Biochemical and X-ray analyses of the players involved in the faRel2/aTfaRel2 toxin-antitoxin operon

The aTfaRel2/faRel2 operon from Coprobacillus sp. D7 encodes a bicistronic type II toxin-antitoxin (TA) module. The FaRel2 toxin is a toxic small alarmone synthetase (toxSAS) that inhibits translation through the pyrophosphorylation of uncharged tRNAs at the 3'-CCA end. The toxin is neutralized by the antitoxin ATfaRel2 through the formation of an inactive TA complex. Here, the production, biophysical analysis and crystallization of ATfaRel2 and FaRel2 as well as of the ATfaRel2-FaRel2 complex are reported. ATfaRel2 is monomeric in solution. The antitoxin crystallized in space group P21212 with unit-cell parameters a = 53.3, b = 34.2, c = 37.6 Å, and the best crystal diffracted to a resolution of 1.24 Å. Crystals of FaRel2 in complex with APCPP, a nonhydrolysable ATP analogue, belonged to space group P21, with unit-cell parameters a = 31.5, b = 60.6, c = 177.2 Å, β = 90.6°, and diffracted to 2.6 Å resolution. The ATfaRel2-FaRel2Y128F complex forms a heterotetramer in solution composed of two toxins and two antitoxins. This complex crystallized in two space groups: F4132, with unit-cell parameters a = b = c = 227.1 Å, and P212121, with unit-cell parameters a = 51.7, b = 106.2, c = 135.1 Å. The crystals diffracted to 1.98 and 2.1 Å resolution, respectively.

Structure of SpoT reveals evolutionary tuning of catalysis via conformational constraint

Stringent factors orchestrate bacterial cell reprogramming through increasing the level of the alarmones (p)ppGpp. In Beta- and Gammaproteobacteria, SpoT hydrolyzes (p)ppGpp to counteract the synthetase activity of RelA. However, structural information about how SpoT controls the levels of (p)ppGpp is missing. Here we present the crystal structure of the hydrolase-only SpoT from Acinetobacter baumannii and uncover the mechanism of intramolecular regulation of 'long'-stringent factors. In contrast to ribosome-associated Rel/RelA that adopt an elongated structure, SpoT assumes a compact τ-shaped structure in which the regulatory domains wrap around a Core subdomain that controls the conformational state of the enzyme. The Core is key to the specialization of long RelA-SpoT homologs toward either synthesis or hydrolysis: the short and structured Core of SpoT stabilizes the τ-state priming the hydrolase domain for (p)ppGpp hydrolysis, whereas the longer, more dynamic Core domain of RelA destabilizes the τ-state priming the monofunctional RelA for efficient (p)ppGpp synthesis.

The structure of DarB in complex with RelNTD reveals nonribosomal activation of Rel stringent factors

Rel stringent factors are bifunctional ribosome-associated enzymes that catalyze both synthesis and hydrolysis of the alarmones (p)ppGpp. Besides the allosteric control by starved ribosomes and (p)ppGpp, Rel is regulated by various protein factors depending on specific stress conditions, including the c-di-AMP-binding protein DarB. However, how these effector proteins control Rel remains unknown. We have determined the crystal structure of the DarB₂:Rel^NTD₂ complex, uncovering that DarB directly engages the SYNTH domain of Rel to stimulate (p)ppGpp synthesis. This association with DarB promotes a SYNTH-primed conformation of the N-terminal domain region, markedly increasing the affinity of Rel for ATP while switching off the hydrolase activity of the enzyme. Binding to c-di-AMP rigidifies DarB, imposing an entropic penalty that precludes DarB-mediated control of Rel during normal growth. Our experiments provide the basis for understanding a previously unknown mechanism of allosteric regulation of Rel stringent factors independent of amino acid starvation.

Direct activation of a bacterial innate immune system by a viral capsid protein

Bacteria have evolved diverse immunity mechanisms to protect themselves against the constant onslaught of bacteriophages1-3. Similar to how eukaryotic innate immune systems sense foreign invaders through pathogen-associated molecular patterns4 (PAMPs), many bacterial immune systems that respond to bacteriophage infection require phage-specific triggers to be activated. However, the identities of such triggers and the sensing mechanisms remain largely unknown. Here we identify and investigate the anti-phage function of CapRelSJ46, a fused toxin-antitoxin system that protects Escherichia coli against diverse phages. Using genetic, biochemical and structural analyses, we demonstrate that the C-terminal domain of CapRelSJ46 regulates the toxic N-terminal region, serving as both antitoxin and phage infection sensor. Following infection by certain phages, newly synthesized major capsid protein binds directly to the C-terminal domain of CapRelSJ46 to relieve autoinhibition, enabling the toxin domain to pyrophosphorylate tRNAs, which blocks translation to restrict viral infection. Collectively, our results reveal the molecular mechanism by which a bacterial immune system directly senses a conserved, essential component of phages, suggesting a PAMP-like sensing model for toxin-antitoxin-mediated innate immunity in bacteria. We provide evidence that CapRels and their phage-encoded triggers are engaged in a 'Red Queen conflict'5, revealing a new front in the intense coevolutionary battle between phages and bacteria. Given that capsid proteins of some eukaryotic viruses are known to stimulate innate immune signalling in mammalian hosts6-10, our results reveal a deeply conserved facet of immunity.

A nucleotide-switch mechanism mediates opposing catalytic activities of Rel enzymes

Bifunctional Rel stringent factors, the most abundant class of RelA/SpoT homologs, are ribosome-associated enzymes that transfer a pyrophosphate from ATP onto the 3' of guanosine tri-/diphosphate (GTP/GDP) to synthesize the bacterial alarmone (p)ppGpp, and also catalyze the 3' pyrophosphate hydrolysis to degrade it. The regulation of the opposing activities of Rel enzymes is a complex allosteric mechanism that remains an active research topic despite decades of research. We show that a guanine-nucleotide-switch mechanism controls catalysis by Thermus thermophilus Rel (Rel_Tt). The binding of GDP/ATP opens the N-terminal catalytic domains (NTD) of Rel_Tt (Rel_Tt^NTD) by stretching apart the two catalytic domains. This activates the synthetase domain and allosterically blocks hydrolysis. Conversely, binding of ppGpp to the hydrolase domain closes the NTD, burying the synthetase active site and precluding the binding of synthesis precursors. This allosteric mechanism is an activity switch that safeguards against futile cycles of alarmone synthesis and degradation.

