The role of interleukin 6 in the pathogenesis and therapy of Castleman disease - an immunologist's perspective

Castleman disease (CD) is a heterogeneous group of diseases characterized by lymphadenopathy and systemic inflammatory manifestations. CD can be divided into uni- (UCD) and multicentric form (MCD) according to the disease extent. MCD is usually accompanied by the features of a systemic inflammatory response including fever, weight loss, hepatosplenomegaly, ascites, and edema. In these patients, we can also observe elevation of inflammatory parameters and anemia within the laboratory assessment. Based on etiological nature, the CD can be further divided into human herpesvirus-8-associated (HHV8-associated) and idiopathic form. Interleukin 6 (IL-6) plays a central role in the disease pathogenesis. Inhibition of IL-6 has been shown to be an effective treatment modality. Currently, siltuximab, a chimeric monoclonal antibody targeting IL-6, is the only approved treatment for MCD. Its short-term and long-term efficacy and safety have been demonstrated in a few clinical studies.

Therapy of Castleman's disease with siltuximab - case report and review of literature

BACKGROUND

Idiopathic multicentric Castleman disease (iMCD) is characterized by constitutional symptoms, enlarged lymph nodes and laboratory test abnormalities, which are primarily related to the overproduction of interleukin-6 (IL-6). This form (iMCD) was treated earlier with cytostatics used for lymphoma, later with bio-logic therapy as rituximab, immunodulatory drugs and proteasome inhibitors, and in the last years with an anti-IL-6 antibody, siltuximab. Siltuximab is a human-mouse chimeric immunoglobulin G1k monoclonal antibody against human IL-6 approved in the European Union for the treatment of iMCD. In view of the limited treatment options for iMCD, this case report aimed to evaluate the efficacy and safety of siltuximab in the management of this condition.

CASE

We describe a young woman with iMCD diagnosed at the age of 25 years. For first line treatment, rituximab and dexamethasone were used without any cytostatic because the patient wished to give birth to a healthy child in the future. However, the response after this first line therapy was short. In addition, after 3 years from the start of rituximab + dexamethasone therapy, it was necessary to administer treatment for the relapse of iMCD. We decided for siltuximab in this young woman, still aged < 30 years, and started administration of siltuximab in 3-week intervals.

RESULTS

After administration of first two infusions of siltuximab, all inflammatory markers returned to normal value. Moreover, serum hemoglobin and albumin levels as well as C-reactive protein normalized after the first two administrations of siltuximab. The clinical response continue, siltuximab is still administered in 3-week intervals. PET/CT with fluorodeoxyglucose confirmed a very good anatomic and metabolic response to the treatment. Siltuximab demonstrated a favorable safety profile, and the prolonged treatment was well tolerated.

CONCLUSION

This result is encouraging and demonstrates the potential of siltuximab as treatment of CD. As earlier published, this case confirms that significantly elevated inflammatory markers in a patient with CD predict a good response to siltuximab.

Presepsin: what is important for correct interpretation

INTRODUCTION

Presepsin (soluble CD14 subtype) is a new biomarker of infection and sepsis. Correct interpretation is based on the knowledge of analytical reliability, biological variation, decision limits, and diagnostic effectivity.

AIM

The aim of the study was to verify analytical precision of presepsin measurements, to assess biological variation in healthy subjects, to verify reference and decision limits, to assess diagnostic effectivity, and to compare data with commonly used septic biomarkers - procalcitonin (PCT), CRP and interleukin 6 (IL6).

MATERIAL AND METHODS

Analyti-cal precision (repeatability and intermediate precision) was estimated by repeated measurements of commercial control materials. Biological variation was evaluated in a group of 20 healthy volunteers in a 7-week experi-ment. Reference ranges were extracted from the literature and compared with data from healthy subjects.

RESULTS

Precisions of presepsin measurements were 2.0-4.0 % (&#8220;within-run&#8221;) and 6.1-9.5 % (&#8220;between-run&#8221;). Intraindividual biological variation of presepsin was 22.3 %, interindividual variation 20.8 %. Index of individuality was 1.07, reference change value (RCV - critical difference) was 72 %. Upper reference limit was around 180 ng/l.

CONCLUSION

Ana-lytical quality of presepsin measurement is suitable for clinical use. Biological variation parameters enable the use of reference limits, upper reference limit of presepsin is around 180 ng/l. None of the tested biomarkers has universal cut-off value, multiple biomarkers are needed and repeated measurements are advisable.