Triclonality in Immunofixation in Multiple Myeloma – Artifact of Therapy, Patient Characteristic or Proper Diagnosis?

Triclonal patterns (TP) in immunofixation (IF), characterized by the presence of three different immunoglobulin bands, are a very rare finding: we have recently reported an incidence of 0.1% (representing 0.82% of all clonal patterns detected), in 0.1% of patients tested, in an 11-year series of 46 249 immunofixation essays, collected from 29 704 patients.

We found that for the majority of patients (56.2%) triclonality in IF was a transient feature, with patients acquiring TP and de-escalating to biclonality or monoclonality, and suggested that transiency could be a feature of clonal evolution, involution and selection.

Such clonal modifications could be induced by chemotherapy (CHTx) or bone marrow transplant or, on the other hand, could also be an indication of disease progression. The presence of TP could also be an intrinsic spontaneous characteristic of the patient or the disease.

This study aims to clarify whether TP should be interpreted as merely an artifact of ongoing therapy, or if it could be deserving of attention by the clinician, by studying the relationship between the identification of TP in IF in multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS) patients and the timing of treatment.

We identified all samples exhibiting a TP among the 47 559 IF essays performed in our center from January 2000 to June 30^th 2011. We found 53 sera with TP, from 35 patients, two of whom were external consultation referrals and, therefore, excluded from our analysis. We also excluded an HIV-positive patient who died within 5 days of a single triclonal IF, a liver transplant recipient undergoing immunosuppression, 2 patients with isolated TP during respiratory infections, 3 lymphomas (one marginal zone lymphoma and 2 follicular lymphomas) presenting with TP during CHTx and a renal transplant recipient who acquired a TP and 4 months later was diagnosed with NHL, dying within 10 days.

Of the 25 remaining patients with MM and MGUS, we recognized a spontaneous development of triclonality at diagnosis, prior to the institution of any treatment, in 28% (7 patients). One patient with MM had a single triclonal IF, and died within 30 days of the presenting symptoms; one maintained the same TP pattern throughout therapy; one MM and one MGUS, both recent diagnoses, have yet to have follow-up IF; the remaining 3 MM patients lost their TP spontaneously (1 patient) or during treatment (2 patients).

An additional 8% (2 patients with MM) had a diagnosis established outside of our centre, with no description of triclonality; the first IF performed in our Hospital had a TP, before the start of therapy, and both lost their TP with treatment.

Five patients (20%) acquired a TP spontaneously after diagnosis, but prior to any therapy. Two MGUS later spontaneously lost their TP; one MM lost it with therapy; one patient had MGUS for 3 years before acquiring an inconstant TP, which he subsequently lost after 6 years, progressing to MM one year later; one patient with an indolent myeloma, developed a TP 6 years after diagnosis, on progression to symptomatic myeloma.

The remaining 44% (11 patients) acquired their TP only after the introduction of therapy. This includes 5 MM after CHTx (4 after thalidomide-containing regimens), 4 MM after autologous hematopoietic stem cell transplantation, one Waldenström's macroglobulinemia and one patient with essential thrombocytosis and MGUS who acquired TP after starting hydroxicarbamide.

In this series we found that 28 to 36% of patients with a TP presented with this pattern upon diagnosis, prior to any therapy, with a further 20 to 28%, who were not triclonal at the outset, acquiring it spontaneously without treatment. Therefore, for 56% of patients, triclonality – though frequently transient – is a feature of their disease.

On the other hand, for the remaining 44% of patients, the appearance of a TP is temporally associated with CHTx or transplantation (though it is impossible to affirm that the patients would not have acquired the patterns in the absence of CHTx).

We conclude that the appearance of a TP on IF, through rare and in most cases transient, should not be discarded as a mere effect of treatment.

In over half the cases, there is no association between triclonality and treatment; the clinician should, therefore, interpret the results on a case-by-case basis, as the acquisition of TP could be a marker of disease progression.

No relevant conflicts of interest to declare.