Mouse TRPA1 function and membrane localization are modulated by direct interactions with cholesterol

The cation channel TRPA1 transduces a myriad of noxious chemical stimuli into nociceptor electrical excitation and neuropeptide release, leading to pain and neurogenic inflammation. Despite emergent evidence that TRPA1 is regulated by the membrane environment, it remains unknown whether this channel localizes in membrane microdomains or whether it interacts with cholesterol. Using total internal reflection fluorescence microscopy and density gradient centrifugation we found that mouse TRPA1 localizes preferably into cholesterol-rich domains and functional experiments revealed that cholesterol depletion decreases channel sensitivity to chemical agonists. Moreover, we identified two structural motifs in transmembrane segments 2 and 4 involved in mTRPA1-cholesterol interactions that are necessary for normal agonist sensitivity and plasma membrane localization. We discuss the impact of such interactions on TRPA1 gating mechanisms, regulation by the lipid environment, and role of this channel in sensory membrane microdomains, all of which helps to understand the puzzling pharmacology and pathophysiology of this channel.

The citrus flavanone hesperetin preferentially inhibits slow-inactivating currents of a long QT syndrome type 3 syndrome Na+ channel mutation

BACKGROUND AND PURPOSE

The citrus flavanone hesperetin has been proposed for the treatment of several human pathologies, but its cardiovascular actions remain largely unexplored. Here, we evaluated the effect of hesperetin on cardiac electrical and contractile activities, on aortic contraction, on the wild-type voltage-gated Na_V 1.5 channel, and on a channel mutant (R1623Q) associated with lethal ventricular arrhythmias in the long QT syndrome type 3 (LQT3).

EXPERIMENTAL APPROACH

We used cardiac surface ECG and contraction force recordings to evaluate the effects of hesperetin in rat isolated hearts and aortic rings. Whole-cell patch clamp was used to record Na_V 1.5 currents (I_Na ) in rat ventricular cardiomyocytes and in HEK293T cells expressing hNa_V 1.5 wild-type or mutant channels.

KEY RESULTS

Hesperetin increased the QRS interval and heart rate and decreased the corrected QT interval and the cardiac and aortic contraction forces at concentrations equal or higher than 30 μmol·L^-1 . Hesperetin blocked rat and human Na_V 1.5 channels with an effective inhibitory concentration of ≈100 μmol·L^-1 . This inhibition was enhanced at depolarized holding potentials and higher stimulation frequency and was reduced by the disruption of the binding site for local anaesthetics. Hesperetin increased the rate of inactivation and preferentially inhibited I_Na during the slow inactivation phase, these effects being more pronounced in the R1623Q mutant.

CONCLUSIONS AND IMPLICATIONS

Hesperetin preferentially inhibits the slow inactivation phase of I_Na , more markedly in the mutant R1623Q. Hesperetin could be used as a template to develop drugs against lethal cardiac arrhythmias in LQT3.

A dual role in regulation and toxicity for the disordered N-terminus of the toxin GraT

Bacterial toxin-antitoxin (TA) modules are tightly regulated to maintain growth in favorable conditions or growth arrest during stress. A typical regulatory strategy involves the antitoxin binding and repressing its own promoter while the toxin often acts as a co-repressor. Here we show that Pseudomonas putida graTA-encoded antitoxin GraA and toxin GraT differ from other TA proteins in the sense that not the antitoxin but the toxin possesses a flexible region. GraA auto-represses the graTA promoter: two GraA dimers bind cooperatively at opposite sides of the operator sequence. Contrary to other TA modules, GraT is a de-repressor of the graTA promoter as its N-terminal disordered segment prevents the binding of the GraT₂A₂ complex to the operator. Removal of this region restores operator binding and abrogates Gr aT toxicity. GraTA represents a TA module where a flexible region in the toxin rather than in the antitoxin controls operon expression and toxin activity.

The Pseudomonas putida toxin GraT and antitoxin GraA form a type II toxin-antoxin module. Here the authors present the crystal structures of the GraA dimer, GraTA and GraA-DNA complexes and show that GraT contains a functionally important N-terminal intrinsic disordered region that prevents the binding of the GraTA complex to the operator.

Phosphorylation decelerates conformational dynamics in bacterial translation elongation factors

Bacterial protein synthesis is intricately connected to metabolic rate. One of the ways in which bacteria respond to environmental stress is through posttranslational modifications of translation factors. Translation elongation factor Tu (EF-Tu) is methylated and phosphorylated in response to nutrient starvation upon entering stationary phase, and its phosphorylation is a crucial step in the pathway toward sporulation. We analyze how phosphorylation leads to inactivation of Escherichia coli EF-Tu. We provide structural and biophysical evidence that phosphorylation of EF-Tu at T382 acts as an efficient switch that turns off protein synthesis by decoupling nucleotide binding from the EF-Tu conformational cycle. Direct modifications of the EF-Tu switch I region or modifications in other regions stabilizing the β-hairpin state of switch I result in an effective allosteric trap that restricts the normal dynamics of EF-Tu and enables the evasion of the control exerted by nucleotides on G proteins. These results highlight stabilization of a phosphorylation-induced conformational trap as an essential mechanism for phosphoregulation of bacterial translation and metabolism. We propose that this mechanism may lead to the multisite phosphorylation state observed during dormancy and stationary phase.

Production, biophysical characterization and crystallization of Pseudomonas putida GraA and its complexes with GraT and the graTA operator

The graTA operon from Pseudomonas putida encodes a toxin-antitoxin module with an unusually moderate toxin. Here, the production, SAXS analysis and crystallization of the antitoxin GraA, the GraTA complex and the complex of GraA with a 33 bp operator fragment are reported. GraA forms a homodimer in solution and crystallizes in space group P21, with unit-cell parameters a = 66.9, b = 48.9, c = 62.7 Å, β = 92.6°. The crystals are likely to contain two GraA dimers in the asymmetric unit and diffract to 1.9 Å resolution. The GraTA complex forms a heterotetramer in solution. Crystals of the GraTA complex diffracted to 2.2 Å resolution and are most likely to contain a single heterotetrameric GraTA complex in the asymmetric unit. They belong to space group P41 or P43, with unit-cell parameters a = b = 56.0, c = 128.2 Å. The GraA-operator complex consists of a 33 bp operator region that binds two GraA dimers. It crystallizes in space group P31 or P32, with unit-cell parameters a = b = 105.6, c = 149.9 Å. These crystals diffract to 3.8 Å resolution.

An intrinsically disordered entropic switch determines allostery in Phd-Doc regulation

Conditional cooperativity is a common mechanism involved in transcriptional regulation of prokaryotic type II toxin-antitoxin operons and is intricately related to bacterial persistence. It allows the toxin component of a toxin-antitoxin module to act as a co-repressor at low doses of toxin as compared to antitoxin. When toxin level exceeds a certain threshold, however, the toxin becomes a de-repressor. Most antitoxins contain an intrinsically disordered region (IDR) that typically is involved in toxin neutralization and repressor complex formation. To address how the antitoxin IDR is involved in transcription regulation, we studied the phd-doc operon from bacteriophage P1. We provide evidence that the IDR of Phd provides an entropic barrier precluding full operon repression in the absence of Doc. Binding of Doc results in a cooperativity switch and consequent strong operon repression, enabling context-specific modulation of the regulatory process. Variations of this theme are likely to be a common mechanism in the autoregulation of bacterial operons that involve intrinsically disordered regions.

