Pure red-cell aplasia due to parvovirus B19 infection in a patient treated with alemtuzumab

Principles of alemtuzumab immunoablation in hematopoietic cell transplantation for non-malignant diseases in children: A review

Alemtuzumab is a humanized mAb targeted to CD52. Alemtuzumab is highly immunosuppressive with the ability to deplete T and B cells (in addition to other immune cell lines). A growing understanding of the PKs, dosing, and timing of administration of alemtuzumab has allowed for the study of its use as a conditioning agent for allogeneic HCT. The highly immunosuppressive properties of the drug are particularly appealing in the setting of non-malignant HCT, where GVHD provides no clinical benefit and relapse of malignancy is not applicable. In addition, the degree of immune suppression achieved with alemtuzumab has allowed for a reduction in the intensity of myeloablative cytotoxic agents included in some HCT conditioning regimens, allowing for fewer acute and late toxicities. This review paper will provide a comprehensive summary of the mechanism of action, PKs, dosing, and timing of alemtuzumab, a brief description of its use in various allogeneic HCT protocols for non-malignant conditions and a summary of the data regarding its use for GVHD therapy. The goal of this review was to provide an understanding as to how alemtuzumab might be safely incorporated into HCT conditioning regimens for children with non-malignant disease, allowing for expanded access to curative HCT therapy.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

CD48 as a novel molecular target for antibody therapy in multiple myeloma

Monoclonal antibody (mAb) drugs are desirable for the improvement of multiple myeloma (MM) treatment. In this study, we found for the first time that CD48 was highly expressed on MM plasma cells. In 22 out of 24 MM patients, CD48 was expressed on more than 90% of MM plasma cells at significantly higher levels than it was on normal lymphocytes and monocytes. CD48 was only weakly expressed on some CD34(+) haematopoietic stem/progenitor cells, and not expressed on erythrocytes or platelets. We next examined whether CD48 could serve as a target antigen for mAb therapy against MM. A newly generated in-house anti-CD48 mAb induced mild antibody-dependent cell-mediated cytotoxicity and marked complement-dependent cytotoxicity against not only MM cell lines but also primary MM plasma cells in vitro. Administration of the anti-CD48 mAb significantly inhibited tumour growth in severe combined immunodeficient mice inoculated subcutaneously with MM cells. Furthermore, anti-CD48 mAb treatment inhibited growth of MM cells transplanted directly into murine bone marrow. Finally and importantly, we demonstrated that the anti-CD48 mAb did not damage normal CD34(+) haematopoietic stem/progenitor cells. These results suggest that the anti-CD48 mAb has the potential to become an effective therapeutic mAb against MM.

Pure red cell aplasia caused by parvovirus B19 in two patients without chronic hemolysis

Infection with human parvovirus B19 (PVB19) induces acquired pure red cell aplasia (PRCA). Chronic hemolytic anemia is well known as an underlying condition. However, additional factors have been recognized to accompany parvoviral PRCA; however, there are only limited reports on iron-deficiency anemia (IDA) and rituximab-induced B-cell dysfunction. We report two patients with PVB19-associated PRCA confirmed by positivity of viral DNA. Although they had no chronic hemolysis, patient 1 had IDA, and patient 2 had remitted small-lymphocytic lymphoma treated with rituximab-containing chemotherapy. Absence of reticulocytes in peripheral blood and marked depletion of erythroid precursors in bone marrow were observed both. Whereas patient 1 received only symptomatic therapy because anemia was not severe, patient 2 was treated with steroids, as PRCA etiology was at first uncertain, and immunological PRCA was not excluded. Both showed rapid increase of reticulocyte counts and recovery from anemia. Although immunoglobulin is considered effective for parvoviral PRCA, notable adverse reactions have been reported. When anemic symptom is not severe, reticulocyte observation only is recommended. The effects of steroids should also be re-evaluated. Optimal treatment according to disease severity remains to be established.

