Selective targeting of multiple myeloma cells with a monoclonal antibody recognizing the ubiquitous protein CD98 heavy chain

Cancer-specific cell surface antigens are ideal therapeutic targets for monoclonal antibody (mAb)-based therapy. Here, we report that multiple myeloma (MM), an incurable hematological malignancy, can be specifically targeted by an mAb that recognizes a ubiquitously present protein, CD98 heavy chain (hc) (also known as SLC3A2). We screened more than 10,000 mAb clones raised against MM cells and identified R8H283, an mAb that bound MM cells but not normal hematopoietic or nonhematopoietic cells. R8H283 specifically recognized CD98hc. R8H283 did not react with monomers of CD98hc; instead, it bound CD98hc in heterodimers with a CD98 light chain (CD98lc), a complex that functions as an amino acid transporter. CD98 heterodimers were abundant on MM cells and took up amino acids for constitutive production of immunoglobulin. Although CD98 heterodimers were also present on normal leukocytes, R8H283 did not react with them. The glycoforms of CD98hc present on normal leukocytes were distinct from those present on MM cells, which may explain the lack of R8H283 reactivity to normal leukocytes. R8H283 exerted anti-MM effects without damaging normal hematopoietic cells. These findings suggested that R8H283 is a candidate for mAb-based therapies for MM. In addition, our findings showed that a cancer-specific conformational epitope in a ubiquitous protein, which cannot be identified by transcriptome or proteome analyses, can be found by extensive screening of primary human tumor samples.

The First Case of Non-leukemic Sarcoma Composed of Mixed-phenotype Acute Leukemia, B/myeloid, Not Otherwise Specified

Isolated sarcoma with features of mixed-phenotype acute leukemia (MPAL) is an extremely rare disease and it can be easily misdiagnosed as lymphoma or other malignancies. We herein report the case of a 61-year-old woman with non-leukemic sarcoma of the right pleura, pretracheal lymph node, and supraclavicular lymph node with features of MPAL, B/myeloid, not otherwise specified, which was first misdiagnosed as diffuse large B cell lymphoma. After performing a detailed re-examination of the biopsy specimens, few scattered eosinophilic myelocytes allowed us to reach a correct diagnosis of MPAL and the patient was thereafter successfully treated by intensified chemotherapy followed by cord blood transplantation.

The activated conformation of integrin β7 is a novel multiple myeloma-specific target for CAR T cell therapy

Cancer-specific cell-surface antigens are ideal targets for monoclonal antibody (mAb)-based immunotherapy but are likely to have previously been identified in transcriptome or proteome analyses. Here, we show that the active conformer of an integrin can serve as a specific therapeutic target for multiple myeloma (MM). We screened >10,000 anti-MM mAb clones and identified MMG49 as an MM-specific mAb specifically recognizing a subset of integrin β₇ molecules. The MMG49 epitope, in the N-terminal region of the β₇ chain, is predicted to be inaccessible in the resting integrin conformer but exposed in the active conformation. Elevated expression and constitutive activation of integrin β₇ conferred high MMG49 reactivity on MM cells, whereas MMG49 binding was scarcely detectable in other cell types including normal integrin β₇⁺ lymphocytes. T cells transduced with MMG49-derived chimeric antigen receptor (CAR) exerted anti-MM effects without damaging normal hematopoietic cells. Thus, MMG49 CAR T cell therapy is promising for MM, and a receptor protein with a rare but physiologically relevant conformation can serve as a cancer immunotherapy target.

Pulmonary Involvement of Acute Myeloid Leukemia Mimicking Transfusion-related Acute Lung Injury

Transfusion-related acute lung injury (TRALI) is defined as a new episode of acute lung injury (ALI) occurring during transfusion or within 6 hours of transfusion completion. A 66-year-old man suffering from acute myeloid leukemia developed acute respiratory distress syndrome after platelet transfusion. TRALI was diagnosed clinically, but an autopsy showed leukemic cells in diffuse pulmonary edema. Anti-human neutrophil antigen (HNA)-3a antibodies were detected in the donor serum, and the HNA-3 genotype of the patient was identified as a/a. This case was considered to represent pulmonary involvement of acute myeloid leukemia, rather than TRALI. A revision of the definition of TRALI accounting for hematological malignancies should therefore be considered.