The intrinsically disordered domain of the antitoxin Phd chaperones the toxin Doc against irreversible inactivation and misfolding

The toxin Doc from the phd/doc toxin-antitoxin module targets the cellular translation machinery and is inhibited by its antitoxin partner Phd. Here we show that Phd also functions as a chaperone, keeping Doc in an active, correctly folded conformation. In the absence of Phd, Doc exists in a relatively expanded state that is prone to dimerization through domain swapping with its active site loop acting as hinge region. The domain-swapped dimer is not capable of arresting protein synthesis in vitro, whereas the Doc monomer is. Upon binding to Phd, Doc becomes more compact and is secured in its monomeric state with a neutralized active site.

Structural and biophysical characterization of Staphylococcus aureus SaMazF shows conservation of functional dynamics

The Staphylococcus aureus genome contains three toxin-antitoxin modules, including one mazEF module, SamazEF. Using an on-column separation protocol we are able to obtain large amounts of wild-type SaMazF toxin. The protein is well-folded and highly resistant against thermal unfolding but aggregates at elevated temperatures. Crystallographic and nuclear magnetic resonance (NMR) solution studies show a well-defined dimer. Differences in structure and dynamics between the X-ray and NMR structural ensembles are found in three loop regions, two of which undergo motions that are of functional relevance. The same segments also show functionally relevant dynamics in the distantly related CcdB family despite divergence of function. NMR chemical shift mapping and analysis of residue conservation in the MazF family suggests a conserved mode for the inhibition of MazF by MazE.

Structural insights into serine protease inhibition by a marine invertebrate BPTI Kunitz-type inhibitor

Proteins isolated from marine invertebrates are frequently characterized by exceptional structural and functional properties. ShPI-1, a BPTI Kunitz-type inhibitor from the Caribbean Sea anemone Stichodactyla helianthus, displays activity not only against serine-, but also against cysteine-, and aspartate proteases. As an initial step to evaluate the molecular basis of its activities, we describe the crystallographic structure of ShPI-1 in complex with the serine protease bovine pancreatic trypsin at 1.7Å resolution. The overall structure and the important enzyme-inhibitor interactions of this first invertebrate BPTI-like Kunitz-type inhibitor:trypsin complex remained largely conserved compared to mammalian BPTI-Kunitz inhibitor complexes. However, a prominent stabilizing role within the interface was attributed to arginine at position P3. Binding free-energy calculations indicated a 10-fold decrease for the inhibitor affinity against trypsin, if the P3 residue of ShPI-1 is mutated to alanine. Together with the increased role of Arg(11) at P3 position, slightly reduced interactions at the prime side (Pn') of the primary binding loop and at the secondary binding loop of ShPI-1 were detected. In addition, the structure provides important information for site directed mutagenesis to further optimize the activity of rShPI-1A for biotechnological applications.

Crystal structure of an anti-ganglioside antibody, and modelling of the functional mimicry of its NeuGc-GM3 antigen by an anti-idiotypic antibody

N-Glycolylated (NeuGc) gangliosides are tumor-specific antigens and as such represent attractive targets for cancer immunotherapy. The chimeric antibody chP3 selectively recognizes a broad variety of NeuGc gangliosides, showing no cross-reactivity to the highly similar N-acetylated (NeuAc) gangliosides that are common cellular antigens in humans. Here, we report the crystal structure of the chP3 Fab and its computer-docking model with the trisaccharide NeuGcalpha3Galbeta4Glcbeta, which represents the carbohydrate moiety of the tumor-antigen NeuGc-GM3. The interaction involves only the heavy chain of the chP3 antibody. The modelled complex is consistent with all available experimental data and shows good surface complementarity. The negatively charged sialic acid residue NeuGc is buried in a pocket flanked by two arginine residues, VH Arg31 and VH Arg100A. We have further investigated the interaction of chP3 with its anti-idiotypic antibody, 1E10 (also known as Racotumomab), currently in clinical trials as a cancer vaccine. While many of the chP3 residues predicted to interact with the NeuGc ganglioside also feature prominently in the modelled complex of chP3 and 1E10, we do not observe structural mimicry. Rather, we suspect that the anti-idiotype 1E10 may serve as an imprint of the structural characteristics of the chP3 idiotype and, consequently, give rise to antibodies with P3-like properties upon immunization.

Nimotuzumab, an antitumor antibody that targets the epidermal growth factor receptor, blocks ligand binding while permitting the active receptor conformation

Overexpression of the epidermal growth factor (EGF) receptor (EGFR) in cancer cells correlates with tumor malignancy and poor prognosis for cancer patients. For this reason, the EGFR has become one of the main targets of anticancer therapies. Structural data obtained in the last few years have revealed the molecular mechanism for ligand-induced EGFR dimerization and subsequent signal transduction, and also how this signal is blocked by either monoclonal antibodies or small molecules. Nimotuzumab (also known as h-R3) is a humanized antibody that targets the EGFR and has been successful in the clinics. In this work, we report the crystal structure of the Fab fragment of Nimotuzumab, revealing some unique structural features in the heavy variable domain. Furthermore, competition assays show that Nimotuzumab binds to domain III of the extracellular region of the EGFR, within an area that overlaps with both the surface patch recognized by Cetuximab (another anti-EGFR antibody) and the binding site for EGF. A computer model of the Nimotuzumab-EGFR complex, constructed by docking and molecular dynamics simulations and supported by mutagenesis studies, unveils a novel mechanism of action, with Nimotuzumab blocking EGF binding while still allowing the receptor to adopt its active conformation, hence warranting a basal level of signaling.

Gangliosides, Ab1 and Ab2 antibodiesII. Light versus heavy chain: An idiotype-anti-idiotype case study

The antibody heavy chain is generally more important than the light chain for the interaction with the antigen, although many reports demonstrate the influence of the light chain in the antibody binding properties. The heavy chains of anti-N-glycolyl-ganglioside P3 mAb and anti-idiotypic 1E10 mAb display complementary charged residues in their H-CDRs, particularly in H-CDR3. A basic residue in P3 mAb H-CDR1 was shown to be crucial for the interaction with the antigen and 1E10 mAb. The immunogenetic features of three other P3 mAb anti-idiotypic mAbs are now analyzed. One of them bears the same heavy chain as 1E10 mAb and a different light chain, but differs in its binding to P3 mAb mutants where H-CDR basic residues were replaced and in the binding to 1E10-specific phagotopes. Chimeric hybrid antibodies with P3 and 1E10 mAb heavy chains and unrelated light chains were obtained to further determine the importance of heavy chains in P3 and 1E10 mAb binding properties. One of the P3 heavy chain hybrid antibodies retained the specificity of P3 mAb with slight affinity differences. The heavy chains appear to play the main role in these mAb interactions, with the light chains modulating the affinity to their ligands.

