Clinicopathological Characteristics of RET Rearranged Lung Cancer in European Patients

INTRODUCTION

Rearrangements of RET are rare oncogenic events in patients with non-small cell lung cancer (NSCLC). While the characterization of Asian patients suggests a predominance of nonsmokers of young age in this genetically defined lung cancer subgroup, little is known about the characteristics of non-Asian patients. We present the results of an analysis of a European cohort of patients with RET rearranged NSCLC.

METHODS

Nine hundred ninety-seven patients with KRAS/EGFR/ALK wildtype lung adenocarcinomas were analyzed using fluorescence in situ hybridization for RET fusions. Tumor specimens were molecularly profiled and clinicopathological characteristics of the patients were collected.

RESULTS

Rearrangements of RET were identified in 22 patients, with a prevalence of 2.2% in the KRAS/EGFR/ALK wildtype subgroup. Co-occurring genetic aberrations were detected in 10 patients, and the majority had mutations in TP53. The median age at diagnosis was 62 years (range, 39-80 years; mean ± SD, 61 ± 11.7 years) with a higher proportion of men (59% versus 41%). There was only a slight predominance of nonsmokers (54.5%) compared to current or former smokers (45.5%).

CONCLUSIONS

Patients with RET rearranged adenocarcinomas represent a rare and heterogeneous NSCLC subgroup. In some contrast to published data, we see a high prevalence of current and former smokers in our white RET cohort. The significance of co-occurring aberrations, so far, is unclear.

Inhibition of protein geranylgeranylation specifically interferes with CD40-dependent B cell activation, resulting in a reduced capacity to induce T cell immunity

Ab-independent effector functions of B cells, such as Ag presentation and cytokine production, have been shown to play an important role in a variety of immune-mediated conditions such as autoimmune diseases, transplant rejection, and graft-versus-host disease. Most current immunosuppressive treatments target T cells, are relatively unspecific, and result in profound immunosuppression that places patients at an increased risk of developing severe infections and cancer. Therapeutic strategies, which interfere with B cell activation, could therefore be a useful addition to the current immunosuppressive armamentarium. Using a transcriptomic approach, we identified upregulation of genes that belong to the mevalonate pathway as a key molecular event following CD40-mediated activation of B cells. Inhibition of 3-hydroxy-3-methylglutaryl CoA reductase, the rate-limiting enzyme of the mevalonate pathway, by lipophilic statins such as simvastatin and atorvastatin resulted in a specific inhibition of B cell activation via CD40 and impaired their ability to act as stimulatory APCs for allospecific T cells. Mechanistically, the inhibitory effect resulted from the inhibition of protein geranylgeranylation subsequent to the depletion of mevalonate, the metabolic precursor for geranylgeranyl. Thus, inhibition of geranylgeranylation either directly through geranylgeranyl transferase inhibitors or indirectly through statins represents a promising therapeutic approach for the treatment of diseases in which Ag presentation by B cells plays a role.

Results of a Phase II clinical trial with Id-protein-loaded dendritic cell vaccine in multiple myeloma: encouraging or discouraging?

Recently gained insight into the role of dendritic cells (DCs) as APCs has attracted the attention of many researchers who hope to use them as a tool in immunotherapy for the induction of tumor-specific immunity in cancer settings. Despite high expectations, in multiple myeloma patients the results of DC-based vaccines in terms of clinical response have been disappointing. The findings of Zahradova et al. in a Phase II clinical trial with multiple myeloma patients corroborated these results. Although no clinical responses were observed, the investigators induced immunity after vaccination with Id-protein-loaded DC vaccine in some patients. These immunological results showed a trend towards a longer duration of stable disease in those patients that received the vaccination. Moreover, this study showed that Id-protein-loaded DC vaccines are safe and nontoxic and that they are able to induce immunity in some patients. Therefore, standardization of vaccination protocols appears to be the key to achieving a better clinical outcome.

The properties of human CD40-activated B cells as antigen-presenting cells are not affected by PGE2

Tumor vaccination represents a promising immuno-therapeutic strategy in cancer. However, the inherent ability of many tumors to evade immune responses by suppression of immune cell function represents a major barrier. Prostaglandin E2 (PGE2) has been shown to be a critical tumor-derived immunosuppressive factor. It affects a broad range of immune cells including T cells, macrophages and dendritic cells (DCs). CD40-activated B cells are being studied as a potential alternative to DCs as antigen-presenting cells for immunotherapy. So far, it is not known whether PGE2 affects their antigen presenting capacity. We, therefore, investigated the influence of PGE2 on the phenotype, migratory potential and antigen-presenting function of CD40-activated human B cells. Here, we demonstrate that the immunostimulatory properties of CD40-activated B cells are not affected by PGE2. These results support the use of CD40-activated B cells as cellular adjuvants, especially in settings where PGE2 is present in the tumor microenvironment.

The immunosuppressive factors IL-10, TGF-β, and VEGF do not affect the antigen-presenting function of CD40-activated B cells

Background

Progress in recent years strengthened the concept of cellular tumor vaccinations. However, a crucial barrier to successful cancer immunotherapy is tumor-mediated immunosuppression. Tumor-derived soluble factors such as IL-10, TGF-β, and VEGF suppress effector cells either directly or indirectly by disruption of dendritic cell (DC) differentiation, migration and antigen presentation. Human B cells acquire potent immunostimulatory properties when activated via CD40 and have been shown to be an alternative source of antigen-presenting cells (APCs) for cellular cancer vaccines. Nevertheless, in contrast to DCs little knowledge exists about their susceptibility to tumor derived immunosuppressive factors. Thus, we assessed whether IL-10, TGF-β, or VEGF do affect key aspects of the immunostimulatory function of human CD40-activated B cells.

