Serum Neurofilaments are a reliable biomarker to early detect PML in Multiple Sclerosis patients

BACKGROUND

The earliest detection of progressive multifocal leukoencephalopathy (PML) is crucial in Natalizumab (NTZ)-treated Multiple Sclerosis (MS) patients. This study aims to assess serum Neurofilaments (sNFL) ability to early detect PML in longitudinal patients' follow-up.

METHODS

NFL were retrospectively measured in four PML cases occurred at the Regional Referring Center for MS (CRESM, Italy), in samples collected since one year before PML diagnosis, at PML diagnosis, during PML and in post-PML follow-up. sNFL levels were interpreted according to previously defined reference values. Clinical examination and EDSS were performed at each NTZ infusion. Routinary MRI was undertaken every six months; after PML diagnosis, MRI was performed according to clinical evaluation. sNFL were also measured in 45 NTZ-treated patients experiencing NEDA-3 status for at least 12 months.

RESULTS

Patients showed different PML onsets and manifestations: in 3 patients routinary brain MRI revealed radiological signs of PML preceding different clinical manifestations, while in one patient brain MRI was performed after the clinical onset. PML diagnosis was defined at the time of the first detection of JCV DNA in cerebrospinal fluid. The following different PML phases were considered: 1. Basal (up to 4 months before PML diagnosis): sNFL values were in the normal range in all patients' samples, except for one (median 9.1 pg/ml, range 6.2-15.1 pg/ml) 2. Pre-PML (within 3 months before PML diagnosis): sNFL were elevated in all available samples (median 19.50 pg/ml, range 15.50-33.80 pg/ml). 3. PML diagnosis: sNFL were elevated in all patients (median 59.20 pg/ml, range 11.1-101.50 pg/ml). 4. PML/IRIS: during this phase, sNFL levels reached their peak (median 96.35 pg/ml, range 20.5-272.9) in all patients. 5. Post-PML (recovery phase, starting from the first MRI without enhancement, up to the end of follow-up): sNFL levels showed a decrease (median 12.80 pg/ml, range 9.30-30.60); however, based on reference values, sNFL were still elevated in 2 out of 4 patients at the end of their follow-up (622 and 887 days after PML diagnosis). sNFL were always elevated when MRI scan suggested a suspicious of PML. In NEDA-3 patients, sNFL levels were in the normal range in all patients' samples (median 4.7 pg/ml, range 1.4-8.6 pg/ml).

CONCLUSION

Elevated sNFL were observed not only at PML diagnosis, but also in pre-PML phase. At PML recovery, sNFL weren't normalized in all patients' samples, suggesting ongoing neuronal degeneration. sNFL represent a reliable biomarker and should be introduced in clinical practice as an additional/alternative parameter to MRI to early detect and monitor PML.

Inheritance of wild and truncated DAT alleles from grand-parents: Opposite transgenerational consequences on the behavioral phenotype in adolescent DAT heterozygous rats

Dopamine plays important roles in implicit memory and motivation of behavior. Environmental inputs can produce transgenerational epigenetic changes. This concept also includes the uterus: experimentally, we sought to create hyper-dopaminergic uterine conditions through ineffective dopamine-transporter (DAT) protein, obtained by inserting a stop-codon into the SLC6A3 gene. By crossing WT-dam with KO-sire (or vice-versa), we obtained a 100% DAT-heterozygous (HET) offspring with known derivation of the wild allele: MAT rats are offspring of WT-female and KO-male; PAT rats are offspring of KO-female and WT-male. We reconstructed inheritance of alleles, by crossing PAT-male with MAT-female or vice-versa, obtaining GIX (PAT-male with MAT-female) and DIX (MAT-male with PAT-female) rats (such offspring present specular paths in allele inheritance from grandparents). We conducted three experiments: first, we assessed maternal behaviour (four epigenotypes: WT, MAT, PAT and WHZ=HET-pups fostered-to-a WT-dam); in the second, we analysed sleep-wake cycles of GIX and DIX epigenotypes with their WIT siblings as controls; in the third, we explored the impact of WT or MAT mother on WT or HET pups. MAT-dams (with GIX-pups) express excessive licking/grooming. However, in the mere presence of "sick" epigenotype, PAT-dams (with DIX-pups) and also WHZ (i.e., WT-dams but with HET-pups) expressed greater nest-building care towards the offspring, compared to "true-wild" litters (WT-dams with WT-pups). In Exp. 2 at adolescence, GIX epigenotype showed locomotor hyperactivity during late waking-phase, while DIX epigenotype exhibited pronounced hypoactivity compared to controls. In Exp. 3, we confirmed that HET adolescent pups receiving cares from a MAT-dam may develop additional hyperactivity when awake, but additional hypoactivity during rest-hours. Thus, behavioral changes observed in DAT-heterozygous offspring have opposite courses based on of DAT-allele inheritance from a grandparent through the sire or the dam. In conclusion, behavioural changes in the offspring have antithetic courses with respect to inheritance of DAT-allele via sperm or egg.

How Is Working Memory Related to Reading Comprehension in Italian Monolingual and Bilingual Children?

This study explored how working memory resources contributed to reading comprehension using tasks that focused on maintenance of verbal information in the phonological store, the interaction between the central executive and the phonological store (WMI), and the storage of bound semantic content in the episodic buffer (immediate narrative memory). We analysed how performance in these tasks was related to text decoding (reading speed and accuracy), listening and reading comprehension. The participants were 62 monolingual and 36 bilingual children (mean age nine years, SD = 9 months) enrolled in the same Italian primary school. Bilingual children were born to immigrant parents and had a long history of exposure to Italian as a second language. The regression analyses showed that reading accuracy and listening comprehension were associated with reading comprehension for monolingual and bilingual children. Two working memory components-WMI and immediate narrative memory-exhibited indirect effects on reading comprehension through reading accuracy and listening comprehension, respectively. Such effects occurred only for monolingual children. We discuss the implications of such findings for text reading and comprehension in monolinguals and bilinguals.

Multiple sclerosis epidemiological trends in Italy highlight the environmental risk factors

Italy is definitely a high-risk country for multiple sclerosis (MS). Over the last 50 years, several epidemiological studies, including longitudinal surveys, have disclosed that MS incidence and prevalence in Italy mainland and Islands (Sardinia and Sicily) have progressively increased, picturing a semi-parabolic curve. Based on the comprehensive scrutiny of 58 papers, we conclude that the latitude risk gradient does not fit to the Italian map of MS. The genetic heterogeneity of the Italian ethnicities, that likely forms the basis of MS predisposition, does not account for the dramatic increase of MS incidence and prevalence observed in Italy over the last half century that, rather, seems better explained by the effect of environmental factors.

