109. Seroprevalence of Protective Antibodies against Varicella, Hepatitis-A and Dengue among Indian Children, Adolescents and Adults

Background

Varicella, Hepatitis-A and Dengue cause significant disease burden in our country. Estimation of age-wise seroprevalence of antibodies against these diseases not only help us in understanding age-specific incidence rates and susceptibility, but also help policy makers in deciding need and timing of vaccination. None of these vaccines are part of current national immunization program in India, yet.

Methods

In this observational cross-sectional study, apparently healthy children (9-12 years), adolescents (15-18 years) and adults (25-30 years) attending OPD of a tertiary care hospital in Northern India over two-year period (July 17- June 19) were enrolled after taking informed written consent, and their 3-ml venous blood sample was collected. Ethical clearance was obtained from Institute Ethics committee, before enrolling subjects. Serum was tested for IgG antibodies using specific commercial ELISA kits. Those who received received Hepatitis-A or Varicella vaccination in past were excluded from enrollment.

Results

Out of total 240 subjects (M:F=117:123) enrolled, 75 were children, 75 adolescents and 90 adults in specified age groups. Mean age in these three groups were 11.04, 16.52 and 26.53 years respectively.

In our study, antibodies (IgG) against Varicella were >12 U/ml (seroprotective) in 36% (27/75), 74.6% (56/75), 64.5% (58/90) in children, adolescent and adults in specified age groups, respectively. Similarly, the antibodies (IgG) against Hepatitis-A were >10 U/ml (seroprotective) in above three groups were 68% (51/75), 85.3% (64/75), 95.5% (86/90). For dengue IgG antibodies also, seropositivity rates in above three groups were 37.3% (28/75), 62.7% (47/75), 53.3% (48/90).

Conclusion

Large proportion of children, adolescents and adults remain susceptible to Varicella and Hepatitis-A infection in India. Early childhood vaccination with Varicella and Hepatitis-A vaccines should be a part of National Immunization Programme in India, as a part of preventive strategy.

Our study also showed a large proportion of children, adolescents and adults remain seronegative for Dengue antibodies in various age groups. Therefore, if currently available dengue vaccine (Dengvaxia) has to be used in our population, it can only be used after individual screening.

Disclosures

All Authors: No reported disclosures.

Molecular and Genetic Characterization of Natural Variants of HIV-1 Nef Gene from North India and its Functional Implication in Down-Regulation of MHC-I and CD-4

BACKGROUND

HIV-1 Nef is an important accessory protein with multiple effector functions. Genetic studies of the HIV-1 Nef gene show extensive genetic diversity and the functional studies have been carried out mostly with Nef derived from regions dominated by subtype B (North America & Europe).

OBJECTIVE

This study was carried out to characterize genetic variations of the Nef gene from HIV-1 infected individuals from North India and to find out their functional implications.

METHODS

The unique representative variants were sub-cloned in a eukaryotic expression vector and further characterized with respect to their ability to downregulate cell surface expression of CD4 and MHC-1 molecules.

RESULTS

The phylogenetic analysis of Nef variants revealed sequence similarity with either consensus subtype B or B/C recombinants. Boot scan analysis of some of our variants showed homology to B/C recombinant and some to wild type Nef B. Extensive variations were observed in most of the variants. The dN/dS ratio revealed 80% purifying selection and 20% diversifying selection implying the importance of mutations in Nef variants. Intracellular stability of Nef variants differed greatly when compared with wild type Nef B and C. There were some variants that possessed mutations in the functional domains of Nef and responsible for its differential CD4 and MHC-1 downregulation activity.

CONCLUSION

We observed enhanced biological activities in some of the variants, perhaps arising from amino acid substitutions in their functional domains. The CD4 and MHC-1 down-regulation activity of Nef is likely to confer immense survival advantage allowing the most rare genotype in a population to become the most abundant after a single selection event.