Methods

Cell surface expression of adhesion and costimulatory molecules and the proliferation capacity of CD40-activated B cells were compared to untreated controls by flow cytometry. Migration towards important chemokines of secondary lymph organs was measured with or without exposure to the immunosuppressive cytokines. Finally, an influence on T cell stimulation was investigated by allogeneic mixed lymphocyte reactions. For statistical analysis Student’s t test or two-way analysis of variance followed by Bonferroni's post-hoc test was used to compare groups. P values of <0.05 were considered statistically significant.

Results

Neither cell adhesion nor the expression of MHC class II and costimulatory molecules CD80 and CD86 was inhibited by addition of IL-10, TGF-β, or VEGF. Likewise, the proliferation of CD40-activated B cells was not impaired. Despite being exposed to IL-10, TGF-β, or VEGF the B cells migrated equally well as untreated controls to the chemokines SLC and SDF-1α. Most importantly, the capacity of CD40-activated B cells to stimulate CD4⁺ and CD8⁺ T cells remained unaffected.

Conclusion

Our findings suggest that key immunostimulatory functions of CD40-activated B cells are resistant to inhibition by the immunosuppressive factors IL-10, TGF-β, and VEGF. This supports considerations to use ex vivo generated CD40-activated B cells as a promising alternative or additional APC for cellular immunotherapy, especially in settings where these immunosuppressive cytokines are present in tumor environment.

Dendritic cell based tumor vaccination in prostate and renal cell cancer: a systematic review and meta-analysis

BACKGROUND

More than 200 clinical trials have been performed using dendritic cells (DC) as cellular adjuvants in cancer. Yet the key question whether there is a link between immune and clinical response remains unanswered. Prostate and renal cell cancer (RCC) have been extensively studied for DC-based immunotherapeutic interventions and were therefore chosen to address the above question by means of a systematic review and meta-analysis.

METHODOLOGY/PRINCIPAL FINDINGS

Data was obtained after a systematic literature search from clinical trials that enrolled at least 6 patients. Individual patient data meta-analysis was performed by means of conditional logistic regression grouped by study. Twenty nine trials involving a total of 906 patients were identified in prostate cancer (17) and RCC (12). Objective response rates were 7.7% in prostate cancer and 12.7% in RCC. The combined percentages of objective responses and stable diseases (SD) amounted to a clinical benefit rate (CBR) of 54% in prostate cancer and 48% in RCC. Meta-analysis of individual patient data (n = 403) revealed the cellular immune response to have a significant influence on CBR, both in prostate cancer (OR 10.6, 95% CI 2.5-44.1) and in RCC (OR 8.4, 95% CI 1.3-53.0). Furthermore, DC dose was found to have a significant influence on CBR in both entities. Finally, for the larger cohort of prostate cancer patients, an influence of DC maturity and DC subtype (density enriched versus monocyte derived DC) as well as access to draining lymph nodes on clinical outcome could be demonstrated.

CONCLUSIONS/SIGNIFICANCE

As a 'proof of principle' a statistically significant effect of DC-mediated cellular immune response and of DC dose on CBR could be demonstrated. Further findings concerning vaccine composition, quality control, and the effect of DC maturation status are relevant for the immunological development of DC-based vaccines.

Early prediction of nonprogression in advanced non-small-cell lung cancer treated with erlotinib by using [(18)F]fluorodeoxyglucose and [(18)F]fluorothymidine positron emission tomography

PURPOSE

Positron emission tomography (PET) with both 2'-deoxy-2'-[(18)F]fluoro-D-glucose (FDG) and 3'-[(18)F]fluoro-3'-deoxy-L-thymidine (FLT) was evaluated with respect to the accuracy of early prediction of nonprogression following erlotinib therapy, independent from epidermal growth factor receptor (EGFR) mutational status, in patients with previously untreated advanced non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Thirty-four patients with untreated stage IV NSCLC were evaluated in this phase II trial. Changes in FDG and FLT uptake after 1 (early) and 6 (late) weeks of erlotinib treatment were compared with nonprogression measured by computed tomography after 6 weeks of treatment, progression-free survival (PFS), and overall survival (OS).

RESULTS

Changes in FDG uptake after 1 week of therapy predicted nonprogression after 6 weeks of therapy with an area under the receiver operating characteristic curve of 0.75 (P = .02). Furthermore, patients with an early metabolic FDG response (cutoff value: 30% reduction in the peak standardized uptake value) had significantly longer PFS (hazard ratio [HR], 0.23; 95% CI, 0.09 to 0.59; P = .002) and OS (HR, 0.36; 95% CI, 0.13 to 0.96; P = .04). Early FLT response also predicted significantly longer PFS (HR, 0.31; 95% CI, 0.10 to 0.95; P = .04) but not OS and was not predictive for nonprogression after 6 weeks of therapy.

CONCLUSION

Early FDG-PET predicts PFS, OS, and nonprogression after 6 weeks of therapy with erlotinib in unselected, previously untreated patients with advanced NSCLC independent from EGFR mutational status.

