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Biomedical subjects

John C Byrd

Publications and source records attributed to John C Byrd.

At least 55 records · Page 3Linked to original sources
PubMed2004

Combination immunotherapy of B-cell non-Hodgkin's lymphoma with rituximab and interleukin-2: a preclinical and phase I study.

PURPOSE: Cytokine-induced modulation of innate immunity is being explored to enhance the activity of monoclonal antibodies. Severe combined immunodeficient (SCID) mice engrafted with peripheral blood leukocytes (PBLs) from Epstein Barr virus-seropositive donors develop human B-cell non-Hodgkin's lymphomas [B-NHLs (hu-PBL-SCID mouse model)]. We used this hu-PBL-SCID mouse model to study the synergism between interleukin (IL)-2 and rituximab. We also conducted a phase I trial of IL-2 and rituximab in relapsed B-NHL to study whether expansion of natural killer (NK) cells and enhanced cellular cytotoxicity could be safely accomplished in vivo. EXPERIMENTAL DESIGN: Hu-PBL-SCID mice were treated with various schedules of rituximab and IL-2, with survival as the end point. Patients with relapsed B-NHL received rituximab (375 mg/m2 weekly x 4) followed by daily low-dose IL-2 (1 MIU/m2/day x 4 weeks) with pulses of intermediate-dose IL-2 (3-15 MIU/m2). Toxicity, NK cell numbers, and cellular cytotoxicity were measured. RESULTS: In the hu-PBL-SCID mouse, the combination of rituximab and IL-2 showed greater activity against B-NHL than either agent alone. Treatment was most effective when IL-2 was given before rituximab. Twelve patients with heavily pretreated B-NHL entered the phase I trial. Toxicity was manageable, and responses were observed. NK cell expansion and enhanced cellular cytotoxicity against a B-cell lymphoma target were observed but did not correlate with response. CONCLUSIONS: The combination of IL-2 and rituximab is synergistic against B-NHL in the hu-PBL-SCID model. In the phase I trial, a sequential combination of rituximab and IL-2 was well tolerated and achieved biological end points. Responses were observed.

Adult↗
PubMed2004

ZAP-70 compared with immunoglobulin heavy-chain gene mutation status as a predictor of disease progression in chronic lymphocytic leukemia.

BACKGROUND: The course of chronic lymphocytic leukemia (CLL) is variable. In aggressive disease, the CLL cells usually express an unmutated immunoglobulin heavy-chain variable-region gene (IgV(H)) and the 70-kD zeta-associated protein (ZAP-70), whereas in indolent disease, the CLL cells usually express mutated IgV(H) but lack expression of ZAP-70. METHODS: We evaluated the CLL B cells from 307 patients with CLL for ZAP-70 and mutations in the rearranged IgV(H) gene. We then investigated the association between the results and the time from diagnosis to initial therapy. RESULTS: We found that ZAP-70 was expressed above a defined threshold level in 117 of the 164 patients with an unmutated IgV(H) gene (71 percent), but in only 24 of the 143 patients with a mutated IgV(H) gene (17 percent, P<0.001). Among the patients with ZAP-70-positive CLL cells, the median time from diagnosis to initial therapy in those who had an unmutated IgV(H) gene (2.8 years) was not significantly different from the median time in those who had a mutated IgV(H) gene (4.2 years, P=0.07). However, the median time from diagnosis to initial treatment in each of these groups was significantly shorter than the time in patients with ZAP-70-negative CLL cells who had either mutated or unmutated IgV(H) genes (P<0.001). The median time from diagnosis to initial therapy among patients who did not have ZAP-70 was 11.0 years in those with a mutated IgV(H) gene and 7.1 years in those with an unmutated IgV(H) gene (P<0.001). CONCLUSIONS: Although the presence of an unmutated IgV(H) gene is strongly associated with the expression of ZAP-70, ZAP-70 is a stronger predictor of the need for treatment in B-cell CLL.

B-Lymphocytes↗
PubMed2004

Adult Burkitt leukemia and lymphoma.

