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Medical Forum / Diseases and Disorders / Cancer / February 2005Radioactive Antibodies: outlook?
Hello everyone, I'm wondering about radiolabeled monoclonal antibodies in the context of ovarian cancer. I see that that a large phase III trial was just completed 6 months ago (Roche's "R1549" phase III trial) and that it showed no improvement in outcomes. (R1549 is a MoAB, linked to yttrium-90, which binds to MUC-1 on the surface of OvCa cells). And yet I see that other institutions are still testing such technology. I'm wondering if I should enter a phase I trial of such a thing myself. Is there reason to think that the Roche study will not apply to different Radioactive MoABs? Why? Do other radioactive MoAbs show promise? (if you have any product names or reputable web links, please post!). > Hello everyone, > [quoted text clipped - 16 lines] > MoAbs show promise? (if you have any product names or > reputable web links, please post!). Radiolabelled monoclonals are fine in theory, but there are many problems in practise. First, you need an antigen binding site which is expressed only on the cancer cells. Then you need an antibody which is very specific for the antigen. Then you need it to behave well once you have a attached a radioisotope to it. It's hard to get all these things right. Some monoclonals work very well for some cancers, but most have only modest success. By all means do a Ph 1 trial - but understand that the antibody is being trialed because nobody knows if it's better, the same or worse than standard. "Steph" <steph@vancouver.island> wrote: > It's hard to get all these things right. Some monoclonals work very well > for some cancers, but most have only modest success. > By all means do a Ph 1 trial - but understand that the antibody is being > trialed because nobody knows if it's better, the same or worse than > standard. Thank you for your answer. I've been looking on the web, and the results for this therapy seem to be all over the place (from useless to great). I've gone through the standard surgery & platinum/taxane therapy. I responded relatively well (ca125 at 18 and 12 after 5th and 6th chemos). But now, 2.5 months after my 6th and last chemo, CA125 reads as 79. (CT scan to follow soon, but expected to be clear since I was clear even at diagnosis). So the choice is: start 2nd round chemo right away (Topotecan? Doxil?) or take a 1 month detour to try this first. Any advice? Also, I understand that the pahse I trial is single injection. Does this mean that even if I show good response, I can't ask for a second injection no matter what? Or are trials usually flexible on this? >> Hello everyone, >> [quoted text clipped - 16 lines] >> MoAbs show promise? (if you have any product names or >> reputable web links, please post!). >> It's hard to get all these things right. Some monoclonals work very well >> for some cancers, but most have only modest success. [quoted text clipped - 19 lines] > > Any advice? There is a third option - if you are feeling well, don't take any treatment until there is a reason to. > Also, I understand that the pahse I trial is single > injection. Does this mean that even if I show good response, > I can't ask for a second injection no matter what? Or are > trials usually flexible on this? It depends on the trial, but if they have said it's a single injection, I suspect that's it. >> I've gone through the standard surgery & platinum/taxane >> therapy. I responded relatively well (ca125 at 18 and 12 [quoted text clipped - 11 lines] > There is a third option - if you are feeling well, don't take > any treatment until there is a reason to. I understand that this is what some doctors recommend, and I understand that since there is no clear evidence that early treatment is better, it is an option. However, logic dictates that early treatment is better. Earlier stage disease responds better to chemo than later stage disease. Also, the fundamental theory of biology, evolution, suggests that the more cancer cells there are, the higher the odds that one of them will have a mutation which will render it immune to chemo. Since cancer grows more or less exponentially, earlier treatment should be better. I certainly wouldn't wait until bacteria had taken over my body before starting antibiotics. So in my mind, treatment is the only way to go. The question I'm left with: is it worth it to 'waste' a month on a treatment which may not help at all (the phase I trial), or should I go straight to 2nd line chemo (which also may not help!). > It depends on the trial, but if they have said it's a single > injection, I suspect that's it. It just seems strange to me that if the response is shown to be good, they wouldn't try to give another injection. To both satisfy their curiosity, get data, and out of compassion! But I guess that there are also regulatory hurdles that stop them... >>> I've gone through the standard surgery & platinum/taxane >>> therapy. I responded relatively well (ca125 at 18 and 12 [quoted text clipped - 17 lines] > > However, logic dictates that early treatment is better. Logic may be a poor guide. And unfortunately, after surgery and multiple chemotherapy, you don't have "early" diesase. > Earlier stage disease responds better to chemo than later > stage disease. Also, the fundamental theory of biology, [quoted text clipped - 22 lines] > But I guess that there are also regulatory hurdles that > stop them... A trial is designed and then accepted by an ethics committee - they can't change it on the fly >>> There is a third option - if you are feeling well, don't take >>> any treatment until there is a reason to. [quoted text clipped - 7 lines] > Logic may be a poor guide. And unfortunately, after surgery and multiple > chemotherapy, you don't have "early" diesase. Poor guide it may be, but if it's a choice between logic and 'gut instinct' (which is really nothing more than a wild assed guess), then I choose logic. As for 'early', perhaps a better way to say it is: "...logic dictates that the earlier treatment the better." >>>> There is a third option - if you are feeling well, don't take >>>> any treatment until there is a reason to. [quoted text clipped - 14 lines] > As for 'early', perhaps a better way to say it is: > "...logic dictates that the earlier treatment the better." It's not a wild assed guess. It's based on the evidence. But you should do what you think best > It's not a wild assed guess. It's based on the evidence. > But you should do what you think best I'm confused. I thought that the evidence for (1) delaying treatment until clinical symptoms appear vs. (2) treating on CA125 rise only was inconclusive. In other words, picking between (1) or (2) was a wild assed guess. Are you saying that there is a *concensus* that shows that (1) is better than (2)? Obviously, if repeated high quality clinical trials showed that option (1) was superior in outcome, I would have to reconsider my position. |
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