Cold agglutinin disease: where do we stand, and where are we going?

Primary cold agglutinin disease (CAD) is characterized by a very indolent bone marrow clonal B-cell lymphoproliferative disorder that initiates an autoimmune hemolytic anemia. The clonal B cells produce a monoclonal autoantibody termed cold agglutinin, most often of the immunoglobulin (Ig) Mκ class. After binding to its antigen, the IgM initiates a complement classical pathway-driven erythrocyte destruction, predominantly mediated by opsonization with complement protein C3b and extravascular hemolysis in the liver. We review the molecular biology, histopathology, clinical features, and diagnostic procedures in CAD. Some patients are only slightly anemic and do not require treatment, but moderate or severe anemia frequently occurs, and the disease burden has been underestimated. CAD should not be treated with corticosteroids. Several B-cell-directed treatment options are available, and complement-directed approaches are being rapidly developed. Current and possible future therapies are reviewed.

Cold agglutinin disease revisited: a multinational, observational study of 232 patients.

We retrospectively studied 232 patients with cold agglutinin disease (CAD) at 24 centers in 5 countries. In Norway and a northern region of Italy, the study was close to being population-based. For the first time, we demonstrate fourfold differences between cold and warmer climates regarding prevalence (20 vs 5 cases/million) and incidence (1.9 vs 0.48 cases/million per 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 includes 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 toward 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.

Cold agglutinin disease: current challenges and future prospects.

Cold agglutinin disease (CAD) is a complement-dependent, classical pathway-mediated immune hemolytic disease, accounting for 15-25% of autoimmune hemolytic anemia, and at the same time, a distinct clonal B-cell lymphoproliferative disorder of the bone marrow. The disease burden is often high, but not all patients require pharmacological treatment. Several therapies directed at the pathogenic B-cells are now available. Rituximab plus bendamustine or rituximab monotherapy should be considered first-line treatment, depending on individual patient characteristics. Novel treatment options that target the classical complement pathway are under development and appear very promising, and the C1s inhibitor sutimlimab is currently being investigated in two clinical Phase II and III trials. These achievements have raised new challenges and further prospects, which are discussed. Patients with CAD requiring therapy should be considered for clinical trials.

Development of Multiple Myeloma of the IgA Type in a Patient with Cold Agglutinin Disease: Transformation or Coincidence?

Cold agglutinin disease (CAD) is an autoimmune hemolytic anemia and a distinct, clonal bone marrow lymphoproliferative disorder, characterized in most cases by a monoclonal IgMκ serum protein. We describe a CAD patient presenting with a monoclonal immunoglobulin of the IgAλ class. For years, she remained asymptomatic apart from the hemolytic anemia until eventually she developed multiple myeloma (MM) of the IgAλ phenotype. Prior to the development of MM, her hemolytic anemia responded to rituximab monotherapy. After she was diagnosed with MM, both conditions responded well to bortezomib-based therapy. We performed further investigations to determine whether her MM represented a progression/transformation of CAD or an independent disease. Flow cytometry and biopsy findings convincingly confirmed two unrelated clonal B-cell disorders. On this background, we also discuss previously published reports on cold agglutinin activity in patients with IgA gammopathy. In conclusion, cold agglutinins of the IgA class do probably not result in CAD. If a monoclonal immunoglobulin other than IgMκ is found in a patient with CAD, the coexistence of two unrelated B-cell clones should be suspected.

Richter syndrome epidemiology in a large population based chronic lymphocytic leukemia cohort from Norway.

BACKGROUND: Transformation to aggressive lymphoma (Richter syndrome, RS) occurs in a substantial subset of patients who must discontinue targeted therapy for chronic lymphocytic leukemia (CLL). RS has an extremely poor prognosis. METHODS: Using the nation-wide database of The Cancer Registry of Norway of 7664 CLL patients registered between 1953-2012, we identified 107 patients experiencing RS. RESULTS: Seventy seven (72%) of RS patients were identified among 2631 CLL patients diagnosed between 2003-2012; diffuse large B-cell lymphoma (DLBCL) was identified in 65 (84%), Hodgkin lymphoma (HL) in 12 (16%) patients and the diagnosis was confirmed in 50 (65%) available biopsy specimens. The incidence rate in this period was 4.7/1000 person-years (95% CI: 3.8-5.9). The median survival from CLL diagnosis was 1.7 years (95% CI: 0.34-2.3) for RS patients while it was 10.3 years (95% CI: 9.5-10.9) for the remaining CLL patients. Male gender predominated among RS patients (69%) compared to CLL population (58%) and RS patients were diagnosed with CLL at a significantly younger age than the remaining patients (65 vs. 72 years). Median time from diagnosis of CLL to RS was 2 years (Range, 0-13 years). No CLL treatment was administered in 25 (33%) patients prior RS diagnosis; a median of 1 treatment line was administered to pretreated patients. The median duration of survival after RS diagnosis was 27 months (95% CI; 9-88). CONCLUSIONS: Collectively, RS was a rare complication of CLL in the chemoimmunotherapy era, occurred early in the CLL course in younger, and both treatment naïve and pretreated patients, and shortened survival substantially.

