The identification of irreversible rituximab-resistant lymphoma caused by CD20 gene mutations

C-terminal mutations of CD20 constitute part of the mechanisms that resist rituximab therapy. Most CD20 having a C-terminal mutation was not recognized by L26 antibody. As the exact epitope of L26 has not been determined, expression and localization of mutated CD20 have not been completely elucidated. In this study, we revealed that the binding site of L26 monoclonal antibody is located in the C-terminal cytoplasmic region of CD20 molecule, which was often lost in mutated CD20 molecules. This indicates that it is difficult to distinguish the mutation of CD20 from under expression of the CD20 protein. To detect comprehensive CD20 molecules including the resistant mutants, we developed a novel monoclonal antibody that recognizes the N-terminal cytoplasm region of CD20 molecule. We screened L26-negative cases with our antibody and found several mutations. A rituximab-binding analysis using the cryopreserved specimen that mutation was identified in CD20 molecules indicated that the C-terminal region of CD20 undertakes a critical role in presentation of the large loop in which the rituximab-binding site locates. Thus, combination of antibodies of two kinds of epitope permits the identification of C-terminal CD20 mutations associated with irreversible resistance to rituximab and may help the decision of the treatment strategy.

Use of circulating endothelial cells to predict response to FOLFOX4 plus bevacizumab in metastatic colorectal cancer

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Background: The purpose of this study was to identify CEC threshold proposal for determining response to FOLFOX4 plus bevacizumab in metastatic colorectal cancer (mCRC).

Methods: All patients were enrolled using institutional review board-approved protocols at the Cancer Institute Hospital and provided informed consent. From July 2007 to June 2008, 33 patients treated with FOLFOX4 plus bevacizumab were enrolled in a prospective study. From January 2007 to June 2007, before bevacizumab was approved by the government in Japan, 31 patients treated with FOLFOX4 as a control were enrolled. The study population consisted of patients aged 18 years or older with histologically proven mCRC. Other inclusion criteria were Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, adequate organ function. CECs of whole blood at the baseline, day 4, 2 weeks after initiation of chemotherapy were isolated and counted using immunomagnetics.

Results: There was no correlation between CEC levels and the outcome in the FOLFOX4. In the FOLFOX4 plus bevacizumab, CEC levels at the baseline were significantly associated with the outcome. Patients with 65 or more CECs at the baseline had shorter median PFS (9.2 months), than the median PFS of fewer than 65 CECs at the baseline (18.9 months) in the FOLFOX4 plus bevacizumab (p = 0.003). Patients with 65 or more CECs at the baseline had shorter median OS (23.3 months), than the median OS of fewer than 65 CEC s at the baseline in the FOLFOX4 plus bevacizumab (p = 0.027). In the univariate analysis, lung metastasis, lymph node metastasis, and CEC levels at the baseline predicted PFS. In the univariate Cox regression analyses, peritoneal metastasis, CEC levels at the baseline were associated with OS. In order to evaluate the independent predictive effect of FOLFOX4 plus bevacizumab, multivariate Cox regression analysis was carried out. CEC levels at the baseline were the strongest predictor.

Conclusions: A threshold of lower than 65 CEC/4mL at the baseline was a significant predictor of the outcome for colorectal cancer patients treated with FOLFOX4 plus bevacizumab.

No significant financial relationships to disclose.

On the origin of visibility contrast in x-ray Talbot interferometry

The reduction in visibility in x-ray grating interferometry based on the Talbot effect is formulated by the autocorrelation function of spatial fluctuations of a wavefront due to unresolved micron-size structures in samples. The experimental results for microspheres and melamine sponge were successfully explained by this formula with three parameters characterizing the wavefront fluctuations: variance, correlation length, and the Hurst exponent. The ultra-small-angle x-ray scattering of these samples was measured, and the scattering profiles were consistent with the formulation. Furthermore, we discuss the relation between the three parameters and the features of the micron-sized structures. The visibility-reduction contrast observed by x-ray grating interferometry can thus be understood in relation to the structural parameters of the microstructures.