The shared tumor associated antigen cyclin-A2 is recognized by high-avidity T-cells

Cyclin-A2, a key cell cycle regulator, has been shown to be overexpressed in various types of malignancies with little expression in normal tissue. Such tumor-associated genes potentially are useful targets for cancer immunotherapy. However, high-avidity cyclin-specific T cells are considered to be thymically deleted. We identified at least one nonameric HLA-A*0201 binding cyclin-A2 epitope by a reverse immunology approach. Using a highly efficient T-cell expansion system that is based on CD40-activated B (CD40-B) cells as sole antigen-presenting cells we successfully generated cyclin-A2 specific CTL from HLA-A*0201(+) donors. Interestingly, high-avidity cyclin-A2 specific CTL lines, which recognized peptide-pulsed and antigen expressing target cells, were indeed generated by stimulation with CD40-B cells when pulsed with low concentrations of peptide, whereas CD40-B cells pulsed at saturating concentrations could only induce low-avidity CTL, which recognized peptide-pulsed target cells only. One high-avidity CTL line was subcloned and CTL clones, whose peptide concentration required for half-maximal lysis were less than 1 nM, could lyse cyclin-A2 expressing tumor cells. Taken together, cyclin A2 is an attractive candidate for immune intervention in a significant number of cancer patients and high-avidity T cells can be readily generated using CD40-B cells as antigen-presenting cells.

CD40-activated B cells can be generated in high number and purity in cancer patients: analysis of immunogenicity and homing potential

Cellular adjuvants such as dendritic cells (DC) are in the focus of tumour immunotherapy. In DC-vaccine trials, induction of tumour antigen-specific immunity is observed frequently and well-documented clinical responses have been reported. However, the overall response rate is less than 3%, therefore alternative strategies are being investigated. CD40-activated B cells (CD40-B) have been characterized previously as an interesting alternative because they present antigen efficiently and can be expanded by several logs from small amounts of peripheral blood. To determine the central technical challenges of cell-based vaccines we performed a single-patient analysis of 502 patients from DC-based tumour vaccine trials and identified at least three factors contributing to their limited efficiency: (1) lack of cell numbers; (2) lack of documented purity thus high contamination of bystander cells; and (3) lack of quality control and thus heterogeneous or unknown expression of important surface molecules such as major histocompatibility complex (MHC) and chemokine receptors. Based on these findings we re-evaluated the CD40-B approach in cancer patients. Here, we show that proliferation of B cells from cancer patients is equivalent to that observed in healthy donors. Purity is always > 90% after 2 weeks and remains stable for several weeks. They have comparable antigen-presenting capability determined phenotypically and by allogeneic mixed lymphocyte reaction. Expression of CCR7 and CD62L was detected in all samples and B cells migrated towards the relevant homing chemokines. Taken together, CD40-B cells from cancer patients can be expanded in virtually unlimited numbers at high purity and full function concerning antigen-presentation and migratory properties.

Activation of autologous leukemia-specific T cells in acute myeloid leukemia: monocyte-derived dendritic cells cocultured with leukemic blasts compared with leukemia-derived dendritic cells

In acute myeloid leukemia (AML) blasts can be differentiated into dendritic cell (DC) like cells (AML-DC). These cells have a mature DC-like phenotype, are strong stimulators in mixed leukocyte reactions and can be used to generate leukemia-specific cytotoxic T cells. However, recent reports about naturally existing leukemic DC with immunoregulatory dysfunctions in peripheral blood of AML patients caused concerns about the use of AML-DC for therapeutic purposes. Systematic intra-individual comparisons between AML-DC and non-leukemic DC derived from monocytes (MoDC) in AML patients are missing. Thus, we investigated the ability to generate MoDC from peripheral blood of 17 AML patients in first remission and their functional integrity to stimulate leukemia-specific T cells by simple coculture with leukemic blasts. Phenotypic analysis of AML-DC and MoDC from the same individual patients revealed that MoDC exhibit a more homogenous mature DC phenotype. Additionally, functional analysis demonstrated the ability of remission MoDC to activate autologous leukemia-specific T cells in 11 of 12 patients, whereas AML-DC led to a specific T cell activation in four of eight patients. The presented findings might have impact on the design of further therapeutic studies using autologous antigen-presenting cells.

Cytomorphologic signs of severe pernicious anemia obscured in a patient with heterozygous hemoglobin Stanleyville II

Here, we report a rare coincidence of heterozygous hemoglobinopathy (Hb) Stanleyville II and severe pernicious anemia due to autoimmune gastritis. Hb Stanleyville II is characterized by a single base exchange (AAC-->AAA) resulting in a substitution Asn --> Lys at position 78 of hemoglobin alpha2-chain. Under normal conditions this hemoglobinopathy does not cause any symptoms even if present as homozygous variant. However, in our case diagnosis of pernicious anemia was hampered by the absence of typical erythrocytic macrocytosis and hyperchromasia. In addition, interpretation of bone marrow smears was difficult as characteristic findings for pernicious anemia were little pronounced. All known reasons for the absence of typical cytomorphologic signs in pernicious anemia as underlying iron deficiency and thalassemia could be excluded.

Efficient activation of autologous tumor-specific T cells: a simple coculture technique of autologous dendritic cells compared to established cell fusion strategies in primary human colorectal carcinoma

Different technologies have been employed to deliver the whole spectrum of tumor antigens (TAs) to dendritic cells (DCs) to be presented to T cells. These include whole tumor RNA-transfected DCs, preparations of DCs loaded with tumor-derived apoptotic bodies or tumor cell lysates, and DC tumor cell fusions. Early clinical trials have been conducted using such techniques. The presented study was aimed to revisit the necessity of tumor cell manipulation in DC-based immunotherapy strategies for colorectal carcinoma. We investigated a simple coculture method of autologous monocyte-derived DCs and human primary colorectal carcinoma (pCC) in comparison with 2 well-described cell fusion strategies for the efficacy of uptake, processing and presentation of TAs to autologous T cells. Before coculture or fusion, pCC had been cryopreserved without further manipulation. Fluorescence microscopy and flow cytometry analyses of fluorescent dye labeled cells were used for monitoring engulfment of pCC by DCs. The coculture procedure resulted in a double positive cell fraction of up to 22% and thus was comparable to that observed after cell fusion. More important, DCs after coculture with autologous pCC induced significant tumor-specific interferon-gamma-producing autologous T cells in the same number of patients as DC/pCC fusions. Furthermore, tumor-specific major histocompatibility complex class I restricted cytotoxic T lymphocytes were generated by stimulation with DCs cocultured with pCC. In prior studies for human carcinomas coculture techniques were described to be inferior. In contrast, our data strongly suggest that at least for human pCC and autologous DCs this simple coculture method is similarly efficient compared to established fusion techniques.

