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Ulrich Keilholz

Publications and source records attributed to Ulrich Keilholz.

At least 19 recordsLinked to original sources
PubMed2007

A clinical development paradigm for cancer vaccines and related biologics.

Therapeutic cancer vaccines are a heterogeneous group of complex biologics with distinctly different clinical characteristics than cytotoxic agents. The current clinical development paradigm used for oncology drug development is based on criteria developed for cytotoxic agents. More flexible and focused developmental guidelines are needed to address the unique characteristics of therapeutic cancer vaccines. Over the course of 1 year, the Cancer Vaccine Clinical Trial Working Group, representing academia and the pharmaceutical and biotechnology industries with participation from the US Food and Drug Administration, defined in a consensus process the cornerstones of a new clinical development paradigm for cancer vaccines and related biologics. Four major topics were addressed: (1) end points for clinical trials, (2) trial designs and statistical methods, (3) technical and developmental challenges, and (4) combination therapy. The proposed paradigm suggests therapeutic cancer vaccines to be investigated in 2 general types of clinical studies: proof-of-principle trials and efficacy trials. Proof-of-principle trials, which introduce a novel cancer vaccine into humans, should include a minimum of 20 or more patients in a homogenous, well-defined population in an adjuvant setting or without rapidly progressive disease in a metastatic setting to allow vaccines adequate time to induce biologic activity and should incorporate immune and molecular markers. Objectives should include initiation of a safety database, determination of dose and schedule, and demonstration of biologic activity as proof-of-principle. Biologic activity is defined as any effect of the vaccine on the target disease or host immune system using biologic markers as study end points, for example, clinical, molecular, or immune response. Immune response is demonstrated if determined in 2 separate, established and reproducible assays at 2 consecutive follow-up time points after the baseline assessment. If proof-of-principle trials show such immune response, or other biologic or clinical activity, efficacy trials may be initiated. If none of these end points is met, the clinical development plan should be reevaluated to decide if further development is warranted. Efficacy trials formally establish clinical benefit either directly or through a surrogate and are encouraged to be randomized studies. This is in contrast to single-arm phase 2 trials used for cytotoxic agents, which often use tumor response rate as the primary end point and historical controls as a comparator. Efficacy trials may use prospectively planned adaptive designs to expand from randomized phase 2 into phase 3 studies if well-defined trigger-point criteria are met, but the cost of incorporating such design elements should be carefully evaluated. Efficacy trials can also be exploratory randomized phase 2 trials or conventional phase 3 trials. In addition, conventional clinical end points can be adjusted to account for biologic features of cancer vaccines. The concept of efficacy trials allows for an early assessment of vaccine efficacy based on credible prospective data. This 2-phase developmental paradigm supports a more flexible, expeditious, and focused clinical developmental process with early and informed decision making. In addition, this report addresses clinical development challenges and issues for combination therapies.

Cancer Vaccines↗
PubMed2006

Identification of a highly immunogenic HLA-A*01-binding T cell epitope of WT1.

PURPOSE: The transcription factor Wilms tumor protein 1 (WT1) belongs to a new generation of tumor antigens, as it is essential for tumor cell proliferation and is highly expressed in various hematologic and solid malignancies. The aim of this study was to apply a modified reverse immunology strategy to identify immunogenic epitopes of WT1 which could be useful for immunotherapy. EXPERIMENTAL DESIGN: Potential HLA-A*01 epitopes predicted by a MHC binding algorithm were screened for recognition by peripheral blood mononuclear cells (PBMC) from patients with spontaneous T cell responses using intracellular cytokine cytometry. Epitope processing was shown by proteasomal cleavage. Epitope-specific T cells were generated from CD4+CD25+ regulatory T cell-depleted PBMC. RESULTS: One of five predicted HLA-A*01-binding candidate epitopes showed high immunogenicity as 5 of 14 patients with hematologic malignancies had WT1.317-327-reactive T cells ranging from 0.4% to 1.5% of CD3+CD8+ T cells. Proteasomal degradation assays indicated the cleavage of WT1.317-327. The depletion of regulatory T cells from PBMCs enabled the rapid expansion of WT1.317-327-specific CTL, whereas no CTL could be generated from unfractionated PBMC. WT1.317-327-specific CTL efficiently lysed an autologous WT1-expressing tumor cell line but not HLA-A*01-negative WT1-expressing tumor cells. Immunogenicity of the epitope across histologies was verified by the demonstration of spontaneous ex vivo WT1.317-327-specific T cell responses in two of six patients with HLA-A*01-positive melanoma or lung cancer. CONCLUSION: In this study, a modified reverse immunology strategy was employed to identify a first immunogenic HLA-A*01-restricted T cell epitope of the tumor antigen WT1, which is of considerable interest for use in vaccination trials.

