I was diagnosed April 2014 with high risk kappa light chain myeloma. At the time of diagnosis, there was no M-spike, and all my immunoglobulins were low. Six months of induction therapy put me into remission without a stem cell transplant, and I started on maintenance therapy.
Shortly after that 6 month period, my serum IFE/SPEP showed evidence of an M-spike, but "below scanner resolution". I thought this was odd since I had light chain myeloma. I feared I was relapsing. That was 18 months ago. I am tested every month and it still says "below scanner resolution". Kappa light chains fluctuate but stay in normal range. My immunoglobulins are still below normal.
My oncologist refers to my situation of reverting back to MGUS state. Is that the same as secondary MGUS?
Also, I've heard that therapy with monoclonal antibodies can cause a false positive in IFE testing.
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Re: Secondary MGUS
Hi Janet,
Secondary MGUS is a phenomenon where an altogether new isotype (IgG kappa, IgA lambda, etc.) develops that is different than your original isotype (as an example, being first diagnosed with IgG lambda multiple myeloma and then having an IgG kappa M-spike show up). This can sometimes happen after a transplant and does not sound like your situation.
But you simply seem to be in a situation where there is some barely detectable (but not measurable) monoclonal protein in your system and your FLC levels remain normal. It's my guess that this is the reason your doc is saying you are in an MGUS-like state – which sounds like a great place to be.
You mentioned monoclonal antibody treatments potentially causing a false IFE reading. Were you treated with a monoclonal antibody? I never considered this possibility before, but this article bears out your statement:
CR McCudden et al, "Interference of Monoclonal Antibody Therapies with Serum Protein Electrophoresis Tests," Clinical Chemistry, Oct 2010 (full text of article)
But I don't know if any administered monoclonal antibodies would be hanging out in your body for more than a few weeks or months that would later interfere with an IFE test? I would instead think that any administered monoclonal antibodies would simply dissipate at some point or would simply go on self-destruct as they attach to various cells and those cells are destroyed - but I'm not entirely clear on that point.
Secondary MGUS is a phenomenon where an altogether new isotype (IgG kappa, IgA lambda, etc.) develops that is different than your original isotype (as an example, being first diagnosed with IgG lambda multiple myeloma and then having an IgG kappa M-spike show up). This can sometimes happen after a transplant and does not sound like your situation.
But you simply seem to be in a situation where there is some barely detectable (but not measurable) monoclonal protein in your system and your FLC levels remain normal. It's my guess that this is the reason your doc is saying you are in an MGUS-like state – which sounds like a great place to be.
You mentioned monoclonal antibody treatments potentially causing a false IFE reading. Were you treated with a monoclonal antibody? I never considered this possibility before, but this article bears out your statement:
CR McCudden et al, "Interference of Monoclonal Antibody Therapies with Serum Protein Electrophoresis Tests," Clinical Chemistry, Oct 2010 (full text of article)
But I don't know if any administered monoclonal antibodies would be hanging out in your body for more than a few weeks or months that would later interfere with an IFE test? I would instead think that any administered monoclonal antibodies would simply dissipate at some point or would simply go on self-destruct as they attach to various cells and those cells are destroyed - but I'm not entirely clear on that point.
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Multibilly - Name: Multibilly
- Who do you know with myeloma?: Me
- When were you/they diagnosed?: Smoldering, Nov, 2012
Re: Secondary MGUS
Multibilly,
Thanks for your reply and explaining secondary MGUS. I was originally thinking that if I didn't have an M-spike at diagnosis, then that was kind of like the new isotope now, but I see that is very different.
Yes, I have been and still am being treated by a monoclonal antibody since diagnosis - elotuzumab (Empliciti). In the maintenance therapy, I get the infusion every other week. It was more often during induction. The article you attached is very interesting. I'm learning more about this disease everyday!
Thanks for your reply and explaining secondary MGUS. I was originally thinking that if I didn't have an M-spike at diagnosis, then that was kind of like the new isotope now, but I see that is very different.
Yes, I have been and still am being treated by a monoclonal antibody since diagnosis - elotuzumab (Empliciti). In the maintenance therapy, I get the infusion every other week. It was more often during induction. The article you attached is very interesting. I'm learning more about this disease everyday!
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Janet1520
Re: Secondary MGUS
Hi Multibilly and Janet,
The prescribing information for elotuzumab (PDF, see section 5.5) warns that taking the drug can interfere with SPEP and IFE testing. Here's the relevant text:
"Empliciti is a humanized IgG kappa monoclonal antibody that can be detected on both the serum protein electrophoresis (SPEP) and immunofixation (IFE) assays used for the clinical monitoring of endogenous M-protein [see Drug Interactions (7.2)]. This interference can impact the determination of complete response and possibly relapse from complete response in patients with IgG kappa myeloma protein."
There is a similar warning in the prescribing information for Darzalex (PDF, see section 5.3):
"Daratumumab is a human IgG kappa monoclonal antibody that can be detected on both the serum protein electrophoresis (SPE) and immunofixation (IFE) assays used for the clinical monitoring of endogenous M-protein [see Drug Interactions (7.1)]. This interference can impact the determination of complete response and of disease progression in some patients with IgG kappa myeloma protein."
The prescribing information for elotuzumab (PDF, see section 5.5) warns that taking the drug can interfere with SPEP and IFE testing. Here's the relevant text:
"Empliciti is a humanized IgG kappa monoclonal antibody that can be detected on both the serum protein electrophoresis (SPEP) and immunofixation (IFE) assays used for the clinical monitoring of endogenous M-protein [see Drug Interactions (7.2)]. This interference can impact the determination of complete response and possibly relapse from complete response in patients with IgG kappa myeloma protein."
There is a similar warning in the prescribing information for Darzalex (PDF, see section 5.3):
"Daratumumab is a human IgG kappa monoclonal antibody that can be detected on both the serum protein electrophoresis (SPE) and immunofixation (IFE) assays used for the clinical monitoring of endogenous M-protein [see Drug Interactions (7.1)]. This interference can impact the determination of complete response and of disease progression in some patients with IgG kappa myeloma protein."
Re: Secondary MGUS
The interference of determining if a patient has relapsed is most concerning.
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Janet1520
Re: Secondary MGUS
Since my transplant in 2013 all involved – 2 specialist and my daily oncologist – have referred to my status as reverted to MGUS. I have had several MRIs, including a recent full body, and 4 or 5 PETs. All clean. My bone marrow biopsies always show some "bad cell" activity, but each time the cells are acting like MGUS. My newest specialist said he put the cells under a microscope and they just kinda sit there, not dividing or multiplying, and one of the specialists did say specifically that if I walked in the door tomorrow and was tested I would be not be diagnosed as having cancer. I am 100% nonsecretory also and have no bone or organ damage, but I had the mother of all plasmacytomas that tore a huge hole in my spine, lost a couple discs, and live in pain.
Now that's a strange one you gotta admit.
Now that's a strange one you gotta admit.
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Bluemountain
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