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Biomedical subjects

Douglas S Tyler

Publications and source records attributed to Douglas S Tyler.

At least 37 records · Page 2Linked to original sources
PubMed2005

Cotransfection of DC with TLR4 and MART-1 RNA induces MART-1-specific responses.

BACKGROUND: Cotransfection of dendritic cells (DC) with MART-1 and constitutively active TLR4 (caTLR4) RNA enhances the maturation of DC. MATERIALS AND METHODS: Immature DC were cotransfected with RNA constructs encoding MART-1 and caTLR4, and CTL responses were analyzed. RESULTS: Cotransfection of DC with MART-1 + caTLR4 enhanced the expression of CD80 and CD83 surface markers and increased the secretion of cytokines IL-6, IL-12, and TNFalpha. Neither the native nor the A27L-modified MART-1 RNA could induce significant DC maturation or cytokine secretion. More importantly, DC cotransfected with caTLR4 + MART-1 RNA induced MART-1-specific CTL responses of a higher magnitude than DC transfected with either the native or A27L MART-1 RNA. When the MART-1 RNA-transfected DC were treated with DC-maturing cytokines, the induced CTL were less frequent and less lytic than those induced with MART-1 + caTLR4. A 2- to 100-fold increase in MART-1 tetramer+ cells and 2- to 10-fold increases in IFNgamma secretion and cytotoxicity were seen in CTL induced with MART-1 + caTLR4 compared to CTL induced with either MART-1 or A27L RNA. CTL induced with the mixed RNA displayed high percentages of CD8+ cells coexpressing CD45RA, CD56, and 2B4 antigens. Transfection with caTLR4 alone induced DC maturation, but did not induce lytic CTL, suggesting that CTL responses were induced solely by MART-1 epitopes. CONCLUSIONS: caTLR4 increases the CTL-inducing capacity of DC generating a lytic response specific for the accompanying antigen. These results demonstrate the possibility of enhancing the immunogenicity of the native MART-1 and other RNA derived from weakly immunogenic tumors in DC-based immunotherapy.

Antigens, Neoplasm↗
PubMed2005

Clear cell hidradenoma: a mimic of metastatic clear cell tumors.

Clear cell hidradenoma is a benign skin appendage tumor that may mimic conventional-type renal cell carcinoma. Histologically, clear cell hidradenoma contains small ductular lumens, focal apocrine and squamoid change, and a less prominent vascular pattern than renal cell carcinoma. Furthermore, immunohistochemical studies can aid in distinguishing the 2 tumors. Knowing the cytologic features of primary skin adnexal neoplasms helps distinguish them from cutaneous metastases, which are more commonly referred for fine-needle aspiration biopsy evaluation. Detailed clinical history, physical findings, and ancillary studies are essential for correct diagnosis and categorization of these tumors. We report the rare case of a patient with renal cell carcinoma who underwent excision of an axillary clear cell hidradenoma, which was clinically suggestive of cutaneous metastatic disease.

Adenoma, Sweat Gland↗
PubMed2005

The importance of total number of sentinel lymph nodes in patients with stage N0 cutaneous melanoma.

Staging of malignant melanoma now relies routinely on the sentinel node (SN) technique. On average, 2.1 SNs are removed per patient. Nevertheless, despite the success of the SN technique, approximately 10% of patients with negative SNs experience metastatic recurrence. Because a prior theoretical analysis using Poisson and Bayes probability models suggested that limited sampling of SNs could cause false-negative results, we undertook this study to see whether the subset of patients with negative SN and only 1 or 2 nodes examined have a shorter time to recurrence than patients with 3 or more nodes examined and found to be negative. Our study cases comprised 178 melanoma cases with SN biopsy: positive SN, 47; negative SN and fewer than 3 nodes examined, 68; and negative SN and more than 2 nodes examined, 63. Patients with negative SNs and fewer than 3 examined had disease-free survival intermediate between patients with positive SNs and those with negative SNs and more than 2 examined (P = .013). These results suggest that among patients with negative SNs, those with fewer than 3 nodes examined have greater risk for recurrence.