German Hodgkin's Lymphoma Study Group Trials: Lessons from the Past and Current Strategies

Over the past decades, Hodgkin's lymphoma has become one of the most curable tumors in adults. This is mainly because of large clinical trials using risk-adapted, highly effective therapy modalities. For a long time, radiation therapy was the standard for treating patients with Hodgkin's lymphoma. Within the past 20 years, management has undergone a paradigm shift from the use of chemotherapy as an adjunct to radiation therapy in advanced-stage disease to combined therapy modalities with chemotherapy and involved-field irradiation in early stages and time- and dose-intensified effective drug regimens in advanced stages. Modern therapeutic strategies aim at reducing therapy-associated acute and late toxicities, while maintaining the highest tumor control. Founded in 1978, the German Hodgkin's Lymphoma Study Group has initiated numerous clinical trials contributing to the high cure rate in all stages of this lymphoma entity. This article gives an overview of the German Hodgkin's Lymphoma Study Group trials and a review of the current treatment strategies.

CD40-activated B cells express full lymph node homing triad and induce T-cell chemotaxis: potential as cellular adjuvants

CD40-activated B cells (CD40-B cells) have previously been introduced as an alternative source of antigen-presenting cells for immunotherapy. CD40-B cells can prime naive and expand memory T cells, and they can be generated in large numbers from very small amounts of peripheral blood derived from healthy individuals or cancer patients alike. Administration of CD40-B cells as a cellular adjuvant would require these cells to migrate toward secondary lymphoid organs and attract T cells in situ, processes guided by specific chemokines and chemokine receptors. Here, we demonstrate that primary, human CD40-B cells express a pattern of adhesion molecules and chemokine receptors necessary for homing to secondary lymphoid organs and have the capacity to migrate to cognate ligands. Furthermore, we show that CD40-B cells express important T-cell attractants and induce strong T-cell chemotaxis. These findings further support the use of CD40-B cells as cellular adjuvant for cancer immunotherapy.

A novel bispecific protein (ULBP2-BB4) targeting the NKG2D receptor on natural killer (NK) cells and CD138 activates NK cells and has potent antitumor activity against human multiple myeloma in vitro and in vivo

The inability of the immune system to recognize and kill malignant plasma cells in patients with multiple myeloma (MM) has been attributed in part to the ineffective activation of natural killer (NK) cells. In order to activate and target NK cells to the malignant cells in MM we designed a novel recombinant bispecific protein (ULBP2-BB4). While ULBP2 binds the activating NK receptor NKG2D, the BB4 moiety binds to CD138, which is overexpressed on a variety of malignancies, including MM. ULBP2-BB4 strongly activated primary NK cells as demonstrated by a significant increase in interferon-gamma (IFN-gamma) secretion. In vitro, ULBP2-BB4 enhanced the NK-mediated lysis of 2 CD138+ human MM cell lines, U-266 and RPMI-8226, and of primary malignant plasma cells in the allogenic and autologous setting. Moreover, in a nude mouse model with subcutaneously growing RPMI-8226 cells, the cotherapy with ULBP-BB4 and human peripheral blood lymphocytes abrogated the tumor growth. These data suggest potential clinical use of this novel construct in patients with MM. The use of recombinant NK receptor ligands that target NK cells to tumor cells might offer new approaches for other malignancies provided a tumor antigen-specific antibody is available.

Immunomagnetic enrichment and detection of isolated tumor cells in bone marrow of patients with epithelial malignancies

The detection of isolated tumor cells (ITC) in the bone marrow of patients with epithelial malignancies is an independant prognostic factor for several entities as breast cancer, colorectal cancer or non-small lung cancer. However, with conventional immunocytology using Ficoll density gradient and APAAP staining, only a small proportion of the bone marrow samples can be scanned for cytokeratin-positive (CK+) cells. To improve detection rates, we evaluated the enrichment of ITC by magnetic activated cell sorting (MACS) compared to regularly stained cytospins. Recovery experiments with a CK+ breast cancer cell line (SKBR3) were performed to calculate the MACS enrichment rate. Bone marrow was obtained by aspiration from 20 patients with carcinomas of epithelial origin and from 17 controls. ITC were enriched and stained with magnetically labeled CAM 5.2 antibodies directed to cytokeratin 7 and 8. MACS of SKBR3 seeded in peripheral blood revealed average recovery rates of 62% and 48% and average enrichment factors of 104-fold and 8139-fold of the CK+ cells after one and after two separations, respectively. After immunomagnetic enrichment, CK+ cells were detected in 16 of 20 (80%) cancer patients, whereas only 7 (35%) patients showed CK+ cells without magnetic enrichment (P = 0.002). Ten of twelve (83%) patients with metastatic disease (stage M1) and six of eight (75%) patients without any overt metastases (M0) had CK+ cells in their bone marrow. None of the negative controls showed any CK+ cells. Enrichment with magnetically labeled anti cytokeratin antibodies increases the detection rate of epithelial cells in bone marrow of cancer patients compared to immunocytology.