An unusual clinical presentation of lupus erythematosus tumidus localized on the thigh

A 44-year-old woman with seronegative polyarthritis presented with a 2-year history of a solitary, bluish-red, oedematous, nonscaly, annular and partially reticulated macule on her right thigh. Histopathological findings revealed perivascular and periadnexal lymphocytic infiltrate in the dermis. Alcian blue and colloidal iron stains highlighted mucinous deposit in the upper and mid dermis. Direct immunofluorescence showed a linear deposit of IgG and C3 along the basement membrane zone. Antinuclear antibody was positive at a titre of 1 : 80, with homogenous and speckled patterns. Except for its unusual localization and lack of photosensitivity, our case had the clinical and histopathological features of lupus erythematosus tumidus. These characteristics were also reminiscent of reticular erythematous mucinosis and erythema annulare centrifugum, both of which are considered to be associated with cutaneous lupus erythematosus (CLE). Hydroxychloroquine 200 mg daily led to improvement of the skin lesion. The unusual clinical presentation of our case emphasizes the heterogeneity of clinical manifestations of CLE.

Phase II study of imatinib-based chemotherapy for newly diagnosed BCR-ABL-positive acute lymphoblastic leukemia

This study investigated the efficacy of imatinib based therapy with intensified consolidation therapy in patients with Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL) to prevent early relapse. We conducted a phase II trial of imatinib-combined chemotherapy for newly diagnosed BCR-ABL-positive ALL in adults. Sixty-eight patients were included in the trial between October 2008 and December 2010. The median age was 49 years, with 28 patients >55 years of age. Sixty-five patients achieved CR (95.6%). The estimated 2-year event-free survival (EFS) and overall survival (OS) were 62.3% and 67.4%, respectively. Allogeneic stem cell transplantation (allo-SCT) at initial CR was performed in 43 patients. Thirty-five of 39 patients <55 years and 8 of 26 patients >55 years underwent allo-SCT at first CR. The 3-year OS in patients <55 years receiving allo-SCT at first CR, patients >55 years receiving allo-SCT at first CR, patients <55 years not receiving allo-SCT at first CR, and patients >55 years not receiving allo-SCT at first CR were 80.4%, 41.1%, 32.5%, and 52.0%, respectively (P = 0.058). The three-year EFS in each group was 76.7%, 53.6%, not reached, and 26.4%, respectively (P = 0.150). A high CR rate was observed with imatinib-based chemotherapy allowing allo-SCT in a high proportion of patients, particularly those <55 years. Moreover, intensified consolidation therapy reduced early relapse rates following induction therapy and resulted in improved OS and EFS rates following allo-SCT. This trial was registered with the UMIN (000001226).

Wilms Tumor 1 (WT1) mRNA Expression Level at Diagnosis Is a Significant Prognostic Marker in Elderly Patients with Myelodysplastic Syndrome

BACKGROUND/AIMS

A high expression of Wilms tumor 1 (WT1) mRNA occurs in most cases of acute leukemia and myelodysplastic syndrome (MDS). Although there are many reports suggesting that acute myeloid leukemia patients with high expression levels of WT1 mRNA have a relatively poor long-term survival, there are few reports addressing the relationship between WT1 levels and prognosis in MDS.

METHODS

We retrospectively analyzed 42 elderly patients with MDS whose WT1 levels at diagnosis were available, and we assessed the relationships between WT1 levels in peripheral blood and preexisting prognostic factors such as World Health Organization prognostic scores and Revised International Prognostic Scoring System risk categories, bone marrow blast percentages, and chromosomal abnormalities linked to a poor prognosis. We also evaluated the relationship between WT1 levels and prognosis.

RESULTS

WT1 levels were significantly different between high- and low-risk MDS patients (p < 0.05). There was a trend towards a significant difference between those with and those without poor prognostic chromosomal rearrangements (p = 0.051). Moreover, the overall survival and progression-free survival were significantly worse in elderly patients with higher levels of WT1 (p = 0.00039 and p = 0.00077, respectively).

CONCLUSIONS

The WT1 mRNA expression level at diagnosis may be a significant independent prognostic marker for elderly patients with MDS.