Adolescent↗
PubMed2004

Iodine-131 metaiodobenzylguanidine treatment for metastatic carcinoid. Results in 98 patients.

BACKGROUND: Iodine-131 metaiodobenzylguanidine (131I-MIBG) is useful for imaging carcinoid tumors and recently has been applied to the palliative treatment of metastatic carcinoid in small studies. The authors now report their results on the therapeutic utility of high-dose 131I-MIBG treatment in a large group of patients with metastatic carcinoid tumors. METHODS: The authors performed a retrospective review of 98 patients with metastatic carcinoid who were treated at their institution with 131I-MIBG over a 15-year period. Endpoints examined included the World Health Organization criteria for treatment response: symptoms, hormone (5-hydroxyindoleacetic acid [5-HIAA]) production, and clinical tumor response. RESULTS: Patients received a median dose of 401 +/- 202 millicuries (mCi) 131I-MIBG. The median survival after treatment was 2.3 years. Patients who experienced a symptomatic response had improved survival (5.76 years vs. 2.09 years; P < 0.01). For the 56 patients who had 5-HIAA levels monitored, the mean urine 5-HIAA levels decreased significantly after 131I-MIBG treatment (126 +/- 122 ng/mL vs. 91 +/- 125 ng/mL; P < 0.01); however, the patients with reduced 5-HIAA levels did not experience improved survival (4.11 years vs. 3.42 years; P = 0.2). Patients who received an initial 131I-MIBG dose > 400 mCi lived longer than patients who received < 400 mCi (4.69 years vs. 1.86 years; P = 0.05). Radiographic tumor response did not predict survival. Toxicity included pancytopenia, thrombocytopenia, nausea, and emesis. CONCLUSIONS: The current data support 131I-MIBG treatment in select patients with metastatic carcinoid who progress despite optimal medical management. Improved survival was predicted best by symptomatic response to 131I-MIBG treatment, but not by hormone or radiographic response.

3-Iodobenzylguanidine↗
PubMed2004

Induction of human dendritic cell maturation using transfection with RNA encoding a dominant positive toll-like receptor 4.

Maturation of dendritic cells (DC) is critical for the induction of Ag-specific immunity. Ag-loaded DC matured with LPS, which mediates its effects by binding to Toll-like receptor 4 (TLR4), induce Ag-specific CTL in vitro and in vivo in animal models. However, clinical use of LPS is limited due to potential toxicity. Therefore, we sought to mimic the maturation-inducing effects of LPS on DC by stimulating TLR4-mediated signaling in the absence of exogenous LPS. We developed a constitutively active TLR4 (caTLR4) and demonstrated that transfection of human DC with RNA encoding caTLR4 led to IL-12 and TNF-alpha secretion. Transfection with caTLR4 RNA also induced a mature DC phenotype. Functionally, transfection of DC with caTLR4 RNA enhanced allostimulation of CD4(+) T cells. DC transfected with RNA encoding the MART (Melan-A/MART-1) melanoma Ag were then used to stimulate T cells in vitro. Cotransfection of these DC with caTLR4 RNA enhanced the generation of MART-specific CTL. This CTL activity was superior to that seen when DC maturation was induced using either LPS or a standard mixture of cytokines (TNF-alpha, IL-6, IL-1beta, and PGE(2)). We conclude that transfection of DC with RNA encoding a functional signaling protein, such as caTLR4, may provide a new tool for studying TLR signaling in DC and may be a promising approach for the induction of DC maturation for tumor immunotherapy.

Cell Line↗
PubMed2004

Pancreatic duct strictures: identifying risk of malignancy.

