Another promising experimental therapy

[AlanMeyer]

This one combines a chemical that binds to prostate tumor cells with another chemical that is radioactive. The radioactive chemical gives off alpha particles (an atom with two protons, two neutrons, and no electrons) that can destroy human cells but only have a range of about 0.1 millimeters. So they destroy the prostate tumor cells that they are brought against but do little damage to healthy tissues that don't attract the tumor sensing chemical. I guess it's like Xofigo, but not just for bones.

As with all the other treatments, some patients experience a dramatic response, some a good response, and some no response. One guy went from a PSA of 3,000 to < 0.1. Only a couple of guys out of 80 in the trial did that well but the researchers claimed that 75% had a positive response with lowered PSA and life extension. They also claimed the main side effect was dry mouth. (I'm thinking that the Budweiser company makes a useful treatment for that.)

medicalxpress.com/news/2016...

[DFZ4835]

Sounds to good to be true. Is there any studies going on in the U.S.? Some of us need that now like Eric. I would be happy to be in a study in this Country.

Dennis

[Hidden]

Alan it would be great if this could be developed intravenously as well to get the little bastards floating around in the vascular and lymphatic systems.

GD

[AlanMeyer in reply to Hidden]

Hi GD,

"Alan it would be great if this could be developed intravenously as well to get the little bastards floating around in the vascular and lymphatic systems."

Maybe it actually will do that. The article didn't say what molecule was used to bind to the tumor cells, or what molecules on the tumor cells provide the binding site. If the same binding site appears on the circulating tumor cells as on the solid tumor cells, then I suppose it could work.

There was also no explanation of why it worked so well for some patients and not at all for others. Perhaps some patients have tumors without the binding site. Or maybe they have it but, for some reason, aren't sensitive to the radiation - which would be surprising. These are the kinds of follow-up studies that can take years, but hopefully enough information about safety and efficacy can be gathered to make the drug available even before we know everything about it.

My very limited understanding of circulating tumor cells is that they all die off eventually, even if no drug kills them. If the drug kills cells that turn into solid tumors, then the CTCs would either die naturally or, if they actually anchored themselves somewhere, they'd be killed by further doses of the drug. ... Maybe.

[Hidden in reply to AlanMeyer]

It uses PSMA-617 to bind to prostate cancer cells. PSMA is on the surface of prostate cancer cells (and saliva so hence the dry mouth side effects). It is an alpha emitting radiation pharmaceutical similar to Xofigo, but unlike Xofigo works on both bone and soft tissue including visceral disease. It is being tested in Germany. Use of PSMA in scans and drug delivery is being developed much more aggressively in Europe. The US is behind the curve in this type of therapy. Weil Cornel in NYC has been testing PSMA 617 with a beta emitter (Lu 177). Maybe they will pick up the research here in the US.

Please note the patients in this trial were very late (end stage) and had an estimated life expectancy of 2-4 months. The isotope is not readily available so it is unlikely that this will be available in the US in the near future. Hopefully it will available to late stage patients in the US via a phase 1 clinical trial.

It is delivered via an IV and treats the whole system not just one area.

I am not an expert only a interested patient

Bill Manning

[efsculpt]

We are living in a better treatment time than when my dad was diagnosed (1982, and he lived 18 more years). It seems that a lot of new possibilities are being offered.

CraIg

[AlanMeyer]

Yes, I understand about the radium 223. As I understand it, because radium and calcium are in the same group in the periodic table they can substitute for each other in many chemical reactions. And because very few tissues in the body other than bones bind calcium, very few other tissues will bind radium, and since the primary uptake of calcium in the bones of older people is not actually healthy bone growth, but growth of bone incorporating prostate tumors, all those factors combine to cause the radioactive radium to be positioned in proximity to the bone tumors and to kill them.

It's a great discovery, built on similar experience with radioactive strontium first used more than 20 years ago.

Yes, the new discovery uses a completely different mechanism of bringing radioactive isotopes to the cancer. In principle, I think it's a superior treatment to Ra-223 or Sr-89 because it can attack cancer in soft tissue as well as in bone.

[Foster007]

Sounds like you are talking about Peptide Receptor Radionuclide Therapy (PRRT). I have a post on it that I put up today. Dry mouth (and dry eyes), leukemia and renal depreciation seem to be the major downsides if you have side effects.

[AlanMeyer in reply to Foster007]

> Sounds like you are talking about Peptide Receptor Radionuclide Therapy (PRRT).

Thanks, yes, I'm sure you're right. The article I found must have been talking about PRRT but did not use that name. That's disappointing in a website named "Medical Press".

I was unable to find anything associating leukemia with PRRT, but I did find "suppression of blood cell counts" as a possible side effect and also renal insufficiency. One site said they are improving the techniques and reducing the incidence of these side effects.

I found a good article from the Society for Nuclear Medicine here:

snmmi.org/AboutSNMMI/Conten...

and there are many other articles at Pubmed and elsewhere.

[Hidden]

All I can say is shoot the juice to me!