[A Case of Small Intestinal Malignant Lymphoma Presenting with Perforated Peritonitis]

An 85-year-old man presented to the emergency department with vomiting. He had tenderness in the left abdomen and under the umbilicus. Laboratory data showed an increase in the inflammatory response. Enhanced abdominal computed tomography showed thickening ofthe small intestinal wall in the lower left abdomen with a small amount ofadjacent free air. The fat tissue around the small intestine also revealed a high density area suggestive of inflammation. A diagnosis of peritonitis caused by intestinal perforation was made and an emergency operation was performed. We resected part of the ileum about 90 cm from the ileum end. The resected specimen showed a 1 by 1 cm mass with an ulcer and perforation at the base of the tumor. Histopathological findings revealed densely increased numbers of monomorphic medium-sized lymphoma cells infiltrating into all layers ofthe intestine. Immunohistochemically, the lymphocytes were positive for CD3, CD20, CD30, and CD79a. We diagnosed diffuse large B-cell lymphoma. Two cycles ofchemotherapy were given post-operatively. A recurrence was not observed. After chemotherapy he was transferred to rehabilitation.

Reversible dasatinib-related pulmonary arterial hypertension in a CML patient

A 59-year-old man diagnosed with the chronic phase of chronic myeloid leukemia (CML) in June 2011 was started on dasatinib (100 mg/day). He had no signs of pleural effusion (PE) or right heart failure before treatment, but symptoms of PE and dyspnea (New York Heart Association class III) appeared in January 2013 and May 2014, respectively. Doppler transthoracic echocardiography and right heart catheterization revealed pulmonary arterial hypertension (PAH) with an estimated pulmonary artery systolic pressure (PASP) of 80 mmHg and estimated mean pulmonary artery pressure of 29 mmHg. Rheumatoid factor, antinuclear antibody, dsDNA antibody, and SCL70 were not elevated, and computed tomography confirmed the absence of a pulmonary embolism. Therefore, dasatinib-related PAH was diagnosed and treatment with this agent was discontinued. The PASP had decreased to 51 and 40 mmHg at one month and one year, respectively, after dasatinib discontinuation. This patient developed PAH while receiving dasatinib administration and only discontinuation of this agent improved his symptoms. The possibility that dasatinib can cause PAH must be considered before administering this agent to patients with CML.

Semi-mechanistic autoinduction model of midazolam in critically ill patients: population pharmacokinetic analysis

WHAT IS KNOWN AND OBJECTIVE

Midazolam (MDZ) is commonly used for sedating critically ill patients. The daily dose required for adequate sedation increases in increments over 100 h after administration. The objectives of this study were to characterize the MDZ pharmacokinetics in critically ill patients and to describe the phenomenon of increasing daily dose by means of population pharmacokinetic analysis.

METHODS

Data were obtained from 30 patients treated in an intensive care unit. The patients received MDZ intravenously as a combination of bolus and continuous infusion. Serum MDZ concentration was assayed by high-performance liquid chromatography. Population pharmacokinetic analysis was performed using the NONMEM software package. The alteration of clearance unexplained by demographic factors and clinical laboratory data was described as an autoinduction of MDZ clearance using a semi-mechanistic pharmacokinetic-enzyme turnover model.

RESULTS AND DISCUSSION

The final population pharmacokinetic model was a one-compartment model estimated by incorporating a semi-mechanistic pharmacokinetic-enzyme turnover model for clearance, taking autoinduction into account. A significant covariate for MDZ clearance was total bilirubin. An increase in total bilirubin indicated a reduction in MDZ clearance. From simulation using the population pharmacokinetic parameters obtained in this study, MDZ clearance increased 2·3 times compared with pre-induced clearance 100 h after the start of 12·5 mg/h continuous infusion.

WHAT IS NEW AND CONCLUSION

Autoinduction and total bilirubin were significant predictors of the clearance of MDZ in this population. Step-by-step dosage adjustment using this population pharmacokinetic model may be useful for establishing a MDZ dosage regimen in critically ill patients.

Recurrent DUX4 fusions in B cell acute lymphoblastic leukemia of adolescents and young adults

The oncogenic mechanisms underlying acute lymphoblastic leukemia (ALL) in adolescents and young adults (AYA; 15-39 years old) remain largely elusive. Here we have searched for new oncogenes in AYA-ALL by performing RNA-seq analysis of Philadelphia chromosome (Ph)-negative AYA-ALL specimens (n = 73) with the use of a next-generation sequencer. Interestingly, insertion of D4Z4 repeats containing the DUX4 gene into the IGH locus was frequently identified in B cell AYA-ALL, leading to a high level of expression of DUX4 protein with an aberrant C terminus. A transplantation assay in mice demonstrated that expression of DUX4-IGH in pro-B cells was capable of generating B cell leukemia in vivo. DUX4 fusions were preferentially detected in the AYA generation. Our data thus show that DUX4 can become an oncogenic driver as a result of somatic chromosomal rearrangements and that AYA-ALL may be a clinical entity distinct from ALL at other ages.

