Biomedical subjects

Ulrich Keilholz

Publications and source records attributed to Ulrich Keilholz.

At least 37 records · Page 2Linked to original sources

PubMed2005

T cell responses against tumor associated antigens and prognosis in colorectal cancer patients.

INTRODUCTION: Spontaneous T cell responses against specific tumor-associated antigens (TAA) are frequently detected in peripheral blood of tumor patients of various histiotypes. However, little is known about whether these circulating, spontaneously occurring, TAA-reactive T cells influence the clinical course of disease. METHODS: Fifty-four HLA-A2 positive colorectal cancer patients had been analyzed for the presence of T cell responses against epitopes derived from the TAA Ep-CAM, her-2/neu, and CEA either by ELISPOT assay or by intracellular cytokine staining. Then, Kaplan-Meier survival analysis was performed comparing T-cell-responders and T-cell-non-responders. For comparison, a group of T-cell-non-responders was compiled stringently matched to T-cell-responders based on clinical criteria and also analyzed for survival. RESULTS: Sixteen out of 54 patients had a detectable T cell response against at least one of the three tested TAA. Two out of 21 patients (9.5%) with limited stage of disease (UICC I and II) and 14 out of 33 patients (42.4%) with advanced disease (UICC III and IV) were T cell response positive. Comparing all T-cell-responders (n = 16) and all T-cell-non-responders (n = 38), no survival difference was found. In an attempt to reduce the influence of confounding clinical factors, we then compared 16 responders and 16 non-responders in a matched group survival analysis; and again no survival difference was found (p = 0.7). CONCLUSION: In summary, we found no evidence that spontaneous peripheral T cell responses against HLA-A2-binding epitopes of CEA, her-2/neu and Ep-CAM are a strong prognostic factor for survival.

Journal Article↗

PubMed2005

Addition of histamine to interleukin 2 treatment augments type 1 T-cell responses in patients with melanoma in vivo: immunologic results from a randomized clinical trial of interleukin 2 with or without histamine (MP 104).

PURPOSE: Preclinical investigations suggest that histamine dihydrochloride (HDC) protects T cells and natural killer cells from inhibition by monocyte-derived reactive oxygen metabolites and synergizes with interleukin (IL) 2 in inducing T-cell activation. Here, we investigate whether this mechanism is operational in patients with melanoma treated with HDC as an adjunct to IL-2. EXPERIMENTAL DESIGN: Melanoma patients having liver metastases were treated with IL-2 with or without HDC within a randomized, multicenter, phase III trial. The effect of HDC on type 1 and type 2 T-cell cytokine production was investigated in peripheral blood samples from 19 patients with the use of intracellular cytokine flow cytometry. Melanoma-specific T-cell responses were analyzed in eight HLA-A2-positive patients. RESULTS: Frequencies of CD3+ T cells producing IFN-gamma (type 1 T cells) in response to phorbol myristate acetate/ionomycin increased (median, 1.8-fold) in patients receiving IL-2 plus HDC but not in those receiving IL-2 alone (P < 0.01 for comparison between arms). In contrast, the number of IL-13-producing type 2 T cells that increased in patients after treatment with IL-2 was not modulated by HDC. Melanoma- and tyrosinase-specific IFN-gamma and IL-13-producing T cells were detected in two of four HLA-A2-positive patients with melanoma following treatment with HDC + IL-2. CONCLUSIONS: Treatment of patients with stage IV melanoma with HDC in combination with IL-2 increases type 1 T-cell responses and may promote induction of melanoma-specific T cells. These effects are of relevance for tumor immunotherapy and provide a potential mechanism for the clinical efficacy of HDC added to IL-2.

CD3 Complex↗

PubMed2005

Spinal paraparesis due to leukemic meningitis in early-stage chronic lymphocytic leukemia.