The World Health Organization Classification of Lymphoid Neoplasms identifies Burkitt lymphoma/leukemia as a highly aggressive mature B-cell neoplasm consisting of endemic, sporadic, and immunodeficiency-associated variants. These subtypes share many morphologic and immunophenotypic features, but differences exist in their clinical and geographic presentations. All of these subtypes possess chromosomal rearrangements of the c-myc oncogene, the genetic hallmark of Burkitt lymphoma that contributes to lymphomagenesis through alterations in cell cycle regulation, cellular differentiation, apoptosis, cellular adhesion, and metabolism. Brief-duration, high-intensity chemotherapy regimens containing aggressive central nervous system prophylaxis have had remarkable success in the treatment of this disease, with complete remission rates of 75% to 90% and overall survivals reaching 50% to 70% in adults. Although Burkitt lymphoma cells are extremely chemosensitive, biologically targeted therapies should be developed because current treatment options are suboptimal for patients with poor prognostic features or in the setting of relapsed disease.

Adult↗
PubMed2004

FCGR3A and FCGR2A polymorphisms may not correlate with response to alemtuzumab in chronic lymphocytic leukemia.

The in vivo mechanism of action of alemtuzumab (anti-CD52; Campath-1H) remains unclear. With rituximab, FCGR3A and FCGR2A high-affinity polymorphisms have been associated with clinical response in lymphoma but not in CLL, suggesting potential divergent mechanisms of action between these 2 diseases. Herein, we examined FCGR3A (V/V, n = 4; V/F, n = 10; F/F, n = 19) and FCGR2A (A/A, n = 5; H/A, n = 22; H/H, n = 6) polymorphisms in 36 patients with relapsed CLL who were treated with thrice-weekly alemtuzumab for 12 weeks to assess the potential influence these high-affinity FcgammaR receptor polymorphisms had on response to alemtuzumab. Response to alemtuzumab was similar regardless of FCGR3A polymorphism (V/V, 25%; V/F, 40%; F/F, 32%) or FCGR2A polymorphism (A/A, 40%; H/A, 32%; H/H, 33%). These findings indicate that FCGR3A and FCGR2A polymorphisms may not predict response to alemtuzumab in CLL. Future studies examining larger cohorts of alemtuzumab-treated patients with CLL will be required to definitively determine the predictive value of specific FCGR polymorphisms to treatment response.

Adult↗
PubMed2004

Addition of rituximab to fludarabine may prolong progression-free survival and overall survival in patients with previously untreated chronic lymphocytic leukemia: an updated retrospective comparative analysis of CALGB 9712 and CALGB 9011.

Fludarabine and rituximab combination therapies in chronic lymphocytic leukemia (CLL) have yielded promising early results, but no comparative efficacy data relative to standard fludarabine treatment regimens have been reported. To assess the effect of the addition of rituximab to fludarabine therapy, we retrospectively compared the treatment outcome of patients with similar clinical characteristics enrolled on 2 multicenter clinical trials performed by the Cancer and Leukemia Group B and the US Intergroup that used fludarabine and rituximab (CALGB 9712, n = 104) or fludarabine (CALGB 9011, n = 178). In multivariate analyses controlling for pretreatment characteristics, the patients receiving fludarabine and rituximab had a significantly better progression-free survival (PFS; P < .0001) and overall survival (OS; P = .0006) than patients receiving fludarabine therapy. Two-year PFS probabilities were 0.67 versus 0.45, and 2-year OS probabilities were 0.93 versus 0.81. Infectious toxicity was similar between the 2 treatment approaches. These comparative data are retrospective and could be confounded by differences in supportive care or dissimilar enrollment of genetic subsets on each trial. Confirmation of these findings will require a prospective randomized trial comparing fludarabine and rituximab to fludarabine.

Adult↗
PubMed2004

Epigenetic profiling in chronic lymphocytic leukemia reveals novel methylation targets.