Successful treatment of severe thrombotic thrombocytopenic purpura with the monoclonal antibody rituximab

The only established treatment for patients with thrombotic thrombocytopenic purpura (TTP) is plasma exchange against fresh frozen plasma. For cases refractory to plasma exchange, no generally treatment schedule exists. One option is immunosuppressive therapy with corticosteroids and vincristine. Rituximab is a chimeric monoclonal antibody directed against the CD20 antigen, and it has been successfully used in B-cell malignancies and is being investigated in autoimmune diseases. Its efficacy in TTP has not yet been determined. We report two female patients with severe TTP refractory to multiple courses of plasmapheresis, high-dose steroid treatment, and vincristine who responded after adding rituximab while continuing plasmapheresis.

Constitutive expression of c-FLIP in Hodgkin and Reed-Sternberg cells

Crosslinking of the transmembrane receptor CD95/Fas leads to activation of a signaling cascade resulting in apoptosis. c-FLIP is a recently described protein that potently inhibits Fas-mediated apoptosis and has been shown to be a key factor in germinal center B cell survival. Because Hodgkin and Reed-Sternberg cells in classical Hodgkin's disease (cHD) are also resistant to Fas-mediated apoptosis we studied the role of c-FLIP in classical HD. High levels of c-FLIP protein were identified in two Fas-resistant Hodgkin-derived cell lines. In contrast to other tumor cells, inhibition of protein synthesis by cycloheximide did not lead to down-regulation of c-FLIP protein in these HD cell lines. Furthermore, Fas-mediated apoptosis was only partially restored suggesting that normal regulation of c-FLIP was disrupted. The in vivo relevance of these findings was supported by demonstration of significant c-FLIP expression by immunohistochemistry in 18 of 19 evaluable cases of primary HD. Taken together, c-FLIP is constitutively expressed in HD and may therefore be a major mechanism responsible for Fas-resistance in HD.

Cell fusion is not involved in the generation of giant cells in the Hodgkin-Reed Sternberg cell line L1236

The mechanism of multinucleated cell formation in Hodgkin's disease has not yet been elucidated. We asked whether the giant multinucleated cells of the H-RS cell line L1236 develop via fusion of the predominant smaller cells. As a positive control for the fusion assay, human B cells from the B-cell lymphoma cell line BJA-B were split into two fractions, stained with the fluorochromes CMTMR and CMFDA, respectively, and fused using the polyethylene glycol 1500 cell hybridization protocol. Double-stained cells indicating fusion of BJA-B cells were detectable for up to 5 days. In parallel, L1236 cells were split into two fractions, stained with the fluorochromes, and mixed. No double-stained L1236 cells were detected. The same result was obtained when using FACS-sorted small mononuclear L1236 cells. It is thus concluded that the large multinucleated cells of the monoclonal H-RS cell line L1236 have emerged by endomitosis rather than by spontaneous cell fusion.

Immunomagnetic enrichment of CD138 positive cells from weakly infiltrated myeloma patients samples enables the determination of the tumor clone specific IgH rearrangement

In multiple myeloma, the polymerase chain reaction (PCR) of the Ig heavy chain with allele-specific oligonucleotide (ASO) primers is a common and well-described method of identifying the tumor clone in peripheral blood (PB), bone marrow (BM) or leukapheresis products (LA). A factor which is crucial to the detection of clonal Ig rearrangements lies in the 'purity' of the tumor tissue used for the consensus PCR. We describe the application of a method to enrich CD138 positive myeloma cells derived from weakly infiltrated PB-, BM- and LA-samples. These are subjected to immunomagnetic enrichment with the MACS system, using an CD138 antibody directly conjugated to magnetic beads to obtain an enriched tumor cell population and the subsequent amplification of tumor specific IgH rearrangements. We investigated 29 samples (ten PB, ten BM, nine LA) with a median myeloma cell content of 0.5%. The approach led to a median enrichment factor of 118. Tumor-specific rearrangements could be amplified reproducibly from samples containing less than 0.1% myeloma cells.

Atypical chronic myeloid leukaemia with trisomy 21 mosaicism as a sole chromosomal abnormality

We present a 46-year-old patient with Ph-chromosome negative, bcr-negative chronic myeloid leukaemia (CML) in accelerated phase with a clonal trisomy 21 in the leukaemic blast cells. A rapid progress of disease with appearance of monocytosis is described, showing similar features to chronic myelomonocytic leukaemia (CMML). Heterogeneous characteristics and possible distinction of these two entities are discussed.

Suppression of the tumorigenic growth of Burkitt's lymphoma cells in immunodeficient mice by cytokine gene transfer using EBV-derived episomal expression vectors

Epstein-Barr virus (EBV)-based expression vectors were tested for cytokine gene transfer-mediated induction of an immune response against human lymphoma cells. These vectors express the EBV latent gene EBNA 1 and carry the EBV latent origin of replication (ori P) for episomal replication in transfected cells. In addition, 3 human immunoglobulin light chain enhancer elements augment expression in B-cells. The suitability of these vectors for expression of cytokine genes in human lymphoma cells in vitro has been demonstrated. In order to extend these experiments in vivo, highly tumorigenic Burkitt's lymphoma (BL) cells were transfected with different cytokine genes of human and murine origin cloned into the EBNA 1/ori P vectors. Tumorigenicity of the transfectants was measured after inoculation into nude mice. No effect on tumorigenicity was observed after hIL 6 transfection and an inconsistent effect after hTNFalpha transfection. In contrast, complete suppression of tumor outgrowth occurred in hIL 10 transfectants. This tumor suppressive effect, however, was restricted to the IL 10 transfectants themselves and not directed against non-transfected cells. By comparison, mIL 4 transfected BL cells also were non-tumorigenic. However, co-inoculation of mIL 4 transfected and non transfected cells resulted in suppression of the tumorigenicity of the non-transfected cells. Thus, highly tumorigenic BL cells in nude mice are sensitive to immune effector mechanisms triggered by cytokine expression. In this experimental model, EBNA 1/ori P expression vectors are a suitable tool for cytokine gene transfer mediated induction of an anti-lymphoma immune response of the host.