Leukemic meningitis is a rare manifestation of chronic lymphocytic leukemia (CLL) and typically occurs in advanced stages. We report the case of a 71-year-old male in whom Binet A, Rai 1 stage CLL was diagnosed in June 2002. The stage called for a "watch and wait" strategy. Six months later the patient presented with paraparesis. Magnetic resonance imaging of the lumbar spine revealed no abnormalities. Lumbar puncture disclosed xanthochromic cerebrospinal fluid (CSF) with 1003 cells/microl, 95% atypical lymphocytes. Flow cytometry confirmed typical features of CLL. Intrathecal injections of methotrexate, cytosine arabinoside and corticosteroids did not substantially reduce the CSF cell count and failed to improve the neurological symptoms. Two weeks later the patient developed a pulmonary embolism complicated by fatal secondary pneumonia. Leukemic meningitis is a rare manifestation of CLL, especially in early stages. Selective spinal paraparesis as the first symptom of meningitis in CLL is even rarer and has been reported only once.

Aged↗

PubMed2005

Phase II trial of cisplatin, gemcitabine and treosulfan in patients with metastatic uveal melanoma.

Gemcitabine plus treosulfan (GeT) is under investigation in metastatic uveal melanoma. In this phase II trial, cisplatin was added to a GeT regimen to investigate the efficacy and toxicity of two alkylating agents in combination with gemcitabine. Patients received 30 or 40 mg/m of cisplatin, 1000 mg/m of gemcitabine and 3000 mg/m of treosulfan on days 1 and 8. Therapy was repeated on day 29. A maximum of six cycles was administered. Nineteen patients were included in the trial, of whom 17 were evaluable for response. No objective response was observed; seven patients (41%) had stable disease and 10 (59%) progressed. The median progression-free survival of all 19 patients was 3.0 months [95% confidence interval (CI), 1.8-3.1]; the median overall survival was 7.7 months (95% CI, 1.9-13.8). Grade 3 and 4 thrombopenia and leucopenia occurred in eight and nine of the 19 patients, respectively. The addition of cisplatin to the GeT regimen results in excessive haematological toxicity without improvement in efficacy.

Adult↗

PubMed2005

A two-cohort phase II clinical trial of gemcitabine plus treosulfan in patients with metastatic uveal melanoma.

In-vitro synergy of treosulfan and gemcitabine has been observed in chemotherapy-resistant tumours. This trial investigated the efficacy of gemcitabine plus treosulfan in metastatic uveal melanoma. Patients received 1000 mg/m of gemcitabine and treosulfan at a dose of 2500 or 3000 mg/m2 in cohort 1 and 3500 or 4000 mg/m2 in cohort 2. Chemotherapy was administered on days 1 and 8 every 4 weeks. Thirty-three patients were treated, 14 in cohort 1 and 19 in cohort 2. In cohort 1 with a treosulfan dose of or=3500 mg/m2 in cohort 2, one had partial remission (5%), 10 showed disease stabilization and eight progressed. An increased survival was observed in the second cohort with higher treosulfan doses, with median survival times of 6.0 versus 9.0 months (P=0.03) in cohort 1 and 2, respectively, and a 1-year survival of 7.1% versus 47.3%, respectively. Based on the observation of prolonged disease stabilization, we recommend further investigation of the gemcitabine/treosulfan combination with a dose of 3500 mg/m2 of treosulfan in metastatic uveal melanoma.

Adult↗

PubMed2004

Expression of Wilms' tumor gene 1 at different stages of acute myeloid leukemia and analysis of its major splice variants.