Antigens, Neoplasm↗
PubMed2006

Disappearing cancer.

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Colorectal Neoplasms↗
PubMed2006

Phase II trial of second-line bendamustine chemotherapy in relapsed small cell lung cancer patients.

PURPOSE: The efficacy and toxicity of bendamustine chemotherapy in relapsed small cell lung cancer (SCLC) was determined in this phase II trial. PATIENTS AND METHODS: Patients with cytologically or histologically proven SCLC, who had a sensitive relapse, which was defined as a relapse>or=2 months after completion of primary therapy, were eligible for this study. After informed consent patients received 120 mg/m2 of bendamustine on Days 1 and 2 every 3 weeks. A maximum of six cycles was administered. Primary endpoint was response rate, secondary endpoints included toxicity, progression free survival and overall survival (OS). RESULTS: Twenty-one patients with a median age of 59 years (range 47-76) were accrued to this trial. Six (29%) of 21 patients achieved a confirmed partial remission, 6 (29%) had stable disease and 9 (42%) patients progressed according to RECIST criteria. Median progression free survival was 4 months (95% CI 0-8, 3), median overall survival was 7 months (95% CI 5, 8-8, 2). One- and 2-year survival was 16% and 8%, respectively. Grade III/IV neutropenia occurred in 3 (15%) of 21 patients, 1 patient had a lethal Gram-negative sepsis in neutropenia. Two additional patients had pneumonia in the absence of neutropenia. Two patients (10%) had a grade III anemia, no grade III or IV thrombocytopenia was observed. CONCLUSION: This trial demonstrates efficacy of bendamustine in relapsed SCLC and a favourable toxicity profile. Therefore, single-agent bendamustine is a treatment option for patients with SCLC, who have responded to initial platinum containing chemotherapy and should further be investigated in randomized trials.

Aged↗
PubMed2006

Addition of GM-CSF to a peptide/KLH vaccine results in increased frequencies of CXCR3-expressing KLH-specific T cells.

T-cell trafficking is determined by expression patterns of chemokine receptors. The chemokine receptor CXCR3 is expressed on a subpopulation of type 1 T cells and plays an important role for migration of T cells into inflamed and tumor tissues. Here, we studied the chemokine receptor expression on specific T cells generated against the neoantigen keyhole limpet hemocyanin (KLH) in patients who had been immunized in the context of a tumor peptide vaccination trial with or without the adjuvant granulocyte-macrophage colony-stimulating factor (GM-CSF). In patients immunized in the presence of GM-CSF the fraction of CXCR3(+) KLH-specific T cells was significantly higher than in patients immunized in the absence of GM-CSF (median 45 vs. 20%, P = 0.001). In contrast, the chemokine receptor CCR4, associated with migration to the skin was found in both cohorts on less than 10% of KLH-specific T cells. These results show that CXCR3 expression on vaccine-induced T cells can be modulated by modifying the local vaccine milieu.

Adjuvants, Immunologic↗
PubMed2006

Chemokine receptor CCR6 expression level and liver metastases in colorectal cancer.

PURPOSE: The liver is the primary organ of metastasis in colorectal cancer (CRC). Chemokine receptor CCR6 is expressed on a subset of T cells and is associated with their migration into the liver. This study was performed to analyze a possible association between CCR6 expressed by primary CRC and liver metastases. PATIENTS AND METHODS: CCR6 expression levels were evaluated by immunohistology in 64 CRC primary tumor specimens. Twenty-four of 64 patients had synchronous liver metastases. Evaluation of immunostaining was performed semiquantitatively by visual assessment and quantitatively by digital image analysis (DIA). Multiple logistic regression analysis was performed to assess relevant parameters for liver metastases. RESULTS: CCR6 expression was verified in all 64 primary tumor specimens with considerable variations in intensity; 21 tumors (33%) demonstrated weak CCR6 staining, 32 (50%) demonstrated intermediate staining, and 11 (17%) demonstrated strong staining. Quantitative assessment by DIA showed an up to 5-log difference in CCR6 values. CCR6 staining was significantly stronger in tumor cells compared with adjacent colon epithelial cells (P < .0005). Multiple logistic regression analysis, controlling for age, sex, tumor stage, nodal status, pathologic grade, and preoperative carcinoembryonic antigen levels, revealed that CCR6 staining in the primary tumor was independently associated with the presence of liver metastases (odds ratio = 2.1; P = .002). CONCLUSION: The association between expression level of CCR6 in primary CRC and synchronous liver metastases suggests that CCR6 and its ligand may be involved in the metastatic spread to the liver. Therefore, CCR6 may be a potential target for specific therapeutic interventions.