Acquired pure red cell aplasia associated with malignant lymphomas: a nationwide cohort study in Japan for the PRCA Collaborative Study Group

Pure red cell aplasia (PRCA) has been reported in association with lymphoma as one of the autoimmune diseases seen during the course of lymphoid malignancies. However, the relation of PRCA with the underlying lymphomas remains unclear. The aim of this study was to clarify the histologic subtypes of lymphomas, the chronological sequence of anemia and lymphoma, and the response to treatment. We conducted a nationwide survey in Japan. From a cohort of 185 PRCA patients, 8 patients with lymphoma were evaluated. Histologic subtypes varied and the lymphoma was of the B-cell type in four cases and of the T-cell type in four. Four patients simultaneously developed PRCA and lymphoma. Three patients developed PRCA following lymphoma, two of whom developed anemia during remission of lymphoma. PRCA preceded lymphoma in one patient. Effective chemotherapy was associated with remission of anemia in concurrent lymphoma and PRCA. Overall, anemia responded to chemotherapy and/or immunosuppressive therapy in seven patients. In four responding patients, PRCA remained in durable remission without maintenance immunosuppressive therapy, which is different from a recurrent feature of idiopathic PRCA. We suggest that the mechanism of lymphoma-associated PRCA is heterogeneous and that durable maintenance-free remission of anemia can be obtained in some patients.

Acquired pure red cell aplasia: updated review of treatment

Pure red cell aplasia (PRCA) is a syndrome characterized by a severe normocytic anaemia, reticulocytopenia, and absence of erythroblasts from an otherwise normal bone marrow. Primary PRCA, or secondary PRCA which has not responded to treatment of the underlying disease, is treated as an immunologically-mediated disease. Although vigorous immunosuppressive treatments induce and maintain remissions in a majority of patients, they carry an increased risk of serious complications. Corticosteroids were used in the treatment of PRCA and this has been considered the treatment of first choice although relapse is not uncommon. Cyclosporine A (CsA) has become established as one of the leading drugs for treatment of PRCA. However, common concerns have been the number of patients treated with CsA who achieve sustained remissions and the number that relapse. This article reviews the current status of CsA therapy and compares it to other treatments for diverse PRCAs.

Late onset of autoimmune hemolytic anemia and pure red cell aplasia after allogeneic hematopoietic stem cell transplantation using in vivo alemtuzumab

Hemolytic anemia and pure red cell aplasia (PRCA) after allogeneic hematopoietic stem cell transplantation (HSCT) have been reported to be mainly related to ABO-incompatibility between donor and recipient. Autoimmune hemolytic anemia (AIHA) without ABO-incompatibility has been also reported after allogeneic HSCT, especially with T-cell depletion. However, optimal management of AIHA or PRCA remains unclear. A 54-year-old male with myelodysplastic syndrome (MDS) underwent haploidentical human leukocyte antigen-mismatched HSCT using in vivo alemtuzumab and developed AIHA and PRCA simultaneously 15 months after transplantation, following the administration of cidofovir and probenecid for persistent cytomegalovirus (CMV) antigenemia and retinitis. AIHA was successfully treated with rituximab, and subsequently PRCA with cyclosporine without relapse of MDS or recurrence of CMV infection. The clinical course suggested that AIHA was mainly caused by humoral immune response, while PRCA was mainly caused by cell-mediated immune response in this patient, although these immune responses might be related to each other.

Spectrum of infection, risk and recommendations for prophylaxis and screening among patients with lymphoproliferative disorders treated with alemtuzumab*

There is an increasing use of monoclonal antibodies in the treatment of haematological malignancies. Alemtuzumab (Campath-1H; Ilex Pharmaceuticals, San Antonio, TX, USA) is a monoclonal antibody reactive with the CD52 antigen used as first and second line therapy for two types of lymphoproliferative disorders: chronic lymphocytic leukaemia (CLL), and T-cell lymphomas [both peripheral (PTCL) and cutaneous (CTCL)]. With alemtuzumab therapy, viral, bacterial and fungal infectious complications are frequent, and may be life threatening. An understanding of the patients at highest risk and duration of risk are important in developing recommendations for empirical management, antimicrobial prophylaxis and targeted surveillance. This review discusses the infection risks associated with these lymphoproliferative disorders and their treatment, and provide detailed recommendations for screening and prophylaxis.

Pure red cell aplasia in B-cell lymphoproliferative disorder treated with rituximab: Report of two cases and review of the literature

Pure red cell aplasia (PRCA) is an unusual cause of anemia in patients with chronic lymphoproliferative disorders. Here, we present two cases of PRCA, one associated with chronic lymphocytic leukemia (CLL) and the other with splenic marginal zone lymphoma, in which the PRCA responded dramatically to treatment with rituximab. We then review the literature on PRCA in lymphoma and response to rituximab. PRCA associated with CLL or lymphoma may be another indication for rituximab therapy.

