We retrospectively studied 232 patients with cold agglutinin disease (CAD) at 24 centers in five countries. In Norway and a northern region of Italy, the study was close to being population-based. For the first time, we demonstrate 4-fold differences between cold and warmer climates regarding prevalence (20 versus 5 cases/million) and incidence (1.9 versus 0.48 cases/million/year). Mean baseline hemoglobin level was 9.3 g/dL, but 27% had hemoglobin < 8 g/dL. Identification of typical features of 'CAD-associated lymphoproliferative disorder' in the bone marrow was greatly increased by centralized biopsy assessment. CAD seems to be associated with a slightly increased risk of venous thrombosis. This work included a follow-up study of therapies, focusing on the long-term outcomes of the rituximab plus bendamustine and rituximab plus fludarabine regimens. Rituximab plus bendamustine therapy resulted in responses in 35 (78%) of 45 patients; 24 (53%) achieved complete response. Interestingly, these rates were still higher than observed in the original (2017) prospective trial, and we also found a shift towards deeper responses with time. This is explained by the prolonged time to response seen in many patients, probably related to long-lived plasma cells. In patients responding to rituximab-bendamustine, median response duration was not reached after 88 months, and estimated 5-year sustained remission was 77%. The regimen appeared safe regarding late-occurring malignancies. Rituximab plus fludarabine therapy seems to carry a higher risk of long-term adverse effects.

IntroductionThe epidemiology, pathogenetic mechanisms and clinical features of chronic cold agglutinin disease (CAD) have been quite extensively elucidated in the literature, 1-5 but therapy remains suboptimal. [6][7][8][9][10] Although most authors emphasize the importance of avoiding cold exposure, a population based study showed that drug therapy had been attempted in more than 70% of the patients, 9 indicating that counseling is insufficient as sole therapeutic measure in a majority. The requirement for effective pharmacologic treatment is also highlighted by hemoglobin (Hgb) levels less than 8.0 g/dL in one-third and cold-induced circulatory symptoms in more than 90% of unselected patients with CAD, whereas 50% of such patients were found to have received blood transfusions during the course of the disease. 9 Corticosteroids, conventional immunosuppressive drugs and alkylating agents are generally ineffective. 6,9 Treatment with the monoclonal anti-CD20 antibody rituximab is the only well-documented effective therapy, leading to partial responses (PRs) in 45%-60% of the patients, but complete responses (CRs) are rare. 9,11,12 A median response duration of 11 months (range, 2-42 months) has been reported. 11 Although rituximab therapy is effective in polyclonal autoimmune diseases, 13,14 part of the rationale for rituximab in CAD was the demonstration of a monoclonal, B-cell lymphoproliferative bone marrow disorder in more than 90% of patients traditionally classified as having primary CAD. 4,9,11 Histologic signs of nonHodgkin B-cell lymphoma were present in bone marrow biopsy specimens from 75% of unselected patients with CAD in a population based study. 9 The most frequent type was lymphoplasmacytic lymphoma (LPL), which was found in 50% of the patients.We wanted to improve on the results achieved by rituximab single-agent therapy in patients with primary CAD. The purine analogues, eg fludarabine and cladribine, are powerful therapeutic agents in a variety of lymphoproliferative diseases. Although therapy with fludarabine for CAD has not been studied systematically, successful treatment was reported in one patient. 15 Histologic remission of the bone marrow lymphoproliferative disorder was observed after cladribine therapy in a series of 5 patients, but clinical remission was not achieved. 8 Fludarabine therapy, alone or in combination with rituximab, has yielded high response rates in Waldenström macroglobulinemia (WM), which is considered a closely related entity. [16][17][18] Furthermore, treatment with the fludarabine and rituximab combination has been found feasible and efficient in follicular lymphoma. 19 In the present study we have investigated the potential of fludarabine and rituximab in combination in patients with CAD requiring treatment. Methods Study designWe conducted a prospective, uncontrolled multicenter trial of combination therapy with fludarabine and rituximab in patients with CAD requiring An Inside Blood analysis of this article appears at the front of this issue.The publication cos...

Key Points Bendamustine-rituximab therapy results in high overall and CR rates with sustained remissions in CAD. Bendamustine plus rituximab may be considered in first line for most patients with CAD requiring therapy.

IntroductionHuman cytomegalovirus (HCMV) infection represents a major clinical problem in immunocompromised persons, including transplant recipients and AIDS patients. Prevalence of HCMV seropositivity ranges between 50% and 90% in healthy adults; after primary infection, the virus establishes lifelong latency in the host. 1 Usually, CMV in immunocompromised patients is caused by the reactivation of latent virus. A number of studies have suggested that the virus may aggravate immunodeficiency by interfering with antigen presentation. [2][3][4][5][6][7] In these publications, dendritic cells (DCs) have been generated from monocytes or CD34 ϩ bone marrow progenitor cells after 5 to 12 days of cytokine-supplemented culture. Such monocyte-derived DCs (moDCs) or bone marrowderived Langerhans cells are highly potent stimulators of T-cell activation. Exposure of these DCs to HCMV leads to functional paralysis of the cells, causing impaired T-cell activation. [2][3][4][5][6][7] Several mechanisms for this immunosuppression have been suggested. First, major histocompatibility complex (MHC) class I and class II and costimulatory molecules are down-regulated, resulting in impaired antigen presentation and increased susceptibility to natural killer cell-mediated lysis. [2][3][4][5][6][7][8] Second, a virally induced, soluble immunosuppressive factor released by mature moDCs has been postulated by several groups and was recently identified as CD83. 5,7 Third, infection of immature moDCs is lytic and leads to cell death. 7 Studies of HCMV effects on moDCs and Langerhans cells have shed light on mechanisms for viral immune evasion. However, the results showing paralysis of antigen presentation also raise questions as to how HCMV can be so effectively controlled in the immunocompetent host. Most primary infections induce minimal symptoms, and there is no clear evidence for clinically relevant immunosuppression. 1 Reactivation of the latent virus is believed to happen frequently, 9,10 but it proceeds asymptomatically in a healthy host, indicating a successful immune response. Indeed, an impressively large part of the T-cell repertoire is HCMV specific in seropositive persons. Labeling with MHC class I tetramers in complex with HCMV peptides has shown that 1% to 4% of all CD8 ϩ T cells are specific for HCMV proteins. 11,12 In view of the low pathogenicity of HCMV in immunocompetent persons, paralysis of key antigen-presenting cells by the virus seems unlikely.Elegant studies in mice have elucidated mechanisms for successful immunity to murine CMV (MCMV). 13 After injection of virus into mice, a small subset of DCs, termed plasmacytoid dendritic cells (PDCs), produce high levels of IFN-␣, IL-12, and TNF-␣. The rapid innate response is followed by maturation of several welldefined DC subsets in the mouse spleen and initiation of a strong MCMV-directed T-cell response. Frequencies of infected DCs were generally low and were restricted to a subset expressing CD8␣. These results show a high degree of specialization between murine DCs ...