Aged↗
PubMed2006

Immune monitoring of T-cell responses in cancer vaccine development.

Monitoring cellular immune responses is one prerequisite for rational development of cancer vaccines. The primary objective of immune monitoring is to determine the efficacy of a vaccine to induce or augment a specific T-cell response. Further questions relate to the prevalence and functional relevance of spontaneous tumor-directed immune responses, the functional characteristics of T-cell responses, and, finally and most importantly, the relationship between immune monitoring assay results and clinical end points. The issue of T-cell monitoring has become more complex as different types and generations of assays have been adopted during the past decade and both standardization and validation of assays have often been insufficient. Because the development of assays parallel the clinical development of cancer vaccines, technical advances have been achieved simultaneously with broadening understanding of cancer immunity. Suitable animal models for immune monitoring are, however, lacking, because preclinical vaccine development in rodents does not allow serial immune monitoring of the peripheral blood, as is commonly used in patients. The current situation is characterized by a lack of universal standards for T-cell assessment, uncertainty about the association between immune monitoring assay results and clinical antitumor end points, and lack of knowledge regarding the contribution of different aspects of T-cell function to clinical efficacy. It is acknowledged that T-cell monitoring will have to be validated in large trials with clinically effective vaccines, but this necessity should not discourage the current application of novel assays within clinical trials of all stages.

Animals↗
PubMed2006

Innovations and challenges in melanoma: summary statement from the first Cambridge conference.

Innovations and Challenges in Melanoma, chaired by Michael Atkins and cochaired by Ulrich Keilholz, John Kirkwood, and Jeffrey Sosman, was held July 15 to 16, 2005, in Cambridge, Massachusetts. The conference brought together leading experts in the fields of cancer research, medical oncology, surgical oncology, anatomic pathology, dermatology, and immunotherapy who wished to advance the field of melanoma treatment by exchanging information and perspectives regarding recent advances and recommendations for further study. The conference proceedings published in this educational supplement to Clinical Cancer Research are intended to provide timely information and recommendations on how genetics, biology, and data information can enhance our understanding of melanoma biology and help inform the use of therapies for this disease.

Humans↗
PubMed2006

Circulating tumor cells: the 'leukemic phase' of solid cancers.

It is well known that malignant cells circulate in the bloodstream of patients with solid tumors. However, the biological significance of circulating tumor cells (CTCs) and the clinical relevance of their detection are still debated. Besides technical issues regarding CTC-detection methods, discontinuous shedding of CTCs from established cancer deposits, genomic instability and metastatic inefficiency might underlie the conflicting results currently available. Nevertheless, technological advances and recent clinical findings are prompting researchers to dissect CTC biology further. Here, we review these recent findings, and discuss the prospects for the identification and molecular characterization of the CTC subset that is responsible for metastasis development. This would provide a formidable tool for prognosis evaluation, anticancer-drug development and, ultimately, cancer-therapy personalization.

DNA, Neoplasm↗
PubMed2005

Lymphomas are sensitive to perforin-dependent cytotoxic pathways despite expression of PI-9 and overexpression of bcl-2.

There is considerable interest in immunotherapeutic approaches for lymphoma. The expression of proteinase inhibitor 9 (PI-9), a molecule that inactivates granzyme B, is considered an immune escape mechanism in lymphoma. Further, lymphomas frequently overexpress the antiapoptotic molecule bcl-2, which is able to inhibit perforin-dependent cytotoxic pathways. In this study, the impact of PI-9 and bcl-2 expression on the sensitivity of lymphomas to T- and natural killer (NK) cell-mediated cytotoxicity was analyzed. We found PI-9 expression in 10 of 18 lymphoma cell lines and in 9 of 14 primary lymphomas. Overexpression of bcl-2 was found in 8 of 18 cell lines and in 12 of 14 primary lymphomas. All lymphoma cells were sensitive to cytolysis by specific T cells and cytokine-activated NK cells, and no difference in sensitivity was observed with respect to PI-9 or bcl-2 expression. Cytolysis was mediated predominantly through perforin-dependent pathways despite expression of PI-9 and bcl-2. Interestingly, the majority of lymphoma cells were resistant to cytolysis by resting allogeneic NK cells. This was due to the failure of lymphomas to induce degranulation of resting NK cells. These results show that resistance to perforin-dependent pathways is not a relevant immune escape mechanism in lymphoma and therefore is unlikely to impair clinical outcome of immunotherapeutic approaches.