Analysis of the protective effects of a neuronal Cav2.1 calcium channel in brain injury

We previously reported that rolling Nagoya mice carrying a mutation in the α1 subunit of the Cav2.1 channel protective from ischemia- and kainate-induced neuronal damage. However, the protective effect of this mutation and its relationship to brain injury recovery have not been examined. To examine the relationship between Cav2.1 channel function and brain injury, we induced cryogenic brain damage in homozygous rolling Nagoya (rol/rol), control wild-type (+/+), ω-agatoxin IVA-pretreated +/+ (ω-aga +/+), and ω-agatoxin IVA-post-treated +/+ (ω-aga-post-treated +/+) mice. We measured the lesion area, blood brain-barrier permeability and performed immunohistochemistry and western blot analysis. The lesions of rol/rol and ω-aga +/+ mice were significantly smaller than those observed in +/+ mice at both day 1 and day 7 after injury. Similar results were shown in blood-brain barrier permeability. We observed more reactive astrogliosis in +/+ mice than in rol/rol or ω-aga +/+ mice. rol/rol and ω-aga +/+ mice had fewer degenerating cells due to cryogenic injury than did +/+ mice at both day 1 and day 7. ω-Aga-post-treated +/+ mice 24h after injury were sacrificed on day 7. The lesions were smaller in ω-aga-post-treated +/+ mice than those in vehicle-treated +/+ mice. We also examined phosphorylated p38 (pp38) at the injured site. ω-Aga-post-treated +/+ mouse brain slices showed weak pp38 signal; vehicle-treated +/+ mouse brain slices were pp38-positive. These findings demonstrate that the mutant Cav2.1 channel exerts a protective effect against cryogenic brain injury in rolling Nagoya mice. Our results indicate that inhibitors of the Cav2.1-dependent p38 signaling cascade would be useful as therapeutic agents in the treatment of brain injury.

[Effectiveness of azacitidine in chronic myelomonocytic leukemia harboring del(20q) - a case report]

A 7 1-year-old man was admitted to our hospital with leukocytosis and anemia. Chronic myelomonocytic leukemia (CMML)harboring del(20q)was diagnosed by peripheral blood examination and bone marrow aspiration. The patient was subsequently treated with azacitidine, which resulted in rapid disappearance of monocytosis and resolved his dependency on red cell transfusion. With regard to the chromosomal abnormality, although del(20q)is estimated to be encountered in approximately 0.7-1.0% of all CMML cases, its significance in prognosis has not been fully analyzed. Hence, more such cases need to be evaluated to elucidate the therapeutic outcome of CMML involving del(20q). In addition, the Wilms tumor-1(WT 1)level in the patient gradually decreased after the initiation of azacitidine therapy. This phenomenon of WT1 decrease synchronizing with the patient's clinical improvement might reflect therapeutic efficacy with regard to the clinical course, as had been observed in acute myeloid leukemia and myelodysplastic syndrome.

[Neutropenic enterocolitis after autologous peripheral blood stem cell transplantation in non-Hodgkin's lymphoma - a case report]

Here we report a case of a 59-year-old man who developed neutropenic enterocolitis(NE)after autologous peripheral blood stem cell transplantation for non-Hodgkin's lymphoma in his second complete remission.Four days after transplantation, the patient suffered from diarrhea, abdominal pain, fever, and paralytic ileus.Abdominal computerized tomography scan revealed bowel wall thickening consistent with NE.Owing to his poor performance status, only medical management, including antibiotics and bowel rest, was administered, and the patient died 18 days after transplantation.Although NE after autologous peripheral blood stem cell transplantation is a relatively rare complication, it is important to be aware that this condition can occur as one of the early complications in stem cell transplantation.

der(5;17)(p10;q10) is a recurrent but rare whole-arm translocation in patients with hematological neoplasms: a report of three cases

We report the cases of 3 patients with hematological malignancies and complex karyotypes involving der(5; 17) (p10;q10), which results in the loss of 5q and 17p. Although deletions of 5q and 17p are recurrent abnormalities in hematological disease, only about 20 cases harboring der(5; 17) (p10;q10) have been reported. We address the tumorigenesis and morphological characteristics of hematological malignancies involving der(5; 17)(p10;q10), along with a review of the literature.