Preparation and Characterization of Nb-1Zr-0.1C Alloy Suitable for Liquid Metal Coolant Channels of High Temperature Reactors

A novel process comprising of aluminothermic coreduction of mixed oxides followed by arc and electron beam melt refining was developed for preparation of Nb-1Zr-0.1C alloy. The parameters of the process were optimized by considering the thermodynamic (heat) and mass balance phenomenon. The ingots of the homogenized alloy produced after electron beam melt consolidation were further extruded into tubes. The alloy was vacuum annealed at 1350–1800 °C to study the stability of Nb2C and Nb(Zr)C carbide precipitates in the microstructure. Compression creep tests conducted at 900 and 1000 °C revealed a stress exponent value of 2 and activation energy of 508 kJ/mol. NbSi2-based coatings were developed on the Nb-1Zr-0.1C alloy tubes using pack siliconizing process. The coated alloy was tested for oxidation at 1250 °C, and corrosion in liquid lead-bismuth eutectic (LBE) alloy at 875 °C for prolonged duration. The silicide-coated alloy showed superior oxidation and LBE corrosion resistance at high temperatures. The alloy was found to be a promising material for coolant channels of high temperature reactors.

Neurofilament results for the phase II neuroprotection study of phenytoin in optic neuritis

BACKGROUND

A randomized trial of phenytoin in acute optic neuritis (ON) demonstrated a 30% reduction in retinal nerve fiber layer (RNFL) loss with phenytoin versus placebo. Here we present the corresponding serum neurofilament analyses.

METHODS

Eighty-six acute ON cases were randomized to receive phenytoin (4-6 mg/kg/day) or placebo for 3 months, and followed up for 6 months. Serum was collected at baseline, 3 and 6 months for analysis of neurofilament heavy chain (NfH) and neurofilament light chain (NfL).

RESULTS

Sixty-four patients had blood sampling. Of these, 58 and 56 were available at 3 months, and 55 and 54 were available at 6 months for NfH and NfL, respectively. There was no significant correlation between serum NfH and NfL at the time points tested. For NfH, the difference in mean placebo - phenytoin was -44 pg/ml at 3 months (P = 0.019) and -27 pg/ml at 6 months (P = 0.234). For NfL, the difference was 1.4 pg/ml at 3 months (P = 0.726) and -1.6 pg/ml at 6 months (P = 0.766).

CONCLUSIONS

At 3 months, there was a reduction in NfH, but not NFL, in the phenytoin versus placebo group, while differences at 6 months were not statistically significant. This suggests a potential neuroprotective role for phenytoin in acute ON, with the lower NfH at 3 months, when levels secondary to degeneration of the anterior visual pathway are still elevated, but not at 6 months, when levels have normalized.

Effect of prophylactic granulocyte-colony stimulating factor (G-CSF) on acute hematological toxicity in medulloblastoma patients during craniospinal irradiation (CSI)

OBJECTIVES

Haematological toxicity and treatment breaks are common during cranio-spinal irradiation (CSI) due to irradiation of large volume of bone marrow. We conducted this study to see the effect of prophylactic granulocyte colony stimulating factor (GCSF) in reducing treatment breaks.

PATIENTS AND METHODS

The study was conducted over a period of 15 months from August 2017 to November 2018. Histopathologically proven Medulloblastoma patients received prophylactic GCSF during CSI. Acute hematological toxicities and treatment breaks were noted and effect of age and pretreatment blood counts were analyzed by SPSS (Statistical Package for Social Sciences) version 23.

RESULTS

A total of 28 patients were included in the study. During CSI, hematological toxicity leading to treatment breaks was observed in 11 (39.3 %) patients, of which grade 3 and 2 toxicities were seen in ten and one patients respectively. Younger age (<10 years) at diagnosis was significantly associated with the development of hematological toxicity (p = 0.028, Chi-Square). No correlation was found with pre-treatment blood counts.

CONCLUSION

Prophylactic use of GCSF may be effective in preventing radiation induced hematological toxicity and treatment breaks.

Factors Associated With Cerebral Edema at Admission in Indian Children with Diabetic Ketoacidosis

OBJECTIVE

To evaluate the time course and predictors of cerebral edema in diabetic ketoacidosis (DKA).

METHODS

Review of hospital records of 107 episodes of DKA between January 2013 to March 2019.

RESULTS

Cerebral edema was identified in 26 (24.3%; 22 at presentation and 4 during treatment). Cerebral edema at presentation was associated with lower (<10 mmHg) arterial carbon dioxide (OR 3.6, 95% CI 1.0,12.7; P=0.04), prior fluid treatment (OR 4.7, 95% CI 1.8,12.7; P=0.001) and new onset diabetes (OR 3.5, 95% CI 1.1,11.1; P=0.03). Prior fluid was the only significant predictor on multivariate analysis (P=0.013). Cerebral edema resulted in a longer ICU stay [4.1 (2.3) vs 1.8 (0.9) d; P<0.001].