Risk of multiple sclerosis relapses when switching from fingolimod to cell-depleting agents: the role of washout duration

BACKGROUND

Fingolimod (FTY) induces sequestration of lymphocytes in secondary lymphoid organs and the average lymphocyte recovery following discontinuation takes 1-2 months. It has been hypothesized that the therapeutic effects of subsequent cell-depleting agents may be compromised if initiated before lymphocyte recovery has occurred.

OBJECTIVE

To assess the risk of relapses following FTY discontinuation and the initiation of a B/T cell-depleting agent in relation to washout duration using data from the Italian MS Register.

METHODS

The risk of relapses was assessed in relation to different washout durations (< 6, 6-11, 12-17 and > / = 18 weeks) in patients starting alemtuzumab, rituximab, ocrelizumab or cladribine following FTY discontinuation.

RESULTS

We included 329 patients in the analysis (226F, 103 M; mean age 41 ± 10 years). During the cell-depleting treatment, the incidence rate ratio for a relapse was significantly greater in patients with a washout period of 12-17 and > / = 18 weeks compared to the reference period (< 6 weeks). The risk of a relapse was significantly influenced by the occurrence of relapses during FTY treatment and by washout length, with hazard ratios markedly increasing with the washout duration.

CONCLUSION

The risk of relapses increases with the washout duration when switching from FTY to lymphocyte-depleting agents.

Italian multiple sclerosis register as the basis for post-authorization safety studies

While the safety and efficacy of Disease Modifying Therapy (DMT) in multiple sclerosis (MS) are assessed in clinical trials, these are of relatively short duration and always confined to highly selected patient groups. The evaluation of real-world data such as patient registries, is vital as it offers long-term data collection and is patient rather than product-focused during the lifetime of MS, and allows to document a patient's treatment history throughout the disease course. Patient registries can play an important role in monitoring the safety of drus. Regulators and the pharmaceutical industry have shown interest in complementing or even replacing phase 4 clinical studies with data from MS registries.

The Italian MS Register (IMSR), in collaboration with the Big MS Data initiative, that also includes the national MS registries of Denmark, France, and Sweden and the international database network MSBase, came together with industry to conduct studies on post-authorization safety (PASS) and treatment effectiveness. The IMSR includes the clinical history of approximately 55,000 patients, or approximatively 45% of the estimated cases of MS in Italy. More than 10,000 patients have a follow-up duration of over 10 years.

A Core Protocol outlining principles of PASS projects was created in which aggregated results made available to sponsors and health authorities. The Core Protocol specifies variables, emphasizes improved capture of adverse events, in particular cancer, non-melanoma skin cancers and immunosuppression-related infections, all MedDRA-coded. EUROCAT codes for pregnancy outcomes are also documented.

Regulators, the pharmaceutical industry and national-level registries have jointly identified a format of collaboration on PASS for DMT in MS to benefit patients and the larger society. In this way, we hope to contribute to a framework that will include emerging and existing registries with the common goal of contributing to the advancement of knowledge in MS.

Key messages

The real-world data can contribute to understanding of the impact of disease-modifying therapy on long term. A format of collaboration among clinical research, regulators and pharmaceutical industry could be a winning framework to improve the knowledge on safety and treatment effectiveness in MS.

Intersections and Divergences Between Empathizing and Mentalizing: Development, Recent Advancements by Neuroimaging and the Future of Animal Modeling

Both mentalization and empathy allow humans to understand others, through the representation of their mental states or their mood, respectively. The present review aims to explain those characteristics which are shared between empathy and the Theory of Mind. Research in neuroscience, based on naturalistic paradigms, has shown that abilities to mentalize and to empathize are associated with the activation of different neuro-cognitive circuits. As far as mirror-neuron processes are concerned, some structures (like Anterior Insula, AI; Anterior Cingulate Cortex, ACC) play a role both in the representation of one's own affective states and in comprehension of the same affective state when experienced by others. As for mentalization, the temporal parietal junction (TPj) and temporal poles (TP), the upper posterior temporal sulcus (pSTS) and the medial prefrontal cortex (mPFC) are greatly involved: the latter appears involved in the attribution of one's own and others' temperaments. Interestingly, the ventral/orbital portion of the PFC (orbito-frontal cortex, OFC) is involved in subserving shared affective experience during cognitive mentalizing. This brain region represents a point of overlap, from a psycho-biological point of view, where emotional mirroring and affective cognition meet up. As for animal models, laboratory rodents can well be tested for prosocial behavior. Some examples include deliberate actions, allowing another conspecific the possibility to feed ("giving food"): this willingness can vary across donors, depending on how the recipient is perceived. Other examples include the possibility to let a trapped conspecific come out ("giving help"). The state-of-the-art knowledge about this theme can inform the programming of specific clinical interventions, based on the reinforcement of empathic and/or mentalization abilities.

Case Report: Evaluation strategies and cognitive intervention: the case of a monovular twin child affected by selective mutism

The present work describes the assessment process, evaluation strategies, and cognitive intervention on a 9 years old child with selective mutism (SM), a monovular twin of a child also affected by mutism. Currently, the cognitive behavioral multimodal treatment seems the most effective therapeutic approach for children diagnosed with selective mutism (Capobianco & Cerniglia, 2018). The illustrated case confirms the role of biological factors involved in mutacic disorder but also highlights the importance of environmental influences in the maintenance of the disorder with respect to relational and contextual dynamics (e.g. complicity between sisters, family relationships). The article discusses furthermore the importance of an early diagnosis as a predictor of positive treatment outcomes.

Early language development in preterm children without neurological damage: a longitudinal study

Children born at a very low gestational age, even those without neurosensory damages, are at risk of linguistic disorders. This longitudinal study aimed at analyzing communicative and language abilities in preterm children during their second year of life, through a standardized questionnaire, with particular attention to the communicative and language abilities that predict the first verbal skills. Our results showed that preterm children are slower than full-terms in language acquisition particularly at earlier stages of development. The differences between the two groups of children was significant only at 16 and 18 months. Preterms use more simplistic linguistic categories for longer than full-terms, with regards to lexicon composition and syntactic complexity. This different pattern could involve more qualitative, rather than quantitative, aspects of developmental processes that characterize language acquisition in preterms and full-term children.