BACKGROUND: This study aimed to define PDS characteristics that predict malignancy and would thus invoke further diagnostic evaluation or aggressive treatment. METHODS: 355 cases of PDS were diagnosed by ERCP during a 7-year period at a single institution. A retrospective review identified clinical/demographic patient data and ERCP results. RESULTS: 218 (61%) patients with a PDS were found to have an isolated PDS. Twelve percent of isolated PDS and 79% of CBD stricture-associated PDS were malignant. The sensitivity and specificity for the double duct sign for malignancy were 77% and 80% respectively, and the positive predictive value was 65%. Predictors of malignancy were statistically similar for both isolated PDS and those associated with a CBD stricture. Univariate predictors of malignancy included stricture location in the pancreatic head/neck, jaundice, and patient age. Predictors of benign disease included a history of pancreatitis, the presence of multiple strictures, pancreatic duct stones, pseudocyst, pancreas divisum anatomy, irregular side branches, and irregular pancreatic duct morphology. Less than 1% of patients with either pancreas divisum anatomy, pancreatic duct stones, or pancreatic pseudocyst had malignancy. Using malignancy as the dependent variable, multivariate factors included in the final prognostic equation were history of pancreatitis (odds ratio 0.009 with history of pancreatitis), stricture location in the head or neck (odds ratio 42) and irregular pancreatic duct side branches (odds ratio 0.05 with irregular branches). CONCLUSIONS: This study demonstrates that certain characteristics of PDS can predict the subset of patients who have an increased risk of cancer.

Algorithms↗
PubMed2004

A Phase I trial of preoperative eniluracil plus 5-fluorouracil and radiation for locally advanced or unresectable adenocarcinoma of the rectum and colon.

PURPOSE: Eniluracil, an effective inactivator of dihydropyrimidine dehydrogenase, allows for oral dosing of 5-fluorouracil (5-FU), which avoids the morbidity of continuous infusion 5-FU. We addressed the safety of oral eniluracil and 5-FU combined with preoperative radiotherapy and determined the recommended Phase II dose and dose-limiting toxicity in patients with locally advanced rectal and colon cancer. METHODS AND MATERIALS: Patients with TNM Stage II or III rectal cancer and residual or recurrent colon cancer received eniluracil (starting at 6.0 mg/m(2) every 12 h) and 5-FU (starting at 0.6 mg/m(2) every 12 h). Eniluracil and 5-FU were given with a 5-week course of preoperative radiotherapy of 4500 cGy, with a possible 540-cGy boost. Surgery was performed approximately 4 weeks after completion of chemoradiotherapy. RESULTS: Twenty-two patients were enrolled; 1 patient was withdrawn owing to noncompliance. Chemotherapy was completed in all patients; radiotherapy was completed in 20 patients. The recommended Phase II dose of eniluracil and 5-FU was 8 mg/m(2) every 12 h and 0.8 mg/m(2) every 12 h, respectively. Diarrhea was the dose-limiting toxicity. Eleven of the 17 patients with primary rectal cancer underwent a sphincter-sparing procedure. One patient had a pathologic complete response. CONCLUSION: Preoperative chemoradiotherapy with oral eniluracil and 5-FU is feasible and well tolerated. Additional investigation is warranted.

Adenocarcinoma↗
PubMed2004

Temozolomide is a novel regional infusion agent for the treatment of advanced extremity melanoma.

BACKGROUND: Regional infusion therapy with melphalan (LPAM) is an accepted treatment for advanced extremity melanoma. However, much room exists for improving the therapeutic index of this type of therapy. METHODS: Isolated limb infusion (ILI) with temozolomide (TMZ), a novel methylating agent, was performed using a nude rat bearing human melanoma xenograft. Additional rats were treated systemically with TMZ, or regionally with LPAM or 10% dimethyl sulfoxide (DMSO; control) using ILI. RESULTS: Rats that received systemic TMZ showed a poor tumor response and no tumor regression. In contrast, intra-arterial TMZ demonstrated a prolongation of tumor growth delay in a dose-responsive manner. In comparison with LPAM of equitoxic dose, TMZ provided both longer tumor growth delay and a greater number of tumor regressions. CONCLUSIONS: These data suggest that ILI with TMZ is an effective treatment for advanced extremity melanoma and may be better than LPAM in this setting.

Analysis of Variance↗
PubMed2004

Dendritic cells pulsed with pancreatic cancer total tumor RNA generate specific antipancreatic cancer T cells.