Gangliosides, Ab1 and Ab2 antibodies

This report is focused on the molecular basis for the interaction of a monoclonal antibody (mAb) and its anti-idiotypic mAb. P3 mAb (Ab1) recognizes N-glycolyl-gangliosides, and 1E10 mAb is one of its anti-idiotypic mAbs (Ab2). Chimeric versions of both antibodies retained their specificity. Charged residues in their H-CDRs, particularly H-CDR3, were considered to play a major role in their binding and immunogenic properties. P3 mAb has the unusual property of generating a strong antibody response in syngeneic mice, even when it is administered in saline. We selected phagotopes from a 12mer peptide library displayed on filamentous phage to characterize amino acid motifs recognized by these antibodies. The peptides were enriched in charged amino acids similar to those present in P3 and 1E10 mAb H-CDR3. We also report the construction of four mutants of the P3 antibody, where arginine residues in the heavy chain CDRs were substituted by serine residues, and the characterization of their interaction with 1E10 mAb and GM3(NeuGc) ganglioside, as well as their immunogenic properties in Balb/c mice. H-CDR1 R31 residue appears to have a central role in P3 mAb reactivity and antigenicity. H-CDR3 R100a residue seems to be more involved in the immunogenicity of the P3 idiotype.

Process development for a Cuban cholera vaccine based on the attenuated strain Vibrio cholerae 638

Genetically modified Vibrio cholerae strain 638 (biotype El Tor, serotype Ogawa) has previously been shown to be immunogenic in animal models and in human trials. Our objective in the work reported herein was to describe the process development methods for the production of the 638 attenuated cholera vaccine. Cell seed bank, culture of biomass, lyophilization and final formulation were processes were developed. The results show kinetics of culture that fulfils a logistical model. The microbiological properties, colonizing capability, immunogenicity and non-toxigenicity of the final product were indistinguishable from the properties of the working seed lot. We conclude that the non-reactogenic, immunogenic and protective strain 638 is robust and can withstand the fermentation processes required for large-scale production of a vaccine.

Formulation in tablets of a cholera whole cells inactivated vaccine candidate

Licensed as well as candidate cholera vaccines available at the present requires the dose preparation (included buffer) at the moment of application. The aim of this work was to evaluate the presentation in oral tablets of an inactivated cholera vaccine to avoid that inconveniences during application. We have therefore compared inactivated cultures of Vibrio cholerae with tablets formulation vaccine. We obtained that antigenic activity (ELISA) and immunogenicity in animal model (ELISA and vibriocidal tests) of V. cholerae inactivated cell remained unaltered in the final tablet formulation. The results suggest that the oral tablet formulation could be a useful pharmaceutical form in order to produce a new and affordable cholera vaccine.

Biological modifiers as cytoreductive therapy before stem cell transplant in previously untreated patients with multiple myeloma

BACKGROUND

High dose chemotherapy with supporting autologous stem cell transplantation is now considered the treatment of choice in patients with multiple myeloma <65 years old. The best regimen appears to be VAD (vincristine, doxorubicin and dexamethasone), but acute and late toxicity can limit the use of this combination. The use of biological modifiers has not been considered in this situation. We developed a new cytoreductive regimen, in an attempt to retain clinical efficacy but reduce toxicity.

PATIENTS AND METHODS

Thirty-six patients, previously untreated with diagnosis of multiple myeloma were enrolled to received the DAI regimen (dexamethasone 30 mg/m(2), i.v., days 1-4, all-trans-retinoic acid 45 mg/m(2), p.o., days 5-14 and interferon alpha 2a, 4.5 MU s.c., days 5-14) administered every 28 days for six cycles before high-dose chemotherapy (melphalan 200 g/m(2)) and autologous stem cell transplantation.

RESULTS

Overall response was observed in 29 cases (80%), complete response in 19 and partial response in 10 patients. Five patients were >65 years old and were treated with dexamethasone/thalidomide. Twenty-four patients underwent transplants. At a median follow-up of 31.6 months, no relapse or disease progression was observed, thus actuarial curves at 3-years showed that event-free survival was 86% and overall survival was 94%. Toxicity was mild.

CONCLUSIONS

This regimen appears to be an excellent alternative as cytoreductive treatment before high-dose chemotherapy and autologous stem cell transplantation with excellent overall response and minimal toxicity. Controlled clinical trials are warranted to define the role of this new therapeutic approach.

Light-chain shuffling results in successful phage display selection of functional prokaryotic-expressed antibody fragments to N-glycolyl GM3 ganglioside

Phage display technology makes it possible to introduce and rapidly screen diversity in antibody binding sites. Chain shuffling has been successfully used to humanize murine antibody fragments and also to obtain affinity matured variants. Here we report a different application of this method: the use of chain shuffling to overcome improper prokaryotic expression behavior of a hybridoma-derived single-chain antibody fragment. Construction and expression of such recombinant antibody fragments remain as empirical entities, hampered by the inability to express some antibody genes coming from eukaryotic cells in bacterial expression systems. Such problems are different for each combination of variable regions and can be serious enough to preclude the use of some hybridomas as sources of V regions to obtain recombinant antibody fragments. The particular binding properties and potential usefulness of some monoclonal antibodies make it highly desirable to bypass these technical limitations in order to develop smaller size therapeutic agents in the form of antibody fragments. The 14F7 mouse monoclonal antibody is one such attractive candidate due to its high specificity for the N-glycolyl GM3 ganglioside overexpressed in tumor cells and its ability to distinguish this antigen from closely related gangliosides like N-acetyl GM3. Our goal was to construct a phage-displayed single-chain Fv antibody fragment derived from 14F7. After cloning the original variable regions from the 14F7 hybridoma in a phagemid vector, we were unable to detect either binding activity or even expression of antibody fragments in bacteria, despite repetitive efforts. We constructed light-chain shuffling libraries, from which functional antibody fragments were readily selected. These combined the original 14F7 heavy chain variable region with a wide variety of unrelated murine and human light-chain variable regions. New antibody fragments retained the valuable properties of the monoclonal antibody in terms of fine specificity, affinity and tumor recognition. They were readily produced by bacteria, either in phage-displayed form or as soluble molecules, and provided a panel of potentially useful variants for cancer diagnosis and immunotherapy. Chain shuffling and phage display were found to be useful strategies for selecting antibody fragments on the basis of both prokaryotic expression and antigen binding criteria.

