Cytomegalovirus infection in patients with malignant lymphomas who have not received hematopoietic stem cell transplantation.

BACKGROUND: Life-threatening cytomegalovirus infection (CMVI) has been reported even in patients with malignant lymphoma (ML) who have not received hematopoietic stem cell transplantation (w/o HSCT) but had been treated with chemotherapy or radiotherapy. However, the CMVI incidence and risk factors (RFs) in patients with ML w/o HSCT have not been fully elucidated. This study aimed to evaluate the clinical aspects, including incidence and RFs, of CMVI in patients with ML w/o HSCT. METHODS: We retrospectively reviewed all patients with ML who received chemotherapy or radiotherapy in our department from 2005 to 2013. The overall survival (OS), incidence and RFs of CMVI, and other characteristics of patients with CMVI were analyzed. RESULTS: Overall, 236 patients with ML w/o HSCT were evaluated. Of these, 5.5% (13/236) developed CMVI; 54% (7/13) received steroid pretreatment before primary therapy (PT) for ML; and 62% (8/13) received > 2 therapeutic regimens for ML. The OS curve of patients with CMVI was significantly worse than that of patients without CMVI (p < 0.0001, log-rank test). A univariate analysis identified B symptoms (p = 0.00321), serum albumin < 3.5 g/dL (p = 0.0007837), C-reactive protein level > the upper limit of normal (p = 0.0006962), steroid pretreatment before PT for ML (p = 0.0004262), > 2 therapeutic regimens for ML (p = 0.0000818), T cell lymphoma (p = 0.006406), and non-complete remission (p = 0.02311) as RFs for CMVI. A multivariate analysis identified steroid pretreatment before PT for ML [odds ratio (OR): 4.71 (95% confidence interval [CI]: 1.06-21.0); p = 0.0419] and > 2 therapeutic regimens for ML [OR: 9.25 (95% CI: 2.33-36.8); p = 0.00159] as independent RFs for CMVI in patients with ML w/o HSCT. CONCLUSIONS: Attention should be paid to CMVI development in patients with ML w/o HSCT pretreated with steroids or who had multiple therapeutic regimens.

Clinical significance of comprehensive genomic profiling tests covered by public insurance in patients with advanced solid cancers in Hokkaido, Japan.

BACKGROUND: Comprehensive cancer genomic profiling has been used recently for patients with advanced solid cancers. Two cancer genomic profiling tests for patients with no standard treatment are covered by Japanese public health insurance since June 2019. METHODS: We prospectively analyzed data of 189 patients with solid cancers who underwent either of the two-cancer genomic profiling tests at Hokkaido University Hospital and its liaison hospitals and whose results were discussed in molecular tumor board at Hokkaido University Hospital between August 2019 and July 2020. RESULTS: All 189 patients had appropriate results. Actionable gene alterations were identified in 93 patients (49%). Frequent mutations included PIK3CA (12%) mutation, BRCA1/2 alteration (7%), ERBB2 amplification (6%) and tumor mutation burden-High (4%). The median turnaround time from sample shipping to acquisition by the expert panel was 26 days. Although 115 patients (61%) were provided with information for genotype-matched therapies, only 21 (11%) received them. Notably, four of eight patients below the age of 20 years were provided information for genotype-matched therapies, and three received them. Their response rates and disease control rates were 29% and 67%, respectively. Most patients who did not undergo the genotype-matched therapies were provided information for only investigational drugs in phases I and II at distant clinical trial sites in central Japan. Twenty-six patients were informed of suspected germline findings, while 11 patients (42%) received genetic counseling. CONCLUSIONS: The publicly reimbursed cancer genomic profilings may lead to the modest but favorable therapeutic efficacy of genotype-matched therapy for solid cancer patients with no standard therapy. However, poor access to genotype-matched therapy needs to be resolved.

A nationwide survey of hypoplastic myelodysplastic syndrome (a multicenter retrospective study).