CpG island methylation is an epigenetic alteration that contributes to tumorigenesis by transcriptional inactivation of genes. Little is known about the overall levels of CpG island methylation in chronic lymphocytic leukemia (CLL). To provide a baseline estimate of global aberrant methylation and identify target sequences for additional investigation, we performed Restriction Landmark Genomic Scanning on 10 CLL samples. Two methylation-sensitive landmark enzymes were used (NotI and AscI), allowing assessment of over 3000 CpG islands in each sample. Tumor-derived Restriction Landmark Genomic Scanning profiles were compared with profiles from CD19-selected B cells from normal volunteers and matched normal neutrophils from 4 CLL patients. We found 2.5-8.1% (mean 4.8%) of the CpG islands in CLL samples were aberrantly methylated compared with controls, and the methylation events had a nonrandom distribution (P < 0.0001). Furthermore, we identified 193 aberrantly methylated sequences, of which 93% have CpG island characteristics and 90% have homology to genes or expressed sequences. One such gene, the G protein-coupled metabotropic glutamate receptor 7 (GRM7), possibly inhibits cyclic AMP signaling in the induction of apoptosis. Bisulfite sequencing of GRM7 confirmed extensive CpG island methylation, and treatment with 5-aza-2'-deoxycytidine (decitabine) resulted in up-regulated expression of several genes in vitro with concurrent cellular depletion of DNMT1 protein. Our dual-enzyme global methylation study shows that CLL is characterized by widespread nonrandom CpG island methylation similar to other tumors and provides a panel of novel methylation targets that can be used in larger studies designed to assess impact on disease progression and survival.

Adult↗
PubMed2004

Repetitive cycles of high-dose cytarabine benefit patients with acute myeloid leukemia and inv(16)(p13q22) or t(16;16)(p13;q22): results from CALGB 8461.

PURPOSE: To study the impact of repetitive (three to four courses) versus a single course of high-dose cytarabine (HDAC) consolidation therapy on outcome of patients with acute myeloid leukemia (AML) and inv(16)(p13q22) or t(16;16)(p13;q22). PATIENTS AND METHODS: We examined the cumulative incidence of relapse (CIR), relapse-free survival (RFS), and overall survival (OS) for 48 adults younger than 60 years with inv(16)/t(16;16) who had attained a complete remission on one of four consecutive clinical trials and were assigned to receive HDAC consolidation therapy. Twenty-eight patients were assigned to either three or four courses of HDAC, and 20 patients were assigned to one course of HDAC followed by alternative intensive consolidation therapy. RESULTS: Pretreatment features were similar for the two groups. The CIR was significantly decreased in patients assigned to receive three to four cycles of HDAC compared with patients assigned to one course (P=.03; 5-year CIR, 43% v 70%, respectively). The difference in RFS also approached statistical significance (P=.06). In a multivariable analysis that adjusted for potential confounding covariates, only treatment assignment (three to four cycles of HDAC) predicted for superior RFS (P=.02). The OS of both groups was similar (P=.93; 5-year OS, 75% for the three to four cycles of HDAC group v 70% for the one cycle of HDAC group), reflecting a high success rate with stem-cell transplantation salvage treatment administered among patients in both treatment groups. CONCLUSION: We conclude that, in AML patients with inv(16)/t(16;16), repetitive HDAC therapy decreases the likelihood of relapse compared with consolidation regimens including less HDAC.

Acute Disease↗
PubMed2004

Zn2+-chelating motif-tethered short-chain fatty acids as a novel class of histone deacetylase inhibitors.

Among various classes of histone deacetylase (HDAC) inhibitors, short-chain fatty acids exhibit the least potency, with IC(50) in the millimolar range. We rationalized that this weak potency was, in part, attributable to their inability to access the zinc cation in the HDAC active-site pocket, which is pivotal to the deacetylation catalysis. We thus explored the structural optimization of valproate, butyrate, phenylacetate, and phenylbutyrate by coupling them with Zn(2+)-chelating motifs (hydroxamic acid and o-phenylenediamine) through aromatic omega-amino acid linkers. This strategy has led to a novel class of Zn(2+)-chelating, motif-tethered, short-chain fatty acids that exhibited varying degrees of HDAC inhibitory potency. One hydroxamate-tethered phenylbutyrate compound, N-hydroxy-4-(4-phenylbutyrylamino)benzamide (HTPB), displayed nanomolar potency in inhibiting HDAC activity. Exposure of several cancer cell lines to HTPB at the submicromolar level showed reduced cell proliferation accompanied by histone hyperacetylation and elevated p21(WAF/CIP1) expression, which are hallmark features associated with intracellular HDAC inhibition.

