Safety, tolerability, and activity of the active C1s antibody riliprubart in cold agglutinin disease: a phase 1b study

ABSTRACT

Cold agglutinin disease is a rare autoimmune hemolytic anemia characterized by complement pathway-mediated hemolysis. Riliprubart (SAR445088, BIVV020), a second-generation classical complement inhibitor, is a humanized monoclonal antibody that selectively inhibits only the activated form of C1s. This Phase 1b study evaluated the safety, tolerability, and effect on hemolysis of riliprubart in adult patients with cold agglutinin disease. On day 1, 12 patients received a single IV dose of either 30 mg/kg (n = 6) or 15 mg/kg (n = 6) of riliprubart and were subsequently followed for 15 weeks. Riliprubart was generally well tolerated; there were no treatment-emergent serious adverse events, or treatment-emergent adverse events leading to death or permanent study discontinuation. There were no reports of serious infections, encapsulated bacterial infections including meningococcal infections, hypersensitivity, or thromboembolic events. Rapid improvements in hemoglobin (day 5) and bilirubin (day 1) were observed in both treatment cohorts. Mean hemoglobin levels were maintained at >11.0 g/dL from day 29 and mean levels of bilirubin were normalized by day 29; both responses were maintained throughout the study. Improvements in clinical markers closely correlated with a sustained reduction in the 50% hemolytic complement (CH50) throughout the study. Mean C4 levels, an in vivo marker of treatment activity, increased 1 week after treatment with either dose of riliprubart and were sustained throughout the study. In conclusion, a single IV dose of riliprubart was well tolerated, and led to rapid classical complement inhibition, control of hemolysis, and improvement in anemia, all of which were sustained over 15 weeks. This trial was registered at www.ClinicalTrials.gov as #NCT04269551.

Long-term sutimlimab improves quality of life for patients with cold agglutinin disease: CARDINAL 2-year follow-up

Cold agglutinin disease (CAD) is a rare form of autoimmune hemolytic anemia with a substantial burden on patient's quality of life. CARDINAL was a 2-part, open-label, single-arm, multicenter phase 3 study evaluating the C1s inhibitor, sutimlimab, for treatment of CAD. Part A consisted of the pivotal study phase, with the part B extension phase assessing long-term safety and durability of response including patient-reported outcomes, which is the focus of this report. Altogether, 22 patients continued from part A to part B, majority female (68.2%) with a median age of 71.5 years (range, 55-85). Throughout treatment, score improvement on the Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue scale exceeded a predefined, group-level clinically important change of ≥5 points vs baseline, with a mean (standard error [SE]) change of 11.7 (3.7) points at week 135. The 12-Item Short Form Health Survey physical and mental component scores remained above baseline, with week 123 mean change (SE) exceeding clinically important changes of 3.9 for physical and 2.8 for mental component scores at 4.7 (2.8) and 3.8 (5.7) points, respectively. EuroQol Visual Analogue Scale, scoring patients' self-rated health, also remained above baseline with a change of 17.1 (5.6) points at week 135. Patient Global Impression of (fatigue) Severity improved vs baseline, corroborating FACIT-Fatigue scores. Patient Global Impression of Change indicated a reduction in perceived disease burden. Data from CARDINAL part B support sustained alleviation of CAD disease burden after long-term treatment with sutimlimab over 2 years, returning toward baseline upon treatment cessation. This trial was registered at www.clinicaltrials.gov as #NCT03347396.