Structure and Molecular Interactions of a Unique Antitumor Antibody Specific for N-Glycolyl GM3

N-glycolyl GM3 ganglioside is an attractive target antigen for cancer immunotherapy, because this epitope is a molecular marker of certain tumor cells and not expressed in normal human tissues. The murine monoclonal antibody 14F7 specifically recognizes N-glycolyl GM3 and shows no cross-reactivity with the abundant N-acetyl GM3 ganglioside, a close structural homologue of N-glycolyl GM3. Here, we report the crystal structure of the 14F7 Fab fragment at 2.5 A resolution and its molecular model with the saccharide moiety of N-glycolyl GM3, NeuGcalpha3Galbeta4Glcbeta. Fab 14F7 contains a very long CDR H3 loop, which divides the antigen-binding site of this antibody into two subsites. In the docking model, the saccharide ligand is bound to one of these subsites, formed solely by heavy chain residues. The discriminative feature of N-glycolyl GM3 versus N-acetyl GM3, its hydroxymethyl group, is positioned in a hydrophilic cavity, forming hydrogen bonds with the carboxyl group of Asp H52, the indole NH of Trp H33 and the hydroxyl group of Tyr H50. For the hydrophobic methyl group of N-acetyl GM3, this environment would not be favorable, explaining why the antibody specifically recognizes N-glycolyl GM3, but not N-acetyl GM3. Mutation of Asp H52 to hydrophobic residues of similar size completely abolished binding. Our model of the antibodycarbohydrate complex is consistent with binding data for several tested glycolipids as well as for a variety of 14F7 mutants with replaced VL domains.

Treatment of refractory Hodgkin's disease with modified Stanford V program

This study analyzes the results using an Stanford V modified program in the treatment of refractory Hodgkin's disease (RHD). We used cyclophosphamide instead of mechloretamine, and epirubicin instead of doxorubicin to avoid the risk of acute and late side effects associated with this drugs. Seventy-one patients with RHD were treated. All were at an advanced stage at therapy and had associated adverse prognostic factors. The complete response (CR) rate was 84% (60 patients; 95% confidence interval [CI]: 72-91%). At 5 yr, actuarial overall survival (CS) is 71% (95% Cl: 59-78%) and event-free survival (EFS) is 70% (95% CI: 59-79%). Only the duration of the initial complete response (> 12 mo) influenced the duration of EFS and OS. Toxicity was mild. Granulocyte colony-stimulating factor to ameliorate the presence of severe myelosuppression was used only in a few patients. Cardiac function was not affected and, until now, late side effects has not been observed. Thus, the use of this modified Stanford program retains the usefulness of the original scheme both with less frequent and less severe acute and late side effects. A controlled clinical trial in untreated patients comparing the Stanford program with standard chemotherapy is warranted to define the role of this therapeutic option in patients with Hodgkin's disease.

Chemotherapy plus interferon-alpha2b versus chemotherapy in the treatment of follicular lymphoma

The best treatment of follicular lymphoma remains to be determined because the long natural history of follicular lymphoma requires mature data for accurate analysis. Although the goal of primary treatment remains durable remission, the sequential application of effective treatments may also result in a prolongation of median survival time. The use of interferon (IFN) with doxorubicin-based chemotherapy has demonstrated an increase of event-free survival but not in overall survival; however, its acute and late cardiac toxicity limits its use. For this reason, we began a controlled clinical trial to assess the efficacy and toxicity of chemotherapy: COPP (cyclophosphamide, vincristine, prednisone, and procarbazine) + IFN alternating every month for six cycles compared to six cycles of chemotherapy. In an intent-to treat analysis, 55 patients were enrolled (median age 61 years). Most cases (91%) with advanced disease were randomly assigned to chemotherapy + IFN (28 cases) or chemotherapy (27 cases). Complete remission was observed in 16 patients: 59% (95% CI, 53-70%) in the chemotherapy arm compared to 20 patients 71% (95% CI, 58-79%) in the chemotherapy + IFN arm; total responses were 74% and 86%, respectively. At a median follow-up of 60 months, event-free survival was 100% for patients treated with chemotherapy + IFN, which was statistically different from patients treated with chemotherapy 70%. At 7 years, median survival has not yet been reached; 72% of patients chemotherapy + IFN remain alive without disease (95% CI, 59-81%), which is not statistically different from 72% (95%CI, 50-73%) in the chemotherapy arm. Non-hematological toxicity was most frequent and severe in the chemotherapy arm; hematological toxicity was similar in both groups. Thus, it appears that chemotherapy + IFN, as described herein, improves event-free survival but the overall survival rates remain unchanged. The use of COPP appears to be better that anthracycline-based chemotherapy because it avoids the presence of acute and late cardiac toxicity.

Late lethal events in patients with diffuse large B cell lymphoma: a review of 714 patients treated in a single centre

Presence of late lethal events has been recognized as a complication in patients with malignant lymphoma. We reviewed 714 cases of patients treated during 1975-1995 with a long term follow-up (>4 years) in an attempt to identify all late events secondary to malignant lymphoma, either to the treatment or those which are unrelated. Forty-three patients died, and of these 21 (2.8%) were secondary to relapse and tumor progression; deaths associated with second neoplasm and cardiac events were increased 9.6 fold and 26.4 fold respectively compared to the general population. The risk factors for these complications did not differ from those in previous reports and included alkylating agents and/or radiotherapy for second neoplasms and anthracycline therapy and radiotherapy for cardiac toxicity. Moreover, 10 patients died secondary to non-related events. Nevertheless, at 10 years overall survival was 94% (95% confidence interval (CI): 82% to 98%) and event free survival was 97.1% (95% CI: 81% to 98%), for these patients. Thus, second events, fatal in most cases, will be considered as an expected risk in the treatment of patients with malignant lymphoma. The proposed modifications of therapy many indeed be useful to avoid or diminish these complications in the future.

Evaluation on a six-dose treatment of anti CD 20 monoclonal antibody in patients with refractory follicular lymphoma

Treatment of refractory follicular lymphoma with monoclonal antibody CD 20 has been proven to be a good therapeutic option. However, most studies used four weekly doses and time to treatment failure (TTF) and overall survival (OS) could be considered very short: 11.0 and 13.6 months respectively. We started a pilot study to evaluate if six infusions at the same doses and schedule could improve the outcome in these patients. Seventeen patients with refractory follicular lymphoma heavily treated with chemotherapy (> 2 regimens), radiotherapy and biological modifiers were enrolled in a pilot study. They received 6 weekly doses, at 375 mg/m2, of monoclonal anti CD 20. In an intent to treat analysis, overall response was 76%, of which 47% (8 patients) were complete response and 5 patients were partial response. With a median follow-up of 28.6 months, 7 complete responders remain alive, free of disease, and 2 partial responses remain stable without additional treatment. Median to TTF has not been reached; yet, actuarial curves showed that at 3 years, 53% of patients are alive. The four patients who were failure died secondary to tumor progression. Overall survival (OS) at 3-year was 76%. Toxicity was mild, all patients completed the schedule on time and doses. The addition of two doses of anti CD 20 clearly improved OS and TTF in a group of patients with refractory follicular lymphoma heavily treated and with poor prognostic factors. However, the number is too short to draw definitive conclusions; more clinical trials are necessary to determine if 4 or 6 doses of anti CD 20 therapy are better in this setting of patients.