Neutropenia caused by hairy cell leukemia in a patient with myelofibrosis secondary to polycythemia vera: a case report.

BACKGROUND: Polycythemia vera is a myeloproliferative disease that sometimes evolves to myelofibrosis, causing splenomegaly and neutropenia. In this case report, we describe a patient with polycythemia vera and unexplained neutropenia who later turned out to also have hairy cell leukemia. CASE PRESENTATION: A middle-aged Caucasian man with polycythemia vera presented to our hospital with chronic mouth ulcers. Later he developed leukopenia and pancytopenia. Bone marrow biopsies showed fibrosis. Further morphological analyses of bone marrow and blood smears revealed probable transformation into acute myeloid leukemia. However, there were also cells indicating hairy cell leukemia. Morphological and immunohistochemical analyses later confirmed the presence of hairy cell leukemia in biopsies that had been present for 3 years. Treatment with cladribine temporarily reversed the patient's neutropenia. CONCLUSIONS: Hairy cell leukemia may mimic development to myelofibrosis in patients with polycythemia vera.

Bendamustine plus rituximab for chronic cold agglutinin disease: results of a Nordic prospective multicenter trial.

Primary chronic cold agglutinin disease (CAD) is a well-defined clinicopathologic entity in which a bone marrow clonal B-cell lymphoproliferation results in autoimmune hemolytic anemia and cold-induced circulatory symptoms. Rituximab monotherapy and fludarabine-rituximab in combination are documented treatment options. In a prospective, nonrandomized multicenter trial, 45 eligible patients received rituximab 375 mg/m2 day 1 and bendamustine 90 mg/m2 days 1 and 2 for 4 cycles at a 28-day interval. Thirty-two patients (71%) responded; 18 (40%) achieved complete response (CR) and 14 (31%) partial response (PR). Among 14 patients previously treated with rituximab or fludarabine-rituximab, 7 (50%) responded to bendamustine-rituximab (3 CR and 4 PR). Hemoglobin levels increased by a median of 4.4 g/dL in the complete responders, 3.9 g/dL in those achieving PR, and 3.7 g/dL in the whole cohort. The 10th percentile of response duration was not reached after 32 months. Grade 3-4 neutropenia occurred in 15 patients (33%), but only 5 (11%) experienced infection with or without neutropenia. Thirteen patients (29%) had their dose of bendamustine reduced. In conclusion, bendamustine-rituximab combination therapy is highly efficient, sufficiently safe, and may be considered in first line for patients with CAD requiring therapy. The trial was registered at www.clinicaltrials.gov as #NCT02689986.

Cold agglutinin-mediated autoimmune hemolytic anemia.

Cold antibody types account for about 25% of autoimmune hemolytic anemias. Primary chronic cold agglutinin disease (CAD) is characterized by a clonal lymphoproliferative disorder. Secondary cold agglutinin syndrome (CAS) complicates specific infections and malignancies. Hemolysis in CAD and CAS is mediated by the classical complement pathway and is predominantly extravascular. Not all patients require treatment. Successful CAD therapy targets the pathogenic B-cell clone. Complement modulation seems promising in both CAD and CAS. Further development and documentation are necessary before clinical use. We review options for possible complement-directed therapy.

Primary cold agglutinin-associated lymphoproliferative disease: a B-cell lymphoma of the bone marrow distinct from lymphoplasmacytic lymphoma.

Primary chronic cold agglutinin disease is a rare hemolytic disease mediated by monoclonal IGHV4-34-encoded cold agglutinins with a predominant specificity for the blood group antigen I. Bone marrow from 54 patients was studied to type the underlying lymphoproliferative disorder better. Bone marrow biopsies showed circumscribed intra-parenchymatous nodules with small monotonous monoclonal B cells in 40/54 patients (median infiltration: 10% of marrow cells) with a CD20(+), IgMs(+), IgDs(+), CD27(+), CD5(-/+), CD11c(-), CD23(-), CD38(-) immunophenotype. Neither plasmacytoid cytological features nor expression of plasma cell differentiation-associated transcription factors MUM1, XBP1 and BLIMP1 were noted in these B cells. However, a limited number of mature monoclonal IgM(+), IgD(-) plasma cells were present outside the lymphoid nodules and were diffusely scattered throughout the marrow. Of interest, the MYD88 L265P mutation, typical of lymphoplasmacytic lymphoma, was not detected (17/17 cases). Somatically mutated monoclonal IGHV4-34 gene rearrangement was demonstrated in eight patients with frozen samples (mean sequence homology 95.4%). However, mutations of BCL6 intron 1 were not demonstrated, except in one patient, suggesting that the lymphoma cells had not matured in the germinal center. In conclusion, cold agglutinin-associated lymphoproliferative disease displays homogeneous histological and immunophenotypic features. The absence of plasmacytoid cells, the presence of plasma cells predominantly outside the nodular lymphoid infiltrates, IGHV4-34 restriction and absence of MYD88 L265P mutation strongly suggest that cold agglutinin-associated lymphoproliferative disease is a distinct entity that is different from lymphoplasmacytic lymphoma.