Hypoplastic myelodysplastic syndrome (hMDS) is a distinct entity with bone marrow (BM) hypocellularity and the risk of death from BM failure (BMF). To elucidate the characteristics of hMDS, the data of 129 patients diagnosed between April 2003 and March 2012 were collected from 20 institutions and the central review team of the National Research Group on Idiopathic Bone Marrow Failure Syndromes, and compared with 115 non-hMDS patients. More RA and fewer CMMoL and RAEB-t in French-American-British (FAB) and more RCUD and MDS-U and fewer RCMD in World Health Organization (WHO) classifications were found in hMDS than non-hMDS with significant differences. The overall survival (OS) and AML progression-free survival (AML-PFS) of hMDS were higher than those of non-hMDS, especially in patients at age ≥50 and of lower risk in Revised International Prognostic Scoring System (IPSS-R). In competing risks analysis, hMDS exhibited decreased risk of AML-progression in lower IPSS or IPSS-R risk patients, and higher risk of death from BMF in patients at age ≥50. Poor performance status (PS ≥2) and high karyotype risks in IPSS-R (high and very high) were significant risk factors of death and AML-progression in Cox proportional hazards analysis.

Hepatic nerve growth factor induced by iron overload triggers defenestration in liver sinusoidal endothelial cells.

The fenestrations of liver sinusoidal endothelial cells (LSECs) play important roles in the exchange of macromolecules, solutes, and fluid between blood and surrounding liver tissues in response to hepatotoxic drugs, toxins, and oxidative stress. As excess iron is a hepatotoxin, LSECs may be affected by excess iron. In this study, we found a novel link between LSEC defenestration and hepatic nerve growth factor (NGF) in iron-overloaded mice. By Western blotting, NGF was highly expressed, whereas VEGF and HGF were not, and hepatic NGF mRNA levels were increased according to digital PCR. Immunohistochemically, NGF staining was localized in hepatocytes, while TrkA, an NGF receptor, was localized in LSECs. Scanning electron microscopy revealed LSEC defenestration in mice overloaded with iron as well as mice treated with recombinant NGF. Treatment with conditioned medium from iron-overloaded primary hepatocytes reduced primary LSEC fenestrations, while treatment with an anti-NGF neutralizing antibody or TrkA inhibitor, K252a, reversed this effect. However, iron-loaded medium itself did not reduce fenestration. In conclusion, iron accumulation induces NGF expression in hepatocytes, which in turn leads to LSEC defenestration via TrkA. This novel link between iron and NGF may aid our understanding of the development of chronic liver disease.

A selective splicing variant of hepcidin mRNA in hepatocellular carcinoma cell lines.

Hepcidin is a main regulator of iron metabolism, of which abnormal expression affects intestinal absorption and reticuloendothelial sequestration of iron by interacting with ferroportin. It is also noted that abnormal iron accumulation is one of the key factors to facilitate promotion and progression of cancer including hepatoma. By RT-PCR/agarose gel electrophoresis of hepcidin mRNA in a hepatocellular carcinoma cell line HLF, a smaller mRNA band was shown in addition to the wild-type hepcidin mRNA. From sequencing analysis, this additional band was a selective splicing variant of hepcidin mRNA lacking exon 2 of HAMP gene, producing the transcript that encodes truncated peptide lacking 20 amino acids at the middle of preprohepcidin. In the present study, we used the digital PCR, because such a small amount of variant mRNA was difficult to quantitate by the conventional RT-PCR amplification. Among seven hepatoma-derived cell lines, six cell lines have significant copy numbers of this variant mRNA, but not in one cell line. In the transient transfection analysis of variant-type hepcidin cDNA, truncated preprohepcidin has a different character comparing with native preprohepcidin: its product is insensitive to digestion, and secreted into the medium as a whole preprohepcidin form without maturation. Loss or reduction of function of HAMP gene by aberrantly splicing may be a suitable phenomenon to obtain the proliferating advantage of hepatoma cells.

Current therapeutic strategies for multiple myeloma.

The introduction of novel molecular targeting agents against multiple myeloma has dramatically and rapidly changed the therapeutic strategies for this incurable hematologic disease. Novel agents such as thalidomide, bortezomib and lenalidomide have significantly improved the response rate, progression-free survival, and overall survival compared with conventional chemotherapies, and made it easy to control the disease for longer periods of time. Initial therapies for newly diagnosed myeloma patients depend on the individual's clinical condition. Induction therapy with novel agents and high-dose chemotherapy followed by autologous stem cell transplantation is a standard therapy for newly diagnosed younger myeloma patients. On the other hand, several combinations of novel agents and other drugs (melphalan, prednisone, dexamethasone, etc.) are widely used as initial therapy for transplantation-ineligible myeloma patients. Although the clinical advantage of maintenance therapy after induction therapy has been reported, it is not recommend in routine practice. Maintenance therapy would be an option for some patients. Despite the significant improvements with the use of novel agents, the majority of patients eventually relapse. A number of treatment options including novel agents, which demonstrated marked clinical effects, are reported in the setting of salvage therapy. The choice of appropriate therapy for relapsed or refractory patients must take the disease status or patient status in consideration. Furthermore, a new generation of novel agents such as pomalidomide, carfilzomib or panobinostat has recently become available for relapsed or refractory myeloma. It is necessary to determine the optimal combination of drugs, administration timing and patients to be treated in future clinical trials.

