Reasons for non-feasibility of therapeutic drug monitoring of oral targeted therapies in oncology - an analysis of the closed cohorts of a multicentre prospective study.

BACKGROUND: Therapeutic drug monitoring (TDM) - performing dose adjustments based on measured drug levels and established pharmacokinetic (PK) targets - could optimise treatment with drugs that show large interpatient variability in exposure. We evaluated the feasibility of TDM for multiple oral targeted therapies. Here we report on drugs for which routine TDM is not feasible. METHODS: We evaluated drug cohorts from the Dutch Pharmacology Oncology Group - TDM study. Based on PK levels taken at pre-specified time points, PK-guided interventions were performed. Feasibility of TDM was evaluated, and based on the success and practicability of TDM, cohorts could be closed. RESULTS: For 10 out of 24 cohorts TDM was not feasible and inclusion was closed. A high incidence of adverse events resulted in closing the cabozantinib, dabrafenib/trametinib, everolimus, regorafenib and vismodegib cohort. The enzalutamide and erlotinib cohorts were closed because almost all PK levels were above target. Other, non-pharmacological reasons led to closing the palbociclib, olaparib and tamoxifen cohort. CONCLUSIONS: Although TDM could help personalising treatment for many drugs, the above-mentioned reasons can influence its feasibility, usefulness and clinical applicability. Therefore, routine TDM is not advised for cabozantinib, dabrafenib/trametinib, enzalutamide, erlotinib, everolimus, regorafenib and vismodegib. Nonetheless, TDM remains valuable for individual clinical decisions.

Intraperitoneal chemotherapy for peritoneal metastases of gastric origin: a systematic review and meta-analysis.

BACKGROUND: Gastric cancer with peritoneal metastases is associated with a dismal prognosis. Normothermic catheter-based intraperitoneal chemotherapy and normothermic pressurized intraperitoneal aerosol chemotherapy (PIPAC) are methods to deliver chemotherapy intraperitoneally leading to higher intraperitoneal concentrations of cytotoxic drugs compared to intravenous administration. We reviewed the effectiveness and safety of different methods of palliative intraperitoneal chemotherapy. METHODS: Embase, MEDLINE, Web of Science and Cochrane were searched for articles studying the use of repeated administration of palliative intraperitoneal chemotherapy in patients with gastric cancer and peritoneal metastases, published up to January 2024. The primary outcome was overall survival. RESULTS: Twenty-three studies were included, representing a total of 999 patients. The pooled median overall survival was 14.5 months. The pooled hazard ratio of the two RCTs using intraperitoneal paclitaxel and docetaxel favoured the intraperitoneal chemotherapy arm. The median overall survival of intraperitoneal paclitaxel, intraperitoneal docetaxel and PIPAC with cisplatin and doxorubicin were respectively 18.4 months, 13.2 months and 9.0 months. All treatment methods had a relatively safe toxicity profile. Conversion surgery after completion of intraperitoneal therapy was performed in 16% of the patients. CONCLUSIONS: Repeated intraperitoneal chemotherapy, regardless of method of administration, is safe for patients with gastric cancer and peritoneal metastases. Conversion surgery after completion of the intraperitoneal chemotherapy is possible in a subset of patients.

Staging laparoscopy in gastric cancer patients: From a Dutch nationwide Delphi consensus towards a standardized protocol.

