Tumor necrosis factor inhibitors (TNFi) have significantly improved treatment outcome of rheumatic diseases since their incorporation into treatment protocols two decades ago. Nevertheless, a substantial fraction of patients experiences either primary or secondary failure to TNFi due to ineffectiveness of the drug or adverse reactions. Secondary failure and adverse events can be related to the development of anti-drug antibodies (ADA). The earliest studies that reported ADA toward TNFi mainly used drug-sensitive assays. Retrospectively, we recognize this has led to an underestimation of the amount of ADA produced due to drug interference. Drug-tolerant ADA assays also detect ADA in the presence of drug, which has contributed to the currently reported higher incidence of ADA development. Comprehension and awareness of the assay format used for ADA detection is thus essential to interpret ADA measurements correctly. In addition, a concurrent drug level measurement is informative as it may provide insight in the extent of underestimation of ADA levels and improves understanding the clinical consequences of ADA formation. The clinical effects are dependent on the ratio between the amount of drug that is neutralized by ADA and the amount of unbound drug. Pharmacokinetic modeling might be useful in this context. The ADA response generally gives rise to high affinity IgG antibodies, but this response will differ between patients. Some patients will not reach the phase of affinity maturation while others generate an enduring high titer high affinity IgG response. This response can be transient in some patients, indicating a mechanism of tolerance induction or B-cell anergy. In this review several different aspects of the ADA response toward TNFi will be discussed. It will highlight the ADA assays, characteristics and regulation of the ADA response, impact of immunogenicity on the pharmacokinetics of TNFi, clinical implications of ADA formation, and possible mitigation strategies.

BH3 mimetic drugs may be useful to treat acute lymphoblastic leukemia (ALL) but the sensitivity of primary tumor cells has not been fully evaluated. Here B-lineage ALL cell cultures derived from a set of primary tumors were studied with respect to sensitivity to the BH3 mimetics ABT-263 and ABT-199 and to Bcl-2 dependence and function. These ALL cells each expressed high levels of Bcl-2 and exhibited great sensitivity to ABT-263 and ABT-199, which induced rapid apoptotic cell death. BH3 profiling indicated that the ALL cultures were Bcl-2 dependent. Co-immunoprecipitation studies revealed a multi-faceted role for Bcl-2 in binding pro-apoptotic partners including Bax, Bak, Bik and Bim. ABT-263 disrupted Bcl-2:Bim interaction in cells. Mcl-1 overexpression rendered ALL cells resistant to ABT-263 and ABT-199 with Mcl-1 assuming the role of Bcl-2 in binding Bim. Freshly isolated pediatric ALL blasts also expressed high levels of Bcl-2 and exhibited high sensitivity to Bcl-2 inhibition by the BH3 mimetic compounds. Overall our results showed that primary ALL cultures were both more sensitive to BH3 mimetics and more uniform in their response than established ALL cell lines which have been evaluated previously. Further, the primary cell model characterized here offers a powerful system for preclinical testing of novel drugs and drug combinations to treat ALL.

Severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infections often cause only mild disease that may evoke relatively low Ab titers compared with patients admitted to hospitals. Generally, total Ab bridging assays combine good sensitivity with high specificity. Therefore, we developed sensitive total Ab bridging assays for detection of SARS-CoV-2 Abs to the receptor-binding domain (RBD) and nucleocapsid protein in addition to conventional isotype-specific assays. Ab kinetics was assessed in PCRconfirmed, hospitalized coronavirus disease 2019 (COVID-19) patients (n = 41) and three populations of patients with COVID-19 symptoms not requiring hospital admission: PCR-confirmed convalescent plasmapheresis donors (n = 182), PCR-confirmed hospital care workers (n = 47), and a group of longitudinally sampled symptomatic individuals highly suspect of COVID-19 (n = 14). In nonhospitalized patients, the Ab response to RBD is weaker but follows similar kinetics, as has been observed in hospitalized patients. Across populations, the RBD bridging assay identified most patients correctly as seropositive. In 11/14 of the COVID-19-suspect cases, seroconversion in the RBD bridging assay could be demonstrated before day 12; nucleocapsid protein Abs emerged less consistently. Furthermore, we demonstrated the feasibility of finger-prick sampling for Ab detection against SARS-CoV-2 using these assays. In conclusion, the developed bridging assays reliably detect SARS-CoV-2 Abs in hospitalized and nonhospitalized patients and are therefore well suited to conduct seroprevalence studies.