RNA-based dendritic cell immunotherapy with the use of total tumor RNA provides the potential to generate a polyclonal immune response to multiple known and unknown tumor antigens without HLA restriction. Our study evaluated this approach as potential immunotherapy for patients with pancreatic cancer. Dendritic cells were generated using adherent monocytes isolated from peripheral blood of patients with pancreatic cancer and evaluated phenotypically by flow cytometry to determine whether dendritic cells could be generated from the blood of patients with pancreatic cancer. Immature dendritic cells were transfected with mRNA encoding full-length carcinoembryonic antigen (CEA) or pancreatic cancer total tumor messenger RNA, and then matured. Matured dendritic cell phenotypes were also analyzed by flow cytometry. Transfected, matured dendritic cells were used to stimulate autologous T cells, and the resultant antigen-specific effector T cells were analyzed by interferon-gamma Elispot assay. Immature dendritic cells with characteristic phenotypic markers CD40, CD80, and CD86 were successfully isolated from the blood of patients with pancreatic cancer. Incubation with maturation agents increased expression of CD80 and CD83, demonstrating the induction of a mature antigen-presenting phenotype. Dendritic cells transfected with a pancreatic cancer-associated antigen (CEA) generated antigen-specific T cells (P<0.05). Dendritic cells transfected with autologous total tumor pancreatic cancer RNA generated T cells that specifically recognized HLA-matched pancreatic cancer cell lines (P<0.05 compared to control cell lines). Dendritic cells from patients with pancreatic cancer maintain the ability to translate and process transfected RNA and serve as mature antigen-presenting cells. These RNA-transfected dendritic cells from pancreatic cancer patients successfully generate specific T cells against the pancreatic cancer-associated antigen CEA as well as T cells that specifically recognize pancreatic cancer cells. These data suggest that total tumor RNA-pulsed dendritic cells may have potential as an adjuvant immunotherapy for patients with pancreatic cancer.

Adenocarcinoma↗
PubMed2004

In-transit melanoma: the role of alkylating-agent resistance in regional therapy.

BACKGROUND: Regional perfusion treatments for melanoma, using the alkylating agent melphalan, show variable responses in magnitude and duration. Surprisingly, the potential contribution of alkylating-agent resistance mechanisms to diminish tumor responses, especially the crucial cellular detoxifying system formed by glutathione (GSH) and its associated enzyme glutathione-S-transferase (GST), has remained unexplored. Objectives of this study were to characterize GSH levels and GST activity in melanoma of patients undergoing regional perfusion and examine the effect of melphalan concentration in both an in vitro human melanoma cell line and in the extremity melanoma of an in vivo rodent limb infusion model. STUDY DESIGN: Human in-transit melanoma, muscle, subcutaneous tissue, and skin (n = 9) and metastatic regional lymph nodes (n = 7) were evaluated for GSH level and GST activity. Effects of increasing melphalan exposure on GSH and GST were studied in an in vitro human melanoma cell line. A survival human melanoma xenograft model of isolated limb infusion using increasing dosages of melphalan was used, with evaluation of GSH and GST in the recurrent tumor. RESULTS: GSH levels in human in-transit lesions and muscle were significantly higher than that of skin and subcutaneous tissue. Four of 9 patients had tumor-to-muscle GSH ratio > 1. A strong correlation was seen between in vitro melphalan dose and resultant GSH level and GST activity. In vivo recurrent tumor GSH levels correlated with increasing melphalan infusion dose. CONCLUSIONS: A GSH-based resistance pathway may play a role in effecting response and toxicity to regional melphalan perfusion.

Animals↗
PubMed2004

Sequential delivery of maturation stimuli increases human dendritic cell IL-12 production and enhances tumor antigen-specific immunogenicity.