Acetylation↗
PubMed2004

Alemtuzumab is an effective therapy for chronic lymphocytic leukemia with p53 mutations and deletions.

The presence of p53 mutation or deletion predicts for poor response to conventional therapy in chronic lymphocytic leukemia (CLL). We sought to determine whether the humanized anti-CD52 antibody alemtuzumab was effective in this patient group. Thirty-six patients with fludarabine-refractory CLL were treated with alemtuzumab, 15 (42%) of whom had p53 mutations or deletions. Clinical responses in patients with p53 mutations, deletions, or both were noted in 6 (40%) of 15 versus 4 (19%) of 21 of patients without. The median response duration for this subset of patients was 8 months (range, 3-17 months). These data suggest that alemtuzumab may be an effective therapy for patients with CLL with p53 mutations or deletions.

Aged↗
PubMed2004

Antibody therapy for chronic lymphocytic leukemia: a promising new modality.

Therapeutic options for chronic lymphocytic leukemia (CLL) have been limited, with low complete response rates (CR) and no treatments demonstrating a survival advantage. The recent introduction of the monoclonal antibodies rituximab and alemtuzumab into clinical trials for patients with CLL has generated promising results. Rituximab targets the CD20 antigen and demonstrates varied single-agent activity that is highly dependent upon the dosing schedule and treatment status of the patient. More importantly, when rituximab is combined with fludarabine or fludarabine and cyclophosphamide, a high frequency of CR and prolonged progression-free survival are observed without an appreciable increase in significant toxicity. Alemtuzumab targets the more ubiquitously expressed CD52 antigen and is therefore associated with a higher frequency of toxicity, particularly immunosuppression, but has appreciable activity in fludarabine refractory CLL. Additionally, alemtuzumab is effective against CLL clones that have p53 mutations or deletions. Future efforts in developing combination strategies with rituximab, alemtuzumab, and potentially other new antibodies offer great promise for the future treatment of CLL.

Alemtuzumab↗
PubMed2004

Differential expression of histone post-translational modifications in acute myeloid and chronic lymphocytic leukemia determined by high-pressure liquid chromatography and mass spectrometry.

The post-translational modification of the core histones is critical to the regulation of chromatin structure. Traditional methods for the determination of histone modification utilize immunoassay techniques to determine the extent and site of post-translational modification. These methods, though sensitive, require site-specific antibodies. This manuscript describes the application of reverse-phase high-pressure liquid chromatography and mass spectrometry (LC-MS) to analyze global modification levels of core histones. The method is fast, sensitive, and easily automated. Furthermore, the technique gives the global patterns of modification for all four core histones in a single experiment. The LC-MS method was optimized using histones extracted from bovine thymus. These methods were then applied to the characterization of changes in histone modification in acute myeloid leukemia (AML) cell lines treated with histone deacetylase (HDAC) inhibitors. Dose-dependent changes in the distribution of modified core histones were observed. These results were validated in primary leukemia cells from patients with refractory or relapsed AML or chronic lymphocytic leukemia (CLL) treated on a Phase I clinical trial of the HDAC inhibitor depsipeptide. An increase in the relative abundance of specific acetylated forms of histone H4 was readily observable in these patients at intervals of 4 and 24 h after treatment.

Animals↗
PubMed2004

Atypical lymphocytic lobular panniculitis.