Bone metastasis and poor performance status are prognostic factors for survival of carcinoma of unknown primary site in patients treated with systematic chemotherapy

BACKGROUND

Cancer of unknown primary site (CUP) generally has a poor prognosis, and there is no established standard therapy. There have been no reports of a prognostic model for CUP patients treated with a single regimen of systemic chemotherapy.

METHODS

Univariate and multivariate prognostic factor analysis for overall survival (OS) were conducted retrospectively in 58 consecutive CUP patients treated with carboplatin plus paclitaxel (Taxol) therapy as a first-line treatment.

RESULTS

Univariate prognostic factor analysis revealed baseline performance status (PS) of two or more, low serum albumin level, pleural effusion, bone metastasis, and liver metastasis as adverse prognostic factors. Cox proportional hazards analysis showed that poor PS and bone metastasis had the most powerful adverse impact on survival. We developed a prognostic model using those two variables-a good-risk group (PS 0-1 without bone metastasis) and a poor-risk group (PS > or =2 or bone metastasis). The poor-risk group showed significantly poorer OS than the good-risk group (1 year OS 36.8% versus 67.1%, P = 0.0003).

CONCLUSIONS

Poor PS and bone metastasis were identified as independent adverse prognostic factors in CUP. A simple prognostic model was developed and seems useful for decision making as to whether chemotherapy is indicated for CUP patients.

Circulating tumor cells (CTCs) as a surrogate marker for determining response to chemotherapy in advanced gastric cancer (AGC)

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Background: The purpose of this study was to quantitate circulating tumor cells (CTCs) in advanced gastric cancer (AGC) patients and to demonstrate the role of CTCs in cancer therapy. This study investigates the hypothesis that CTC levels can predict clinical outcomes in patients with AGC. Methods: Eligibility criteria: PS (ECOG) of 0 to 2; histopathology of adenocarcinoma; adequate major organ functions. Chemotherapy regimen was S-1 based regimen (S-1 with or without cisplatin) or paclitaxel. Treatment was continued unless disease progression was observed. CTCs of whole blood in baseline, 2 week and 4 week after initiation of chemotherapy were isolated and enumerated using immunomagnetics. Results: From November 2007 to September 2008, thirty patients with unresectable or recurrent gastric cancer were enrolled onto a prospective study. Pts characteristics were as follows: median age: 60 years (range 24–78), PS 0/1/2: 21/8/1, primary tumor ±: 21/9 and regimen S-1/S-1with cisplatin/paclitaxel: 3/15/12. Among 30 pts, best response rates were 36.7% (CR/PR/SD/PD: 0/11/8/11). Patients with ≥4 CTCs at 2 week points and 4 week points had the shorter median progression-free survival (PFS) (1.4, 1.4 months, respectively), than the median PFS of <4 CTCs (6.3, 6.3 months, respectively) (logrank test; p=0.0008, p=8.78E-07, respectively). A finding of <4, CTCs of 2 week and 4 week after initiation of chemotherapy was associated with significantly longer overall survival (OS) as compared with these patients with ≥4 CTCs (p=0.016702, p=0.027788 respectively). Conclusions: These data demonstrate that CTC measurement may be useful as a surrogate marker for determining response to S1 based regimen or paclitaxel regimen in AGC.

No significant financial relationships to disclose.

Soluble interleukin-2 receptor retains prognostic value in patients with diffuse large B-cell lymphoma receiving rituximab plus CHOP (RCHOP) therapy

BACKGROUND

Soluble interleukin-2 receptor (SIL-2R) is known to be a prognostic parameter in patients with diffuse large B-cell lymphoma (DLBCL) receiving cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) therapy. However, its prognostic value has not been well known since the introduction of rituximab.

PATIENTS AND METHODS

We retrospectively evaluated the prognostic impact of SIL-2R in 228 DLBCL patients, comparing 141 rituximab-combined CHOP (RCHOP)-treated patients with 87 CHOP-treated patients as a historical control.