BACKGROUND: Staging laparoscopy is a common diagnostic tool in gastric cancer, but its performance varies widely. The aim of this study was to gain Dutch nationwide consensus regarding the indications for and execution of staging laparoscopy in patients with gastric cancer. METHODS: All surgeons in the Netherlands specialized in gastric cancer surgery (n = 52) were asked to participate in a Delphi consensus study. The study involved an initial questionnaire with a 3-point Likert scale, an online consensus meeting, and a second questionnaire using a 2-point Likert scale (agree/disagree). Consensus was defined as 70% or more agreement among participants. RESULTS: In total, 45 experts completed both questionnaires (87% response rate). Consensus was reached on the indication to perform staging laparoscopy in cT3-4 or cN + or diffuse-type gastric cancer, including Siewert type III oesophagogastric junctional cancer. The experts agreed that if preoperative scans suggest infiltration of surrounding organs (cT4), the tumour's resectability should explicitly be investigated. Consensus was also reached for a systematic peritoneal cavity inspection according to Sugarbaker's Peritoneal Cancer Index (PCI) score. All regions should be inspected routinely, although the omental bursa may be inspected on indication. Aspiration of ascites or peritoneal washing should be performed for cytology. The experts agreed that restaging laparoscopy should be performed before resection in case of progressive disease on preoperative imaging. Without progression, global inspection was considered sufficient. CONCLUSIONS: The results of this Dutch nationwide Delphi consensus study exposed the variability of performing staging laparoscopy in patients with gastric cancer and provided the concept for a standardized protocol.

Population pharmacokinetics of intraperitoneal irinotecan and SN-38 in patients with peritoneal metastases from colorectal origin.

Peritoneal metastases (PM) are common in patients with colorectal cancer. Patients with PM have a poor prognosis, and for those who are not eligible for cytoreductive surgery (CRS) with or without hyperthermic intraperitoneal chemotherapy (HIPEC), palliative chemotherapy is currently the only option. Recently, we conducted a phase I trial (INTERACT) in which irinotecan was administered intraperitoneally (IP) to 18 patients ineligible for CRS-HIPEC. The primary objective was to evaluate covariates influencing the PK profile of irinotecan and SN-38 after IP administration. Secondly, a population PK model was developed to support the further development of IP irinotecan by improving dosing in patients with PM. Patients were treated with IP irinotecan every 2 weeks in combination with systemic FOLFOX-bevacizumab. Irinotecan and SN-38 were measured in plasma (588 samples) and SN-38 was measured in peritoneal fluid (267 samples). Concentration-Time data were log-transformed and analyzed using NONMEM version 7.5 using FOCE+I estimation. An additive error model described the residual error, with inter-individual variability in PK parameters modeled exponentially. The final structural model consisted of five compartments. Weight was identified as a covariate influencing the SN-38 plasma volume of distribution and GGT was found to influence the SN-38 plasma clearance. This population PK model adequately described the irinotecan and SN-38 in plasma after IP administration, with weight and GGT as predictive factors. Irinotecan is converted intraperitoneal to SN-38 by carboxylesterases and the plasma bioavailability of irinotecan is low. This model will be used for the further clinical development of IP irinotecan by providing dosing strategies.

Intraperitoneal pharmacokinetics of systemic oxaliplatin, 5-fluorouracil and bevacizumab in patients with colorectal peritoneal metastases.

BACKGROUND: Peritoneal metastases (PM) commonly occur in colorectal cancer patients. Systemic chemotherapy yields poor outcomes for these patients. It is hypothesised that traditional systemic chemotherapy is not very effective for this patient population. This study investigates to what extent systemic anti-cancer therapy crosses the peritoneal barrier. METHODS: In a Phase I study, eighteen patients received systemic oxaliplatin, 5-FU, and bevacizumab. Plasma and peritoneal fluid samples were collected to measure drug concentrations. A non-compartmental analysis determined the Area Under the Curve (AUC) for oxaliplatin and 5-FU in both matrices. Intraperitoneal (IP) and intravenous (IV) exposure ratios were calculated, along with the bevacizumab concentration IP/IV ratio. The relationship between tumour load and IP/IV ratios and the correlation between the IP/IV ratios of different treatments were assessed statistically. RESULTS: A total of 438 5-FU samples and 578 oxaliplatin samples were analysed in plasma and peritoneal fluid. Bevacizumab was quantified with 17 measurements in plasma and 15 measurements IP. Median IP/IV ratios were 0.143, 0.352 and 0.085 for 5-FU, oxaliplatin and bevacizumab, respectively. Oxaliplatin exhibited a longer IP half-life than 5-FU. A correlation was found between oxaliplatin and bevacizumab IP/IV ratios (R=0.69, p=0.01). No statistical correlations were found between the other investigated drugs. CONCLUSIONS: Our findings indicate that only a small percentage of systemically administered anti-cancer treatment reaches the IP cavity, questioning their efficacy against PM. This strengthens the hypothesis for repeated intraperitoneal chemotherapy to reach adequate anti-cancer drug levels.