Dexamethasone, carmustine, etoposide, cytarabine, and melphalan (dexa-BEAM) followed by high-dose chemotherapy and stem cell rescue--a highly effective regimen for patients with refractory or relapsed indolent lymphoma

We performed a phase II study to determine the efficacy of maximal cytoreductive therapy with up to five cycles of Dexa-BEAM (dexamethasone, carmustine [BCNU], etoposide, cytarabine, and melphalan) followed by high-dose chemotherapy (HDCT) and autologous stem cell transplantation (ASCT) for patients with advanced relapsed or refractory indolent lymphoma. Thirty-two patients with primary refractory or relapsed indolent lymphoma were treated with the Dexa-BEAM regimen. Thirteen patients had primary refractory disease, 4 patients partial remission, and 15 patients first or subsequent relapse. Patients achieving PR or CR received HDCT with ASCT. The conditioning regimen used was BEAM (carmustine [BCNU], etoposide, cytarabine, and melphalan). Twenty-two patients responded to Dexa-BEAM resulting in a response rate of 78%. Maximum response was observed after 3.2 (range 2-5) courses. One patient with progressive disease died in septic shock during neutropenia. Nineteen patients with partial or complete remission after Dexa-BEAM received HDCT. Hematopoietic stem cells (HSC) were collected after two cycles of Dexa-BEAM. The median number of CD34+ HSC reinfused was 3.1 x 10(6)/kg (range 1.6-8.2 x 10(6)/kg). There was no transplantation-related death. All patients receiving HDCT achieved complete remission. Overall survival (OS) and freedom from treatment failure (FFTF) for all patients are estimated to be 68% and 65% at two years, respectively. With a mean follow-up of 20 months (range 8-42 months), 16/19 patients receiving HDCT are in continuous complete remission. The Dexa-BEAM regimen is effective in overcoming drug resistance in patients with indolent lymphoma who failed to respond to conventional treatment or who relapsed. The CR rate of 100% of those patients receiving HDCT and ASCT after maximal cytoreductive treatment with Dexa-BEAM suggests the use of HDCT at the time of maximal response.

Dexa-BEAM: an effective regimen for cytoreduction prior to high-dose chemotherapy with autologous stem cell support for patients with relapsed/refractory mantle-cell lymphoma

Mantle-cell lymphoma (MCL) is not a curable disease using conventional chemotherapy. Patients with MCL have the shortest median time to progression and the shortest median survival of all lymphoma subtypes after first-line treatment. In the present study we determined the efficacy of maximal cytoreductive therapy with up to four cycles of Dexa-BEAM (dexamethasone, carmustine [BCNU], etoposide, cytarabine, and melphalan) followed by high-dose chemotherapy (HDCT) and autologous hematopoietic stem cell support (ASCT) for patients with advanced relapsed or refractory MCL. Nine consecutive patients with relapsed or refractory MCL were included. Three patients had partial remission (PR), three patients progressive disease (PD) upon first line tretment, and three patients first or subsequent relapse. After 2 to four cycles of Dexa-BEAM eight patients achieved complete remission (CR), resulting in a response rate of 88%. Six of 8 patients responding to Dexa-BEAM received high-dose chemotherapy HDCT (BEAM) and autologous hematopoietic stem cell transplantation (ASCT). With a median follow up of 24 months six patients are alive. Five of those six patients are still in contiuous CR (range 13-54 months).

[Thrombotic thrombocytopenic purpura (Moschkowitz-syndrome) caused by ticlopidine]

BACKGROUND

Only in a few case reports the thrombotic thrombocytopenic purpura was related to ticlopidine with a controversial discussion about this association.

CASE REPORT

In a 57-year-old female patient, who was admitted with fluctuating central neurological abnormalities and generalized purpura, was made the diagnosis of a thrombotic thrombocytopenic purpura (TTP, Moschcowitz' syndrome). On admission there were a distinct anemia and thrombocytopenia. Corresponding to the hemolysis the laboratory findings showed raised reticulocytes and elevated LDH with > 900 U/l. The peripheral blood smear showed an enrichment of fragmented red cells (15%) and the bone marrow indicated a hyperplastic erythrocytopoesis and a left shift in megakaryocytopoesis. An increase of eosinophilic granulocytes and the tissue basophilic cells directed to a possible allergic phenomenon of the underlying disease. Until 3 weeks before admission she had been on ticlopidine after a left heart catheter with stenting the left coronary artery 6 weeks earlier. Beside taking of acetylsalicylacid and thyroid hormone there was no other regular medication. An early treatment with fresh frozen plasma and plasmapheresis with plasma exchange with fresh frozen plasma led directly to an elevation of thrombocytes and a normalization of hemolytic parameters.

CONCLUSION

This case demonstrates the possible relationship between thrombotic thrombocytopenic purpura and the administration of ticlopidine.

High platelet contamination in progenitor cell concentrates results in significantly lower CD34+ yield after immunoselection

BACKGROUND

Selection of CD34+ cells by specific immunoselection leads to a significant loss of those cells. The factors influencing the yield and purity are not well identified. The results of CD34+ selection from peripheral blood progenitor cells (PBPCs) with high and low platelet contamination that are harvested with two different cell separators are reported.