Risk factor analysis of non-Hodgkin lymphoma-associated haemophagocytic syndromes: a multicentre study.

Haemophagocytic syndrome is often associated with malignant lymphoma; however, few studies have examined lymphoma-associated haemophagocytic syndrome (LAHS). A total of 1239 patients with non-Hodgkin lymphoma were analysed at 12 institutions in Hokkaido prefecture between January 2007 and December 2011 to assess the incidence, prognosis and risk factors of LAHS. The cumulative incidence rate of LAHS was 2·8% (35/1239). Overall survival (OS) in patients with LAHS was significantly inferior to those without LAHS (3-year OS: 35·6 vs. 59·0% respectively, P < 0·0001). The cumulative incidence of LAHS was higher in patients with T/Natural Killer (NK)-cell lymphoma than in those with B-cell lymphoma (8·2 vs. 1·8% respectively, P < 0·0001). The characteristics of patients with and without early death (within the first 120 d after developing LAHS) were subsequently compared to evaluate the prognostic factor of LAHS. The results obtained showed that the rate of early death after developing LAHS was higher in patients with T/NK-cell lymphoma than in those with B-cell lymphoma (62·5 vs. 10·5%, P = 0·0033). In conclusion, the complication and mortality rates of LAHS were higher in patients with T/NK-cell lymphoma after they developed LAHS than in those with B-cell lymphoma.

Upregulation of iron regulatory hormone hepcidin by interferon α.

BACKGROUND AND AIM: Interferon (IFN) activates various immune systems in vivo and is administered to patients with diseases such as viral hepatitis B, C, and malignant tumors. Iron dysregulation has been reported during treatment with IFN; however, it remains unclear whether IFN itself affects iron metabolism. We therefore determined the effect of IFN on iron metabolism. METHODS: Mouse IFNα was administered to mice, and serum, spleen, bone marrow, liver, and duodenum tissue samples were subsequently collected. The messenger RNA (mRNA) and protein expression of genes involved in iron metabolism were then analyzed by real-time reverse transcription-polymerase chain reaction, Western blotting, and liquid chromatography-tandem mass spectrometry. Immunofluorescence for ferroportin was also performed. RESULTS: Among the gene expressions analyzed, we found that the expression of hepcidin, an iron regulatory hormone produced in the liver, was highly upregulated after IFNα treatment. Serum hepcidin levels and hepcidin mRNA expression in the liver were both found to be increased in the IFNα-treated mice. The expression of ferroportin (the target molecule of hepcidin) in the duodenum of the IFNα-treated mice was observed to be decreased, indicating that hepcidin upregulation could be physiologically functional. In vitro analysis of primary hepatocytes treated with IFNα and human hepatoma-derived cells showed an upregulation of hepcidin mRNA, including an activation of signal transducer and activator of transcription3, which was shown to be involved in the hepcidin upregulation. CONCLUSIONS: Results indicate that iron absorption is decreased during IFN treatment; this favorable effect could inhibit iron overload during IFN treatment and may enhance the action of IFN.

Iron facilitator LS081 reduces hypoxia-inducible factor-1α protein and functions as anticancer agent in hepatocellular carcinoma.

Hypoxia inducible factor-1α (HIF-1α) has a central role in cellular oxygen-sensing, and its overexpression in many types of cancer is considered important in tumor progression. Thus, targeting HIF-1α production and activity has been of great therapeutic interest. In normoxic conditions, HIF-1α is hydroxylated by oxygen-dependent prolyl-hydroxylases, which require ferrous iron for its activity. The tumor suppressor protein von Hippel Lindau binds to the hydroxylated HIF-1α, which is then ubiquitinated and degraded by proteasomes. We focused on the physiological degradation machinery of HIF-1α mediated by prolyl hydroxylases. Previously, we identified a small molecule, LS081, that is capable of stimulating iron uptake into cells. In the present study, we aimed to inhibit the expression of HIF-1α protein and growth of hepatocellular carcinoma by using the iron-facilitating activity of LS081. In the human hepatocellular carcinoma cell lines Hep3B and HepG2, a combination of LS081 and ferric ammonium citrate (LS081/FeAC) inhibited HIF-1α protein expression but did not inhibit HIF-1α mRNA expression. A mutated HIF-1α protein, which has proline residues that were replaced with alanine and transfected into HEK293 cells, was not affected by the combination of LS081 and FeAC. Furthermore, the iron-facilitating activity of LS081 resulted in Hep3B and HepG2 growth inhibition in vitro and in vivo. These results indicate that the iron-facilitating activity of LS081 inhibits HIF-1α expression through prolyl-hydroxylation of HIF-1α and might have a therapeutic effect in the treatment of hepatocellular carcinoma.