The OCT2/MATE1 Interaction Between Trifluridine, Metformin and Cimetidine: A Crossover Pharmacokinetic Study.

BACKGROUND AND OBJECTIVES: Trifluridine/tipiracil, registered for the treatment of patients with metastatic gastric and colorectal cancer, is a substrate and inhibitor for the organic cation transporter 2 (OCT2) and the multidrug and toxin extrusion protein 1 (MATE1), which raises the potential for drug-drug interactions with other OCT2/MATE1 modulators. Therefore, we prospectively examined the effect of an OCT2/MATE1 inhibitor (cimetidine) and substrate (metformin) on the pharmacokinetics of trifluridine. METHODS: In this three-phase crossover study, patients with metastatic colorectal or gastric cancer were sequentially treated with trifluridine/tipiracil alone (phase A), trifluridine/tipiracil concomitant with metformin (phase B) and trifluridine/tipiracil concomitant with cimetidine (phase C). The primary endpoint was the relative difference in exposure of trifluridine assessed by the area under the curve from timepoint zero to infinity. A > 30% change in exposure was considered clinically relevant. A p-value of < 0.025 was considered significant because of a Bonferroni correction. RESULTS: Eighteen patients were included in the analysis. Metformin did not significantly alter the exposure to trifluridine (- 12.6%; 97.5% confidence interval - 25.0, 1.8; p = 0.045). Cimetidine did alter the exposure to trifluridine significantly (+ 18.0%; 97.5% confidence interval 4.5, 33.3; p = 0.004), but this increase did not meet our threshold for clinical relevance. Metformin trough concentrations were not influenced by trifluridine/tipiracil. CONCLUSIONS: Our result suggests that the OCT2/MATE1 modulators cimetidine and metformin can be co-administered with trifluridine/tipiracil without clinically relevant effects on drug exposure. CLINICAL TRIAL REGISTRATION: NL8067 (registered 04-10-2019).

Intraperitoneal irinotecan with concomitant FOLFOX and bevacizumab for patients with unresectable colorectal peritoneal metastases: protocol of the multicentre, open-label, phase II, INTERACT-II trial.