STUDY DESIGN AND METHODS

A progenitor cell concentrator (Ceprate SC, CellPro) was used to select CD34+ cells from 41 PBPC concentrates from 23 consecutive patients with relapsed non-Hodgkin's lymphoma (n = 3), breast cancer (n = 17), and multiple myeloma (n = 3). PBPC collection was performed by using two cell separators (CS3000 Plus, Fenwal: Group A, n = 11; and Spectra, COBE: Group B, n = 9). To reduce platelet contamination in the Spectra PBPC concentrates, an additional low-speed centrifugation was performed before CD34+ cell selection (Group C, n = 3). Leukapheresis components were stored overnight at 4 degrees C and combined with the next day's collection before the CD34+ selection procedure in 19 patients.

RESULTS

A median of 1.5 leukapheresis procedures per patient were performed. Pooled PBPC concentrates showed no statistical difference in median numbers of white cells and CD34+ cells in Groups A and B: 3.2 (0.8-9.2) versus 4.4 (1.6-8. 3) x 10(10) white cells per kg and 15.0 (4.7-24.0) versus 12.0 (5. 6-34.0) x 10(6) CD34+ cells per kg. Platelet contamination was significantly higher in Group B: 0.67 (0.15-2.4) versus 2.3 (0.5-7. 1) x 10(11) (p = 0.0273). After the selection process, there was a significantly greater loss of CD34+ cells in Group B than in Group A: 39.1 versus 63.2 percent (p = 0.0070), with a median purity of 78. 0 percent versus 81.0 percent. An additional low-speed centrifugation before CD34+ cell selection seemed to reduce CD34+ cell loss in Group C with 16.9, 31.9, and 37.5 percent, respectively.

CONCLUSION

CD34+ cell selection from PBPC concentrates resulted in an increased loss of CD34+ cells in concentrates with a higher platelet content. To improve CD34+ yield, PBPC concentrates with an initially low platelet contamination should be used, or additional low-speed centrifugation should be performed.

Using at least 5x10(6)/kg CD34+ cells for autologous stem cell transplantation significantly reduces febrile complications and use of antibiotics after transplantation

For autologous stem cell transplantation, it is common practice to infuse at least 2 x 10(6)/kg CD34+ cells to ensure rapid engraftment. However it was recently claimed that increasing the threshold to 5 x 10(6)/kg leads to a faster platelet engraftment. To evaluate these threshold values in our patient population we undertook a retrospective analysis of 127 autologous transplants performed at our institution between 1992 and 1998. Diagnoses included Hodgkin's and non-Hodgkin's lymphoma, myeloma, acute leukaemias and solid tumours. The transplant was peripheral blood stem cells in 107 cases and CD34-selected peripheral blood stem cells in 20 cases. The median number of transplanted CD34+ cells was 3.2 x 10(6)/kg (range 0.64-25.9 x 10(6)/kg). Haematopoietic recovery to a neutrophil count >0.5 x 10(9)/l took a median of 10 (range 5-16) days from transplant. When comparing patients receiving at least 5 x 10(6)/kg and 2-5 x 10(6)/kg CD34+ cells we found a significant reduction in the median number of days with fever (1 vs 3.5 days, P = 0.0025), incidence of fever (78.8 vs 92.1%, P = 0.032) as well as duration of antibiotic treatment (7 vs 10 days, P = 0.038). This was paralleled by a faster neutrophil recovery to 0.5 x 10(9)/l (9 vs 10 days, P = 0.047). There was no significant difference in the number of platelet or red cell transfusions between the two groups. We conclude that transplantation with a stem cell dose of at least 5 x 10(6)/kg CD34+ cells reduces infectious complications and should thereby increase the safety of this type of therapy while reducing duration (and cost) of antibiotic therapy. The transplantation threshold should thus not remain at 2 x 10(6)/kg particularly in patients with a good stem cell mobilisation capacity.

Successful peripheral blood stem cell mobilization with etoposide (VP-16) in patients with relapsed or resistant lymphoma who failed cyclophosphamide mobilization

High-dose chemotherapy (HDCT) followed by autologous blood stem cell transplantation is considered the treatment of choice for patients with relapsed or resistant aggressive non-Hodgkin's lymphoma (NHL) or Hodgkin's disease (HD). However, several authors report failure of standard mobilization regimens in 29% to 56% of these patients making the completion of HDCT impossible and as a result, negatively influencing long-term outcome. Thus, effective new regimens for patients failing initial mobilization are needed. Here we report the results of using etoposide as a mobilizing agent in 16 patients with primary resistant or relapsed malignant lymphoma who had failed prior mobilization of peripheral blood stem cells (PBSC) with cyclophosphamide (4 g/m2) followed by G-CSF. The use of etoposide 500 mg/m2 (days 1-4) + G-CSF resulted in the successful collection of adequate numbers of PBSC with a median harvest of 3.6 x 10(6)/kg (range 2.2-12.6) CD34+ cells in all 16 patients. In 7/16 (44%) patients, the target yield of at least 2.0 x 10(6) CD34+ cells was harvested by a single apheresis and the maximum number of separations for all patients was two. No excessive toxicities appeared, allowing all patients to proceed to myeloablative chemotherapy. In addition, median peak values of circulating CD34+ cells were significantly higher after etoposide as compared to cyclophosphamide (49.2/microl vs 4.7/microl; P = 0.0004). These results indicate that etoposide + G-CSF is a highly effective mobilization regimen in patients who have failed cyclophosphamide mobilization.