CONCLUSIONS

Cerebral edema at admission is common in Indian children with DKA and should be suspected with severe metabolic acidosis and inappropriate prior fluid treatment.

FDG-PET response and outcome from anti-PD-1 therapy in metastatic melanoma

Background

Immune checkpoint inhibitor therapy has resulted in impressive and durable clinical activity for many cancers including melanoma; however, there remain few reliable predictors for long-term response. This study investigated whether [18F]2-fluoro-2-deoxy-D-glucose (FDG-PET) imaging may better predict long-term outcomes compared with standard computed tomography (CT) response criteria.

Patients and methods

Retrospective analysis of metastatic melanoma patients treated with anti-PD-1-based immunotherapy with baseline and 1-year FDG-PET and CT imaging at Melanoma Institute Australia. One-year response was determined using RECIST for CT and EORTC criteria for PET, coded as complete response (CR or CMR), partial response (PR or PMR), stable disease (SD or SMD) or progressive disease (PD or PMD). Progression-free survival (PFS) was determined from the 1-year landmark.

Results

Patients (n = 104) were evaluated with median follow-up 30.1 months and 98% remain alive. Most received anti-PD-1 as monotherapy (67%) or combined with ipilimumab (31%). At 1 year, 28% had CR, 66% had PR and 6% had SD on CT, while 75% had CMR, 16% PMR and 9% SMD/PMD on PET. CMR was observed in 68% of patients with PR on CT. RECIST PFS post 1-year landmark was similar in patients with CR versus PR/SD, but improved in patients with CMR versus non-CMR {median not reached [NR] versus 12.8 month; hazard ratio [HR] 0.06 [95% confidence interval (CI) 0.02-0.23]; P < 0.01}. In patients with PR on CT, PFS was improved in patients with PR + CMR versus PR + non-CMR (median NR versus 12.8 months; HR 0.07 [95% CI 0.02-0.27]; P < 0.01). In the 78 CMR patients, 78% had discontinued treatment and 96% had ongoing response.

Conclusions

Whilst only a small proportion of patients have a CR at 1 year, most patients with a PR have CMR on PET. Almost all patients with CMR at 1 year have ongoing response to therapy thereafter. PET may have utility in predicting long-term benefit and help guide discontinuation of therapy.

P14.06 Phase II randomized trial of short course hypofractionated radiotherapy with or without temozolomide in elderly patients with Glioblastoma

BACKGROUND

Glioblastoma (GBM) is the most aggressive primary brain tumor. Although treatment advances and introduction of temozolomide has improved the outcome in young patients, it is still a concern in elderly patients. Elderly population is often excluded from the trials, thus established treatment guidelines are not available. Trials have shown that short course hypofractionated radiotherapy (HRT) is equally effective in terms of overall survival (OS) and progression free survival (PFS) as compared to standard RT in elderly population. While the benefit of adding Temozolomide (TMZ) to standard dose radiotherapy is well established, there is lack of evidence that addition of TMZ to HRT improves survival in elderly patients.We conducted this study to see if addition of temozolomide to HRT improves OS, PFS and quality of life (QOL) in elderly GBM patients.

MATERIAL AND METHODS

The study was conducted over a period of 21 months from January 2017 to September 2018. Histologically proven 70 newly diagnosed Glioblastoma patients (age>60 years) were enrolled and randomized into two arms (Arm I- HRT alone, Arm II- HRT and TMZ) using computer generated randomization table (1:1 ratio). The radiotherapy dose in both arms was same and consisted of a dose of 25Gy in 5 daily fractions over 1 week. In addition, arm II patients received daily concurrent TMZ 75mg/m2 1 hour prior to RT followed by adjuvant TMZ 175mg/m2 from Day1-5 for 6 cycles (q 4weeks), started after a month of RT completion. Quality of life score and global health status was assessed in both arms at baseline, 1, 3, 6 and 9 months after the treatment using QOL questionnaire EORTC QLQ-C 30 and QLQ-BN20. Data entry was done in Microsoft Excel 2016 and analysis was done in SPSS version 18. Kaplan Meier survival analysis was done for OS and PFS. To see the trend of time related observations at different point of time repeated ANOVA was used. A p value of <0.05 was taken significant.