INTRODUCTION: The peritoneum is the second most affected organ for the dissemination of colorectal cancer (CRC). Patients with colorectal peritoneal metastases (CPM) face a poor prognosis, despite the majority of patients being treated with palliative systemic therapy. The efficacy of palliative systemic therapy is limited due to the plasma-peritoneum barrier. The poor prognosis of unresectable CPM patients has resulted in the development of new treatment strategies where systemic therapy is combined with local, intraperitoneal chemotherapy. In the recently published phase I study, the maximum tolerated dose and thus the recommended phase II dose of intraperitoneal irinotecan was investigated and determined to be 75 mg. In the present study, the overall survival after treatment with 75 mg irinotecan with concomitant mFOLFOX4 and bevacizumab will be investigated. MATERIALS AND METHODS: In this single-arm phase II study in two Dutch tertiary referral centres, 85 patients are enrolled. Eligibility criteria are an adequate performance status and organ function, histologically confirmed microsatellite stable and unresectable CPM, no previous palliative therapy for CRC, no systemic therapy<6 months for CRC prior to enrolment and no previous cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS and HIPEC). Patients will undergo a diagnostic laparoscopy as standard work-up for CPM and if the peritoneal disease is considered unresectable (eg, Peritoneal Cancer Index (PCI)>20, too extensive small bowel involvement), a peritoneal access port and a port-a-cath are placed for administration of intraperitoneal and intravenous chemotherapy, respectively. Patients may undergo up to 12 cycles of study treatment. Each cycle consists of intravenous mFOLFOX4 with bevacizumab and concomitant intraperitoneal irinotecan (75 mg), which is repeated every 2 weeks, with a maximum of 12 cycles. Modified FOLFOX-4 regimen consists of 85 mg/m2 oxaliplatin plus 200 mg/m2 LV and 5-FU 400 mg/m2 bolus on day 1 followed by 1600 mg/m2 5-FU as a 46 hours infusion. Study treatment ends after the 12th cycle, or earlier in case of disease progression or unacceptable toxicity. The primary outcome is overall survival and key secondary outcomes are progression-free survival, safety (measured by the amount of grade ≥3 adverse events (Common Terminology Criteria for Adverse Events V.5.0)), patient-reported outcomes and pharmacokinetics of irinotecan. It is hypothesised that the trial treatment will lead to a 4 month increase in overall survival; from a median of 12.2 to 16.2 months. ETHICS AND DISSEMINATION: This study is approved by the Dutch Authority (CCMO, the Hague, the Netherlands), by a central medical ethics committee (MEC-U, Nieuwegein, the Netherlands) and by the institutional research boards of both research centres. Results will be submitted for publication in peer-reviewed medical journals and presented to patients and healthcare professionals. TRIAL REGISTRATION NUMBER: NCT06003998.

Therapeutic Drug Monitoring of Kinase Inhibitors in Oncology.

Although kinase inhibitors (KI) frequently portray large interpatient variability, a 'one size fits all' regimen is still often used. In the meantime, relationships between exposure-response and exposure-toxicity have been established for several KIs, so this regimen could lead to unnecessary toxicity and suboptimal efficacy. Dose adjustments based on measured systemic pharmacokinetic levels-i.e., therapeutic drug monitoring (TDM)-could therefore improve treatment efficacy and reduce the incidence of toxicities. Therefore, the aim of this comprehensive review is to give an overview of the available evidence for TDM for the 77 FDA/EMA kinase inhibitors currently approved (as of July 1st, 2023) used in hematology and oncology. We elaborate on exposure-response and exposure-toxicity relationships for these kinase inhibitors and provide practical recommendations for TDM and discuss corresponding pharmacokinetic targets when possible.

Pharmacokinetic boosting of olaparib: A randomised, cross-over study (PROACTIVE-study).

BACKGROUND: Pharmacokinetic (PK) boosting is the intentional use of a drug-drug interaction to enhance systemic drug exposure. PK boosting of olaparib, a CYP3A-substrate, has the potential to reduce PK variability and financial burden. The aim of this study was to investigate equivalence of a boosted, reduced dose of olaparib compared to the non-boosted standard dose. METHODS: This cross-over, multicentre trial compared olaparib 300 mg twice daily (BID) with olaparib 100 mg BID boosted with the strong CYP3A-inhibitor cobicistat 150 mg BID. Patients were randomised to the standard therapy followed by the boosted therapy, or vice versa. After seven days of each therapy, dense PK sampling was performed for noncompartmental PK analysis. Equivalence was defined as a 90% Confidence Interval (CI) of the geometric mean ratio (GMR) of the boosted versus standard therapy area under the plasma concentration-time curve (AUC0-12 h) within no-effect boundaries. These boundaries were set at 0.57-1.25, based on previous pharmacokinetic studies with olaparib capsules and tablets. RESULTS: Of 15 included patients, 12 were eligible for PK analysis. The GMR of the AUC0-12 h was 1.45 (90% CI 1.27-1.65). No grade ≥3 adverse events were reported during the study. CONCLUSIONS: Boosting a 100 mg BID olaparib dose with cobicistat increases olaparib exposure 1.45-fold, compared to the standard dose of 300 mg BID. Equivalence of the boosted olaparib was thus not established. Boosting remains a promising strategy to reduce the olaparib dose as cobicistat increases olaparib exposure Adequate tolerability of the boosted therapy with higher exposure should be established.