Severe and prolonged myeloid haematopoietic toxicity with myelodysplastic features following alemtuzumab therapy in patients with peripheral T-cell lymphoproliferative disorders

Alemtuzumab is effective therapy for B- and T-cell lymphoproliferative disorders (LPD) but is associated with prolonged lymphopenia. Myeloid haematological toxicities are less well described, especially in T-cell disorders, and are usually transient. We report myeloid toxicities in a phase II trial of alemtuzumab for T-cell LPD. Five of 11 patients treated developed severe neutropenia and thrombocytopenia. Three cases had prolonged cytopenias (32-88+ weeks), including two with severe marrow hypoplasia. We observed three incidences of trilineage morphological myelodysplasia, two with new clonal cytogenetic abnormalities. Alemtuzumab can be associated with prolonged severe multilineage cytopenias, marrow hypoplasia and myelodysplasia in T-cell LPD.

Successful high-titer immunoglobulin therapy for persistent parvovirus B19 infection in a lymphoma patient treated with rituximab-combined chemotherapy

A 40-year-old female diagnosed with follicular lymphoma was treated with rituximab-combined chemotherapy. Although she achieved complete remission, she developed progressive anemia and reticulocytopenia. Bone marrow examination revealed features of pure red cell aplasia and hemophagocytosis. In addition, the appearance of large pronormoblasts suggested that she was infected with parvovirus B19. Excess viral DNA in her bone marrow confirmed that her illness was caused by persistent parvovirus B19 infection. Serum immunoglobulin levels decreased beyond the lower normal limit, which indicated that her humoral immunity was impaired after rituximab-combined chemotherapy. Although she had been infected with parvovirus B19, she was re-infected and failed to control the viral expansion. High-titer immunoglobulin against parvovirus B19 was intravenously administrated and resulted in remarkable reticulocytosis and improvement of anemia. High-titer immunoglobulin, which contained a sufficient amount of neutralizing antibodies against parvovirus B19, likely inactivated most viruses in vivo. We successfully eradicated the virus after 2 courses of high-dose therapy at 0.5 g/kg/day every week followed by 8 courses of maintenance therapy at 0.1 g/kg/day every other week. It is important to consider that parvovirus B19 infection is a possible cause of progressive anemia in B-cell lymphoma patients treated with rituximab-combined chemotherapy. We propose that the use of high-titer immunoglobulin against parvovirus B19 may enable such immunocompromised patients to eradicate the virus before sufficient immune system reconstruction.

Alemtuzumab: effective monotherapy for simultaneous B-cell chronic lymphocytic leukaemia and Sézary syndrome

The simultaneous presentation of chronic lymphocytic leukaemia (CLL) and cutaneous T-cell lymphoma (CTCL) is a very rare occurrence where optimal treatment is unknown. We present the case of a 65-yr-old man who was successfully treated with alemtuzumab monotherapy for both disorders, but at a cost of severe infectious morbidity and prolonged pancytopenia.

Treatment of patients with advanced mycosis fungoides and Sézary syndrome with alemtuzumab

OBJECTIVES

Alemtuzumab (anti-CD52, Campath-1H) has recently been shown to be effective in the treatment of a range of hematological malignancies, including B-cell chronic lymphocytic leukemia and T-cell prolymphocytic leukemia. We undertook a phase II study to evaluate the safety, tolerability and efficacy of alemtuzumab in patients with relapsed or refractory advanced stage cutaneous T-cell lymphoma.

PATIENTS AND METHODS

A total of eight patients were enrolled, seven with mycosis fungoides/Sézary syndrome (MF/SS) and one with large-cell transformation of MF. Seven patients had disease refractory to multiple previous therapies. Alemzumab (30 mg) was administered intravenously three times per week for 12 wk or until maximum response.

RESULTS

The overall response rate was 38%, with three patients achieving partial remission, two patients with stable disease and three patients with progressive disease (PD) during treatment. The time to progression was short, with all patients developing PD within 4 months of starting alemtuzumab. Response duration in the three PR patients was also brief, with responses lasting less than 3 months in all three cases. Significant hematological and immunosuppressive toxicity was observed, with both grade 3-4 cytopenias and significant infectious complications occurring in a majority of cases.

CONCLUSIONS

Our findings suggest that in heavily pretreated, refractory, advanced stage MF/SS, although alemtuzumab has biological activity, it is associated with significant toxicity and only modest clinical utility. As such, combination regimens incorporating alemtuzumab merit further investigation in this difficult to treat patient group.