Dexa-BEAM is not effective in patients with relapsed or resistant aggressive high-grade non-Hodgkin's lymphoma

The aim of the present study was to evaluate the feasibility and response of the Dexa-BEAM regimen as a salvage therapy followed by high-dose chemotherapy (HDCT) with peripheral blood stem cell transplantation (PBCST) in responding patients with high-grade relapsed or resistant aggressive non-Hodgkin's lymphoma (NHL). Sixteen pretreated patients (mean age 44, range 26-59) with relapsed (8) or resistant (8) NHL were treated with 1-4 cycles of Dexa-BEAM (dexamethasone, BCNU, etoposide, cytarabine, melphalan) in order to attain maximal response. Patients achieving complete response (CR) or partial response (PR) received HDCT with PBSCT. The conditioning regimen used was BEAM. Three patients achieved CR and one patient PR, resulting in an overall response rate of 25%. Three of four responding patients underwent high-dose chemotherapy and were successfully transplanted with autologous blood stem cells. Progressive disease developed in one patient after transplantation. Myelosuppression (WHO grade III- grade IV), the major side effect, was observed in all courses of Dexa-BEAM. Myelosuppression-related infection WHO grade IV occurred in four patients. The protocol was not well tolerated in this heavily pretreated group of patients with four severe myelosuppression-related infections WHO grade IV and one treatment-related death. The overall response rate in this study is not comparable to other salvage regimens published and led to the discontinuation of the trial. In conclusion Dexa-BEAM was only effective in a minority of patients with refractory or relapsed aggressive NHL and was not useful as a cytoreductive regimen prior to HDCT.

Stable nontumorigenic phenotype of somatic cell hybrids between malignant Burkitt's lymphoma cells and autologous EBV-immortalized B cells despite induction of chromosomal breakage and loss

Fusion of the highly tumorigenic Burkitt's lymphoma (BL) cell line BL60-P7 with the nontumorigenic autologous EBV-immortalized lymphoblastoid cell line (LCL) IARC 277 results in suppression of the tumorigenic phenotype of the parental cell line BL60-P7 after s.c. inoculation into T cell-deficient nude mice. We analyzed whether, after long-term cultivation of these lymphoma hybrid cells, expression of tumorigenicity could be observed and correlated to the loss of particular chromosomes or chromosomal fragments, akin to numerous nonlymphoid hybrid cell models described previously. Two years after fusion, in vitro proliferation of some BL x LCL hybrid cells accelerated, and they partially lost LCL-typical aggregation. However, no major changes in the expression pattern of B cell-associated surface antigens and the EBV latent membrane protein LMP 1 were observed. Cytogenetic evaluation of these cells revealed spontaneous loss of chromosomes. Karyotyping of long-term cultivated hybrid cells demonstrated the occurrence of disomy for each chromosome in at least one metaphase analyzed. Therefore, if suppression of tumorigenicity in these hybrid cells would have been the result of the presence of a single LCL-derived chromosome, there should have been a high probability of its loss, leading to tumorigenic segregants. Surprisingly, the tumorigenic phenotype remained suppressed in nude mice. To induce chromosomal breakage and maldistribution, in addition to spontaneous chromosomal loss, the hybrid cell lines were irradiated at various doses. Again, none of the hybrid cell clones treated in this manner became tumorigenic in nude mice. Immunohistological analysis of the regressing hybrid cell tumors revealed that the hybrid cells had retained their LCL-like differentiation phenotype in vivo. In addition, infiltration with mononuclear cells of murine origin was observed in these regressing hybrid grafts. We conclude that suppression of the tumorigenic Burkitt's lymphoma phenotype in these hybrid cells cannot be attributed to a function encoded by a distinct chromosome or chromosomal fragment. Rather, the unexpected stable nontumorigenic phenotype reflects a LCL-specific activated B-cell phenotype of these hybrids, most probably induced by the expression of numerous copies of episomal latent EBV proteins.

Suppression of Burkitt's lymphoma tumorigenicity in nude mice by co-inoculation of EBV-immortalized lymphoblastoid cells

EBV-immortalized B-lymphoblastoid cell lines (LCL) inoculated s.c. into T-cell-deficient nude mice regress completely after a short initial growth period. We tested whether the putative host response underlying this phenomenon might also be directed against progressively growing Burkitt's lymphoma (BL) tumors in nude mice. Outgrowth of BL tumors was suppressed when cells of the highly tumorigenic BL cell line BL 60 were mixed with cells of the autologous LCL IARC 277 before s.c. inoculation into nude mice. Even when the cells were inoculated separately and simultaneously into contralateral flanks of the mice, regression of initially growing BL tumors could be observed, albeit with reduced frequency and dependent on the dose of LCL cells. Tumor growth of BL 60 cells could also be suppressed by co-inoculation with the non-autologous LCL IARC 174 and IARC 277 cells could suppress growth of the non-autologous BL cell line Eli. Pronounced infiltration with murine (m)CD-11b-positive mouse macrophages and mCD-8a-positive mouse lymphoid cells, most probably natural killer cells, was seen in histological tissue sections of regressing BL 60 tumors when LCL cells were inoculated contralaterally. In regressing BL tumors, these mouse cells were present not only in necrotic areas but also in vital BL tissue, indicating that infiltration of mouse cells had taken place before the development of necrosis. Since tumor-infiltrating mouse cells can be activated at least by some human cytokines, we measured cytokine production of BL 60 and IARC 277. High amounts of IL 6 and IL 10 were produced by the LCL cells, whereas IL-6 and IL-10 production by the BL 60 cells was beyond or close to the detection threshold. In addition, IL 8 was secreted up to 5-fold more by the LCL than by the BL cells. The results presented here thus suggest a host response of the nude mouse, which is triggered by cytokines released from the LCL but, once induced, is directed also against BL cells.