Bone marrow histology in monoclonal B-cell lymphocytosis shows various B-cell infiltration patterns.

Monoclonal B-cell lymphocytosis (MBL) is defined as less than 5 × 10(9)/L monoclonal B cells in the blood of otherwise healthy patients and is detected in 5% to 10% of individuals older than 60 years. The bone marrow findings in MBL have hitherto not been systematically described. We have studied the histologic and immunophenotypic findings in paired trephine biopsy specimens and bone marrow aspirates of 26 patients with MBL. Abnormal lymphoid infiltration was detected in trephine biopsy specimens of 20 patients and was demonstrated by flow cytometry of bone marrow in all 26 patients. Three infiltration patterns were discerned: focal interstitial lymphoid infiltration, focal rounded and nonparatrabecular lymphoid aggregates, and discrete diffuse lymphocytosis. Focal interstitial lymphoid infiltration was seen only in patients with chronic lymphocytic leukemia (CLL)-like or atypical CLL-like MBL, whereas the other patterns were not related to a particular MBL immunophenotype. Our results show that most patients with MBL also have bone marrow lymphoid infiltration. The latter should be distinguished from lymphoma infiltration by clinical correlation.

Splenic marginal zone lymphoma with VH1-02 gene rearrangement expresses poly- and self-reactive antibodies with similar reactivity.

One-third of all splenic marginal zone lymphomas (SMZL) use the IgH VH1-02 gene. These cases are usually not associated with hepatitis C virus infection. Of interest, the rearranged VH1-02 genes display similar complementarity determining regions 3, a finding confirmed by our study. The latter suggests that these SMZL may produce antibodies with similar reactivity. We produced recombinant antibodies from 5 SMZL cases with VH1-02 gene rearrangement to study the binding reactivity of these antibodies. Surprisingly, the recombinant antibodies demonstrated poly- and self-reactivity as demonstrated by their reactivity with nuclear, cytoplasmic, as well as membranous antigens expressed by human cells and by reactivity with human serum. This polyreactivity was specific as demonstrated by ELISA. The antibodies did not react with proteins on the cell surface that are induced by apoptosis as shown for antibodies produced by chronic lymphatic leukemia with VH1-02 gene rearrangement. The results indicate that a common subset of SMZL arises from polyreactive B cells, a subset of marginal zone B cells that are important in the immunologic defense against infection.

Mantle cell lymphoma with features of marginal-zone lymphoma.

We present seven cases of mantle cell lymphoma with morphological features of marginal-zone lymphoma. Of particular interest, four of the patients had predominant involvement of the gastrointestinal tract. All cases displayed the translocation t(11;14)(q13;q32) and expressed cyclin D1. Cytogenetic analysis revealed trisomy 3 in one case and somatic hypermutation of immunoglobulin heavy genes could be demonstrated in two out of four cases. The latter features are reminiscent of marginal-zone lymphoma. The localization of these lymphomas mainly in the gastrointestinal tract and the higher exposure to antigens in this area may explain why this variant of mantle cell lymphoma harbours features of marginal-zone lymphoma.

High response rate and durable remissions following fludarabine and rituximab combination therapy for chronic cold agglutinin disease.

Most patients diagnosed with primary chronic cold agglutinin disease (CAD) have a clonal lymphoproliferative bone marrow disorder. Treatment with rituximab is the only well-documented effective therapy, leading to 45%-60% partial responses (PR). Complete responses (CR) are rare, and median response duration is only 11 months. In a prospective multicenter trial, 29 patients received rituximab 375 mg/m(2) on days 1, 29, 57 and 85; and fludarabine orally, 40 mg/m(2) on days 1-5, 29-34, 57-61 and 85-89. Twenty-two patients (76%) responded, 6 (21%) achieving CR and 16 (55%) PR. Among 10 patients nonresponsive to rituximab monotherapy, 1 achieved CR and 6 PR. Median increase in hemoglobin level was 3.1 g/dL among the responders and 4.0 g/dL in those who achieved CR. Lower quartile of response duration was not reached after 33 months. Estimated median response duration was more than 66 months. Grade 3-4 hematologic toxicity occurred in 12 patients (41%). In conclusion, fludarabine and rituximab combination therapy is very efficient in patients with CAD. Toxicity may be a concern, and benefits should be carefully weighed against risks in very old and comorbid patients. It remains to be established whether the combination should be first-line or an efficient second-line therapy in CAD patients requiring treatment.