WT1 is a transcription factor involved in differentiation and proliferation of acute myeloid leukemia (AML) blasts and is expressed in 90% of cases, as determined by nested reverse transcription polymerase chain reaction (RT-PCR). It is proposed to be a key molecule in leukemia promotion. To assess the relevance of WT1 expression, we analyzed blood and bone marrow samples from 58 AML patients (37 at diagnosis, 8 in hematological remission, and 13 at relapse) for the level of WT1 expression, using quantitative real-time RT-PCR. In addition, 21 randomly chosen samples were also analyzed for the quantitative expression of the main WT1 splice variants. As expected, samples from patients at the time of diagnosis or relapse showed significantly higher WT1 expression compared to samples from patients in remission or control samples. No striking difference in expression levels was found between various French-American-British (FAB) subtypes. The level of WT1 expression observed in patients at the time of initial diagnosis was similarly high in patients at relapse. Expression of the four main isoforms (E5+/KTS+, E5-/KTS+, E5+/KTS-, and E5-/KTS-) was found in all samples with significantly higher expression levels of the E5+ variants. Together, these findings support the potential of WT1 as a target for novel treatment approaches in AML.

Adult↗

PubMed2004

Quantitative detection of circulating tumor cells in cutaneous and ocular melanoma and quality assessment by real-time reverse transcriptase-polymerase chain reaction.

PURPOSE: Inconsistent reports on the detection of melanoma cells in peripheral blood by reverse transcriptase-PCR (RT-PCR) have resulted in uncertainty on the prognostic value of circulating melanoma cells. EXPERIMENTAL DESIGN: We developed real-time RT-PCR assays for quantitation of tyrosinase, MelanA/MART1, and gp100 and for porphobilinogen deaminase housekeeping gene. Melanoma tissue (n = 18), peripheral blood samples from healthy donors (n = 21), and patients with cutaneous (n = 122) and uveal (n = 64) melanoma from our institution were analyzed. For quality control, an additional 251 samples from ongoing multicenter studies were compared with in-house samples. RESULTS: Tyrosinase was not detected in healthy donor blood samples. For the two other markers, cutoff values had to be defined to distinct patient samples from controls. Patients with stage IV uveal and cutaneous melanoma expressed all three markers more frequently and at higher levels in peripheral blood as compared with earlier stages. The variation of expression was 4 logs and correlated with tumor load and serum lactate dehydrogenase. In 2 of 3 uveal melanoma patients, detection of circulating tumor cells preceded the development of liver metastases. The diagnostic sensitivity was optimal in blood samples containing >0.1pg/ microl porphobilinogen deaminase (95.7% of in-house samples and 57.4% of multicenter samples). CONCLUSIONS: Real-time RT-PCR is able to quantitatively define the quality of a sample and provides quantitative data for melanoma markers. Disparities in the results of previous studies may be attributable to undetected differences in sample quality. The prognostic relevance of this assay is currently under evaluation in several prospective randomized trials.

Antigens, Neoplasm↗

PubMed2004

Quantitative real-time RT-PCR for detection of disseminated tumor cells in peripheral blood of patients with colorectal cancer using different mRNA markers.

The detection of disseminated tumor cells in peripheral blood from colorectal cancer patients by RT-PCR could be an attractive method for selecting patients for adjuvant therapy. We here report on real-time RT-PCR assays (LightCycler) to quantitate potential mRNA markers. We investigated specimens from colon carcinoma and normal colon mucosa tissues, cell lines, blood samples from 129 patients with colorectal cancer (all stages) and 58 reference blood samples (healthy donors, persons suffering from inflammatory bowel or infectious diseases). The expression profile in tissues showed high values for CEA and CK20, whereas in cell lines ProtM was predominant. All markers were detected in reference and patient blood samples (ProtM, 22, 17%; CEA, 84, 86%; CK20, 85, 88%). After quantitative analysis, the definition of cutoff values for each marker and the combination of markers, 13% of patients were judged to have elevated marker concentrations in their blood, from which only 6 had values significantly differing from cutoff value. There were no differences between stages of disease. In the case of 19 patients, investigated prior to and 1 week after surgery, 2 samples revealed a significant postoperative increase in CEA or CK20 mRNA concentration. In spite of high expression levels in tissues and cell lines, we were not able to differentiate satisfyingly mRNA markers originating from tumor cells and those from illegitimate transcription in hematopoetic cells in blood. We conclude that either copy numbers of analyzed markers in circulating tumor cells are not sufficient for detection or, more probably, peripheral blood is not a suitable compartment for detection of tumor cells in colorectal cancer.