Background At present, no real‐world studies are available on different dupilumab dosing regimens in controlled atopic dermatitis (AD). The aim of this study was to clinically evaluate a patient‐centered dupilumab dosing regimen in patients with controlled AD and to relate this to serum drug levels and serum biomarkers. Methods Ninety adult AD patients from the prospective BioDay registry were included based on their dupilumab administration interval according to a predefined patient‐centered dosing regimen. Group A (n = 30) did not fulfill the criteria for interval prolongation and continued using the standard dupilumab dosage (300 mg/2 weeks), group B (n = 30) prolonged dupilumab interval with 50% (300 mg/4 weeks), and group C (n = 30) prolonged dupilumab interval with 66%–75% (300 mg/6–8 weeks). AD severity score, patient‐reported outcomes, serum dupilumab levels, and serum biomarkers were analyzed over time. Results Disease severity scores did not significantly change over time during the tapering period in any of the groups. In groups B and C, the Numeric Rating Scale (NRS)‐pruritus temporarily significantly increased after interval prolongation but remained low (median NRS‐pruritus≤4). Median dupilumab levels remained stable in group A (standard dosage), but significantly decreased in groups B and C (24.1 mg/L (IQR = 17.1–45.6); 12.5 mg/L (IQR = 1.7–22.3)) compared with the levels during the standard dosage (88.2 mg/L [IQR = 67.1–123.0, p < .001]). Disease severity biomarker levels (CCL17/CCL18) remained low in all study groups during the whole observation period. Conclusions This study showed that dose reduction was successful in a subgroup of patients with controlled AD by using a patient‐centered dosing regimen. These patients showed stable low disease activity and low severity biomarkers over time.

; for the British Association of Dermatologists Biologic and Immunomodulators Register (BADBIR) Study Group and the Psoriasis Stratification to Optimise Relevant Therapy (PSORT) Consortium IMPORTANCE High-cost biologic therapies have transformed the management of immune-mediated inflammatory diseases. To optimize outcomes and reduce costs, dose adjustment informed by measurement of circulating drug levels has been shown to be effective in various settings. However, limited evidence exists for this approach with the interleukin 12 and interleukin 23 inhibitor ustekinumab. OBJECTIVE To evaluate clinical utility of therapeutic drug monitoring for ustekinumab in patients with psoriasis. DESIGN, SETTING, AND PARTICIPANTS A prospective observational cohort of 491 adults with psoriasis was recruited to the multicenter Biomarkers of Systemic Treatment Outcomes in Psoriasis study within the British Association of Dermatologists Biologic and Immunomodulators Register from June 2009 to December 2017; samples from some patients were taken between 2009 and 2011 as part of a pilot study with the same inclusion criteria. EXPOSURE Serum ustekinumab level measured at any point during the dosing cycle using an enzyme-linked immunosorbent assay. MAIN OUTCOMES AND MEASURES Disease activity measured using the Psoriasis Area and Severity Index (PASI) score. Treatment response outcomes were PASI75 (75% reduction in PASI score from baseline [primary outcome]), PASI90 (90% reduction of PASI score from baseline), and absolute PASI score of 1.5 or less. RESULTS A total of 491 patients (171 women and 320 men; mean [SD] age, 45.7 [12.8] years) had 1 or more serum samples (total, 853 samples obtained 0-56 weeks from start of treatment) and 1 or more PASI scores within the first year of treatment. Antidrug antibodies were detected in only 17 of 490 patients (3.5%). Early measured drug levels (1-12 weeks after starting treatment) were associated with PASI75 response 6 months after starting treatment (odds ratio, 1.38; 95% CI, 1.11-1.71) when adjusted for baseline PASI score, age, and ustekinumab dose. However, this finding was not consistent across the other PASI outcomes (PASI90 and PASI score of Յ1.5). CONCLUSIONS AND RELEVANCE This real-world study provides evidence that measurement of early serum ustekinumab levels could be useful to direct the treatment strategy for psoriasis. Adequate drug exposure early in the treatment cycle may be particularly important in determining clinical outcome.