Results of a Controlled Clinical Trial Radiotherapy versus Combined Therapy in the Management of Stage IE Orbital Marginal Zone B-cell Lymphoma

The aim of the present study was to compare the usefulness of radiotherapy (34-40 Gy, median 3.8 Gy) versus radiotherapy following by adjuvant chemotherapy in the management of 73 patients with stage I marginal zone B cell lymphoma (MZBCL) of the orbit. Complete response was similar in both arms: 95% (95% confidence interval (CI): 89-99%) in the radiotherapy group and 100% (95% CI: 92-104%) in the combined therapy arm. At a median follow-up of 8 years no median has been reached in event free survival (EFS) and overall survival (OS). At 8-years EFS shown that 87% (95%CI: 82-93%) and 82%, (95%CI: 78-87%), respectively remain in first complete response (p=0.6). OS was very similar 87% (95% CI: 84-89%) and 90%, (95% CI: 84-95%), respectively (p=0.5). Because we use low-radiation therapy (<50Gy) acute and late toxicities were mild. We concluded that combined therapy it is not useful in the treatment of MZBCL primary of the orbit and confirm that radiotherapy is the treatment of choice in this setting of patients.

In vitro hematopoiesis in patients with malignant lymphoma during active disease and at complete clinical remission after chemotherapy

Malignant lymphomas are neoplastic diseases of lymphoid cells, which usually originate in the lymph nodes. During the last two decades, significant progress has been made in the characterization of chromosomal and molecular alterations in these malignancies. To date, however, the composition and function of the hematopoietic system in this group of hematological disorders is still not fully understood. In the present study, we have determined the progenitor cell content in 10 patients with diffuse large-cell lymphoma (DLCL) and characterized the proliferation of these cells in long-term marrow cultures. We have also addressed some issues regarding the composition and function of the hematopoietic microenvironment in this malignancy. All the patients included in this study showed normal hematological parameters in peripheral blood, both before and after chemotherapy, however, significant hematopoietic alterations were consistently observed. As compared to normal subjects, lymphoma patients showed a 35% reduction in progenitor cell numbers, including myeloid, erythroid and multipotent progenitors. The in vitro proliferation of these cells was also deficient, since their levels in long-term marrow cultures were significantly lower than those observed in normal bone marrow cultures. Fibroblastic progenitors were reduced by >50% and this correlated with a deficient adherent cell layer development in culture. A reduction was also seen in the levels in culture supernatant of the stimulatory cytokines Stem Cell Factor and Interleukin-6. Interestingly, all the hematopoietic alterations mentioned above were still present in patients at complete clinical remission after chemotherapy. Thus, in the present study we have demonstrated significant in vitro deficiencies in the composition and function of the hematopoietic system in patients with diffuse large-cell lymphoma, both during active disease and at the time of complete clinical remission.

Passive protection of serum from volunteers inoculated with attenuated strain 638 of Vibrio cholerae O1 in animal models

As part of the studies to obtain an oral vaccine against cholera disease, the protective effect of serum from volunteers inoculated in a controlled trial with a candidate live attenuated vaccine of Vibrio cholerae O1, El Tor Ogawa (638; CTX&phi; mutant, hap::celA), was tested. It was confirmed that the serum, as well as the purified IgG and IgA from the volunteers had a protective effect in both of the animal models used, although the purified antibodies needed the presence of complement to be protective. These results emphasize the expectations about the protective potential of the candidate in challenge studies in humans to be conducted very soon.

Angiocentric nasal T/natural killer cell lymphoma: a single centre study of prognostic factors in 108 patients

Angiocentric T cell/natural killer (NK) nasal lymphoma remains a rare clinical presentation in North America and Europe but is more common in Asia and Latin America. We have reviewed 108 cases of angiocentric T/NK cell lymphoma of the nasal cavity with a view to establishing prognostic factors. Most patients were high or high intermediate clinical risk and had additional poor prognostic factors such as bulky disease, high levels of beta 2 microglobulin, advanced stage and multiple extranodal involvement. At 8 years, overall survival was 82%, 90% and 84% for low-intermediate, high-intermediate and high clinical, respectively. Disease free survival was very similar: 79%, 83% and 80%, respectively. Multivariate analysis did not identify any factor influencing overall survival and disease-free survival. There was no evidence that the international prognostic index (IPI) was applicable in these patients and it appears that angiocentric T/NK cell lymphoma is an independent prognostic factor itself.

Interferon as maintenance therapy in refractory malignant lymphoma

Patients with refractory malignant lymphoma (RML) have a poor prognosis when treated with conventional chemotherapy, as less than 20% remain alive and free of disease after 5 years. The use of myeloablative chemotherapy followed by BMT has improved the complete remission (CR) rate. Nevertheless, relapse rates remain unchanged, and only a few patients remain alive and free of disease for more than 3 years. For this reason, we began a prospective randomized clinical trial to determine if IFN-alpha2B (5.0 MU three times a week for 1 year) can improve the prognosis in RML. Ninety-six patients with high or high-intermediate clinical risk RML and in CR after intensive chemotherapy were randomly assigned to receive or not to receive IFN as maintenance therapy. A median follow-up of 48.1 months, the time to treatment failure and survival were similar in both groups. Toxicity secondary to IFN administration was mild, and all patients received the planned doses of IFN. We conclude that IFN is not recommended at this dose and schedule as maintenance therapy in patients with RML who achieve CR. Different therapeutic approaches may be developed to improve outcomes for these patients.

Dexamethasone, all trans retinoic acid and interferon alpha 2a in patients with refractory multiple myeloma

Few effective regimen are available for patients with refractory multiple myeloma (RMM). Generally, responses are scarce and disease free survival is very short. We developed a new therapeutic option in these patients using dexamethasone (40 mg/m2, i.v., daily, days 1 to 4), all-trans retinoic acid (45 mg/m2, po, daily, days 5 to 14) and interferon alpha 2a (9.0 MU, daily, subcutaneously, days 5 to 14). The treatment was administered every 21 days for 6 cycles. In a pilot study, 12 patients, heavily treated with chemotherapy and radiotherapy and in some cases with interferon, were allocated to receive the afore mentioned treatment. Response was observed in 10 patients (83%). With a median follow-up of 36.1 months (range 27 to 41), seven patients remain alive and disease-free without any treatment. Two patients were failures and have died due to tumor progression. Toxicity was mild and all patients received treatment according to the planned doses of drugs. The use of biological modifiers in combination with dexamethasone offer a safe and effective therapeutic option in patients with refractory multiple myeloma. More studies are warranted to define the role of this type of treatment.