Biomarkers, Tumor↗

PubMed2004

A clinical phase I trial of gemcitabine and treosulfan in uveal melanoma and other solid tumours.

This trial was performed to define the maximum tolerated dose (MTD) of treosulfan administered in combination with a fixed dose of gemcitabine in uveal melanoma patients. Preclinical studies suggested synergistic activity against uveal melanoma. Gemcitabine (1 g/m2) and treosulfan (2.5-4 g/m2) were administered on days 1 and 8, and cycles were repeated on day 29 for a maximum of six cycles. For treosulfan, dose escalation cohorts of 2-4 patients were enrolled. An additional 25 patients were entered at treosulfan dose levels II (3 g/m2) and III (3.5 g/m2). Thirty three patients with uveal melanoma and six patients with other histologies were accrued. Side-effects were predominantly haematological. The MTD was 3.5 g/m2 of treosulfan together with 1 g/m2 of gemcitabine. In the uveal melanoma patients, one partial response (PR) and 15 stablisations of disease (SD) were recorded and whether this translates into a survival gain should be explored further.

Adult↗

PubMed2004

Independent prognostic factors for distant metastases and survival in patients with primary uveal melanoma.

Adjuvant treatment strategies in uveal melanoma require determination of prognostic factors. Patients, who received primary therapy in 1994 and 1995 at our institution, were analysed. Of 271 patients 85% and 71% were available for follow up of 4 and 5 years. Forty three patients (15.9%) developed metastases. Kaplan-Meier analysis revealed a 5-year progression free survival (PFS) of 79% for the whole patient cohort. Extraocular tumor growth (EOG), ciliary body involvement or a largest tumor diameter (LTD) >14 mm were associated with a significantly lower 5-year PFS of 28%, 61.4% or 67.6%. In multivariate analysis time to progression was significantly associated with ciliary body involvement and LTD, and survival was associated with ciliary body involvement. Ciliary body involvement profoundly increased the risk for metastases (hazard ratio 6.9, P<0.001) within the first 3 years. This study determined patients with ciliary body involvement to be candidates for future adjuvant therapeutic interventions.

Adolescent↗

PubMed2004

A phase II study of bendamustine chemotherapy as second-line treatment in metastatic uveal melanoma.

Uveal melanoma is the most frequent primary malignant neoplasm of the eye and has a poor prognosis in metastatic stage. Fotemustine or a combination of gemcitabine and treosulfan has demonstrated some efficacy in metastatic disease. We conducted a phase II trial to assess the second-line activity and toxicity of bendamustine hydrochloride, a nucleoside analogue with alkylating activity. Inclusion criteria were a Karnofsky performance status of > or = 60% and progressive disease during or after first-line chemotherapy. Bendamustine was administered at a dose of 120 mg/m2 on days 1 and 2. Cycles were repeated on day 22. The primary endpoint of the study was the determination of the number of patients achieving an objective response or stable disease. The secondary endpoint was toxicity. Eleven patients were enrolled into the trial. Grade III and IV toxicity consisted of anaemia, thrombocytopenia and leucocytopenia in two, one and two patients, respectively. No grade III or IV non-haematological toxicity was observed. According to Response Evaluation Criteria in Solid Tumours (RECIST), all patients showed progressive disease. We conclude that bendamustine is ineffective as second-line chemotherapy for metastatic uveal melanoma.

Adult↗

PubMed2004

Functional CCR9 expression is associated with small intestinal metastasis.