Diagnostics in Waldenström's macroglobulinemia: a consensus statement of the European Consortium for Waldenström's Macroglobulinemia

The diagnosis of Waldenström's macroglobulinemia (WM), an IgM-associated lymphoplasmacytic lymphoma, can be challenging due to the different forms of disease presentation. Furthermore, in recent years, WM has witnessed remarkable progress on the diagnostic front, as well as a deeper understanding of the disease biology, which has affected clinical practice. This, together with the increasing variety of tools and techniques available, makes it necessary to have a practical guidance for clinicians to perform the initial evaluation of patients with WM. In this paper, we present the consensus recommendations and laboratory requirements for the diagnosis of WM developed by the European Consortium of Waldenström's Macroglobulinemia (ECWM), for both clinical practice as well as the research/academical setting. We provide the procedures for multiparametric flow cytometry, fluorescence in situ hybridization and molecular tests, and with this offer guidance for a standardized diagnostic work-up and methodological workflow of patients with IgM monoclonal gammopathy of uncertain significance, asymptomatic and symptomatic WM.

102 The cost of misdiagnosis in POEMS syndrome

Background

POEMS syndrome is a rare cause of neuropathy misdiagnosed as Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP) in 60% of cases. Ineffective CIDP directed therapy is expensive, introduces risk of complications, and often results in disease progression. Vascular endothelial growth factor (VEGF) is a sensitive and specific biomarker in the diagnosis of POEMS syndrome costing approximately £50. Introducing early directed screening with VEGF more accurately distinguishes POEMS syndrome from CIDP than the current standard of care (SOC).

Methods

100 cases from the UCLH POEMS database were selected. We grouped patients according to diagnostic pathway and compared health outcomes. We conducted a model-based cost-effectiveness analysis to compare diagnostic outcomes and costs of the current SOC with intervention pathways using VEGF screening. We used a study cohort of 1,250 patients with polyneuropathy (UK incidence) and conducted costing from a health-services perspective.

Results

Treatments associated with POEMS misdiagnosis led to a total healthcare expenditure in our cohort of £808,550-£1,111,756 over 20 years, with an average cost-per-POEMS-syndrome-patient misdiagnosed of

£14,701-£20,214. Our intervention pathway which introduces VEGF screening into the current SOC results in 4 additional early POEMS diagnoses per year and a cost-saving of almost £40,000 through avoidance of non-POEMS directed therapy and related hospital costs.

Conclusion

VEGF testing should be routine for patients presenting with an acquired demyelinating neu- ropathy. This will improve early diagnosis of POEMS syndrome, enable effective therapy and reduce cos8ts5.

stephen.keddie@nhs.net

103 High rates of venous and arterial thrombotic events in POEMS patients

Background

Arterial and venous thrombotic events occur in patients with POEMS (Polyneuropathy, Organomegaly, Endocrinopathy, M-protein, Skin changes) syndrome with a previously reported rate of 20%. We reviewed the UK POEMS Registry to describe the rate of venous thromboembolism (VTE), arterial events and risk factors.

Methods

The UK POEMS Registry is the largest single-centre cohort in Europe and comprises 100 patients. Data were collected on arterial and venous thrombotic events from 1999 to present day.

Results

Of the 83 assessable patients, median age at presentation was 52 years. Twenty-five patients expe- rienced 35 clinically apparent arterial or venous events. Eleven patients had 14 VTEs including deep vein thrombosis (DVT, 4/14), pulmonary embolism (4/14) and peripherally inserted central catheter-associated DVT occurring during autologous stem cell transplant (4/14). Sixteen patients experienced 21 arterial events: stroke (7/21), peripheral arterial occlusion (6/21), myocardial infarction (4/21) and microvascular disease (2/21), with no discernible relationship with thrombocytosis or polycythaemia. The combined venous and arterial event rate was 42%, over double that previously reported. There were more arterial than venous events, and most occurred during active pre-treated disease indicating a need for a pre- emptive approach to thromboprophylaxis.

Conclusion

Arterial and venous thromboses are more common in POEMS syndrome than previously reported and appear associated with disease pathology and activity. We propose a management strategy for appropriate thromboprophylaxis in POEMS patients throughout the course of disease.

stephen.keddie@nhs.net

106 Inflammatory peripheral neuropathy in haematological malignancies

Background

We report the case of a 62-year-old female with demyelinating sensorimotor polyneuropathy in the context of lymphoplasmacytic lymphoma.