Intraperitoneal Chemotherapy for Unresectable Peritoneal Surface Malignancies.

Malignancies of the peritoneal cavity are associated with a dismal prognosis. Systemic chemotherapy is the gold standard for patients with unresectable peritoneal disease, but its intraperitoneal effect is hampered by the peritoneal-plasma barrier. Intraperitoneal chemotherapy, which is administered repeatedly into the peritoneal cavity through a peritoneal implanted port, could provide a novel treatment modality for this patient population. This review provides a systematic overview of intraperitoneal used drugs, the performed clinical studies so far, and the complications of the peritoneal implemental ports. Several anticancer drugs have been studied for intraperitoneal application, with the taxanes paclitaxel and docetaxel as the most commonly used drug. Repeated intraperitoneal chemotherapy, mostly in combination with systemic chemotherapy, has shown promising results in Phase I and Phase II studies for several tumor types, such as gastric cancer, ovarian cancer, colorectal cancer, and pancreatic cancer. Two Phase III studies for intraperitoneal chemotherapy in gastric cancer have been performed so far, but the results regarding the superiority over standard systemic chemotherapy alone, are contradictory. Pressurized intraperitoneal administration, known as PIPAC, is an alternative way of administering intraperitoneal chemotherapy, and the first prospective studies have shown a tolerable safety profile. Although intraperitoneal chemotherapy might be a standard treatment option for patients with unresectable peritoneal disease, more Phase II and Phase III studies focusing on tolerability profiles, survival rates, and quality of life are warranted in order to establish optimal treatment schedules and to establish a potential role for intraperitoneal chemotherapy in the approach to unresectable peritoneal disease.

COVID-19 Incidence and Disease Course Among Patients at an Allergy Department.

Background: Since the coronavirus pandemic in 2020, there is not much reported about the disease course of COVID-19 in patients with allergic diseases. Objectives: The aim of this study was to investigate the cumulative incidence and severity of COVID-19 among patients from the allergy department compared with the general Dutch population and people from their household. Design: We conducted a comparative longitudinal cohort study. Methods: In this study patients of the allergy department were included with their household members as a control group. Data from the beginning of the pandemic were systematically obtained through questionnaires by telephonic interviews and retrieved from electronic patient files between October 15, 2020 and January 29, 2021. Main outcomes were confirmed SARS-CoV-2 infection, disease duration, hospitalization, intensive care admission, and mortality. Questions regarding applied social distancing measures were inventoried as well. Results: Three hundred and eighty nine patients (median age 39.1 (18.7-84.7) years, 69.9% female) and 441 household members (median age 42.0 (18.0-91.5), 44.1% female) were included. The cumulative COVID-19 incidence in patients was higher compared with the general population (10.5% vs 5.6%, P < .001). In total, 41 (10.5%) patients attending the allergy clinic compared to 38 (8.6%) household members were infected with SARS-CoV-2 (P = .407). Median disease duration was 11.0 (0.0-61.0) days in patients compared to 10.5(1.0-232.0) days in household members (P = .996). Conclusion: The cumulative COVID-19 incidence in patients from the allergy cohort was higher compared with the general Dutch population, but similar compared with household members. There was no difference in symptoms, disease duration, or hospitalization rate between the allergy cohort and their household members.

CYP3A4*22 Genotype-Guided Dosing of Kinase Inhibitors in Cancer Patients.