Disease-modifying drugs in childhood-juvenile multiple sclerosis: results of an Italian co-operative study

Objective: Immunomodulatory drugs (IDs) (interferon beta (IFNβ) and glatiramer acetate (GA)) reduce relapse rate and disease progression in relapsing-remitting multiple sclerosis (RRMS) but extensive data are not available on the effectiveness and tolerability of these drugs in childhood or adolescence. The aim of this study was to evaluate the impact of IFNβ and GA in MS patients treated before 16 years of age. Methods: A research group (Immunomodulatory Treatment of Early onset MS (ITEMS)) was promoted in Italy to collect a large series of patients affected by clinically definite and RRMS and treated with IDs before 16 years of age. Fifteen centres recognized subjects suitable for inclusion: 76 patients (52 females) were collected with a mean age at onset of 12.4 (SD 2.5) years, a mean disease duration of 18.6 (SD 14.7) and a relapse rate of 3.1 (SD 2.9). Results: Results were evaluated in 65 (45 females) subjects with a pretreatment and a treatment duration >3 months: 38 were treated with IFNβ-1a once weekly (Avonex), 18 with IFNβ three times weekly (16 with Rebif, 2 with Betaferon) and nine with GA (Copaxone). The mean pretreatment period was respectively 20, 18 and 9.2 months. The treatment duration lasted respectively 23.3, 40.7 and 33.3 months. The mean annualized relapse rate decreased dramatically during the treatment: from 2.4 to 0.4 in the Avonex group, from 3.2 to 0.8 in the Rebif-Betaferon group and from 2.8 to 0.25 in the GA group. The mean final EDSS scores were respectively (in brackets the initial scores): 1.3 (1.4), 1.6 (1.8) and 0.6 (1.1). In the whole group, the final score was unchanged or reduced in all subjects except eight. Clinical side effects were recorded in 41/65 subjects (mainly in subjects treated with IFNβ), abnormal laboratory findings were observed in 13/65 subjects: they were transient in most cases. IFNβ was stopped in six cases: in four because of inefficacy and in two cases because of side effects. Conclusions: Sixty-five clinically definite MS subjects were treated during childhood or adolescence with IDs. The treatment reduced the relapse rate and the progression of the disease in most cases. Side effects were common in subjects treated with IFNβ, but were well tolerated in most cases.

Rituximab in the treatment of Neuromyelitis optica: a multicentre Italian observational study

Rituximab (RTX) efficacy in NMO is suggested by several case series. No consensus exists on optimal dosing strategies. At present the treatment schedules more frequently used are 375 mg/m2/week iv for 4 weeks (RTX-A) and 1000 mg iv twice, 2 weeks apart (RTX-B). Aim of this study is to confirm RTX efficacy and safety in the treatment of NMO and to evaluate whether a most favourable dosage regimen exists. Data on RTX-treated NMO patients were collected from 13 Italian Hospitals. 73 patients (64 F), were enlisted. RTX-A was administered in 42/73 patients, RTX-B in 31/73. Median follow-up was 27 months (range 7-106). Mean relapse rate in the previous year before RTX start was 2.2 ± 1.3 for RTX-A and 2.3 ± 1.2 for RTX-B. ARR in the first year of treatment was 0.8 ± 0.9 for RTX-A and 0.2 ± 0.4 for RTX-B, in the second year of treatment was 0.9 ± 1.5 for RTX-A and 0.4 ± 0.8 for RTX-B patients (p = 0.001 for the first year, ns (0.09) for the second year). RTX-B was more effective in delaying the occurrence of a relapse (HR 2.2 (95 % IC 1.08-4.53) p = 0.02). Adverse events were described in 19/73 patients (mainly urinary tract and respiratory infections, and infusion reactions). Two deaths were reported in severely disabled patients. Though with the limitations of an observational study, our data support RTX efficacy in NMO and suggest that high dose pulses might be more effective than a more fractioned dose.

No impact of current therapeutic strategies on disease reactivation after natalizumab discontinuation: a comparative analysis of different approaches during the first year of natalizumab discontinuation

BACKGROUND AND PURPOSE

Natalizumab discontinuation induces the recurrence of multiple sclerosis disease activity: currently no therapeutic approach has been found able to abolish disease reactivation.

METHODS

The recurrence of disease activity after natalizumab discontinuation was retrospectively evaluated in 79 patients who had been treated with immunomodulating agents, other first-line therapies, fingolimod or not treated.

RESULTS

No differences have been found in clinical or magnetic resonance imaging recurrence of disease activity amongst the groups. Interestingly, no disease reactivation was observed only in one patient treated for 6 months with monthly pulses of cyclophosphamide.

CONCLUSION

Disease modifying treatment or 'no treatment' is unable to abolish disease activity reactivation after natalizumab discontinuation.

Autologous haematopoietic stem cell transplantation with an intermediate intensity conditioning regimen in multiple sclerosis: the Italian multi-centre experience

BACKGROUND

Over recent years numerous patients with severe forms of multiple sclerosis (MS) refractory to conventional therapies have been treated with intense immunosuppression followed by autologous haematopoietic stem cell transplantation (AHSCT). The clinical outcome and the toxicity of AHSCT can be diverse, depending on the various types of conditioning protocols and on the disease phase.

OBJECTIVES

To report the Italian experience on all the consecutive patients with MS treated with AHSCT with an intermediate intensity conditioning regimen, named BEAM/ATG, in the period from 1996 to 2008.

METHODS

Clinical and magnetic resonance imaging outcomes of 74 patients were collected after a median follow-up period of 48.3 (range = 0.8-126) months.

RESULTS

Two patients (2.7%) died from transplant-related causes. After 5 years, 66% of patients remained stable or improved. Among patients with a follow-up longer than 1 year, eight out of 25 subjects with a relapsing-remitting course (31%) had a 6-12 months confirmed Expanded Disability Status Scale improvement > 1 point after AHSCT as compared with one out of 36 (3%) patients with a secondary progressive disease course (p = 0.009). Among the 18 cases with a follow-up longer than 7 years, eight (44%) remained stable or had a sustained improvement while 10 (56%), after an initial period of stabilization or improvement with median duration of 3.5 years, showed a slow disability progression.

CONCLUSIONS

This study shows that AHSCT with a BEAM/ATG conditioning regimen has a sustained effect in suppressing disease progression in aggressive MS cases unresponsive to conventional therapies. It can also cause a sustained clinical improvement, especially if treated subjects are still in the relapsing-remitting phase of the disease.

Variable responses to rituximab treatment in neuromyelitis optica (Devic's disease)

We have described two cases of Devic's disease patients treated with rituximab with different outcomes. The results indicate that there may be early unresponsiveness in very aggressive cases. Well designed clinical trials are needed to assess treatment effects in such a rare disease.