BACKGROUND: Although subcutaneous T-cell lymphoma (SCTCL) is considered an aggressive form of lymphoma, some patients manifest a long waxing and waning phase unaccompanied by constitutional symptoms. METHODS: Twelve patients were prospectively encountered, presenting with a lymphocytic panniculitis accompanied by lymphoid atypia, although not fulfilling criteria for SCTCL. Clinical, histologic, phenotypic, and genotypic analyses were conducted. RESULTS: There were five men, one boy, and six women; none had symptoms compatible with lupus erythematosus or aggressive SCTCL. All but two had a waxing and waning course of years. Four patients had periodic cytopenias accompanied by fevers. While responding somewhat to prednisone, the lesions relapsed. In one patient, treatment with alemtuzumab (CAMPATH-1) led to complete lesional resolution with no recurrence. Light microscopy showed expansion of the interstices of the fat lobule by mildly atypical lymphocytes of the CD4 subset in 10 biopsies from eight patients; in the other four patients, there was an increase in CD8 lymphocytes. There was diminished expression of CD5 and/or CD7 in the majority of biopsies. Ten of 13 biopsies showed clonal T-cell receptor-gamma rearrangements. CONCLUSIONS: We apply the term atypical lymphocytic lobular panniculitis to this distinctive form of lymphocytic panniculitis manifesting this light microscopic, phenotypic, and genotypic profile.

Adipose Tissue↗
PubMed2004

Chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is one of the most commonly diagnosed leukemias managed by practicing hematologists. For many years patients with CLL have been viewed as similar, with a long natural history and only marginally effective therapies that rarely yielded complete responses. Recently, several important observations related to the biologic significance of V(H) mutational status and associated ZAP-70 overexpression, disrupted p53 function, and chromosomal aberrations have led to the ability to identify patients at high risk for early disease progression and inferior survival. Concurrent with these investigations, several treatments including the nucleoside analogues, monoclonal antibodies rituximab and alemtuzumab have been introduced. Combination of these therapies in clinical trials has led to high complete and overall response rates when applied as initial therapy for symptomatic CLL. Thus, the complexity of initial risk stratification of CLL and treatment has increased significantly. Furthermore, when these initial therapies do not work, approach of the CLL patient with fludarabine-refractory disease can be quite challenging. This session will describe the natural history of a CLL patient with emphasis on important decision junctures at different time points in the disease. In Section I, Dr. Stephan Stilgenbauer focuses on the discussion that occurs with CLL patients at their initial evaluation. This includes a review of the diagnostic criteria for CLL and prognostic factors utilized to predict the natural history of the disease. The later discussion of risk stratification focuses on molecular and genomic aberrations that predict rapid progression, poor response to therapy, and inferior survival. Ongoing and future efforts examining early intervention strategies in high risk CLL are reviewed. In Section II, Drs. Ian Flinn and Jesus G. Berdeja focus on the discussion of CLL patients when symptomatic disease has developed. This includes an updated review of monotherapy trials with nucleoside analogs and recent trials that have combined these with monoclonal antibodies and/or alternative chemotherapy agents. Appropriate application of more aggressive therapies such as autologous and allogeneic immunotherapy and less aggressive treatments for appropriate CLL patient candidates are discussed. In Section III, Dr. John Byrd focuses on the discussion that occurs with CLL patients whose disease is refractory to fludarabine. The application of genetic risk stratification in choosing therapy for this subset of patients is reviewed. Available data with conventional combination based therapies and monoclonal antibodies are discussed. Finally, alternative promising investigational therapies including new antibodies, kinase inhibitors (CDK, PDK1/AKT, PKC) and alternative targeted therapies (DNA methyltransferase inhibitors, histone deacetylase inhibitors, etc.) are reviewed with an emphasis on the most promising agents for this patient population.

Antineoplastic Agents↗
PubMed2004

Management guidelines for use of alemtuzumab in B-cell chronic lymphocytic leukemia.