INTRODUCTION: A genetic variant explaining a part of the exposure of many kinase inhibitors (KIs) is the single nucleotide polymorphism (SNP) CYP3A4*22, resulting in less CYP3A4 enzyme activity. The primary aim of this study was to investigate if the systemic exposure is non-inferior after a dose reduction of KIs metabolized by CYP3A4 in CYP3A4*22 carriers compared to patients without this SNP (i.e., wildtype patients) receiving the standard dose. METHODS: In this multicenter, prospective, non-inferiority study, patients were screened for the presence of CYP3A4*22. Patients with the CYP3A4*22 SNP received a 20-33% dose reduction. At steady state, a pharmacokinetic (PK) analysis was performed and compared to the PK results from wildtype patients treated with the registered dose using a two-stage individual patient data meta-analysis approach. RESULTS: In total, 207 patients were included in the final analysis. The CYP3A4*22 SNP was found in 16% of the patients in the final analysis (n = 34). Most of the included patients received imatinib (37%) or pazopanib (22%) treatment. The overall geometric mean ratio (GMR) comparing the exposure of the CYP3A4*22 carriers to the exposure of the wildtype CYP3A4 patients was 0.89 (90% confidence interval: 0.77-1.03). CONCLUSION: Non-inferiority could not be proven for dose reduction of KIs metabolized by CYP3A4 in CYP3A4*22 carriers compared to the registered dose in wildtype patients. Therefore, an up-front dose reduction based upon the CYP3A4*22 SNP for all KIs does not seem an eligible new way of personalized therapy. TRIAL REGISTRATION: International Clinical Trials Registry Platform Search Portal; number NL7514; registered 11/02/2019.

Intraperitoneal paclitaxel for patients with primary malignant peritoneal mesothelioma: a phase I/II dose escalation and safety study-INTERACT MESO.

INTRODUCTION: Malignant peritoneal mesothelioma (MPM) is a rare, aggressive tumour arising primarily from the peritoneum. The only potentially curative treatment is cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC). However, the majority of patients are not eligible to undergo this treatment. The benefit of systemic treatment for these patients is limited at the cost of considerable morbidity. Hence, there is a need for appropriate palliative treatment options for patients with MPM. As MPM rarely disseminates outside the abdominal cavity, these patients might benefit from local treatment. A higher, more effective dose of chemotherapy can directly be delivered at the site of the disease. Systemic uptake will be limited, likely resulting in less toxicity. The aim of the INTERACT MESO trial is to determine the maximum tolerable dose of intraperitoneal paclitaxel monotherapy in patients with MPM. Secondary endpoints are to assess safety and toxicity, feasibility and the pharmacokinetic profile of this treatment. METHODS AND ANALYSIS: The INTERACT MESO trial is a prospective, open-label, single-centre, phase I study with a classic three-plus-three dose escalation design. The study population consists of adult patients with primary MPM, without extra-abdominal disease, who are not eligible to undergo CRS-HIPEC. According to standard of care work-up for CRS-HIPEC, patients will undergo diagnostic laparoscopy to determine the feasibility of CRS-HIPEC. In case CRS-HIPEC is not considered feasible, a peritoneal port-a-cath (PAC) system will be placed. Through this PAC, 8-16 weekly cycles of intraperitoneal chemotherapy will be administered. ETHICS AND DISSEMINATION: The Central Committee on Research Involving Human Subjects (CCMO, The Hague, The Netherlands) and the Medical Research Ethics Committee (METC, Rotterdam, The Netherlands) have granted permission to carry out this study protocol. The results of this trial will be submitted for publication in a peer-reviewed scientific journal. TRIAL REGISTRATION NUMBER: NL9718. EudraCT: 2021-003637-11.

Feasibility of therapeutic drug monitoring of sorafenib in patients with liver or thyroid cancer.