Successful Treatment of Myeloid Sarcoma in an Elderly Patient with Myelodysplastic Syndrome with Reduced-Dose Azacitidine.

Myeloid sarcoma (MS), which involves extramedullary lesions, is classified as a unique subtype of acute myeloid leukemia (AML). At present, no standard treatments for MS have been established. The patient was an 89-year-old man with myelodysplastic syndrome-excess blast-2 (MDS-EB-2) with a 2-year history of intermittent treatment with azacitidine (AZA) during a 4-year history of MDS. He developed painful cutaneous tumors 8 months after the second discontinuation of AZA. They were refractory for antibiotics and topical tacrolimus hydrate. A tumor biopsy was performed, and the histological findings of the tumor lesion showed a proliferation of tumor cells that were positive for myeloperoxidase and CD68 and negative for CD4 and CD123. The patient was diagnosed with MDS-associated MS. MDS-EB-2 quickly progressed to AML with the appearance of peripheral blood blasts and 25% bone marrow blasts. Monotherapy with reduced-dose AZA (37.5 mg/m2 for 7 days, every 4-6 weeks) was restarted, and the MS quickly disappeared. The patient's MS was successfully treated with 16 cycles of AZA treatment over a 22-month period. There have been 10 reported cases in which MS was successfully treated with AZA. Among the 10 cases, the patient in the present case was the oldest. Treatment with reduced-dose AZA should be considered as a therapeutic option for MS in elderly patients with MDS, especially patients who are ineligible for intensive chemotherapy.

Acquired hemophilia A associated with Epstein-Barr-virus-associated T/natural killer-cell lymphoproliferative disease: A case report.

INTRODUCTION: Acquired hemophilia A (AHA) is a rare bleeding disorder caused by autoantibodies against factor VIII (FVIII). Hematological malignancies, especially lymphoid malignancies, are known to be underlying causes of AHA; however, thus far, there is no report of AHA associated with Epstein-Barr-virus-associated T/natural killer-cell lymphoproliferative disease (EBV-T/NK-LPD). Here, we present a case of AHA that developed during treatment for EBV-T/NK-LPD. HISTORY: A 69-year-old man visited our hospital because of general fatigue. Blood examination showed pancytopenia, and computed tomography revealed whole-body lymphadenopathy, but there were no findings indicating hematological malignancy from bone marrow aspiration and cervical lymph node biopsy. The level of EBV DNA in peripheral blood was extremely high, and he was diagnosed with EBV-T/NK-LPD. EBV-T/NK-LPD improved with prednisolone (PSL) administration. Seventeen months after starting treatment, the patient complained of back and right leg pain. At that time, he had been treated with low-dose PSL, and EBV-T/NK-LPD was well controlled. Imaging revealed hematoma of the right iliopsoas muscle. Prolonged activated partial thromboplastin time (APTT) was the only abnormal finding in a screening coagulation test. FVIII coagulant activity was below detection limit, and FVIII inhibitor level was increased. From these results, he was diagnosed with AHA.A higher dose of PSL was administered, and, after 1 month of treatment, FVIII activity gradually increased, and FVIII inhibitor level became undetectable. APTT also normalized, and complete remission was achieved and maintained for 13 months with low-dose PSL. During treatment, EBV-T/NK-LPD was well controlled. CONCLUSION: It is speculated that proliferating lymphocytes interfere with normal immune functions and that abnormal autoantibodies are produced from those lymphocytes in patients with LPD. Therefore, we speculate that EBV-infected and proliferating monoclonal NK cells might have modulated the immune system and produced autoantibodies against FVIII, thus causing AHA in this patient with EBV-T/NK-LPD.

Atypical Takayasu arteritis with solitary stenosis in the short segment of right axillary artery.