RESULTS

Patients with high serum SIL-2R showed significantly poorer event-free survival (EFS) and overall survival (OS) than patients with low SIL-2R in both the RCHOP group (2-year EFS, 66% versus 92%, P<0.001; OS, 82% versus 95%, P=0.005) and the CHOP group (2-year EFS, 40% versus 82%; OS, 61% versus 90%, both P<0.001). Multivariate analysis including the five parameters of International Prognostic Index (IPI) and two-categorized IPI revealed that SIL-2R was an independent prognostic factor for EFS and OS in the RCHOP group as well as in the CHOP group.

CONCLUSIONS

Our results demonstrate that SIL-2R retains its prognostic value in the rituximab era. The prognostic value of SIL-2R in DLBCL patients receiving rituximab-combined chemotherapy should be reassessed on a larger scale and by long-term follow-up.

CD5 expression is potentially predictive of poor outcome among biomarkers in patients with diffuse large B-cell lymphoma receiving rituximab plus CHOP therapy

BACKGROUND

Several biomarkers indicating poor prognosis have been reassessed in patients receiving rituximab combination chemotherapy for diffuse large B-cell lymphoma (DLBCL). However, few studies have investigated outcome in relation to a combination of these biomarkers. In addition, no large-scale studies have reassessed the outcome of patients with CD5-positive DLBCL treated with rituximab.

PATIENTS AND METHODS

We conducted a retrospective study and investigated the predictive value of three biomarkers -- BCL2, germinal center (GC) phenotype and CD5 -- in 121 DLBCL patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone.

RESULTS

CD5-positive patients showed significantly poorer event-free survival (EFS) and overall survival (OS) than CD5-negative patients (2-year EFS, 18% versus 73%, P < 0.001; 2-year OS, 45% versus 91%, P = 0.001). However, no significant difference in outcome according to BCL2 or GC phenotype was observed. Multivariate analysis revealed that CD5 expression was a significant prognostic factor for EFS [hazard ratio 14.2, 95% confidence interval (CI) 4.7-43.2] and OS (hazard ratio 20.3, 95% CI 3.6-114.4).

CONCLUSIONS

CD5 expression was the only significant prognostic factor among the biomarkers examined in this study. Further studies with larger numbers are warranted to confirm the prognostic significance of CD5 expression for patients with DLBCL receiving rituximab-containing chemotherapy.

Use of C-terminal deletion mutation of CD20 molecule to predict CD20 expression and time to progression after rituximab in non- Hodgkin lymphoma

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Background: Rituximab was the first chimeric antibody that is most frequently used for CD20-posistive B-cell lymphomas and gives better response and prognosis. However, resistance to rituximab is one of the important issues to be clarified in the increasing number of monoclonal antibody therapy, and we experienced the case whose lymphoma cells never expressed CD20 at the relapsed phase during rithuximab therapy. We investigated whether CD20 mutation is related to expression level of CD20, relapse or resistance to rituximab therapy, and prognosis. Methods: We analyzed 50 patients with fresh or relapsed/resistant B- cell lymphomas and DNA sequencing analysis of CD20 products from genomic PCR and RT-PCR was performed. CD20 mutants were subcloned by TA cloning, and tested CD20 expression after transfection to K562 cells. Results: Four types of CD20 mutations were found in 11 of 50 NHL patients (22.0%), which include C- terminal deletion (8.0%) extracellular domain (2.0%) transmembrane domain (2.0%) and early termination (10.0%). The group of C-terminal deletion mutations significantly showed lower CD20 expression (3.26, 95%CI = 0.09 to 6.89) than non-mutation (30.8, 95%CI = 22.4 to 39.2) (p 0.05). Although there was no significant difference between the groups with non-mutation and C-terminal deletion mutation in CR rate (49% versus 25%, Fisher's exact test; p = 0.6137), time to progression after rituximab therapy in C-terminal deletion mutation (7 months, 95%CI = 0 to 18 months) was significantly shorter than that in non-mutation (31 months, 95% CI = 18 to 44 months) by log-rank test (p = 0.0481). Non-mutation and early termination groups did not show any significant differences in TTP and CD20 expression. Conclusion: The important mutations of CD20 gene related to shorter duration to progression disease after rituximab therapy were discovered. Especially, point mutations bearing during rituximab therapy should be examined at progression disease after partial remission.

No significant financial relationships to disclose.