RESULTS

The median OS in arm I and II was 121 (range 40–360 days) and 146 (range 40–450 days) days respectively (P=0.146). The median PFS in arm 1 and arm 2 were 77 (range 30–300 days) and 109.50 (range 30–300) days respectively (p-0.028). On further analysis, the prognostic factors were type of surgery (Median PFS 159 days in gross total excision and 129 days in subtotal excision or biopsy, p-0.03) and KPS (0.04). QOL score for symptom and functional domain was comparable in both arms. However score of nausea and vomiting was higher during concurrent chemoradiotherapy. A non significant improvement in QLQ BN 20 score was observed at 9 months in arm I.

CONCLUSION

Addition of Temozolomide to HRT is a compelling option in elderly Glioblastoma patients as it significantly improves the PFS and a non significant improvement in OS without compromising quality of life.

Etiology and characteristics of pediatric urethral strictures in a developing country in the 21st century

BACKGROUND

Urethral stricture disease in children is not uncommon as assumed; however, most of the information about the etiology, features, and natural history of pediatric strictures is extrapolations from adult series as the literature on this common entity is sparse, and most of the studies are small series.

OBJECTIVE

The current etiology and clinical features of urethral stricture disease in the pediatric population in the developing world were determined.

MATERIALS AND METHODS

The data of children with urethral stricture disease, who had undergone treatment in the tertiary center from 2001 to 2017, were retrospectively analyzed. After excluding girls, the database was analyzed for clinical presentation, possible causes of stricture, site and number of strictures, and length of stricture and for previous interventions. Subanalysis was performed for stricture etiology by patient age, stricture length, site, previous treatments, and presentation with paraurethral abscess.

RESULTS

A total of 195 boys with strictures were identified. The common causes of pediatric urethral stricture were traumatic (36.9%), iatrogenic (31.8%), and idiopathic (28.7%). The anterior urethra was the location of the stricture in 141 patients (72.3%). Iatrogenic causes (due to catheterization, hypospadias repair, and valve fulguration) accounted for the majority of anterior urethral strictures (61/141 or 43.2%). Younger children had a tendency to have an iatrogenic and idiopathic cause for strictures, whereas older children had a traumatic etiology; 18.6% of strictures in children younger than 10 years were secondary to trauma, whereas 44.9% of the strictures in patients older than 10 years were traumatic in origin. Trauma was the major cause of posterior urethral strictures (53/54 or 98.1%) and was always associated with pelvic fracture. Strictures due to lichen sclerosus or infectious cause were rare (5 patients or 2.6%). The length of strictures was longer in pan anterior urethral strictures (mean: 82.0 mm) than that of those due to lichen sclerosus (mean: 42.5 mm) and in patients who had undergone previous treatment (mean: 28.7 mm).

CONCLUSION

Iatrogenic causes such as catheterization and hypospadias repair account for the majority of anterior urethral stricture disease in the pediatric population, especially the younger age-group. However, as the child grows, there is a gradual preponderance of traumatic urethral strictures, including posterior urethral strictures.

Introducing FDG PET/CT-guided chemoradiotherapy for stage III NSCLC in low- and middle-income countries: preliminary results from the IAEA PERTAIN trial

Purpose

Patients with stage III non-small-cell lung cancer (NSCLC) treated with chemoradiotherapy (CRT) in low- and middle-income countries (LMIC) continue to have a poor prognosis. It is known that FDG PET/CT improves staging, treatment selection and target volume delineation (TVD), and although its use has grown rapidly, it is still not widely available in LMIC. CRT is often used as sequential treatment, but is known to be more effective when given concurrently. The aim of the PERTAIN study was to assess the impact of introducing FDG PET/CT-guided concurrent CRT, supported by training and quality control (QC), on the overall survival (OS) and progression-free survival (PFS) of patients with stage III NSCLC.

Methods

The study included patients with stage III NSCLC from nine medical centres in seven countries. A retrospective cohort was managed according to local practices between January 2010 and July 2014, which involved only optional diagnostic FDG PET/CT for staging (not for TVD), followed by sequential or concurrent CRT. A prospective cohort between August 2015 and October 2018 was treated according to the study protocol including FDG PET/CT in treatment position for staging and multimodal TVD followed by concurrent CRT by specialists trained in protocol-specific TVD and with TVD QC. Kaplan–Meier analysis was used to assess OS and PFS in the retrospective and prospective cohorts.

Results

Guidelines for FDG PET/CT image acquisition and TVD were developed and published. All specialists involved in the PERTAIN study received training between June 2014 and May 2016. The PET/CT scanners used received EARL accreditation. In November 2018 a planned interim analysis was performed including 230 patients in the retrospective cohort with a median follow-up of 14 months and 128 patients in the prospective cohort, of whom 69 had a follow-up of at least 1 year. Using the Kaplan–Meier method, OS was significantly longer in the prospective cohort than in the retrospective cohort (23 vs. 14 months, p = 0.012). In addition, median PFS was significantly longer in the prospective cohort than in the retrospective cohort (17 vs. 11 months, p = 0.012).