Takayasu arteritis is a rare, idiopathic, and chronic inflammatory large vessel vasculitis, involving mainly the aorta and its major branches. Takayasu arteritis predominantly affects women. The clinical presentation is characterized by an acute phase with constitutional symptoms, followed by a chronic phase in which symptoms relate to stenosis or occlusion of vessels. We here report a rare case of Japanese male patient with a fever of unknown origin, and showed a solitary stenosis in the short segment of right axillary artery.

Incidence and risk of postherpetic neuralgia after varicella zoster virus infection in hematopoietic cell transplantation recipients: Hokkaido Hematology Study Group.

To assess the incidence of and risk factors associated with postherpetic neuralgia (PHN) after hematopoietic cell transplantation (HCT) varicella zoster virus (VZV) infection, we conducted a retrospective chart review of 418 consecutive patients who underwent HCT between April 2005 and March 2007. The male/female ratio was 221/197, median age at HCT was 47 years (range: 0-69 years), and autologous/allogeneic/syngeneic HCT ratio was 154/263/1. Seventy-eight patients developed VZV infection after HCT. Sixty-two patients had localized zoster, 11 patients had disseminated zoster (rash like chicken pox), and 4 patients had visceral zoster. All cases were treated with acyclovir (ACV) or valacyclovir (VACV), and there was no VZV infection-related death. Twenty-seven (35%) of the 78 patients with VZV infection suffered PHN after resolution of VZV infection. Multivariate analysis showed that advanced age is the only risk factor in autologous HCT (P = .0075; odds ratio [OR] = 1.14; 95% confidence interval [CI], 0.97-1.33). On the other hand, advanced age (P = .0097; OR = 1.06; 95% CI, 1.01-1.12), male gender (P = .0055; OR = 12.7; 95% CI, 1.61-100.1), and graft-versus-host disease (GVHD) prophylaxis with a tacrolimus-based regimen (P = .0092; OR = 9.56; 95% CI, 1.44-63.3) were associated with increased risk of PHN in allogeneic HCT. This study for the first time clarified the risk of PHN in HCT recipients.

Genetic analysis of postoperative recurrence of pancreatic cancer potentially owing to needle tract seeding during EUS-FNB.

Background and study aims Needle tract seeding during endoscopic ultrasound fine-needle biopsy (EUS-FNB) remains a concern. We investigated whether such seeding occurred in a patient with pancreatic ductal adenocarcinoma (PDA). Patient and methods Surgically resected and EUS-FNB-derived specimens were genotyped to determine if a gastric wall tumor that emerged 3 years after curative resection of an early-stage PDA was clonally related to the original tumor. Results The gastric tumor histologically resembled the primary PDA; the lesions also shared KRAS , SMAD4 , and RNF43 mutations. Genotyping of the preoperative EUS-FNB specimen, in which cancer was not detected, nevertheless revealed mutations that were identical to those in the resected primary and recurrent tumors. While the primary PDA had a low frequency of mutant SMAD4 , such mutations were highly prevalent in both the EUS-FNB and recurrent tumor specimens. Conclusions The genetic lineages of sampled tissues from our patient revealed that needle tract seeding may have incidentally occurred when a subset of neoplastic cells within a heterogeneous tumor ( i. e. , an aggressive clone) was targeted during EUS-FNB.

Induction of leukemia-specific antibodies by immunotherapy with leukemia-cell-derived heat shock protein 70.

Cancer immunotherapy using heat shock protein (HSP) derived from autologous tumor requires cluster of differentiation (CD)4(+) as well as CD8(+) T-cells for the prolongation of patient survival, suggesting that a humoral immune response through CD4(+) T-cells is important in addition to cellular immunity. However, the role of humoral responses in HSP-based autologous tumor immunotherapy remains unclear. In the present study, we investigated whether leukemia-specific antibodies and antibody-mediated cytotoxicity against autologous leukemia cells have a crucial role in a mouse A20 leukemia model by immunizing A20-derived HSP70. Immunization with A20-derived HSP70 induced the production of anti-A20-antibodies and the antibodies recognized HSP70-binding peptides derived from A20. One of those was a major histocompatibility complex (MHC) class-I binding peptide, which has been clarified as the target peptide of CD8+ cytotoxic T-cells (CTL) against A20. The anti-A20-antibodies produced by immunization with A20-derived HSP70 induced complement-dependent cytotoxicity (CDC) against A20 in vitro. In addition, immunization with A20-derived HSP70 increased intracellular interleukin-4 (IL4)-production of CD4(+) T-cells, confirming the activation of type-2 helper T-cells. Taken together, immunization with leukemia-cell-derived HSP70 induces antibodies against leukemia-cell-specific peptides and might play a crucial role in the eradication of leukemia cells by CDC in mice. These findings will enable future establishment of a novel therapeutic strategy using antileukemia antibodies in HSP-based autologous tumor immunotherapy.

