[sphilip]

Monosomy 13 and Velcade

by sphilip on Tue Sep 16, 2014 8:36 pm

Hi,

I'm new on the forum. I was diagnosed in 2010, underwent induction (Velcade, dex) to nCR, postponed doing an auto stem cell transplant, relapsed in 2012 (with new chromosomal abnormalities), started Revlimid + dex, responded pretty well, then in 2013 added Velcade (subcutaneous) and response even better.

I just had a biopsy, and it is pretty good. Here's the one thing, though. One abnormality I had in 2010 was chromosome 13 abnormality (deletion 13q14 and 13q34). This disappeared after induction, but returned in the relapse. Now, after 2.5 years of Revlimid / dex, plus Velcade, my biopsy shows almost complete remission, but the FISH test shows a little remaining monosomy 13.

I am wondering if this indicates increased resistance to Velcade (or generally the chemo). It seems as though the monosomy 13 is persisting even through this chemo. Is this how resistance works? I thought resistance developed when new abnormalities emerged that were known not to respond. But here is an abnormality that responded before, but perhaps now is not responding (if I cam put it in those terms).

In other words, Velcade worked against 13- before. Can it stop working against the same abnormality later? So then, does this indicate growing resistance? (If so, I might change my current treatment.)

There is a detail about my Velcade usage, though. I added it in 2013, subq, whereas in 2010 it was by IV. Also, I think my dosage since 2013 has been somewhat less -- once a week rather than twice a week as in 2010. Also, since my free light chain numbers were so good, I reduced the Velcade in 2014 to once every two weeks. So that is definitely a lower dosage of Velcade, and much easier to tolerate. So, perhaps my monosomy 13 persists now because of this lower dosage.

Sorry for such a detailed and somewhat technical question, but I thought I would float it out there in case anyone has any info.

Thanks.

[JimNY]

Re: Monosomy 13 and Velcade

by JimNY on Wed Sep 17, 2014 7:02 pm

Hi sphilip,

I'm far from an expert on these things, but I think you are confusing two different things. I don't think "monosomy 13" and, say, del 13q14 or del13q34 are the same thing.

When your myeloma cells have monosomy 13, it means that they only have one copy of chromosome 13 instead of the usual two copies.

With deletions like del13q14, the long (q) arm of the chromosomes is missing part of the genetic material that would normally be there. But you still have two pairs of chromosome 13.

Hope this helps a bit.