BACKGROUND: Despite the increasing use of dendritic cells (DCs) in clinical trials, questions regarding the optimal means of DC preparation, in particular how to achieve optimal maturation, remain unanswered. We hypothesized that delivering two separate sequential maturation signals to DC in vitro, mimicking the process of DC maturation that occurs in vivo, would enhance the ability of DCs to generate antigen-specific effector T cells in an experimental in vitro antimelanoma model. MATERIALS AND METHODS: Human monocyte-derived DCs were transfected with mRNA encoding melanoma-associated antigen Mart-1 (MART) or influenza M1 matrix protein (M1). After mRNA transfection, DCs were left untreated or exposed to different maturation stimuli either added simultaneously or delivered sequentially 18 h after first stimulation. Phenotypic DC cell-surface marker changes and IL-12 secretion were analyzed. Specific antigen presentation by DCs was measured by IFN-gamma release Elispot assay using a CD8(+) MART peptide-specific T cell clone. RNA-transfected and treated DCs were cultured with autologous naive T cells and the induction of antigen-specific effector T cells were assessed by IFN-gamma release Elispot assay. RESULTS: DCs transfected and matured had increased cell-surface expression of CD40 and costimulatory molecules CD80, and CD86. DCs matured and further treated by soluble CD40 ligand (sCD40L) had a 10- and 2-fold increase in MART antigen presentation compared to untreated (immature) DCs and DCs treated only with a first maturation signal, respectively (Elispot P = 0.02). Delivery of sequential maturation stimuli resulted in maximal DC IL-12 secretion compared to simultaneous stimuli. Last, generation of antigen-specific effector T cells more than doubled with the sequential addition of sCD40L to mature DC stimulators (Elispot P = 0.009). CONCLUSIONS: Maturation of DCs following mRNA transfection increases expression of cell-surface costimulatory molecules. Delivery of a second sequential maturation stimulus enhances antigen presentation, increases IL-12 secretion, and augments immunogenicity as evidenced by generation of tumor antigen-specific effector T cells. This strategy should be considered in the future development of RNA-based DC vaccine strategies for the treatment of cancer.

Antigen-Presenting Cells↗
PubMed2004

Neoadjuvant therapy for pancreatic cancer: the Duke experience.

The advantages of neoadjuvant (preoperative) chemoradiation therapy for pancreatic cancer include the assurance that all resected patients receive multimodality therapy; the opportunity for patients with occult metastatic disease to manifest themselves; and the potential to improve resectability. Since 1994, Duke University Medical Center has treated over 180 patients with localized pancreatic cancer using neoadjuvant 5-fluorouracil (5FU)-based chemoradiation therapy (CRT). Approximately 20% of patients demonstrate distant disease progression during CRT and avoid the morbidity of laparotomy. Almost 20% of locally advanced tumors on initial-staging CT can be resected following CRT. Patients who have successfully undergone resection have experienced favorable survival with an estimated 5-year survival rate of 36%. This article reviews the authors' experience and the lessons learned from it.

Adult↗
PubMed2004

Modulation of resistance to regional chemotherapy in the extremity melanoma model.

BACKGROUND: The presence of resistance to chemotherapy is associated with poor tumor response and patient survival in a variety of tumors. Attempts to modulate resistance in conjunction with systemic chemotherapy have been limited by the toxicity of combined therapy, particularly gastrointestinal or hematopoetic toxicity. This study explored systemic modulation of resistance in conjunction with intra-arterial regional therapy to determine if tumor responses to melphalan could be improved with acceptable toxicity. METHODS: Using a nude rat human xenograft model of extremity melanoma,we analyzed tumors for glutathione (GSH), the main protein in the melphalan resistance pathway. Modulation of GSH was performed with intraperitoneal buthionine sulfoximine (BSO). In parallel, BSO-modulated and nonmodulated animals underwent survival studies after regional intra-arterial perfusion with melphalan or saline. Rats were monitored daily for tumor growth and toxicity. RESULTS: BSO depleted tumor GSH levels by 71.8% with minimal toxicity. Survival studies using increasing melphalan concentrations demonstrated similar tumor growth. The combined use of modulator and chemotherapeutic agent showed a significant tumor growth delay as compared to control and drug-alone group without enhanced toxicity. CONCLUSIONS: Modulation of resistance in conjunction with regional chemotherapy allows for improved tumor responses with minimal toxicity. These results demonstrate that BSO can potentiate the cytotoxic effects of regional melphalan therapy in the setting of extremity melanoma.

