A case of pembrolizumab-induced autoimmune haemolytic anaemia with polymyalgia rheumatica

Polymyalgia rheumatica and giant cell arteritis induced by immune checkpoint inhibitors: A systematic literature review highlighting differences from the idiopathic forms

INTRODUCTION

An altered immune tolerance disturbed by immune checkpoint inhibitors (ICIs) may contribute to new-onset polymyalgia rheumatica (PMR) and giant cell arteritis (GCA). This systematic literature review (SLR) examines the characteristics of PMR and GCA-like syndromes following anticancer treatment with ICIs, summarizing their demographic, clinical and treatment-related features to provide insights whether they differ from the idiopathic forms.

METHODS

The SLR was conducted in Medline and EMBASE databases from inception to July 2024, and in the EULAR/ACR abstract database (2021-2023). ICI-induced PMR and GCA syndromes were compared to the primary forms of the diseases using data from studies that included both groups as comparators. For manuscripts lacking direct comparisons, we summarized the main findings and discussed the differences using systematic reviews or large observational studies on the primary forms.

RESULTS

From 1237 screened abstracts, 46 met the inclusion criteria, involving 358 patients (314 with ICI-PMR and 44 with ICI-GCA). ICI-PMR had an estimated pooled prevalence of 0.1% [95% CI: 0.07%, 0.14%] among ICI recipients and 15.9% [95% CI: 12.6%, 19.9%] among patients experiencing rheumatic immune-related adverse events. Patients with ICI-PMR had a male-to-female ratio of 1.7:1 and a mean age of 71 ± 4 years. Most cases were associated with PD1/PDL1 blockers (87%). Clinical features included inflammatory pain in the girdles (100%), though pelvic girdle involvement was under-reported in some cases (3/28 studies). Peripheral arthritis was present in 35% of patients. Laboratory tests showed normal or slightly elevated inflammatory markers in 26% of cases. Glucocorticoids (GCs) led to symptom improvement in 84% of cases although 20% required immunosuppressive treatment and 14% experienced relapses. ICI-GCA had a prevalence of 0.06% among ICI recipients, with equal gender distribution and a mean age of 71 ± 5 years. Most patients received anti-PD1/PDL1 blockers (57%). Clinical manifestations included cephalic symptoms (75%), permanent visual loss (23%) and symptoms related to large-vessel involvement (54%). High-dose GCs were effective, with 96% achieving remission, though 17% experienced relapses.

CONCLUSIONS

ICI-induced PMR and GCA may have distinct clinical profiles compared to idiopathic forms, with potentially milder symptoms and better treatment responses. Further studies are needed to confirm these findings and better understand the long-term outcomes and pathophysiology of these conditions.

C-Reactive Protein Enhances IgG-Mediated Cellular Destruction Through IgG-Fc Receptors in vitro

Antibody-mediated blood disorders ensue after auto- or alloimmunization against blood cell antigens, resulting in cytopenia. Although the mechanisms of cell destruction are the same as in immunotherapies targeting tumor cells, many factors are still unknown. Antibody titers, for example, often do not strictly correlate with clinical outcome. Previously, we found C-reactive protein (CRP) levels to be elevated in thrombocytopenic patients, correlating with thrombocyte counts, and bleeding severity. Functionally, CRP amplified antibody-mediated phagocytosis of thrombocytes by phagocytes. To investigate whether CRP is a general enhancer of IgG-mediated target cell destruction, we extensively studied the effect of CRP on in vitro IgG-Fc receptor (FcγR)-mediated cell destruction: through respiratory burst, phagocytosis, and cellular cytotoxicity by a variety of effector cells. We now demonstrate that CRP also enhances IgG-mediated effector functions toward opsonized erythrocytes, in particular by activated neutrophils. We performed a first-of-a-kind profiling of CRP binding to all human FcγRs and IgA-Fc receptor I (FcαRI) using a surface plasmon resonance array. CRP bound these receptors with relative affinities of FcγRIa = FcγRIIa/b = FcγRIIIa > FcγRIIIb = FcαRI. Furthermore, FcγR blocking (in particular FcγRIa) abrogated CRP's ability to amplify IgG-mediated neutrophil effector functions toward opsonized erythrocytes. Finally, we observed that CRP also amplified killing of breast-cancer tumor cell line SKBR3 by neutrophils through anti-Her2 (trastuzumab). Altogether, we provide for the first time evidence for the involvement of specific CRP-FcγR interactions in the exacerbation of in vitro IgG-mediated cellular destruction; a trait that should be further evaluated as potential therapeutic target e.g., for tumor eradication.

Diagnosis and Management of Hematological Adverse Events Induced by Immune Checkpoint Inhibitors: A Systematic Review

There has been less volume of literature focusing on the Immune-related Hematological Adverse Drug Events (Hem-irAEs) of Immune Checkpoint Inhibitors (ICPis) in cancer patients. Furthermore, there has been no consensus about the management of hematological toxicity from immunotherapy in the recently published practice guidelines by the European Society for Medical Oncology (ESMO). We conducted a systematic review of case reports/series to describe the diagnosis and management of potentially rare and unrecognized Hem-irAEs. We searched Medline, OVID, Web of Science for eligible articles. Data were extracted on patient characteristics, Hem-irAEs, and management strategies. We performed quality assessment using the Pierson-5 evaluation scheme and causality assessment using the Naranjo scale. Our search retrieved 49 articles that described 118 cases. The majority of patients had melanoma (57.6%) and lung cancer (26.3%). The most common Hem-irAEs reported with ICPis (such as nivolumab, ipilimumab, and pembrolizumab) were thrombocytopenia, hemolytic and aplastic anemias. Less reported adverse events included agranulocytosis and neutropenia. Steroids were commonly used to treat these adverse events with frequent success. Other used strategies included intravenous immunoglobulins (IVIG), rituximab, and transfusion of blood components. The findings of this review provide more insights into the diagnosis and management of the rarely reported Hem-irAEs of ICPis.

Pathogenesis, Diagnosis and Management of Polymyalgia Rheumatica

Polymyalgia rheumatica is an inflammatory rheumatic disease of the elderly characterised by pain and stiffness in the neck and pelvic girdle, and is the second most common inflammatory rheumatic condition in this age group, after rheumatoid arthritis. Polymyalgia rheumatica can occur independently or in association with giant cell arteritis, which is the most common form of primary vasculitis. The diagnosis of polymyalgia rheumatica is usually based on clinical presentation and increase of inflammatory markers. There are no pathognomonic findings that can confirm the diagnosis. However, different imaging techniques, especially ultrasonography, can assist in the identification of polymyalgia rheumatica. Glucocorticoids are the cornerstone of the treatment of polymyalgia rheumatica, but they might be associated with different adverse events. A subgroup of patients presents with a refractory disease course and, in these cases, adding methotrexate as a steroid-sparing agent could be useful. In this review, we summarise the latest findings regarding the pathogenesis, diagnosis and management of polymyalgia rheumatica and try to highlight the possible pitfalls, especially in elderly patients.