[Kevin J]

Re: Kyprolis treatment after Darzalex treatment?

by Kevin J on Tue Jun 12, 2018 10:06 pm

My doctor and I had that discussion (about the many different types of myeloma cells that can be present) about a year or so back. The discussion was similar to what you mention, but with a few subtle differences.

He indicated that generally one type of myeloma cell is dominant at any time and tends to keep the others at bay. Symptoms and response to treatment are determined by the dominant type. Some types tend to be more aggressive, others less so. If treatment beats back a particular type, then another type that had been held at bay will rise to the occasion and become the dominant type.

In our discussion he said that he and others were considering whether it might be preferable, if you had a less aggressive type, to get it to stable response with minimal symptoms, rather than try to obtain complete response and risk a more aggressive type becoming dominant. Obviously, this would depend on being able to distinguish between more and less aggressive types, which currently cannot be done, only inferred from observation of symptoms and response.

Regardless, given this theory, you are correct that if the type that is dominant changes, a prior treatment that had ceased to work, could likely be effective again.

[MrPotatohead]

Re: Kyprolis treatment after Darzalex treatment?

by MrPotatohead on Wed Jun 13, 2018 7:15 pm

KevinJ wrote

'Research' in this context was used in a more general sense ... As [my doctor] and I discussed it, the hypothesis appears to be that the cancer cells may acclimate to a particular category of drug and therefore make it more likely to resist another drug in the same category. Switching to a new category would disrupt its defenses and therefore make it less likely to resist the different drug.

Thank you, Kevin J.

Yes, I have heard this theory before (many times in fact), but as I mentioned, the broad categories of drugs like “proteasome inhibitors” and IMiDs span drugs with different modes of action and molecular structures, so it is not only possible but often likely that one drug in a given category won’t work, while another in the same category does, as in the examples I gave drawn from my own experience.

It is also true, as you have noted elsewhere, that a given drug that has never been effective, or has ceased being effective, can become effective after a switch to another drug regimen, or after a stem cell transplant.

Thanks very much for the clarification.