Point mutation of C-terminal region of CD20 molecule predicts rituximab-induced complement-dependent cytotoxicity and clinical response to rituximab in non-Hodgkin’s lymphoma

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Background: Although rituximab is commonly used as induction and maintenance therapy for malignant lymphoma, some patients become refractory to treatment and the mechanism of resistance is unclear. The aim of this study was to investigate the relationship between CD20 mutations and rituximab resistance. Methods: To investigate whether CD20 mutations affect response to rituximab, fresh CD19+ lymphoma cells were isolated from the lymph nodes, or bone marrow of 68 patients with NHL. The cells were subsequently sorted by flow cytometry. RNA was prepared from the isolated cells and RT-PCR was performed. The PCR products were sequenced, subcloned into an expression vector pTARGET, transfected into K562 cells. CD20 expression was examined by flow cytometry and laser scanning confocal microscopy. Results: In all 68 patients, overall response rate (CR+CRu+PR) to rituximab was 91.2% (62/68), but t four cases became PD after PR. DNA sequence analysis revealed that point mutations were mostly observed in three CD20 domains - extracellular/cytoplasmic domains, the third transmembrane domain and the C-terminal cytoplasmic domain. Two cases had point mutations in extracellular/cytoplasmic domains, one patient had point mutations in the transmembrane domain, four cases showed point mutations in the C-terminal cytoplasmic domain and six cases had non-specific CD20 mutations, which did not affect CD20 expression. 56 patients showed no mutations of CD20 gene. CD20 expression was very weak in patients with point mutations in the C-terminal cytoplasmic domain, whereas expression was increased in patients with point mutations in the transmembrane domain. Conclusions: Point mutations in CD20 may cause rituximab resistance and identification of CD20 mutations upon diagnosis may help to predict a patient’s response to rituximab.

No significant financial relationships to disclose.

Bisabosquals, novel squalene synthase inhibitors. II. Physico-chemical properties and structure elucidation

The squalene synthase inhibitor bisabosqual A was isolated from the culture broth of Stachybotrys sp. RF-7260, and its structure was determined on the basis of spectroscopic methods including detailed 2D NMR analyses. The structures of bisabosquals B, C and D isolated from Stachybotrys ruwenzoriensis RF-6853 were determined by spectroscopic methods and chemical reactions. The absolute stereochemistry of bisabosquals A, B and D was determined by X-ray crystallographic analysis. They have novel cis-fused tetracyclic structures with a bisabolane-type sesquiterpene and phenol moieties.

Determination of traces of cadmium in natural water samples by flow injection on-line preconcentration-graphite furnace atomic absorption spectrometry

A flow injection on-line preconcentration-graphite furnace atomic absorption spectrometric method was developed for the determination of traces of cadmium in natural water samples. Cadmium in samples was adsorbed on an iminodiacetate-type chelating resin, Muromac A-1 microcolumn (3 mm i.d. and 10 mm long), and then eluted with 2 mol l-1 HNO3. The eluate was introduced into the injection tip of an autosampler. The eluate zone with the highest analyte concentration was injected into the graphite furnace by cooperation of a peristaltic pump and a syringe pump of the autosampler, which were controlled by a programmable controller. The present system was successfully applied to the determination of cadmium in natural water samples. A detection limit of 0.2 ng l-1 was obtained with 12 ml sample loading. The recoveries were 99 and 108% for tap water (4 ml loading) and underground water (12 ml loading), respectively. Analytical results obtained for a river water reference material (JAC-0031, Japan Society for Analytical Chemistry) were close to the reference value.

CAM-cytarabine, aclarubicin plus macrophage colony-stimulating factor in the treatment of acute myelogenous leukemia with trilineage dysplasia: usefulness of in vitro apoptosis in leukemic cells

A 67-year-old woman was treated for acute myelogenous leukemia with trilineage dysplasia (AML-TLD) by combination chemotherapy with cytarabine, aclarubicin plus macrophage colony-stimulating factor (M-CSF) (referred to as CAM therapy). Complete remission was achieved after two courses of CAM therapy. After coculture of her bone marrow mononuclear cells with M-CSF in vitro, differentiation of leukemic cells into macrophages with apoptotis was observed. This case confirms an earlier report that an effect of M-CSF inducible by differentiation with apoptotic phenomena, against human leukemic cells was shown both in vitro and in vivo when achieving complete remission.

