PET and MRI correlation with molecular markers of disease aggressiveness in multiple myeloma

Objectives FDG PET and MRI are increasingly used in oncology owing to their ability to differentiate active from inactive disease, with degree of abnormality associated with molecular derangements portending poor prognoses in some tumors. We investigated whether imaging findings in treatment-naïve multiple myeloma (MM) pts correlate with molecular markers of disease behavior.

Methods In 239 untreated MM pts, baseline FDG PET and MRI findings--number of active bone lesions (FL) and max lesion activity on PET (SUV-FL)--were correlated with serum labs, and with bone marrow aspirate and biopsy for flow cytometry, cytogenetics, and gene expression profile (GEP) analyses of CD138-purified plasma cells.

Results Pts with low-bone disease by GEP were more likely to have FL=0 on PET and MRI (63%, p=0.002; 56%, p=0.02), whereas pts with GEP proliferation features were more likely to have FL>0 (PET p=0.02; MRI p=0.002). Pts with 70-gene high-risk GEP score had higher SUV-FL (p=0.009), with 89% having SUV-FL≥4.1. Abnormal cytogenetics did not correlate with FL number by PET or MRI, or with SUV. Pts with β2m >3.5 had more FL by PET but not MRI (p=0.02; p=0.12), though SUV in these pts was not significantly different.

Conclusions Our data suggests that number of active bone lesions in MM pts correlates with serum markers of disease burden and molecular profile. Lesion SUV may serve as a surrogate indicator of disease aggressiveness, as it is known that pts with high-risk GEP features have poorer OS and EFS.