Conclusion

In the PERTAIN study, the preliminary results indicate that introducing FDG PET/CT-guided concurrent CRT for patients with stage III NSCLC in LMIC resulted in a significant improvement in OS and PFS. The final study results based on complete data are expected in 2020.

Electronic supplementary material

The online version of this article (10.1007/s00259-019-04421-5) contains supplementary material, which is available to authorized users.

Radiotherapy treatment of human inflammatory diseases and conditions: Optimal dose

During the early part of the past century, hundreds of clinical studies involving more than 37,000 patients were conducted that showed radiotherapy (RT) to be a successful and safe alternative to drug therapy for the treatment of many diverse inflammatory conditions and diseases (e.g. tendonitis, bursitis, arthritis, and serious inflammatory lung conditions). Data from these studies were collected and analyzed with the intent of estimating an optimal dosing range for RT that would induce an efficacious treatment response. RT was reported to be frequently effective after only a single treatment, with a rapid (within 24 h) and often long-lasting (from months to years) relief from symptoms. Over a two-decade span from the 1920s to the 1940s, the therapeutic responses to a single RT treatment consistently improved as the dosing for multiple ailments decreased over time to between 30 roentgen (r) and 100 r. These findings are significant and in agreement with a number of contemporary reports from Germany where RT has been commonly and successfully employed in treating ailments with an inflammatory origin. A proposed mechanism by which RT mitigates inflammation and facilitates healing is via the polarization of macrophages to an anti-inflammatory or M2 phenotype.

Outcomes of Primary Arteriovenous Fistula for Hemodialysis in Elderly Patients (>65 Years) with End Stage Renal Disease: A Study on Indian Population

Introduction:

The outcome of arteriovenous fistula (AVF) for hemodialysis (HD) in elderly population remains an issue. The aim of our study was to evaluate the outcomes of arteriovenous fistulas created at our institute in patients older than 65 years.

Methods:

All chronic HD patients with age >65 years who had an AVF created between January 1, 2010 and January 1, 2017 were included retrospectively. Baseline demographic information including age, gender, etiology of renal failure and comorbidities were recorded. Access characteristics including access type and anatomic location were recorded. The end point of study was primary and secondary patency. Minimum follow up period of study was 1 year.

Results:

A total of 422 AVF were created within the study period. The mean age was 69.3 years. The anatomical site of AVF creation was radiocephalic (RCF) in 74.8% (n = 316), brachiocephalic (BCF) in 18.9% (n = 80) and brachiobasilic (BBF) in 6.1% (n = 26). At one year after creation, cumulative survival of the AVF was 64.7%. At 36 months the primary and secondary patency of RCF, BCF and BBF was 43.6%, 58.6%, 42.6% and 47.3%, 62.5%, 56.9% respectively. The overall median survival did not differ between RCF and BBF fistulas. However, when both were compared with BCF (median survival 1034 days), BBF (median survival 741 days) and RCF (median survival 592 days) had significantly poorer survival (P = 0.004). The most common reason for access failure was thrombosis (28.4%) followed by failure to mature (9%) and aneurysm related complications (9%).

Conclusions:

Age should not be a limiting factor when choosing AVF as the preferred HD access. Brachiocephalic AVF has better primary and secondary patency with higher overall median survival. However RCF also provides reasonably good survival rates with acceptable complications in elderly population. Thrombosis and fistulas that fail to mature present as a primary concern to patients in elderly population, and demand further study.

Treatment data and technical process challenges for practical big data efforts in radiation oncology

The term Big Data has come to encompass a number of concepts and uses within medicine. This paper lays out the relevance and application of large collections of data in the radiation oncology community. We describe the potential importance and uses in clinical practice. The important concepts are then described and how they have been or could be implemented are discussed. Impediments to progress in the collection and use of sufficient quantities of data are also described. Finally, recommendations for how the community can move forward to achieve the potential of big data in radiation oncology are provided.

