV max of 10 is adequate. Ask for an FDG PET/CT too.

spw1 profile image
spw1 in reply to Tall_Allen

Thank you. They had said that the Radiologist would ask for an FDG if they felt it necessary. They had MRI bone and CT scans for comparison. We are assured on the telephone that there is no discordance. The person telling us this wants my husband to enter the Potentia trial first and says that Lu177 (after obtaining approval etc) could only be given at the end of January (assuming that the cancer remains PSMA+). I am a bit concerned to leave it. If my husband does not enter the trial, we have nothing to assure that come end of of Jan he is going to have a place in the queue to get Lu177. The other option is to fly to India and do the treatment there.

Tall_Allen profile image
Tall_Allen in reply to spw1

Don't you get a say? I think they practice shared decision making in the UK.

spw1 profile image
spw1 in reply to Tall_Allen

We are not in the regular treatment area here. They only contacted us because I asked about another trial. My husband is not qualified for that trial as his disease is not stable. Like the Marsden, this hospital too offered the Potentia trial. We were only there because they said that they would give treatment Lu177 while waiting for a slot to be free on the trial. As soon as we visited them, the treatment option took a back seat as two spots are to be filled on the trial. I make notes and feel that the goal posts keep moving.

Kayakbob profile image
Kayakbob in reply to spw1

Lu177 treatment is available in Germany (multiple sites) and Mexico City (MedicaSur) , also.

spolyu profile image
spolyu in reply to Kayakbob

Do you know what other countries outside the US offer LU-177 ? Thank you

tango65 profile image
tango65

If there are mets with a SUV values 10 or greater, it is considered a good PSMA expression and indicates that there will be a good response to the Lu 177 PSMA treatment.

If he has many bone marrow mets, you could ask if there is diffuse infiltration of the bone marrow by the cancer, which could be a contra indication for the treatment. It is usually reported in the PSMA PET/CT report.

spw1 profile image
spw1 in reply to tango65

The scan report says, 'The known multiple sites of bony metastases within the axial and the visualised appendicular skeleton show abnormal tracer uptake, especially the pelvic bones are diffusely infiltrated by PSMA-avid bony deposits (the bilateral iliac bony deposits are associated with intensely PSMA-avid soft tissue components), SUV max up to 10.2 within the left iliac bone. No obvious evidence of intraspinal tumour extension. Diffuse PSMA-avid bony infiltration within the visualised left humerus has SUV max of 11.1. The majority of the bony metastases are occult on CT while others show evidence of osteosclerotic changes'.

The report was prepared to check eligibility for the Potentia trial and not for Lu177 treatment. I do not see any reference to bone marrow in the report.

spw1 profile image
spw1 in reply to tango65

The MRI has a heading 'bone marrow' so I suspect there is infiltration at multiple points but the red blood count has been around 3.8 or 3.5 over the last few months. What other signs for contraindications?

tango65 profile image
tango65 in reply to spw1

WBC, and platelets.

spw1 profile image
spw1 in reply to tango65

Thank you.

tango65 profile image
tango65

Consult with your doctors.The report says "the pelvic bones are diffusely infiltrated by PSMA-avid bony deposits" and "Diffuse PSMA-avid bony infiltration within the visualised left humerus".

If the bones are diffusely infiltrated the treatment could lead to damage to bone marrow normal cells and problems with all the blood cells.

spw1 profile image
spw1 in reply to tango65

Thank you. We will ask.

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