Animals↗
PubMed2004

A wolf in sheep's clothing: a non-functioning islet cell tumor of the pancreas masquerading as a microcystic (serous cystic) adenoma.

CONTEXT: The endosonographic appearance of a microcystic "honeycomb" lesion of the pancreas usually indicates a serous cystic adenoma. CASE REPORT: We report a case of a non-functioning islet cell tumor that has the typical microcystic "honeycomb" appearance of a serous cystic adenoma. The implications for endoscopic ultrasound diagnosis and management of cystic pancreatic lesions are discussed. CONCLUSION: Islet cell tumors are a rare differential diagnosis of microcystic pancreatic lesions. If fine needle aspiration remains non-diagnostic preoperative distinction from serous cystic adenomas may be impossible.

Adenoma↗
PubMed2003

Induction of anti-melanoma CTL response using DC transfected with mutated mRNA encoding full-length Melan-A/MART-1 antigen with an A27L amino acid substitution.

Modification of the parental immunodominant Melan-A/MART-1 peptide (MART-1(26-35)) by replacing the alanine with leucine (A27L) enhances its immunogenicity. Because of the reported advantages of RNA over peptides in DC vaccines, we sought to mutate the MART-1 gene to encode a full-length MART-1 antigen with an A27L amino acid substitution. Human DC were transfected with A27L-mutated MART-1 RNA (A27L RNA) or native MART-1 RNA, and then used to stimulate autologous T cells from a series of 8 HLA-A2+ volunteers. After three stimulations, all CTL induced with DC/A27L RNA exhibited more tetramer+ cells, and demonstrated stronger antigen-specific IFNgamma-secreting activity compared to CTL induced with DC/native RNA. A potent MART-1-specific, and predominantly class-I-restricted lysis was detected in most CTL induced with DC/A27L RNA, while native RNA-induced CTL showed minimal and non-specific lysis. HLA-A2+ DC and MART-1 negative/A2+ melanoma cells transfected with the A27L RNA were recognized and killed by MART-1-specific CTL, suggesting that these APC efficiently processed the A27L RNA and presented correct MART-1-specific epitope(s). In summary, introducing an A27L mutation into the MART-1 full-length mRNA sequence enhanced the immunogenicity of the encoded MART-1 Ag. The ease with which such a mutation can be made in RNA presents another potential advantage of using RNA for immunotherapy. Our results support considering this strategy for enhancing the immunogenicity of DC-based RNA vaccines.

Amino Acid Substitution↗
PubMed2003

Iodine -131 metaiodobenzylguanidine is an effective treatment for malignant pheochromocytoma and paraganglioma.

INTRODUCTION: Iodine 131-meta-iodobenzylguanidine ((131)I-MIBG) has been applied to the palliative treatment of metastatic pheochromocytoma in small studies. We report our institutional experience for the treatment of metastatic pheochromocytoma and paraganglioma. METHODS: We performed a retrospective review of 33 patients with metastatic pheochromocytoma (n=22) and paraganglioma (n=11) treated at our institution with (131)I-MIBG over a 10-year period. RESULTS: Patients received a mean dose of 388+/-131 mCi (131)I-MIBG. Median survival after treatment was 4.7 years. Most patients experienced a symptomatic response leading to an improved survival (4.7 years vs 1.8 years, P<.01). Patients with a measurable hormone response demonstrated an increased survival in comparison to those with no response (4.7 years vs 2.6 years, P=.01). Patients who received a high dose (>500 mCi) as their initial therapy also had improved survival (3.8 years vs 2.8 years, P=.02). CONCLUSION: These data support (131)I-MIBG treatment for select patients with metastatic pheochromocytoma. In our experience, prolonged survival was best predicted by symptomatic and hormone response to (131)I-MIBG treatment. An initial dose of 500 mCi may be optimal. The benefit of (131)I-MIBG treatment for metastatic pheochromocytoma must also be weighed against its side effects.

3-Iodobenzylguanidine↗