Elevated soluble MUC1 levels and decreased anti-MUC1 antibody levels in patients with multiple myeloma

Soluble MUC1 (sMUC1) levels are elevated in many MUC1(+) cancers. We and ot hers have shown that MUC1 is expressed on multiple myeloma (MM) plasma cell s and B cells. In this study, we measured sMUC1 levels in bone marrow (BM) plasma from 71 MM patients and 21 healthy donors (HDs), and in peripheral b lood (PB) plasma from 42 MM patients and 13 HDs using an immunoassay that d etects the CA27.29 epitope of MUC1. sMUC1 levels were found to be significa ntly greater (mean 31.76 U/mL, range 5.69 to 142.48 U/mL) in MM patient BM plasma versus HD BM plasma (mean 9.68 U/mL, range 0.65 to 39.83 U/mL) (P < .001). Importantly, BM plasma sMUC1 levels were related to tumor burden bec ause sMUC1 levels were significantly higher for NIM patients with active di sease (34.62 U/mL, range 5.69 to 142.48 U/mL) versus MM patients with minim al residual disease (16.16 U/mL, range 5.7 to 56.68 U/mL) (P = .0026), sMUC 1 levels were also elevated in the PB plasma of MM patients (32.79 U/mL, ra nge 4.15 to 148.84 U/ml) versus HDs (18.47 U/ml, range 8.84 to 42.49) (P = .0052). Lastly, circulating immunglobulin M (IgM) and IgG antibodies to MUC 1 were measured in 114 MM patients and 31 HDs, because natural antibodies t o MUC1 have been detected in patients with other MUC1-bearing malignancies. These studies demonstrated lower levels of circulating IgM (P < .001) and IgG (P = .078) antibodies to MUC1 in MM patients compared with HDs. Our dat a therefore show that in MM patients, sMUC1 levels are elevated and correla te with disease burden, whereas anti-MUC1 antibody levels are decreased. (C ) 2000 by The American Society of Hematology.