INTRODUCTION: Sorafenib is a tyrosine-kinase inhibitor approved for the treatment of renal cell carcinoma, hepatocellular carcinoma, thyroid carcinoma, and desmoid fibromatosis. As high inter-individual variability exists in exposure, there is a scientific rationale to pursue therapeutic drug monitoring (TDM). We investigated the feasibility of TDM in patients on sorafenib and tried to identify sub-groups in whom pharmacokinetically (PK) guided-dosing might be of added value. METHODS: We included patients who started on sorafenib (between October 2017 and June 2020) at the recommended dose of 400 mg BID or with a step-up dosing schedule. Plasma trough levels (Ctrough) were measured at pre-specified time-points. Increasing the dose was advised if Ctrough was below the target of 3750 ng/mL and toxicity was manageable. RESULTS: A total of 150 samples from 36 patients were collected. Thirty patients (83 %) had a Ctrough below the prespecified target concentration at a certain time point during treatment. Toxicity from sorafenib hampered dosing according to target Ctrough in almost half of the patients. In 11 patients, dosing was adjusted based on Ctrough. In three patients, this resulted in an adequate Ctrough without additional toxicity four weeks after the dose increase. In the remaining eight patients, dose adjustment based on Ctrough did not result in a Ctrough above the target or caused excessive toxicity. CONCLUSIONS: TDM for sorafenib is not of added value in daily clinical practice. In most cases, toxicity restricts the possibility of dose escalations.

The value of anti-neutrophil cytoplasmic antibodies (ANCA) testing for the diagnosis of ANCA-associated vasculitis, a systematic review and meta-analysis.

The testing of anti-neutrophil cytoplasmic antibodies (ANCA) takes an important place in the diagnostic workup to ANCA-associated vasculitis (AAV). Nowadays, it is recommended to screen for the presence of PR3 and MPO specific antibodies first using immunoassay, without the need for ANCA measurement by indirect immunofluorescence (IIF). A literature search was performed to assess the diagnostic test value of ANCA IIF and PR3- and MPO-antibody immunoassay to diagnose AAV. This meta-analysis shows that the c-ANCA testing by IIF has a pooled sensitivity of 75.2% and a pooled specificity of 98.4%. For PR3-antibody immunoassay, the pooled sensitivity depended on the immunoassay method used, and ranged from 79.8% to 86.6%, whereas the pooled specificity ranged from 96.8% to 98.3%. For both p-ANCA IIF and MPO-antibody immunoassay (all methods) sensitivity varied considerably showing pooled values of respectively 46.3% and 58.1%, whereas respective pooled specificity was 91.4% and 95.6%. These findings support the 2017 international consensus that primary anti-PR3 and anti-MPO screening by immunoassay, based on superior immunoassay sensitivity without the need for IIF ANCA testing, improves the diagnostic workup of AAV.

Characteristics of COVID-19 infection and antibody formation in patients known at a tertiary immunology department.

BACKGROUND: Knowledge about COVID-19 infections is expanding, although knowledge about the disease course and antibody formation in patients with an auto-immune disease or immunodeficiency is not fully unraveled yet. It could be hypothesized that immunodeficient patients, due to immunosuppressive drugs or their disease, have a more severe disease course due to their immunocompromised state. However, it could also be hypothesized that some of the immunosuppressive drugs protect against a hyperinflammatory state. METHODS: We collected data on the incidence of COVID-19, disease course and SARS-CoV-2 antibody formation in COVID-19 positive patients in a cohort of patients (n â€‹= â€‹4497) known at the Clinical Immunology outpatient clinic in a tertiary care hospital in the Netherlands. RESULTS: In the first six months of the pandemic, 16 patients were identified with COVID-19, 14 by nasal swab PCR, and 2 patients by SARS-CoV-2 antibodies. Eight patients were admitted to the hospital. SARS-CoV-2 antibodies were measured in 8 patients and were detectable in all, including one patient on B-cell ablative therapy and one patient with Common Variable Immunodeficiency Disorder. CONCLUSION: This study indicates that the disease course differs among immunocompromised patients, independently of (dis)continuation of immunosuppressive drugs. Antibody production for SARS-CoV-2 in immunocompromised patients was shown. More research needs to be conducted to confirm these observations and guidelines regarding (dis)continuation of immunosuppressive drugs in COVID-19 positive immunocompromised patients should be developed.