Antitumor effect of beta2-microglobulin in leukemic cell-bearing mice via apoptosis-inducing activity: activation of caspase-3 and nuclear factor-kappaB

We have reported previously that beta2-microglobulin (beta2m) induces apoptosis in leukemic cells in vitro, and that an interaction between beta2m and HLA class I antigen induces apoptosis. Here we examined whether beta2m can induce apoptosis in leukemic cells in vivo and whether it has an antitumor effect in tumor-bearing mice. Daily administration of 50 or 250 microg of beta2m induced apoptosis and an antitumor effect on K562 leukemia cell-bearing mice in the same manner as tumor necrosis factor-alpha. In tumor tissues in beta2m-treated mice, both caspase-3 and nuclear factor-kappaB (NF-kappaB) were stained more strongly than in control mice by anti-caspase-3 and anti-NF-kappaB p65/Rel A polyclonal antibodies. We also observed the in vivo immunological effects of beta2m on lymphoid and hematopoietic organs, such as thymus, bone marrow, Peyer's patches, liver, and spleen in normal mice. Using antibodies against caspase-3 and NF-kappaB, immunohistochemical staining showed that no specific tissues were damaged or stained in normal mice. We conclude that beta2m stimulates caspase-3 and NF-kappaB pathways to induce apoptosis, making it a useful approach to a new therapy for leukemia.

Acute cholestatic hepatitis caused by a probable allergic reaction to paracetamol in an adolescent

We reported on an adolescent who suffered from cholestatic hepatitis after taking a low dose of paracetamol. It was suspected that the condition was brought about by an allergic reaction to paracetamol. Paracetamol is one of the representative intrinsic hepatotoxic drugs. There have been only a few reports on liver damage due to an allergic reaction to paracetamol. There is a need to call attention to this particular reaction.

A new apoptotic pathway for the complement factor B-derived fragment Bb

Apoptosis is involved in both the cellular and humoral immune system destroying tumors. An apoptosis-inducing factor from HL-60 myeloid leukemia cells was obtained, purified, and sequenced. The protein found has been identified as a human complement factor B-derived fragment Bb, although it is known that factor B is able to induce apoptosis in several leukemia cell lines. Monoclonal antibodies against fragment Ba and Bb inhibited the apoptotic activity of factor B. When the purified fragment Bb was used for apoptosis induction, only the anti-Bb antibody inhibited Bb-induced apoptosis, and not the anti-Ba antibody. The apoptosis-inducing activity was found to be enhanced under conditions facilitating the formation of Bb. Blocking TNF/TNFR or FasL/Fas interactions did not interfere with the factor B-induced apoptosis. CD11c (iC3bR) acts as the main subunit of a heterodimer binding to fragment Bb in the apoptosis pathway, and the factor B-derived fragment Bb was found to possess the previously unknown function of inducing apoptosis in leukemic cells through a suicide mechanism of myeloid lineage cells during the differentiation stage.

Lamivudine as an alternative therapy for interferon-resistant chronic hepatitis B and the characteristics of hepatitis B virus: a case report

A 27-year-old man who had been diagnosed as having chronic hepatitis B suffered disease exacerbation with marked reactivation of hepatitis B virus (HBV). Treatment with interferon (IFN) did not improve his condition, and his serum HBV DNA level increased to over 10 000 pg/ml during IFN administration. Following replacement with lamivudine, there was a substantial reduction in HBV DNA to an undetectable level, and liver function parameters subsequently improved to within the normal range. Quantitative analysis of the precore mutant HBV DNA, which is a variant that cannot express hepatitis B e antigen due to a G-to-A point mutation in the precore region of the viral genome, revealed that the amount present was greater than for the precore wild-type HBV DNA in the serum taken before IFN treatment. This case suggests that lamivudine would be an appropriate alternative to IFN, particularly in patients infected with HBV containing an excess of precore mutants resistant to IFN therapy.