[Usefulness of measuring serum procalcitonin levels by immunochromatographic assay in febrile neutropenia]

In order to clarify the usefulness of measuring procalcitonin (PCT) values under the extreme condition called febrile neutropenia (FN), PCT was measured with immunochromatographic assay (ICA) and electro-chemi-luminescence immunoassay (ECLIA) at two time points: upon FN occurrence and 12 to 24 hours after FN occurrence, and correlations and associations between the two methods were reviewed. A strong correlation between the ICA and ECLIA results was observed when Spearman's rank correlation coefficient was 0.878, and the association was also demonstrated by Fisher's direct test since P=4.68×10(-10). Special equipment is not required, the operations are simple, and the ICA method currently adopted by many facilities can be used as the standard method even for the clinical condition known as FN.

Chronic myelogenous leukemia after postoperative adjuvant S-1 therapy for rectal cancer: a case report

We report a case in which chronic myelogenous leukemia (CML) developed after postoperative adjuvant S-1 therapy for rectal cancer. A 56-year-old man was diagnosed with rectal adenocarcinoma, which was treated with abdominoperineal resection followed by a year of adjuvant S-1 therapy. At 39 postoperative months, he was diagnosed with CML. Although it remains unclear that CML that develops after treatment involving cytotoxic agents is treatment-related, clinicians should be aware of the possibility of CML developing after S-1 therapy.

A rare der(Y)t(Y;1)(q12;q12) in a patient with post-polycythemic myelofibrosis: a case report

We describe a case of post-polycythemic myelofibrosis harboring der(Y)t(Y;1)(q12;q12). The patient was a 69-year-old man and was initially diagnosed with polycythemia vera. During the clinical course of his condition, the polycythemia developed into myelofibrosis. Chromosome analysis detected der(Y)t(Y;1)(q12;q12). We discuss the association between der(Y)t(Y;1)(q11~12;q12~21) and tumorigenesis along with a review of literature.

Derivative (5;19)(p10;q10): a rare but recurrent whole-arm translocation in acute myeloid leukemia

A previous study of cases of myelodysplastic syndrome harboring der(5;19)(p10;q10) found that they displayed common characteristics including predominance in elderly men, dysplasia involving three hematopoietic lineages and CD7 expression in blasts. However, the whole-arm translocation der(5;19)(p10;q10) has not been fully analyzed because of its rarity. In this study we used flow cytometry to evaluate the immunophenotype of two patients' bone marrow mononuclear cells. Both patients had involved der(5;19)(p10;q10) in their karyotype analyzed by standard G-banding technique. Both patients had the CD7+ and CD41+ phenotype, and the CD41 positivity suggested that the myeloid neoplasms involving der(5;19)(p10;q10) were of megakaryoblastic origin. The der(5;19)(p10;q10) abnormality is associated with unique characteristics of the immunophenotype. We address the clinical, immunophenotypic and morphological aspects of hematological malignancy involving der(5;19)(p10;q10), along with a review of the literature.

Reflux esophagitis after esophagectomy: impact of duodenogastroesophageal reflux

Reflux esophagitis (RE) is a known complication disturbing patients' quality of life after esophageal resection. It is generally recognized that bile reflux as well as acid reflux cause RE. However, the clinical influence of acid and bile reflux, and Helicobacter pylori (H. pylori) infection on RE in the cervical esophagus after esophagectomy is not yet clarified. Sixty patients who underwent cervical esophagogastrostomy following esophagectomy were enrolled in this study. They underwent examination for H. pylori infection, endoscopic examination, and continuous 24-hour pH and bilirubin monitoring, at 1 month after surgery. The influence of acid and/or bile reflux, H. pylori infection, and others on the development of RE were investigated. RE was observed in 19 patients (32%) at 1 month after esophagogastrostomy, mild RE in 16 (27%), and severe RE in 3 (5%). The percentage of time duration of both acid and bile reflux into the cervical esophagus was higher in patients with RE than in those without (P = 0.027, P < 0.001). A significant difference in %time pH < 4 acid reflux was found between mild RE and severe RE (P = 0.014), and a statistical difference in %time abs. > 0.14 between non-RE and mild RE (P = 0.017). Acid and/or bile reflux was observed in 31 patients (52%), acid-only reflux in 6 (10%), bile-only reflux in 15 (25%), and acid-and-bile reflux in 10 (17%). Severe RE was observed only in patients having acid-and-bile reflux. On the univariate analysis, no infection of H. pylori, acid reflux, and bile reflux were determined to be the influencing factors to RE among the clinical factors including age, gender, route of esophageal reconstruction, H. pylori infection, and acid-and-bile reflux. In the subanalysis using the logistic model, there were significant correlations between bile reflux and RE irrespective of the presence of H. pylori infection (P = 0.016, P = 0.007). On the other hand, there was a significant correlation between acid reflux and RE only in patients without H. pylori infection (P = 0.039). In the early period after esophagogastrostomy, bile reflux could cause RE irrespective of H. pylori infection, while acid reflex could cause RE only in patients without H. pylori infection. There is a possibility that bile reflux plays an important role in the development of RE after esophagectomy.