Role of Preoperative Duplex Ultrasonography to Predict Functional Maturation of Wrist Radiocephalic Arteriovenous Fistula: A Study on Indian Population

Radiocephalic arteriovenous fistula (RCAVF) is the first choice for native arteriovenous fistula (AVF). Preoperative vessel assessment with ultrasonography (USG) has been reported to enhance the outcome of native AVF, but data regarding its predictive value for functional maturation of RCAVF are scanty. We aimed to determine the role of preoperative duplex USG (DUS) for prediction of functional maturity of radiocephalic fistula in the wrist. The data from 173 patients were analyzed prospectively. The estimated duplex variable included size, patency, and continuity of cephalic vein and size, peak systolic velocity, and wall calcifications in radial artery at the wrist. The subjects underwent RCAVF creation and were reviewed 6-8 weeks post procedure for adequacy of maturation. Doppler variables between successful and failed maturation groups were compared. Successful functional fistula maturation was noted in 138 (80.9%) patients. Values of radial artery diameter, cephalic vein diameter, and peak systolic velocity were >2 mm, 2.2 mm, and 32.8 cm/s, respectively, for successful maturation of RCAVF in more than 90% of cases. Vascular calcifications were detected preoperatively in 15 diabetic patients and 9 (60%) of them had fistula failure. Preoperative DUS can provide a good prediction on functional maturation of RCAVF. Vascular calcifications were associated with high risk of maturation failure in diabetics.

Melanoma patient imaging in the era of effective systemic therapies

Imaging plays a critical role in the current multi-disciplinary management of patients with melanoma. It is used for primary disease staging, surgical planning, and surveillance in high-risk patients, and for monitoring the effects of systemic or loco-regional therapies. Several different imaging modalities have been utilised in the past. Contemporary imaging practises vary geographically depending on clinical guidelines, physician preferences, availability and cost. Targeted therapies and immunotherapies have revolutionised the treatment of patients with metastatic melanoma over the last few years. With this have come new patterns of disease that were not observed after conventional therapies, and new criteria to assess therapeutic responses. In this article we review the role of imaging for patients with melanoma in the era of effective systemic therapies and discuss likely future developments.

Normal-appearing grey and white matter T1 abnormality in early relapsing–remitting multiple sclerosis: a longitudinal study

Objective

To investigate the presence and evolution of T1 relaxation time abnormalities in normal-appearing white matter (NAWM) and grey matter (GM), early in the course of relapsing–remitting multiple sclerosis (MS).

Methods

Twenty-three patients with early relapsing–remitting MS and 14 healthy controls were imaged six monthly for up to three years. Mean follow-up was 26 months for MS patients and 24 months for controls. Dual-echo fast-spin echo and gradient-echo proton-density and T1-weighted data sets (permitting the calculation of a T1 map) were acquired in all subjects. GM and NAWM T1 histograms were produced and a hierarchical regression model was used to investigate changes in T1 over time.

Results

At baseline, significant patient-control differences were seen, both in NAWM (P = 0.001) and in GM (P = 0.01). At follow-up, there was no evidence for a serial change in either mean T1 or peak-location for either NAWM or GM. There was weak evidence for a decline in patient NAWM peak-height and also evidence for a decline in control GM peak-height.

Conclusion

There are significant and persistent abnormalities of NAWM and GM T1 in early relapsing-remitting MS. Further studies should address whether such T1 measures have a role in prognosis or therapeutic monitoring. Multiple Sclerosis 2007; 13:169–177. http://msj.sagepub.com

Stratification and monitoring of natalizumab-associated progressive multifocal leukoencephalopathy risk: recommendations from an expert group

The use of natalizumab for highly active relapsing-remitting multiple sclerosis (MS) is influenced by the occurrence of progressive multifocal leukoencephalopathy (PML). Through measurement of the anti-JCV antibody index, and in combination with the presence or absence of other known risk factors, it may be possible to stratify patients with MS according to their risk of developing PML during treatment with natalizumab and detect early suspected PML using MRI including a diffusion-weighted imaging sequence. This paper describes a practical consensus guideline for treating neurologists, based on current evidence, for the introduction into routine clinical practice of anti-JCV antibody index testing of immunosuppressant-naïve patients with MS, either currently being treated with, or initiating, natalizumab, based on their anti-JCV antibody status. Recommendations for the frequency and type of MRI screening in patients with varying index-associated PML risks are also discussed. This consensus paper presents a simple and pragmatic algorithm to support the introduction of anti-JCV antibody index testing and MRI monitoring into standard PML safety protocols, in order to allow some JCV positive patients who wish to begin or continue natalizumab treatment to be managed with a more individualised analysis of their PML risk.