In general, metastases to the small intestine are rare, and mostly occur in melanoma. CCR9 has been shown to be the principal chemokine receptor for the thymus expressed chemokine (TECK), a chemokine selectively expressed in the small intestine and thymus. Here we show that CCR9 is highly expressed on melanoma cells and all melanoma cell lines isolated from small intestinal metastases, and on a proportion of cell lines from other sites. Only melanoma cells and cell lines from small intestinal metastases, however, were responsive to the CCR9 ligand TECK, as assessed by receptor downregulation and by actin polymerization. CCR9 expression was also found on the adenocarcinoma cell line CaCo-2 expressing characteristics of enterocytic differentiation, but not on any other cell line isolated from colorectal, breast, and lung cancer. Our data provide evidence that the aberrant functional cell surface expression of an organ-specific chemokine receptor is associated with metastasis to this site. The regulation of receptor function seems to be a critical step in the metastatic process.

Actins↗

PubMed2004

Immunological monitoring of cancer vaccine therapy.

Immunological treatment of malignant diseases in humans aiming at the induction and proliferation of antigen-specific T cells has made rapid progress in recent years. A growing number of tumour-associated antigens, potentially synergistic combinations with adjuvants, and various routes of application provide new opportunities for cancer vaccination. Therefore, a highly accurate assessment of vaccine-induced T cell responses is required. Three T cell assays (tetramers, intracellular cytokine flow cytometry and ELISPOT assay) have emerged as first-line methods for monitoring T cell induction during vaccination. These assays are relatively easy to perform, reliable, sensitive and allow an ex vivo T cell analysis at the single cell level. Although at this stage assays are not a defined surrogate marker for clinical efficacy, they already provide information concerning the immunological potency of a given vaccine. In particular, comparing immune responses under various treatment conditions will help to develop more clinically efficient tumour vaccination. Novel assays, such as CD107 staining, human leukocyte antigen/green fluorescent protein-antigen-presenting cells or microarrays, and assays determining functions, such as proliferation assays, are beginning to complement first-line monitoring assays.

Antigen-Antibody Reactions↗

PubMed2004

Specific tumour localisation of a huA33 antibody--carboxypeptidase A conjugate and activation of methotrexate-phenylalanine.

In antibody-directed enzyme-prodrug therapy (ADEPT), antibody-enzyme conjugates specifically activate non-toxic prodrugs in tumour tissue. The A33 cognate antigen is a promising target for immunotherapy of gastrointestinal cancers. We have explored A33-based ADEPT with carboxypeptidase A (CPA) and the prodrug, methotrexate-phenylalanine (MTX-Phe). In A33-positive SW1222 cells, the toxicity of MTX-Phe was about 3 logarithms lower compared to MTX. Preincubation with a huA33 antibody-CPA conjugate (huA33-CPA), but not with an isotypic control conjugate, rendered MTX-Phe equally toxic to MTX. No toxicity was observed in mice receiving MTX-Phe in 8-fold the LD50 of MTX. Nude mice bearing A33-positive SW1222 colon carcinoma xenografts were injected intravenously (IV) with 125I-labeled huA33-CPA. The conjugate localised to the tumour with a maximum from 6-24 h. Pre-treating these mice with excess A33 substantially reduced subsequent conjugate uptake, demonstrating immunologic specificity of tumour-uptake. Total tumour uptake and ratios of tumour over blood or normal tissues, however, were lower than with unconjugated A33. This may explain in part why no significant tumour responses were observed in xenografted mice. In summary, our results demonstrate in principle the feasibility of A33-based enzyme targeting, but they call for small recombinant antibody-enzyme constructs to facilitate tumour penetration and clearance from the bloodstream.

Animals↗

PubMed2003

Natural T cell immunity against cancer.