An expert opinion roundtable held August 8-9, 2002, brought together clinicians with the most extensive experience with the use of alemtuzumab to pool knowledge and develop treatment goals and guidelines for optimal therapy. By sharing our collective experience, we have been able to formulate recommendations for current clinical practice, which are included in this report, and have emphasized results that have implications for future practice. Guidelines for the management of acute "first-dose" events, prophylaxis for infection, detection and treatment of cytomegalovirus reactivation, and hematologic support are presented, with emphasis on allowing patients to proceed smoothly through therapy while maximizing therapeutic benefit. Management of adverse events is facilitated by the predictable timing of their appearance. In general, hematologic adverse events are transient, manageable, and reversible. Clinicians should be cautious of prematurely terminating treatment at 4-6 weeks in patients whose disease responds to treatment. Although resolution of peripheral blood lymphocytosis occurs early in most patients, bone marrow is unlikely to be clear of disease. In particular, grade 4 neutropenia at this time is common and, because it is manageable, it is not an indication to discontinue treatment. The eradication of minimal residual disease from blood and bone marrow observed with alemtuzumab therapy is a major step forward in the treatment of B-cell chronic lymphocytic leukemia. Combination therapies such as alemtuzumab/fludarabine with the potential to maximize eradication at all disease sites should be systematically investigated. Because high response rates and few complications are observed in previously untreated patients, the use of alemtuzumab earlier in therapy may provide optimum benefit to patients.

Aged↗
PubMed2003

Hu1D10 induces apoptosis concurrent with activation of the AKT survival pathway in human chronic lymphocytic leukemia cells.

The 1D10 antigen is the target for Hu1D10 (apolizumab), a humanized HLA-DR beta-chain-specific antibody that is currently in clinical trials for hematologic malignancies. We demonstrate that Hu1D10 induces caspase-independent apoptosis following secondary cross-linking in primary chronic lymphocytic leukemia (CLL) cells. Generation of reactive oxygen species (ROS) and signal transduction, as evidenced by phosphorylation of Syk and AKT, were noted. The source of the Hu1D10-induced ROS was examined using the Raji lymphoblastic cell line with engineered defects in the mitochondrial respiratory chain. Hu1D10 treatment of clones with deficient mitochondrial respiration produced ROS suggesting a cytoplasmic source. Administration of ROS scavengers to primary CLL cells prior to Hu1D10 treatment diminished AKT activation. Treatment with Hu1D10 and the phosphatidylinositol 3-kinase inhibitor LY294002 demonstrated in vitro synergy with enhanced apoptosis. In conjunction with an ongoing clinical trial, blood samples were collected following intravenous infusion of Hu1D10 and analyzed for phosphorylation of AKT. Two of 3 patient samples showed a sustained increase in AKT phosphorylation following Hu1D10 administration. These data suggest that Hu1D10 ligation in CLL cells induces death and survival signals for which combination therapies may be designed to greatly enhance efficiency of both Hu1D10 and other class II antibodies in development.

Acetylcysteine↗
PubMed2003

Fc gamma RIIIa and Fc gamma RIIa polymorphisms do not predict response to rituximab in B-cell chronic lymphocytic leukemia.

In follicular lymphoma (FL), genomic polymorphisms corresponding to the expression of valine (V) or phenylalanine (F) at amino acid 158 of Fc gamma RIIIa alter the binding affinity of immunoglobulin G1 (IgG1) to the receptor and have been associated with varied responses to rituximab. We examined Fc gamma RIIIa polymorphisms of 30 CLL patients with the phenotypes V/V (n = 6), V/F (n = 12), and F/F (n = 12) treated with thrice-weekly rituximab (375 mg/m(2)) for 4 weeks to correlate polymorphism type with infusion toxicity and response. Infusion toxicity (grade 3 or greater or hypoxia/hypotension requiring transient cessation of therapy) was observed equally among the groups (V/V, 50%; V/F, 33%; F/F, 41.6%; P =.78). The response to rituximab was also similar among the different polymorphism phenotypes (V/V, 33%; V/F, 41.6%; F/F, 50%). These data suggest that Fc gamma RIIIa polymorphisms are not predictive of response in CLL and that, unlike the case with FL, mechanisms of tumor clearance other than antibody-dependent cellular cytotoxicity may be more important.

Aged↗