Detection of antibodies against the non-calcium-dependent epitopes of desmoglein 3 in pemphigus vulgaris and their pathogenic significance

BACKGROUND

Antidesmoglein (anti-Dsg) 3 serum antibody titres are usually correlated with the disease activity of pemphigus vulgaris (PV), but some patients retain high titres even in remission.

OBJECTIVES

The aim of our study was to determine whether anti-Dsg3 antibodies in PV sera recognized calcium (Ca(2+) )-dependent or non-Ca(2+) -dependent epitopes, and to evaluate their pathogenicity.

METHODS

Dsg3 baculoprotein-coated enzyme-linked immunosorbent assay (ELISA) plates were treated with 0.5 mmol L(-1) ethylenediaminetetraacetic acid (EDTA). The binding ability of anti-Dsg3 monoclonal antibodies (mAbs) was analysed. Eight of the 83 patients with PV who were screened had elevated Dsg3 ELISA index values > 00 in remission. The binding ability of these PV sera was analysed. We evaluated the pathogenicity of anti-Dsg3 serum antibodies against the non-Ca(2+) -dependent epitopes using a dissociation assay.

RESULTS

The reactivity of pathogenic anti-Dsg3 mAbs against the Ca(2+) -dependent epitopes diminished markedly in the EDTA-treated ELISA, whereas no such reduction was observed in mAbs against the non-Ca(2+) -dependent epitopes. The sera of all the patients contained antibodies against both Ca(2+) -dependent and non-Ca(2+) -dependent epitopes. In six out of the eight patients, the ratio of antibodies against Ca(2+) -dependent to non-Ca(2+) -dependent epitopes decreased in remission. EDTA-treated Dsg3 baculoproteins adsorbed anti-Dsg3 serum antibodies against the non-Ca(2+) -dependent epitopes, but the remnant PV antibodies retained the ability to induce acantholysis in the dissociation assay.

CONCLUSIONS

We have established an assay to measure indirectly the titres of anti-Dsg3 serum antibodies against the Ca(2+) -dependent epitopes, based on the differences between EDTA-untreated and EDTA-treated ELISA index values, as a routine laboratory test to reflect the pathogenic anti-Dsg3 serum antibody titres more accurately.

[Complication of pernicious anemia during interferon-β treatment for type C chronic hepatitis]

A 62-year-old man with chronic hepatitis C underwent interferon (IFN)-β therapy. After treatment for a period comprising 29 months and 2 weeks, hematological results showed a decrease in white blood cell, hemoglobin, and platelet counts (WBC 2,300/µl, Hb 7.2 g/dl, PLT 4.7×10(4)/µl), and IFN therapy was stopped. Despite therapy discontinuation, the pancytopenia continued to progress with elevation of LDH (LDH 4,898 IU/l), and the patient was admitted to our hospital with suspected hematological disease. The patient underwent clinical screening, and pernicious anemia caused by vitamin B12 deficiency was diagnosed. The anemia rapidly improved with vitamin B12 treatment. Interferon is the mainstay of treatment for patients with viral hepatitis. While the adverse effects of interferon therapy are widely recognized, only a few reports have documented pernicious anemia developing during IFN-therapy. We recommend that particular attention be paid to such clinical and laboratory conditions as megaloblastic anemia when administering IFN. We also recommend checking the vitamin B12 level, as a deficiency of this vitamin may lead to the development of megaloblastic anemia.

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.