Treatment of early-onset multiple sclerosis with intramuscular interferonbeta-1a: long-term results

The objective was to evaluate the safety, tolerability and effectiveness of intramuscular (IM) interferon beta-1a (IFNbeta-1a; Avonex, Biogen) 30 mg once a week in patients with onset of symptoms of multiple sclerosis (MS) in childhood or adolescence. Patients with a diagnosis of definite MS according to McDonald's criteria, relapsing course according to Lublin's criteria, onset of symptoms of MS before 16 years of age, and who had received IM IFNbeta-1a therapy before 16 years of age were eligible for the study if they had a pretreatment and treatment duration of at least 6 months. Clinical and laboratory evaluations were performed every 3 months. A total of 52 patients were identified as receiving treatment with IM IFNbeta-1a 30 mg once a week before 16 years of age. Mean age at onset of symptoms of MS was 11.7+/-2.7 years, mean disease duration was 25.9+/-30.3 months, mean annualised relapse rate was 1.9+/-1.1 and mean Expanded Disability Status Scale (EDSS) score was 1.5+/-1.1. After a mean (+/-SD) treatment duration of 42.9+/-19.9 months, annualised relapse rate decreased to 0.4+/-0.5. Final EDSS score was 1.3+/-1.1. Adverse events were recorded for 35 (67%) patients (flulike syndrome, 33%; headache, 29%; myalgia, 21%; fever, 11%; fatigue, 6%; nausea and vomiting, 6%; and skin reaction, 4%); most were transient. IM IFNbeta-1a was effective and well tolerated in these paediatric patients with MS.

Autologous stem cell transplantation for progressive multiple sclerosis: update of the European Group for Blood and Marrow Transplantation autoimmune diseases working party database

Over the last decade, hematopoietic stem cells transplantation (HSCT) has been increasingly used in the treatment of severe progressive autoimmune diseases. We report a retrospective survey of 183 multiple sclerosis (MS) patients, recorded in the database of the European Blood and Marrow Transplantation Group (EBMT). Transplant data were available from 178 patients who received an autologous graft. Overall, transplant related mortality (TRM) was 5.3% and was restricted to the period 1995-2000, with no further TRM reported since then. Busulphan-based regimens were significantly associated with TRM. Clinical status at the time of transplant and transplant techniques showed some correlations with toxicity. No toxic deaths were reported among the 53 patients treated with the BEAM (carmustine, etoposide, cytosine-arabinoside, melphalan)/antithymocyte globulin (ATG) regimen without graft manipulation, irrespective of their clinical condition at the time of the transplant. Improvement or stabilization of neurological conditions occurred in 63% of patients at a median follow-up of 41.7 months, and was not associated with the intensity of the conditioning regimen. In this large series, HSCT was shown as a promising procedure to slow down progression in a subset of patients affected by severe, progressive MS; the safety and feasibility of the procedure can be significantly improved by appropriate patient selection and choice of transplant regimen.

Development and validation of a real time PCR-based bioassay for quantification of neutralizing antibodies against human interferon-beta

There are two commonly employed types of bioassays for the detection of neutralizing antibodies (NAbs) against interferon-beta (IFNbeta): the cytopatic effect assay (CPE), and the MxA (myxovirus resistance protein A) protein assay (MPA). This article describes a bioassay based on the real time PCR measurement of mRNA that results from the induction, in cultured human cells, of the MxA gene by IFNbeta. Serum samples from 104 patients with multiple sclerosis (MS) treated with IFNbeta were tested for NAbs using our real time PCR bioassay. NAbs also were measured in the same specimens by the MPA assay and CPE assay. The calibration range of the real time PCR bioassay is 0.125-30 LU/mL. The range of the intra- and inter-assay variations (coefficients of variation in log(10)) were 4.05% (range 0.88%-7.90%) and 4.42% (range 0.31%-9.15%), respectively. Samples of the three commercial preparations of IFNbeta-1a and -1b were measured showing dose-response curves parallel to that of the NIH reference IFNbeta (mean SD at the midpoint of the dose-response curve=5%). In addition, the assay was robust with respect to number of cells plated (i.e., increasing cell densities from 12x10(3)/well to 384x10(3)/well resulted in 3.03% variability in MxA expression normalized with glyceraldehyde-3 phosphate dehydrogenase). NAbs titers measured were closely comparable to those obtained by the MPA [r(spearman)=0.899; 89% of observed agreements; K=0.779] and the CPE [r(spearman)=0.7899); 86%; K=0.729] assays. Despite the obvious disadvantage of cost, when carried out according to quality assurance guidelines for molecular diagnostics the new MxA gene-expression assay (MGA) has significant advantages over the other methods for testing NAbs: it has excellent reliability and reproducibility, and utilizes equipment and methodologies already accessible in many clinical laboratories.

Biological markers of interferon-beta therapy: comparison among interferon-stimulated genes MxA, TRAIL and XAF-1

Biological activity of interferon-beta (IFNbeta) can be assessed by measuring IFN-stimulated genes (ISGs). Among them, myxovirus resistance protein A (MxA) appears to have the highest specificity, but it has no role in the pathogenesis of multiple sclerosis (MS). To investigate the reliability of MxA as a biomarker, we compared its expression to that of two other ISGs: TNF-related apoptosis-inducing ligand (TRAIL) and X-linked inhibitor of apoptosis factor-1 (XAF-1). Both were shown to be involved in immunoregulatory mechanisms and might play a role in MS. Quantitative-PCR measurements were performed in peripheral blood mononuclear cells from 73 MS patients after short-term and long-term treatment with IFNbeta. A time-dependent response for multiple ISGs was observed in all patients after short-term treatment. In contrast, long-term treatment induced concurrent inhibition of ISGs in 12.3% (9/73) of patients, in whom neutralizing antibodies (NAbs) were detectable. Besides, 22% (16/73) of chronically treated patients showed a non-NAbs-related abrogation of TRAIL expression. In summary, 1) MxA expression was significantly higher than both TRAIL and XAF-1, and 2) MxA was the most sensitive gene to detect decreased bioavailability due to NAbs. These findings identify MxA as an appropriate biomarker for IFNbeta, although there is no evidence for a functional role of it in MS.

Fate of multiple sclerosis patients positive for neutralising antibodies towards interferon beta shifted to alternative treatments

Relapsing-remitting multiple sclerosis (MS) has a very fluctuating course and responsiveness to interferon beta (IFN-beta) treatment in each patient is extremely difficult. Agreement exists about the negative role of neutralising antibodies (NAbs) on clinical efficacy and markers of IFN-beta bioavailability have been studied; no guidelines exist yet about what to do when a patient becomes NAbs positive or IFN biological activity is lost. In this study 405 MS patients have been longitudinally studied for NAbs and MxA expression. A spontaneous disappearance of NAbs was observed in a few patients with low antibody titre; according to the clinical course, a therapeutic modification has been made in patients persistently NAbs positive; in these patients NAbs persisted over time despite the interruption of IFN therapy.