Cytokines↗
PubMed2005

Post-surgery adjuvant therapy with intermediate doses of interferon alfa 2b versus observation in patients with stage IIb/III melanoma (EORTC 18952): randomised controlled trial.

BACKGROUND: Individuals affected by melanoma with thick primary tumours or regional node involvement have a poor outlook, with only 30-50% alive at 5 years. High-dose and low-dose interferon alfa have been assessed for the treatment of these patients, with the former having considerable toxicity and a consistent effect on disease free survival, but not on overall survival, and the latter no consistent effect on either. Our aim was, therefore, to assess the effect of two regimens of interferon of intermediate dose versus observation alone on distant metastasis-free interval (DMFI) and overall survival in such patients. METHODS: We did a randomised controlled trial in 1388 patients who had had a thick primary tumour (thickness > or = 4 mm) resected (stage IIb) or regional lymph node metastases dissected (stage III) and had been assigned to 13-months (n=553) or 25 months (n=556) of treatment with subcutaneous interferon alfa 2b, or observation (n=279). Treatment comprised 4 weeks of 10 million units (MU) of interferon alfa (5 days per week) followed by either 10 MU three times a week for 1 year or 5 MU three times a week for 2 years, to a total dose of 1760 MU. Our primary endpoint was DMFI. Analyses were by intent to treat. FINDINGS: After a median follow-up of 4.65 years, we had recorded 760 distant metastases and 681 deaths. At 4.5 years, the 25-month interferon group showed a 7.2% increase in rate of DMFI (hazard ratio 0.83, 97.5% CI 0.66-1.03) and a 5.4% improvement in overall survival. The 13-month interferon group showed a 3.2% increase in rate of DMFI at 4.5 years (0.93, 0.75-1.16) and no extension of overall survival. Toxicity was acceptable, with 18% (195 of 1076) of patients going off study because of toxicity or as a result of refusal of treatment because of side-effects. INTERPRETATION: Interferon alfa as used in the regimens studied does not improve outcome for patients with stage IIb/III melanomas, and cannot be recommended. With respect to efficacy of the drug, duration of treatment seemed more important than dose, and should be assessed in future trials.

Adult↗
PubMed2005

Dacarbazine, cisplatin, and interferon-alfa-2b with or without interleukin-2 in metastatic melanoma: a randomized phase III trial (18951) of the European Organisation for Research and Treatment of Cancer Melanoma Group.

BACKGROUND: Based on phase II trial results, chemoimmunotherapy combinations have become the preferred treatment for patients with metastatic melanoma in many institutions. This study was performed to determine whether interleukin-2 (IL-2) as a component of chemoimmunotherapy influences survival of patients with metastatic melanoma. PATIENTS AND METHODS: Patients with advanced metastatic melanoma were randomly assigned to receive dacarbazine 250 mg/m2 and cisplatin 30 mg/m2 on days 1 to 3 combined with interferon-alfa-2b 10 x 10(6) U/m2 subcutaneously on days 1 through 5 without (arm A) or with (arm B) a high-dose intravenous decrescendo regimen of IL-2 on days 5 through 10 (18 x 10(6) U/m2/6 hours, 18 x 10(6) U/m2/12 hours, 18 x 10(6) U/m2/24 hours, and 4.5 x 10(6) U/m2 for 3 x 24 hours). Treatment cycles were repeated in the absence of disease progression every 28 days to a maximum of four cycles. RESULTS: Three hundred sixty-three patients with advanced metastatic melanoma were accrued. The median survival was 9 months in both arms, with a 2-year survival rate of 12.9% and 17.6% in arms A and B, respectively (P = .32; hazard ratio, 0.90; 95% CI, 0.72 to 1.11). There was also no statistically significant difference regarding progression-free survival (median, 3.0 v 3.9 months) and response rate (22.8% v 20.8%). CONCLUSION: Despite its activity in melanoma as a single agent or in combination with interferon-alfa-2b, the chosen schedule of IL-2 added to the chemoimmunotherapy combination had no clinically relevant activity.