Body iron metabolism and pathophysiology of iron overload.

Iron is an essential metal for the body, while excess iron accumulation causes organ dysfunction through the production of reactive oxygen species. There is a sophisticated balance of body iron metabolism of storage and transport, which is regulated by several factors including the newly identified peptide hepcidin. As there is no passive excretory mechanism of iron, iron is easily accumulated when exogenous iron is loaded by hereditary factors, repeated transfusions, and other diseased conditions. The free irons, non-transferrin-bound iron, and labile plasma iron in the circulation, and the labile iron pool within the cells, are responsible for iron toxicity. The characteristic features of advanced iron overload are failure of vital organs such as liver and heart in addition to endocrine dysfunctions. For the estimation of body iron, there are direct and indirect methods available. Serum ferritin is the most convenient and widely available modality, even though its specificity is sometimes problematic. Recently, new physical detection methods using magnetic resonance imaging and superconducting quantum interference devices have become available to estimate iron concentration in liver and myocardium. The widely used application of iron chelators with high compliance will resolve the problems of organ dysfunction by excess iron and improve patient outcomes.

Dysregulation of systemic iron metabolism in alcoholic liver diseases.

Alcoholic liver diseases (ALD) are frequently associated with iron overload. Until recently, the effects of ethanol in hepatic iron uptake and intestinal iron absorption have not been clarified in detail. Two possible mechanisms for iron overload are the uptake of iron into hepatocytes in a specific manner through the increased expression of transferrin receptor (TfR) 1; and increased intestinal iron absorption by the lowering of hepcidin. It is worthwhile to examine whether a similar mechanism is present in the development of steatosis and non-alcoholic steatohepatitis (NASH). Hepatocytes have several iron uptake pathways. Ethanol increases transferrin (Tf)-mediated uptake via a receptor-dependent manner, but downregulates the non-Tf-bound iron uptake. According to immunohistochemical study, TfR1 was increased in hepatocytes in 80% of hepatic tissues of patients with ALD, but was not detected in normal hepatic tissues. In an experimental model, ethanol exposure to the primary cultured-hepatocytes in the presence of iron increased TfR1 expression and (59)Fe-labeled Tf uptake. In patients with ALD, intestinal iron absorption is increased by oral iron uptake assay. The regulatory hormone for iron homeostasis, hepcidin is downregulated in ethanol-loaded mice liver. As well as ALD, a similar mechanism was present in the mouse model fed with a high-fat diet, a model of the initial phenomenon of steatosis. The common mechanism for hepatic iron deposition and the triggering role of iron may be present in the development of ALD and non-alcoholic fatty liver disease/NASH.

[Cyclophosphamide and CYP2B6].

Members of the hepatic cytochrome p450 superfamily(CYP)play an important role in the metabolism of many therapeutic drugs. There is a marked individual variability in the CYP-mediated drug metabolism. One of the main factors of the CYP activities is a polymorphism of the CYP genes. Polymorphisms of the CYP genes contribute to the variation in the drug-metabolic rate. The polymorphic nature of the CYP genes affects the individual drug response and adverse reactions. Cyclophosphamide(CPA)exerts its effect after biotransformation to 4-hydroxy-CPA by hepatic CYP. Several CYPs have been reported to mediate this reaction. Especially CYP2B6 is thought to be the key enzyme in the CPA metabolism. CYP2B6 is highly polymorphic, and it has been reported that the genetic backgrounds of CYP2B6 in Japanese and Caucasians are different. CYP2B6*6, which is a relatively common allele in the Japanese population, affects the gene expression and activities of CYP2B6 in vitro. The homozygote of CYP2B6*6 patients with malignant lymphoma and breast cancer treated with CPA showed higher clearance and shorter half-life of plasma CPA. In addition, homozygous CYP2B6*5 patients with proliferative lupus nephritis had a significantly higher probability of reaching end-stage renal disease by pulse CPA treatment. Other gene polymorphisms of CYP2B6 also affect the CPA metabolism in vitro. However, the current knowledge of CYP2B6 polymorphism is not sufficient to predict its efficacy and safety for the individual patient in CPA therapy. Further studies are needed for clinical use.