Biological responsiveness to first injections of interferon-beta in patients with multiple sclerosis

This study is the first to evaluate biological response to first injections of interferon-beta (IFNbeta) in patients with multiple sclerosis. MxA mRNA was measured in 96 patients receiving IFNbeta-1a (Avonex, n=32), IFNbeta-1b (Betaferon, n=19), IFNbeta-1a (Rebif) 22 microg (n=30), or IFNbeta-1a 44 microg (n=15). Patients were analysed before, 3 and 24 h after the first injection, and 12 h after the second administration. Results showed that up-regulation was evident within 3 h of IFNbeta injection, peaked 12 h after injection, and progressively declined 24 h after administration. The cumulative responses were similar after a single administration, regardless of product/dose. Moreover, data indicate that the abolition of the biological activity detected during IFNbeta therapy is due to underlying phenomena (e.g., neutralizing antibodies), because all patients were constitutively responders to IFNbeta at treatment initiation.

Neutralizing antibodies reduce the efficacy of betaIFN during treatment of multiple sclerosis

OBJECTIVE

To analyze the impact of neutralizing antibodies (NAbs) on the clinical efficacy of IFNbeta.

METHODS

This was an open-label study involving 78 patients with multiple sclerosis treated with Betaferon 8 million IU (MIU) subcutaneously (SC) every other day (n = 20), Rebif 22 micro g SC 3 times weekly (n = 25), or Avonex 30 micro g IM once weekly (n = 33). Every 3 months, blood samples were collected and sera were analyzed for NAbs using an antiviral cytopathic effect assay. Patients were categorized according to their NAb status: NAb negative (NAb-); isolated NAb positive (NAb+), patients with > or =1 positive sample (titer > or = 20); and persistent NAb+, patients with > or =2 consecutive positive samples (titer > or = 20). Patients who were NAb- and persistent NAb+ were compared for relapse rate, time between first and second relapse, percentage of relapse-free patients, and percentage of patients who had a sustained progression of > or =1 point on the Expanded Disability Status Scale (EDSS).

RESULTS

The incidence of persistent NAb+ patients was 35% for Betaferon, 20% for Rebif, and 3% for Avonex. During IFNbeta treatment, both NAb+ and NAb- patients showed a reduction in relapse rate; this reduction (25%) was not significant in NAb+ patients but was significant (67%; p < 0.0001) in NAb- patients. In addition, the mean relapse rate was higher (p = 0.039), mean time between first and second relapse was shorter (13 vs 21 months; p = 0.0064), and there was a trend suggesting that NAbs affected the probability of remaining relapse free (p = 0.08). A higher percentage of NAb+ patients versus NAb- patients had worsening of EDSS scores during follow-up (p = 0.013).

CONCLUSION

Persistent NAbs significantly reduce the clinical efficacy of IFNbeta.

Biological activity of interferon betas in patients with multiple sclerosis is affected by treatment regimen and neutralising antibodies

BACKGROUND

MxA gene expression is one of the most appropriate markers of biological activity of exogenous interferon (IFN) beta.

METHODS

We quantified MxA mRNA for five consecutive days in 62 patients treated with IFN beta (16, Avonex; 10, Betaferon; 24, Rebif 22; 12, Rebif 44), by quantitative-competitive polymerase chain reaction. Every three months, IFN beta induced neutralising antibodies (NAbs) were evaluated in sera using a cytopathic effect assay.

RESULTS

Two categories of patients were identified: one group (49/62) had a sharp post-injection increase in MxA expression (defined as "IFN beta biological responder"), whereas the other group (13/62) had no MxA induction after IFN beta administrations (defined as "IFN beta biological non-responder"). In 11/13 biological non-responders, the persistent presence of NAbs correlated with abolished biological activity, independently of treatment regimen. The two remaining IFN beta biological non-responders were NAb-. Among the 49 IFN beta biological responders, biological activity was comparable between the four preparations on day 2 and 3 (+12 and +36 hours post-injection), but it was greater in Betaferon and both Rebif preparations on day 1, 4, and 5. In biological responders treated three times a week, only 82% (59/72) of injections were considered effective, compared with 100% (13/13) of Avonex injections.

CONCLUSION

Our results suggest that an optimal IFN beta regimen is not yet available: Avonex, given once a week, shows lower cumulative biological activity. On the other hand, both Betaferon and Rebif, given three times a week, show 18% biologically ineffective injections and higher risk of developing NAbs, which abolish biological activity.

Neuromyelitis optica: importance of cerebrospinal fluid examination during relapse

Devic's neuromyelitis optica (NMO) is a clinical entity characterised by severe transverse myelitis, optic neuropathy and monophasic or recurrent course. We report the case of a woman affected by myelitis and optic neuritis suggesting Devic's disease. Diagnosis was supported by clinical, neuroradiological and biochemical findings. In 14 months, the patient developed 5 clinical exacerbations. Six cerebrospinal fluid (CSF) examinations were performed, 3 during relapses and 3 during remitting phases: all the CSF specimens obtained during relapses showed granulocyte pleocytosis and increased protein level, whereas CSF was normal during stationary phases. Oligoclonal banding was always absent. Spinal cord MRI showed altered signal at cervical and thoracic levels. We did not find any concomitant systemic disease. The case we report underlines the importance of CSF examination during clinical relapse in NMO diagnosis.

Persistent neutralizing antibodies abolish the interferon beta bioavailability in MS patients

BACKGROUND

MxA is an antiviral protein exclusively induced by type I interferons (IFN) and some viruses, and MxA gene expression is one of the most appropriate markers for measuring the biologic activity of exogenous IFNbeta.

METHODS

A new quantitative-competitive PCR method was used to quantify MxA mRNA in peripheral blood mononuclear cells of 99 treatment-naïve and 92 IFNbeta-treated patients with MS (22 Avonex, 17 Betaferon, and 53 Rebif-22). Every 3 months, IFNbeta-induced neutralizing antibodies (NAb) were evaluated in sera using a cytopathic effect assay. Three categories of patients were identified: NAb negative (NAb-), persistent NAb positive (NAb+, >or=2 consecutive positive samples), and isolated NAb+ (one positive sample).

