Author Of 3 Presentations
P0094 - Inter-laboratory evaluation of cerebrospinal fluid and serum kappa free light chain measurements (ID 966)
The kappa index, calculated by dividing the cerebrospinal (CSF)/serum kappa free light chain (KFLC) ratio by the CSF/serum albumin ratio, is gaining increasing interest as an indirect marker of intrathecal activation of the humoral immune response. The demonstration of intrathecal synthesis is of particular relevance in the diagnostic work-up of suspected Multiple Sclerosis. However, the lack of consistent data on inter-laboratory agreement in CSF and serum KFLC measurements is one of the factors that hamper the use of kappa index in routine practice.
Aim of this study was to assess agreement in CSF and serum KFLC measurements and kappa index values across different laboratories.
Fifteen paired CSF and serum samples were analyzed in all participating laboratories (nr=8). Four centers used Binding Site instruments and assays, 3 centers used Siemens instruments and assays, and one center used a Siemens instrument and a Binding Site assay.
Absolute individual agreement between laboratories was calculated using a two-way mixed effects intraclass correlation coefficient (ICC). Cohen's kappa coefficient was used to measure inter-laboratory agreement on positive (≥5.8) kappa index values.
Within Binding Site laboratories, ICC for KFLC measurements was 0.96 (95%CI: 0.9-0.98) for CSF, 0.93 (95%CI: 0.63-0.98) for serum and 0.97 (95%CI: 0.94-0.99) for kappa index values. Within Siemens laboratories, ICC for KFLC measurements was 0.99 (95%CI: 0.97-100) for CSF, 0.93 (95%CI: 0.48-0.98) for serum and 0.95 (95%CI: 0.89-0.98) for kappa index values. ICC calculated for all laboratories was 0.93 (95%CI: 0.87-0.97) for CSF KFLC, 0.81 (95%CI: 0.53-0.93) for serum KFLC and 0.65 (95%CI: 0.43-0.84) for kappa index. Cohen's kappa coefficient for a positive kappa index was 0.89 across Binding Site laboratories, 0.70 across Siemens laboratories, and 0.77 across all laboratories.
There was an excellent agreement in CSF KFLC measurements and in kappa index values within laboratories using the same instrument and assay (Binding Site or Siemens), while serum KFLC measurements were less concordant. Agreement across all laboratories was decreased when including the laboratory using a Siemens instrument coupled with a Binding Site assay in the analyses. Concordance for a positive kappa index was substantial across all laboratories and within Siemens laboratories, and very good within Binding Site laboratories.
P0314 - Dimethyl fumarate-induced lymphocyte count drop is related to clinical effectiveness in relapsing-remitting multiple sclerosis (ID 853)
Dimethyl fumarate (DMF) is an effective treatment for relapsing-remitting multiple sclerosis (RRMS) patients. Besides a partially known mechanism of action involving both neuroprotective and antioxidant effects, it causes a mean lymphocyte count drop of approximately 30%, typically occurring within the first year of treatment. Several studies investigated the relationship between this reduction and DMF effectiveness, with heterogeneous methods, obtaining contradictory results.
To investigate if absolute lymphocyte count (ALC) decrease during DMF treatment is associated with drug effectiveness on clinical and MRI disease activity in a real-life cohort of patients treated with DMF for at least 6 months. Secondary aims were to evaluate ALC variations over time and the impact of baseline demographic and clinical factors on DMF-induced lymphopenia.
Demographic, laboratory, clinical and MRI data were collected in this retrospective, observational multicentre study, conducted on RRMS patients attending nine MS centers of Emilia-Romagna region (Northern Italy). Multivariate Cox models were performed to evaluate the impact of six month-ALC drop on time to NEDA-3 (“no evidence of disease activity”) status loss and Kaplan-Meier curves were generated to display the results. Multivariate logistic regression was carried out to analyse possible predictors of lymphopenia.
476 patients (312 females, age at DMF start 38.4 ± 9.97 years) were analysed during a mean follow-up time of 29 months (range 6-61 months). A greater lymphocyte decrease was associated with a longer NEDA-3 status (HR 0.87, p = 0.01), relapse-free (HR 0.85, p = 0.03) and MRI activity-free survival (HR 0.80, p < 0.0001). A higher risk of NEDA-3 status loss (p=0.008) was observed in tertile with lower ALC drop (< 11.5%), compared with other tertiles (11.5-40.5% and >40.5% ALC drop, respectively). A shorter activity-free survival was also influenced by younger age at DMF start (HR 0.98, p = 0.03). The nadir of mean ALC drop (-33.6%) and 35% of grade III lymphopenia cases occurred after 12 months of treatment. An older age at DMF start (OR 1.03, 95% CI 1.00-1.06, p = 0.009) and lower ALC at baseline (OR 1.69, 95% CI 1.34-2.14, p < 0.0001) predicted higher risk of lymphopenia.
A higher lymphocyte count drop at six months is related to better outcomes in DMF-treated patients. A careful ALC monitoring should be pursued up to 24 months of treatment.
P0913 - Risks associated with wash-out duration when switching from fingolimod to cell-depleting agents (ID 1317)
A wash-out duration lasting >1–2 months between the majority of sequential disease-modifying therapies (DMTs) is associated with an increased risk of disease reactivation in Multiple Sclerosis (MS) patients.
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 lymphocyte recovery is still incomplete and that shorter wash-out periods do not affect the disease reactivation risk.
To assess the risk of relapses following FTY discontinuation and the initiation of a B/T cell-depleting agent initiation in relation to the duration of wash-out between the drugs using data from the Italian MS Registry.
Patients who initiated alemtuzumab, rituximab, ocrelizumab or cladribine within six months of FTY discontinuation, and with a follow-up of at least six months, or until a relapse occurred, were included in the study. The risk of relapses was assessed in relation to different wash-out durations (<6, 6-11, 12-17 and >/=18 weeks) using a Poisson regression analysis (and reported as incidence rate ratio - IRR) and a Cox proportional hazards model including age, disease duration, relapses during FTY treatment, EDSS and reason for FTY discontinuation as covariates.
Inclusion criteria were met by 329 patients (226F, 103M; mean age 41±10 years). Following a median wash-out period of 11 weeks [IQR: 6-16], 175 patients started alemtuzumab, 69 rituximab, 68 ocrelizumab and 17 cladribine. Ninety patients relapsed during the wash-out period and 72 during the subsequent cell-depleting therapy. During the cell-depleting treatment, IRR for a relapse was significantly greater in patients with a washout-period of 12-17 (IRR (95%CI): 2.4 (1,1-5,5); p=0.037) and >/=18 weeks (6.0 (2.8-12.7); p<0.001) compared to the reference period (<6 weeks).
The multivariable Cox analysis showed that the time to a relapse was significantly influenced by the occurrence of relapses during FTY treatment (HR (95%CI): 1.4 (1.2-1.7); p<0.001). Moreover, wash-out durations of 6-11, 12-17 and >/=18 weeks were associated with a higher risk of a relapse in comparison to wash-out durations shorter than 6 weeks (3.8 (1.1-13.2); p=0.037; 6.0 (1.7-21.9); p=0.006; 16.3 (4.8-56.3); p<0.001, respectively).
The risk of relapses during a cell-depleting therapy following a sequestering agent, namely FTY, increases progressively with the duration of wash-out, underlining the need of a short wash-out period also in this type of treatment sequence.