Case Presentation

62-year-old woman presenting with distal lower limb numbness bilaterally, with a 9-year progressive course. Over the next 3 years, foot drop developed with gradual lower and upper limb involvement.

Investigations showed raised IgM paraprotein, 20 g/dL. Bone marrow biopsy identified 2-B cell clonal populations with positive MYD88 mutation in keeping with lymphoplasmacytic lymphoma (LPL). Neuro- physiological studies showed very severe length-dependent, sensorimotor neuropathy. She was VEGF/anti-MAG negative, but anti-GM2 positive. Widely-spaced myelin and moderate axonal loss were seen on sural nerve biopsy.

She was diagnosed with a progressive demyelinating neuropathy in the context of LPL.

Initial IVIG treatment failed.

Second line treatment – cyclophosphamide/rituximab/dexamethasone, improved her lower limb weakness. Ibrutinib later stabilised her weakness in the lower but not upper limbs.

Plexus nerve biopsy showed general inflammation, excluding direct clonal infiltration and amyloid deposi- tion. This reconfirmed the diagnosis: inflammatory neuropathy driven by a haematological malignancy. She received further treatment with rituximab-bendamustine.

Conclusion

Understanding the pathological mechanism of polyneuropathies in haematological malignan- cies is of paramount importance for choosing the most effective therapy, as illustrated by the above cas8e7.

a.zirra@nhs.net

THUR 220 To c or not to c

Peripheral T-cell lymphomas (PTCLs) are rare and heterogeneous haematological malignancies that can rarely develop first in the peripheral nervous system, or more commonly, invade nerves from more usual primary locations. Patients with PTCLs usually respond poorly to treatment and have a poor clinical outcome.

We report a patient with multiple skin lesions, multifocal mononeuropathies and constitutional symptoms all suggestive of a lymphoproliferative disorder, in whom repeat skin biopsies and clonality studies failed to achieve a diagnosis. Neurophysiological studies confirmed severe post-ganglionic lesions in the lower limbs including the sciatic, femoral, obturator, tibial and sural territories. Based on this neurotropic presentation we undertook a sural nerve biopsy, despite the clinical and neurophysiological presence of a nerve lesion more proximal to the biopsy site, and this allowed us to establish a final diagnosis of PTCL. The patient was treated successfully with chemotherapy and an autologous stem cell transplant.

In our case PET imaging and MR neurography provided radiological evidence of widespread lesions in the subcutaneous and nerve tissues, and there is emerging evidence for the importance of PET imaging in the diagnostic work-up of PTCLs. Furthermore, a post-treatment PET scan confirmed the complete metabolic remission, highlighting its usefulness as a surveillance tool.

Central nervous system involvement by Waldenström macroglobulinaemia (Bing-Neel syndrome): a multi-institutional retrospective study

Bing-Neel syndrome (BNS) is a rare complication seen in patients with Waldenström macroglobulinaemia (WM), in which lymphoplasmacytic lymphoma cells colonize the central nervous system. In this retrospective multi-centre study, we present the clinicopathological features, imaging findings, therapy, response and outcomes of 34 patients with BNS. The median time from WM diagnosis to BNS diagnosis was 3 years, 15% of patients were diagnosed with BNS at the time of WM diagnosis, and 22% of patients developed BNS when responding to active treatment for WM. Patients with BNS presented with variable clinical features including limb motor deficits, change in mental status and cranial nerve palsies. The diagnosis was made using a combination of cerebrospinal fluid cytology, flow cytometry and detection of the MYD88 L265 mutation, and magnetic resonance imaging. The estimated 3-year overall survival rate was 59%. Of the survivors, 40% have evidence of pathological and/or radiological persistence of disease. Age older than 65 years, platelet count lower than 100 × 10(9) /l, and treatment for WM prior to BNS diagnosis were associated with worse outcome. Exposure to rituximab for treatment of BNS was associated with a better outcome. Multi-institutional collaboration is warranted to improve treatment and outcomes in patients with BNS.