RESULTS

Treatment-naïve patients expressed detectable MxA mRNA levels (mean = 36 +/- 32 fg MxA/pg glyceraldehyde-3-phosphate dehydrogenase (GAPDH); range 1 to 160) and an upper normal threshold was established (mean + 3 SD = 132 fg MxA/pg GAPDH). IFNbeta-treated patients exhibited more than 11-fold higher levels (mean = 412 +/- 282 fg MxA/pg GAPDH; range 16 to 1,172). However, 17 patients did not exhibit an increase in MxA mRNA level; 15 of these 17 patients showed a concurrent Nab+ titer. Moreover, 13 were persistent NAb+. Isolated NAb+ patients did not show a decrease in bioavailability of IFNbeta (n = 9; mean = 567 +/- 366 fg MxA/pg GAPDH; range 83 to 1,120). In NAb- patients, bioavailability was comparable among the three different IFNbeta preparations 12 hours after injection.

CONCLUSION

During IFNbeta therapy, the presence of NAb reduced or abolished bioavailability in a relevant percentage of patients. These data could be important for the early detection of patients with MS who are not responsive to IFNbeta therapy.

Differential effects of three interferon betas on neutralising antibodies in patients with multiple sclerosis: a follow up study in an independent laboratory

OBJECTIVE

To evaluate the incidence and the prevalence of neutralising antibodies (NABs) to three interferon beta (IFNbeta) products in patients with multiple sclerosis (MS).

METHODS

Sera were tested from 125 patients with relapsing-remitting MS. Patients were treated with IFNbeta-1b (Betaferon, n = 29) 8 MIU subcutaneously every other day, IFNbeta-1a (Avonex, n = 44) 30 microg intramuscularly once weekly, or IFNbeta-1a (Rebif, n = 36) 22 microg subcutaneously three times weekly for 6 to 18 months. An additional 16 patients were treated with Rebif 22 microg intramuscularly once or twice weekly. NABs were assessed using the cytopathic effect assay before treatment and every three months during treatment. Patients with two or more consecutive positive samples were considered to be persistent NAB positive (NAB+).

RESULTS

At baseline, no patients were NAB+. NABs developed during the first three months of treatment and continued to develop until month 18. Over 18 months of treatment, the risk of being persistent NAB+ was 31% for Betaferon, 15% for Rebif, and 2% for Avonex (Betaferon versus Avonex, p = 0.001; Betaferon versus Rebif, p = 0.19; Rebif versus Avonex, p = 0.04). In all patients with one or more NAB+ samples, the risk of becoming NAB+ was 38% for Betaferon, 18% for Rebif, and 7% for Avonex (Betaferon versus Avonex, p = 0.0007; Betaferon versus Rebif, p = 0.10; Rebif versus Avonex, p = 0.07). At month 18, the prevalence of persistent NAB+ patients was 31.6% for Betaferon, 18.7% for Rebif, and 4% for Avonex. Numbers of NAB+ patients observed were similar with intramuscular Rebif and with subcutaneous Rebif.

CONCLUSION

The three IFNbeta preparations have different degrees of immunogenicity, with Betaferon producing the highest incidence of NABs and Avonex the lowest. These differences should be considered by neurologists when selecting treatment for their patients with MS because NABs can reduce both bioavailability and clinical efficacy of IFNbeta.

Interferon beta neutralizing antibodies in multiple sclerosis: neutralizing activity and cross-reactivity with three different preparations

The presence and titer of neutralizing antibodies (NABs) was evaluated by an antiviral biological assay in 387 samples of 111 multiple sclerosis (MS) patients treated with one of the three commercial preparations of interferon beta (IFNbeta). Fifty NAB positive samples were found in 19 patients: 11 treated with IFNbeta-1b (Betaferon(R)) and eight with IFNbeta-1a (five with Avonex(R) and three with Rebif(R)). All the 38 NABs+ samples of patients treated with IFNbeta-1b cross-reacted with IFNbeta-1a of both commercial types. The median level of neutralizing units (NUs) of the sera was higher when tested against IFNbeta-1a than against IFNbeta-1b (p=0.000 vs. Avonexr(R) and p=0.003 vs. Rebif(R)). In line with these data, the NABs+ sera of patients treated with IFNbeta-1a cross-reacted with IFNbeta-1b and the level of NUs were lower when tested against IFNbeta-1b than against IFNbeta-1a (p=0.003). The different amount of NUs against IFNbeta types 1a and 1b could be due to the presence of aggregates in the IFNbeta-1b preparation. The different levels of cross-reactivity of NABs could reduce the bioavailability and therapeutic efficacy of IFNbeta in NABs+ patients switching from IFNbeta-1b to IFNbeta-1a.

Quantitative PCR reveals increased levels of tumor necrosis factor-alpha mRNA in peripheral blood mononuclear cells of multiple sclerosis patients during relapses

Quantification of tumor necrosis factor-alpha (TNF-alpha) mRNA in peripheral blood mononuclear cells (PBMC) could provide information about disease activity in multiple sclerosis (MS); however, specific competitive methods must be utilized. A competitor cDNA, having the same sequence of the target TNF-alpha cDNA, a part from an internal 49-bp deletion, was generated and used to set-up a quantitative polymerase chain reaction (PCR) to quantify mRNA of TNF-alpha. Competitor and target were co-amplified using the same primers. The rates of generation of competitor and target TNF-alpha conformed closely to the prediction of the mathematical model, and a high level of accuracy and reproducibility was achieved. The method was applied to quantify TNF-alpha mRNA in PBMC of normal subjects and multiple sclerosis (MS) patients both during clinical relapses and remissions. A statistically significant higher level of TNF-alpha mRNA was detected during relapses than during remissions. High levels of TNF-alpha mRNA were found in 44% of relapses and 12% of samples during remissions, suggesting that TNF-alpha mRNA synthesis is abnormal in MS.

Transforming growth factor beta1 (TGFbeta1) mRNA level correlates with magnetic resonance imaging disease activity in multiple sclerosis patients

Eight relapsing-remitting multiple sclerosis (MS) patients were tested for the level of transforming growth factor beta1 (TGFbeta1) mRNA in peripheral blood mononuclear cells every 15 days for 6 months. Disease activity was evaluated every 4 weeks by magnetic resonance imaging (MRI) and neurological examination. An inverse correlation was found between the level of TGFbeta1 mRNA and MRI disease activity. The level of TGFbeta1 mRNA predicted the presence of disease activity in the scans performed 2-4 weeks later with high sensitivity (88%) and specificity (87.5%) suggesting that TGFbeta1 mRNA quantification could be an indicator of disease activity in MS.