It has long been a matter of debate whether tumors are spontaneously immunogenic in patients. With the availability of sensitive methods, naturally occurring T cells directed against tumor-associated antigens (TAAs) can be frequently detected in cancer patients. In this review, we summarize the current data on T cell responses to TAAs in various malignancies, including melanoma, colorectal cancer, leukemia, and breast cancer. T cell responses against various antigens, including melanoma differentiation antigens, carcinoembryonic antigen, epithelial cell adhesion molecule, her-2/neu, Wilms' tumor protein, proteinase 3, NY-ESO-1, and surviving, have been reported in a substantial number of patients. In contrast, other TAAs, including most antigens of the MAGE family, do not usually elicit spontaneous T cell responses. A distinction between direct ex vivo T cell responses and in vitro-generated T cell responses is provided because in vitro stimulation results in quantitative and functional changes of T cell responses. The possible role of TAA-specific T cells in immunosurveillance and tumor escape and the implications for immunological treatment strategies are discussed. Naturally occurring T cells against TAAs are a common phenomenon in tumor patients. Understanding the mechanisms and behavior of natural TAA-specific T cells could provide crucial information for rational development of more efficient T cell-directed immunotherapy.

Antibodies, Monoclonal↗

PubMed2003

Bone marrow contains melanoma-reactive CD8+ effector T cells and, compared with peripheral blood, enriched numbers of melanoma-reactive CD8+ memory T cells.

Circulating melanoma-specific T cells can be frequently detected in patients with melanoma. Effective T-cell immunity and tumor surveillance, however, requires the presence of specific T cells in tissues populated by tumor cells. The bone marrow (BM) is a compartment frequently harboring micrometastatic tumor cells. Here, we compared directly ex vivo in peripheral blood (PB) and BM frequencies and differentiation phenotypes of T cells reactive with the melanoma-associated antigen tyrosinase and with autologous melanoma cells. Using intracellular cytokine and tetramer staining, we detected tyrosinase- and melanoma-reactive CD3+CD8+ T cells in the BM in similar or enhanced frequencies as in PB. Additional characterization of the differentiation subset using CD45RA and CCR7 revealed the presence of specific effector and memory T cells in the BM in all five patients analyzed. Remarkably, the frequency of tyrosinase- and melanoma-specific memory T cells was significantly increased in BM compared with PB. Thus, the BM may be an important compartment for tumor surveillance harboring a tumor-specific memory T-cell pool in addition to effector T cells.

Bone Marrow Cells↗

PubMed2003

Restricted T-cell receptor repertoire in melanoma metastases regressing after cytokine therapy.

One major rationale for using interleukin-2 and IFN-alpha in cancer immunotherapy is to activate tumor-specific T cells at the tumor site. To study the in situ T-cell response, we determined the T-cell receptor (TCR) repertoire in six melanoma metastases regressing after cytokine treatment obtained from five patients. Sequence analysis of overexpressed TCR beta-chain variable regions revealed the presence of clonally expanded T cells and also of T cells with highly homologous complementarity determining regions 3 in all five patients. This finding indicates that the T-cell response in regressing melanoma lesions is dominated by T cells directed toward a limited number of epitopes and that epitope-specific T cells frequently use a highly restricted TCR repertoire.

Amino Acid Sequence↗

PubMed2003

Differences in T-cell immunity toward tumor-associated antigens in colorectal cancer and breast cancer patients.

There is increasing evidence that tumors elicit specific T-cell responses in a substantial proportion of patients. Recently, we have shown that in patients with colorectal cancer specific T cells against the tumor-associated antigens (TAA) Ep-CAM, her-2/neu or CEA can be detected in peripheral blood using IFNgamma-ELISPOT assay. In our study, we have analyzed T-cell responses against HLA-A*0201-restricted epitopes of these TAA in peripheral blood of patients with breast cancer and colorectal cancer. Surprisingly, a complete absence of ex vivo T-cell responses against these TAA was found in 20 patients with breast cancer. In contrast, specific T cells were detectable in 12 of 49 patients with colorectal cancer against at least 1 of these TAA, confirming our previous results. T-cell responses against influenza-derived peptides were similar in both malignancies. The results of our study indicate a difference either of tumor immunogenicity or of the migratory pattern of tumor-specific T cells between breast cancer and colorectal cancer patients. The findings reported here have implications for the development of antigen-specific T-cell therapies.

Antibodies, Monoclonal↗