Maintenance therapy with interferon alfa 2b in Hodgkin's disease

We performed a randomized clinical trial to assess the efficacy and toxicity of interferon alfa 2b (IFN) as maintenance therapy in patients with advanced Hodgkin's disease in complete remission (CR) after conventional chemotherapy. One hundred and thirty-five patients (stage IIIB-IV B) were initially treated with EBVD (epirubicin, bleomycin, vinblastine, dacarbazine). IF CR was achieved they were randomly assigned to receive either maintenance therapy with IFN 5.0 MU three times a week for one year or no further treatment (control group). Clinical and laboratory characteristics at diagnosis were quite similar in both groups. After a median follow-up of 74.3 months (range 49 to 108), 61 out of 68 patients (91%; 95% confidence interval (CI): 76% to 97%) remain in first complete remission in the IFN-treated group compared to 38 out of 67 (58%; 95% CI: 49% to 71%) in the control group (p<.01). Overall survival was also better in the IFN treated group: 62 patients (92%; 95% CI: 82% to 97%) are alive free of disease at 7-years compared to 40 patients (67%, 95%: 55% to 76%) in the control group (p<.01). Toxicity secondary to IFN administration was mild and no dose modification was necessary during treatment. All patients received the planned dose of IFN. This was not an intent-to treat analysis. IFN administration as maintenance therapy was appears to be the only cause of improvement in outcome in these patients. We feel that IFN should be considered as maintenance therapy in patients with advanced Hodgkin's disease because this treatment improves the final outcome without the excessive toxicities of more aggressive therapeutic approaches such as bone marrow transplantation during first CR. We hope that IFN will be considered in future randomized clinical trials in order to define it's role in the treatment of Hodgkin's disease.

Epirubicin (CEOP-Bleo) versus idaurubicin (CIOP-Bleo) in the treatment of elderly patients with aggressive non-Hodgkin's lymphoma: dose escalation studies

One hundred and sixty nine untreated elderly patients (median age 69 years old; range 60-89 years old) with high or high-intermediate clinical risk non-Hodgkin's lymphoma were enrolled in a controlled clinical trial to evaluate escalated doses of epirubicin in a CEOP-Bleo regimen (cyclophosphamide, vincristine, epirubicin, prednisone and bleomycin), compared to escalated doses of idaurubicin in an CIOP-Bleo regimen (idaurubicin instead of epirubicin). Overall, 71% of the patients in the CEOP-Bleo arm achieved a complete response compared to only 48% in the CIOP-Bleo regimen (p < 0.01). At actuarial 3 year, 72% of the patients treated with the CEOP-Bleo regimen remained alive and free of disease, compared to 34% in the CIOP-Bleo arm (p < 0.01). Dose intensity was 0.86 in the epirubicin regimen, similar to 0.82 in the idaurubicin arm. Toxicities were more frequent and severe in the CEOP-Bleo regimen; however, no death-related treatment was observed in either groups. Cardiac toxicity was also similar in both arms. We conclude that treatment of elderly paitents with aggressive non-Hodgkin's lymphoma should be considered a curative attempt and not only palliative. The use of full doses of chemotherapy should be contemplated in elderly patients. Epirubicin, in escalating doses, is a drug with mild toxicity and improvement in outcome in this setting is observed. We cannot confirm the usefulness of idaurubicin, including escalating doses, in the treatment of patients with aggressive malignant lymphoma, because the complete response rate and survival were worse than other chemotherapy regimens. We feel that the CEOP-Bleo regimen with escalated doses of epirubicin is a useful option in the treatment of elderly patients with aggressive non-Hodgkin's lymphoma.

Bone marrow protection with amifostine in the treatment of high-risk malignant lymphoma

Based on preclinical and clinical studies which suggested that amifostine can protect against haematological toxicity of cyclophosphamide, we conducted a clinical trial of amifostine and intermediate doses of cyclophosphamide in patients with high-risk malignant lymphoma. 40 patients were enrolled to receive amifostine (910 mg/m2) before cyclophosphamide (1500 mg/m2) for two cycles (10 patients); 20 patients were allocated to receive amifostine/cyclophosphamide only on one cycle (patients were their own control) and 10 patients received cyclophosphamide alone without amifostine protection. Patients who received amifostine had fewer days of severe granulocytopenia (grade III or IV) and infectious episodes, and delay on treatment was minimal. Amifostine was well tolerated; only 2 patients developed transient and mild hypotension. The complete response rate was 72% (29/40). We conclude that amifostine is a good protector against haematological toxicity of cyclophosphamide and did not interfere with tumour response. Clinical trials with increasing doses of cytotoxic drugs or combination chemotherapy are needed to define the role of this myeloprotector agent in the treatment of patients with malignant lymphoma.

Dose escalation of epirubicin in the CEOP-BLEO regimen: a controlled clinical trial comparing standard doses for the treatment of diffuse large cell lymphoma

One hundred and forty-seven consecutive patients with previously untreated high-intermedium and high clinical risk diffuse large cell lymphoma (DLCL) were included in a prospective clinical trial to evaluate the efficacy and toxicity of escalating doses of epirubicin compared to standard doses in the CEOP-Bleo (cyclophosphamide, epirubicin, vincristine and prednisone and bleomycin) regimen, 55% of the patients were > 60 years old and most patients had adverse prognostic factors at diagnosis. Complete response rates were similar in both groups (68% in the standard dose compared to 73% in the escalating arm, (p = 0.5). However, time to treatment failure (TFF) and overall survival were better after escalating doses. At 3-years TTF at a medial follow-up of 33.6 months was 76% in the patients whose received escalating dose statistical different to 37% of the patients whose received standard doses (p < .01). Overall survival was 81% in the escalated therapy arm which is statistical different to 40% of the patients treated with standard doses (p < .01). Toxicity was mild in both arms. Neutropenia, mucositis and cardiotoxicity were mild in the escalated dose arm and no severe complications were observed. All patients received the planned doses of all drugs. Patients > 60 years old had the same CR rate, TTF and overall survival as younger patients. In conclusion it seems that the dose of epirubicin can be increased in combination chemotherapy regimens with safety and only mild toxicity. The CR rate was not superior compared to the standard dose but the TTF and overall survival were better. Longer follow-up periods are required in order to determine if the cure rate can also be improved. Older patients can also benefit because they also tolerated the increase in epirubicin without severe side effects and also improved their outcome. The use of more aggressive regimens with increase in dose intensity may be the treatment of choice for more patients poor prognosis, with DLCL provided there is no increase in toxicity. In this respect the use of epirubicin in higher doses/appears to be useful.