Stereoselectivity of human nucleotide excision repair promoted by defective hybridization

To assess helical parameters that dictate fast or slow removal of carcinogen-DNA adducts, we probed human nucleotide excision repair (NER) activity with DNA containing L-deoxyriboses. Unlike natural lesions such as pyrimidine dimers or base adducts, L-deoxyribonucleosides (the mirror images of normal D-deoxyribonucleosides) involve neither the addition nor the loss of covalent bonds or functional groups and hence exclude modulation of repair efficiency by adduct chemistry and size. Previous studies showed that single L-deoxyribonucleosides distort DNA backbones but are accommodated in the double helix with intact hydrogen bonding between complementary strands. Here, we found that such single L-enantiomers are rejected as excision repair substrates in a NER-proficient cell extract. However, the same L-deoxyribose moiety stimulates NER activity upon incorporation into a nonhybridizing site of one or, more effectively, two base mismatches. In contrast to single L-deoxyriboses, multiple consecutive L-deoxyriboses interfere with normal hybridization; in this case, the intrinsic derangement of base pairing was sufficient to promote the excision of a cluster of three adjacent L-deoxyribonucleosides without any requirement for mismatches. Thus, using stereoselective substrates, we demonstrate the participation of a recognition subunit that guides human NER activity to sites of defective Watson-Crick strand pairing. This conformational sensor detects labile hydrogen bonds irrespective of the type of deoxyribonucleotide modification.

[Clear cell renal carcinoma metastatic to the thyroid. A case report]

A case of clear cell renal carcinoma metastatic to the thyroid 5 years after surgical removal of the primary tumor is presented. The differential diagnosis related to cyto-histologic findings, the uncommon occurrence and the unpredictable behaviour of clear cell renal carcinoma are discussed.

Lack of enantiospecificity of human 2'-deoxycytidine kinase: relevance for the activation of beta-L-deoxycytidine analogs as antineoplastic and antiviral agents

We demonstrate that human 2'-deoxycytidine kinase (dCK) is a nonenantioselective enzyme because it phosphorylates beta-D-2'-deoxycytidine (D-dCyd), the natural substrate, and beta-L-2'-deoxycytidine (L-dCyd), its enantiomer, with the same efficiency. Kinetic studies showed that L-dCyd is a competitive inhibitor of the phosphorylation of D-dCyd with a Kl value of 0.12 microM, which is lower than the K(m) value for D-dCyd (1,2 microM). Chemical modifications of either the base or the pentose ring strongly decrease the inhibitory potency of L-dCyd, L-dCyd is resistant to cytidine deaminase and competes in cell cultures with the natural D-dCyd as substrate for dCK, thus reducing the incorporation of exogenous [3H]dCyd into DNA. L-dCyd had no effect on the pool of dTTP deriving from the salvage or from the de novo synthesis, does not inhibit short term RNA and protein syntheses, and shows little or no cytotoxicity. Our results indicate a catalytic similarity between human dCK and herpetic thymidine kinases, enzymes that also lack stereospecificity. This functional analogy underlines the potential role of dCK as activator of L-deoxycytidine analogs as antiviral and antineoplastic agents and lends support to the hypothesis that herpesvirus thymidine kinase might have evolved from a captured cellular dCK gene, developing the ability to phosphorylate thymidine and retaining that to phosphorylate deoxycytidine.

[Bilateral thrombosis of a femoral pseudoaneurysm]

One case has been described of acute thrombosis of bilateral femoral anastomotic pseudoaneurysm. The clinical finding of bilateral acute ischemia of the lower limbs required urgent surgical treatment. The operative technique consisted of excision of anastomotic aneurysms and replacement by a new segment of prosthesis with an end-to-end anastomosis to the deep femoral artery. Pathogenesis of the pseudoaneurysms at the femoral anastomosis generally recognized numerous factors such as mechanical, graft or suture defects, hypertension, wound complications. Recognition of femoral anastomotic aneurysms is usually simple, when a pulsative mass is noted. In such a case (reported) of thrombosis of bilateral femoral pseudoaneurysms, preoperative diagnosis was more difficult. Anastomotic aneurysms of little size that occur later after original intervention require observation by echography and angiodinography. When rapid enlargement arises, urgent surgical treatment is required, before rupture or thrombosis. The surgical intervention consists of excision of the anastomotic aneurysm and replacement by a new segment of prosthesis between the prosthesis and the common or deep femoral artery. If the reconstruction at the level of femoral artery is not possible, the anastomosis is performed more distally, at the level of popliteal artery. The results are affected by the degree of urgency of surgery, with significant difference in favour of the patients Who underwent elective procedures.

Stereospecificity of human DNA polymerases alpha, beta, gamma, delta and epsilon, HIV-reverse transcriptase, HSV-1 DNA polymerase, calf thymus terminal transferase and Escherichia coli DNA polymerase I in recognizing D- and L-thymidine 5'-triphosphate as substrate

L-beta-Deoxythymidine (L-dT), the optical enantiomer of D-beta-deoxythymidine (D-dT), and L-enantiomers of nucleoside analogs, such as 5-iodo-2'-deoxy-L-uridine (L-IdU) and E-5-(2-bromovinyl)-2'-deoxy-L-uridine (L-BVdU), are not recognized in vitro by human cytosolic thymidine kinase (TK), but are phosphorylated by herpes simplex virus type 1 (HSV-1) TK and inhibit HSV-1 proliferation in infected cells. Here we report that: (i) L-dT is selectively phosphorylated in vivo to L-dTMP by HSV-1 TK and L-dTMP is further phosphorylated to the di- and triphosphate forms by non-stereospecific cellular kinases; (ii) L-dTTP not only inhibits HSV-1 DNA polymerase in vitro, but also human DNA polymerase alpha, gamma, delta and epsilon, human immunodeficiency virus reverse transcriptase (HIV-1 RT), Escherichia coli DNA polymerase 1 and calf thymus terminal transferase, although DNA polymerase beta was resistant; (iii) whereas DNA polymerase beta, gamma, delta and epsilon are unable to utilize L-dTTP as a substrate, the other DNA polymerases clearly incorporate at least one L-dTMP residue, with DNA polymerase alpha and HIV-1 RT able to further elongate the DNA chain by catalyzing the formation of the phosphodiester bond between the incorporated L-dTMP and an incoming L-dTTP; (iv) incorporated L-nucleotides at the 3'-OH terminus make DNA more resistant to 3'-->5' exonucleases. In conclusion, our results suggest a possible mechanism for the inhibition of viral proliferation by L-nucleosides.

