ATLANTA – Waldenström macroglobulinemia can present as acquired von Willebrand disease (VWD), and when it does, the finding strongly correlates with high serum IgM levels and the presence of CXCR4 mutations, according to the results of a large, single-center retrospective study.
Further, successfully treating Waldenström macroglobulinemia often resolves acquired VWD, and the depth of treatment response predicts the degree of improvement, Jorge J. Castillo, MD, and his associates wrote in a poster presented at the annual meeting of the American Society of Hematology.
Acquired VWD is an uncommon, poorly understood presentation of Waldenström macroglobulinemia. Because affected patients require treatment, better characterizing this subgroup is important, the investigators noted.
At the Bing Center for Waldenström Macroglobulinemia at Dana-Farber Cancer Institute in Boston, the researchers retrospectively studied 320 individuals with newly diagnosed Waldenström macroglobulinemia and used logistic regression analysis to seek predictors of acquired VWD, which they evaluated by measuring levels of VW factor antigen, VW factor activity, and factor VIII. Levels under 30% were considered VWD and levels between 30% and 50% were considered low-level VWD.
In all, 49 individuals had acquired VWD while 271 patients did not. These two groups were similar in terms of age, sex, hemoglobin level, platelet count, and bone marrow involvement. However, 45% of patients with acquired VWD had serum IgM levels above 6,000 mg/dL versus 6% of patients without acquired VWD (P less than .001), and 47% of patients with acquired VWD had serum IgM levels between 3,000 and 5,999 versus 31% of patients without acquired VWD (P less than .001). Also, 77% of patients with acquired VWD tested positive for CXCR4 mutation versus 37% of patients without acquired VWD (P less than .001).
A significantly higher proportion of patients without acquired VWD had white blood cell concentrations above 6,000/mcL (29% vs. 50%; P = .006). This finding lost statistical significance in the logistic regression model, but all the other variables remained significantly associated. Serum IgM levels above 6,000 mg/dL conferred a 55-fold increase in the odds of having acquired VWD (95% confidence interval, 17-177; P less than .001), and serum IgM levels between 3,000 and 5,999 mg/dL led to an 11-fold increase in these odds (95% CI, 4-34). The presence of CXCR4 mutations was associated with a sixfold increased odds of acquired VWD (95% CI, 2-15). The P value for each of these three associations was at or below .001.
Therapy for Waldenström macroglobulinemia led to statistically significant increases in levels of factor VIII, VW factor antigen, and VW factor activity (P less than .001) and the median of each level improved by at least 35% after treatment. After treatment, 78% of patients with acquired VWD had levels of all three measures above 50% (versus 0% before treatment; P less than .001). Patients with acquired VWD with the best responses to treatment had about a 90% decrease in IgM levels, while those with a partial response had about a two-thirds decrease and patients with stable disease had about a 20% decrease. A linear regression model confirmed that depth of treatment response, based on change in IgM level, correlated with degree of improvement in VWD – that is, the extent of improvement in levels of VW factor antigen, VW factor activity, and factor VIII.
No external funding sources were reported. Dr. Castillo disclosed consulting ties and research funding from Pharmacyclics and Janssen, and research funding from Millenium and Abbvie.
SOURCE: Castillo J, et al. ASH 2017 .