Adult↗
PubMed2005

Ifosfamide/liposomal daunorubicin is a well tolerated and active first-line chemotherapy regimen in advanced soft tissue sarcoma: results of a phase II study.

BACKGROUND: The anthracycline/ifosfamide combination is the most effective chemotherapy in soft tissue sarcoma. To improve the tolerability and potential efficacy of this combination, the authors combined a moderate dose of continuous infusion ifosfamide with liposomal daunorubicin (L-Dauno). METHODS: In a single-arm, Phase II study, 40 patients with a median age of 57 years (range, 19-78 years) were enrolled. Of these, 35 patients were treated with first-line chemotherapy. The treatment regimen was comprised of ifosfamide at a dose of 5 g/m(2) over 24 hours and L-Dauno at a dose of 100 mg/m(2) every 4 weeks with granulocyte-colony-stimulating factor support. RESULTS: Eleven (31%) of 35 anthracycline/ifosfamide-naive patients achieved a partial/complete response, 6 patients (17%) had stable disease, and 13 patients (37%) had disease progression. Three patients were not evaluable, and there were two intermittent deaths. The median time to disease progression was 6 months, the median overall survival was 14 months, and the median time to treatment failure was 15 months. Toxicity was tolerable. CONCLUSIONS: The combination of Ifosfamide and L-Dauno was found to be a highly active chemotherapy regimen for first-line treatment of soft tissue sarcoma. Therefore, we believe randomized studies with this regimen are warranted.

Adult↗
PubMed2005

Peptide vaccination after repeated resection of metastases can induce a prolonged relapse-free interval in melanoma patients.

This pilot study was carried out to gain a first insight into the effects of peptide vaccination in melanoma patients in the high-risk adjuvant disease setting. From the adjuvant peptide vaccination studies carried out in our institution since 1998, we identified all melanoma patients with a history of at least 3 completely resected metastases during the year preceding enrollment into the trial and describe the clinical and immunologic observations. Out of a total of 44 patients with resected cutaneous melanoma entered into adjuvant peptide vaccination trials, 9 patients were identified with more than 3 metastases in the year before vaccination. After initiation of vaccination, 2 patients remained relapse-free for 27 and 42+ months, 2 patients experienced single or several initial relapses and subsequent relapse-free intervals of 18 and 65+ months, whereas 5 patients progressed. In both patients with relapse after prolonged relapse-free intervals, the relapses were initially confined to the small intestine and could be resected. Induction or boosting of functional tyrosinase peptide-specific T cells was noted in 6 of 8 patients, including all 4 patients with prolonged relapse-free intervals. In conclusion, adjuvant peptide vaccination was associated with cessation of recurrences in 4 of 9 patients, of whom all 4 had an immunologic response to the vaccine.

Adjuvants, Immunologic↗
PubMed2005

Molecular staging in stage II and III melanoma patients and its effect on long-term survival.

PURPOSE: To assess the prognostic value of serial reverse transcriptase polymerase chain reaction (RT-PCR) -based measurements of tyrosinase mRNA in peripheral blood of stage II and III melanoma patients. PATIENTS AND METHODS: During routine follow-up of American Joint Committee on Cancer stage II and III melanoma patients, serial testing for tyrosinase transcripts in peripheral blood was performed by RT-PCR. The PCR results were compared with the clinical data collected during the follow-up. RESULTS: Over a period of 3 years, 111 patients (78 stage II and 33 stage III patients) were enrolled, and tyrosinase determinations were carried out. The 6-year disease-specific survival probability was 97% for patients always showing negative RT-PCR results and 67% for patients who tested positive at least once. In a Cox proportional hazards model, the prognostic value of sex, age, site of primary tumor, histologic subtype, stage, Breslow's tumor thickness, Clark level, and the time-dependent variable PCR result was assessed. Patients with a positive RT-PCR test had a distinctly higher risk of dying from melanoma, with a hazard ratio of 12.6 (95% CI, 3.4 to 46.3; P < .001). CONCLUSION: Our study shows a strong association between PCR and disease-specific survival time. Detection of tyrosinase mRNA in peripheral blood may be of similar importance for the clinical course of melanoma as the detection of micrometastatic disease in the sentinel lymph node. Whether a combination of these two factors leads to a better definition of the prognosis of melanoma patients is under investigation in current studies.

Adult↗