Sequence specificity of tetrahydrobenzopsoralen photobinding to DNA

The sequence specificity of photobinding to DNA of two tetrahydrobenzopsoralen derivatives has been investigated by testing the photoreactivity toward a number of self-complementary oligonucleotides. The thermodynamic constant for noncovalent binding to each DNA sequence was evaluated. The extent of photoreactivity was greatly dependent upon base composition. The two tetracyclic compounds show similar behavior in comparison to other bifunctional derivatives. Their overall rate constants were greatly enhanced in comparison to classical psoralens. However, their high efficiency of covalent binding is counterbalanced by low affinity for noncovalent interaction with DNA.

Lack of stereospecificity of some cellular and viral enzymes involved in the synthesis of deoxyribonucleotides and DNA: molecular basis for the antiviral activity of unnatural L-beta-nucleosides

Among enzymes involved in the synthesis of nucleotides and DNA, some exceptions have recently been found to the universal rule that enzymes act only on one enantiomer of a chiral substrate and that only one of the enantiomeric forms of chiral molecules may bind effectively at the catalytic site, displaying biological activity. The exceptions include: herpes virus thymidine kinases, cellular deoxycytidine kinase and deoxynucloside mono- and diphosphate kinases, cellular and viral DNA polymerases, such as DNA polymerase alpha, terminal transferase and HIV-1 reverse transcriptase. The ability of these enzymes to utilize unnatural L-beta-nucleosides or -nucleotides as substrate may be exploited from chemotherapeutic point of view.

Kinetic studies with N2-phenylguanines and with L-thymidine indicate that herpes simplex virus type-1 thymidine kinase and thymidylate kinase share a common active site

It is known that the Herpes simplex virus type 1 (HSV-1)-encoded thymidine kinase (TK) co-purifies with an associated thymidylate kinase (TMPK) activity and that thymidylate (TMP) inhibits the phosphorylation of thymidine by the HSV-1 TK. Here we demonstrate that: (i) TMP phosphorylation catalysed by the viral TMPK is competitively inhibited by thymidine (TdR) with a Ki equal to its Km as substrate for the viral TK; (ii) L-thymidine (L-TdR), the enantiomer of the naturally occurring D-TdR and a substrate for the HSV-1 TK [Spadari, Maga, Focher, Ciarrocchi, Manservigi, Arcamone, Capobianco, Caruso, Colonna, Iotti and Garbesi (1992) J. Med. Chem. 35, 4214-4220], is a powerful inhibitor of the HSV-1 TMPK activity with a Ki value identical with its Km as a substrate for the viral TK; (iii) both viral TK and TMPK activities are inhibited, in a competitive way and with identical Ki values, by novel, non-substrate inhibitors of HSV-1 TK, N2-phenylguanines; (iv) L-TdR is phosphorylated to L-TMP by the viral TK, but L-TMP is not phosphorylated to L-TDP by the viral TMPK activity; and (v) L-TMP inhibits competitively and with identical potencies the phosphorylation of TdR and TMP catalysed respectively by the HSV-1 TK and TMPK activities. In conclusion, our data demonstrate that both TK and TMPK activities encoded by HSV-1 share a common active site which is very tolerant in accepting modified nucleosides, but cannot readily accommodate modified nucleoside monophosphates.

L-thymidine is phosphorylated by herpes simplex virus type 1 thymidine kinase and inhibits viral growth

We have demonstrated that herpes simplex 1 (HSV1) thymidine kinase (TK) shows no stereospecificity for D- and L-beta-nucleosides. In vitro, L enantiomers are not recognized by human TK, but function as specific substrates for the viral enzyme in the order: L-thymidine (L-T) >> 2'-deoxy-L-guanosine (L-dG) > 2'-deoxy-L-uridine (L-dU) > 2'-deoxy-L-cytidine (L-dC) > 2'-deoxy- L-adenosine (L-dA). HSV1 TK phosphorylates both thymidine enantiomers to their corresponding monophosphates with identical efficiency and the Ki of L-T (2 microM) is almost identical to the Km for the natural substrate D-T (2.8 microM). The L enantiomer reduces the incorporation of exogenous [3H]T into cellular DNA in HeLa TK-/HSV1 TK+ but not in wild-type HeLa cells, without affecting RNA, protein synthesis, cell growth, and viability. L-T markedly reduces HSV1 multiplication in HeLa cells. Our observations could lead to the development of a novel class of antiviral drugs characterized by low toxicity.

Association of anthracyclines and synthetic hexanucleotides. Structural factors influencing sequence specificity

The equilibrium and kinetic aspects of the interaction between four anthracyclines and two synthetic self-complementary hexanucleotides was investigated by fluorescence detection. Two of the studied anthracyclines are widely used antitumor drugs: doxorubicin (1, formerly adriamycin) and daunorubicin (2, formerly daunomycin). The other two, 9-deoxydoxorubicin (3) and 3'-deamino-3'-hydroxy-4'-epidoxorubicin (4), are doxorubicin analogues with modifications of the chemical groups that have been proposed as responsible for sequence specificity (Chen, K.-X., Gresh, N. and Pullman, B. (1985). J. Biomol. Struct. Dyn. 3, 445-466). One of the oligonucleotides, d(CGTACG), is identical to that used in the high resolution x-ray structure determination of the daunorubicin intercalative complex (Wang, A. H.-J., Ughetto, G., Quigley, G. J. & Rich, A. (1987). Biochemistry 26, 1152-1163). Binding to this hexanucleotide is compared with intercalation into the d(CGCGCG) duplex, revealing sequence preferences of the four anthracyclines. Taking into account the anthracycline aggregation and the dissociation of the hexanucleotide double standard form, results can be interpreted with a model that assumes complete fluorescence quenching at intercalative sites containing the CG base pair, and a large residual fluorescence after intercalation within the TpA fragment. All four anthracyclines show preferential intercalation at sites near the ends of both hexanucleotide duplexes, partly as a result of positive cooperativity in the formation of di-intercalated species at these sites. Within the limits of experimental error, complete site specificity for the CpG fragment is found in the intercalation of 1 and 2 into d(CGTACG) duplex, whereas analogues 3 and 4 give increasing evidence of intercalation at other sites including the fluorescence-preserving TpA fragment. Site specificity is less pronounced in the association with d(CGCGCG), when cooperativity is taken into account. Kinetic data corroborate the results of equilibrium studies and are interpreted with a mechanism that includes formation of an intermediate bound species followed by drug redistribution to preferential sites. Finally, from a comparison of pertinent site binding constants, approximate free energy contributions to sequence specific DNA interaction, due to C9-OH on the aglycone and -NH3+ on daunosamine, are estimated not to exceed 2 kcal/mol.