Results of a randomized trial of granulocyte colony-stimulating factor in patients with infection and severe granulocytopenia

A study was carried out to investigate the efficacy and toxicity of granulocyte colony-stimulating factor (G-CSF) in the treatment of infection in 119 severely granulocytopenic patients with hematological malignancies after intensive chemotherapy. Patients were assigned randomly to receive either antibiotics alone (ceftazidime, 2 g, i.v., every 8 h + amikacin 7.5 mg/kg, i.v., every 12 h) or the same antimicrobial regimen plus G-CSF (5 micrograms/kg/day, s.c.). Measurements were clinical improvement, eradication of infection and toxicity. Patients who received antibiotics plus G-CSF had more clinical responses (82 versus 60%), less superinfections (6 versus 20%), less mortality (5 versus 15 patients), less days in hospital (median 10 versus 27) and reduced antibiotic usage compared to patients who received only antibiotics. Hematological recovery (granulocytes > 1.0 x 10(9)/l) was also shorter in these patients (12 versus 23 days). Fungal infections occurred only in the group treated with antibiotics alone. Toxicity secondary to G-CSF was absent. We conclude that the addition of G-CSF to broad spectrum antibiotics is useful in selected patients with severe granulocyctopenia after intensive chemotherapy and infection, because if may prove the outcome in these patients.

[Preliminary studies on the design of retroviral vectors for substitutive gene therapy]

We have studied the effect that exerts on the Moloney murine leukemia virus (Mo-MLV) viral cycle the deletion of the 13 bases that constitute the inverted repeat (IR) present at the external U3 region of the pre-proviral DNA. Whereas supernatants of wild type- and modified virus-producing cells contained similar amounts of viral particles, the deleted viruses showed a 100 to 1000-fold decreased infectivity. To determine how the deletion interfered with the infective capacity of the virus, different steps of the viral cycle were studied using deleted viruses. The deletion affected neither reverse transcription nor the entry of the DNA into the cell nucleus; however, the integration of the pre-proviral DNA into the host genome was reduced to undetectable levels. These results open a pathway to the construction of Mo-MLV-derived retroviral vectors for gene targeting purposes.

Interferon alpha 2b as maintenance therapy in low grade malignant lymphoma improves duration of remission and survival

We assessed the efficacy and toxicity of interferon alpha 2b (IFN) as maintenance therapy in patients with low grade malignant lymphoma. Between March 1986 and December 1989, 98 patients with low-grade malignant lymphoma in complete remission after conventional chemotherapy were randomly assigned to received IFN, 5.0 MU three times a week for one year, as maintenance therapy (n = 48), or to receive no treatment (control group, n = 50). In March 1994, the median duration of response had not yet been reached in the patients treated with IFN compared to 46 months in the control group. At 9-years 62% of the patients in the IFN arm remain in first complete remission compared to only 25% in the control group (p <.001). In addition, the median duration of survival has not yet been reached in either the IFN arm compared to 74 months in the control group (p <.001). Quality of life was excellent in both groups and severe side effects secondary to IFN treatment were not observed. All patients completed the planned dose of IFN. We conclude that IFN as maintenance therapy in low-grade malignant lymphoma is an excellent therapeutic option because it improves the duration of remission and survival without producing severe side effects or reducing the quality of life.

Treatment of non-Hodgkin's lymphoma of Waldeyer's ring: radiotherapy versus chemotherapy versus combined therapy

Treatment of stage IA non-Hodgkin's lymphoma (NHL) of Waldeyer's ring remains controversial, probably because of the small number of patients and the scarcity of controlled studies. Between 1981 and 1991, 316 patients with stage I NHL of Waldeyer's ring were randomised for treatment with radiotherapy alone (extended fields), 101 patients; combined chemotherapy with a regimen of CHOP (cyclophosphamide, vincristine, doxorubicin, and prednisone) or CHOP-like (epirubicin instead of doxorubicin), 106 patients; and combined therapy (radiotherapy followed by the same combination chemotherapy), 109 patients. Median follow-up was 6.8 years. Complete response was achieved in 93, 87 and 97%, respectively. Relapses were least frequent in patients treated with combination therapy. The 5-year rate for failure-free survival was 48% for radiation therapy, 45% for the patients who were treated with chemotherapy, which was statistically significantly less than the 83% for patients treated with combined therapy (P < 0.001). Overall survival was also better in the combined therapy arm: 90%, statistically different to 58% for the patients treated with chemotherapy alone and 56% for patients treated with radiation therapy (P < 0.001). Toxicity was mild and late side-effects were not observed in any patients. From these results combined therapy should be considered as the best therapeutic approach in patients with localised NHL of Waldeyer's ring.

Lymphangioma of Vater's ampulla: a rare cause of obstructive jaundice. Endoscopic therapy

BACKGROUND

We report endoscopic excision of a lymphangioma in an infrequent location, Vater's ampulla, with resolution of the obstructive jaundice caused by this tumor.

METHODS

An endoscopic papillotomy was performed together with polypectomy of the tumoral mass.

RESULTS

The patient evolved satisfactorily, with jaundice and biochemical cholestasis disappearing.

CONCLUSIONS

We believe endoscopic therapy is the ideal treatment for small lymphangiomas in the digestive tract.

GM-CSF instead of hematological support during high-dose chemotherapy for refractory malignant lymphoma

Patients with refractory malignant lymphoma (RML) have a poor prognosis when treated with conventional chemotherapy. The use of high-dose chemotherapy has been limited by secondary myelosuppression. We report the use of intensive and short-duration chemotherapy in patients with RML who received granulocyte-macrophage colony-stimulating factor (GM-CSF) instead of hematological support and salvage with bone marrow transplantation or infusion of peripheral blood stem cells. Thirty-one patients with RML were treated with cyclophosphamide: 7 g/m2, iv on day 1, followed by GM-CSF: 5 micrograms/kg/day, subcutaneously until hematological recovery (granulocytes > 1.8 x 10(9)/L) started on day 2. Methotrexate, 5 g/m2, was also given when the granulocytes and platelets counts were normal, followed by leucovorin rescue. Epirubicin, 180 mg/m2, iv, was given on day 29 if the granulocyte count was normal, and GM-CSF was started on day 30. Complete response was obtained in 21 out of 31 patients (67%) and partial response in 4 more, thus an overall response was achieved in 80% of the treated patients. Time to treatment failure was 24+ months, and the overall survival was 28+ months. Hematological toxicity grade IV, according to the WHO criteria was observed in all cycles, however hematological recovery was already evident on day 13 +/- 2. Eleven patients developed infection related to the treatment, but no therapy related death was observed. GM-CSF was well tolerated with minimal toxicity. Is evident that GM-CSF can act as hematological support after high-dose chemotherapy in patients who cannot undergo bone marrow transplantation programs.(ABSTRACT TRUNCATED AT 250 WORDS)