Posttransfusion hyperhemolysis is arrested by targeting macrophage activation with novel use of Tocilizumab.

BACKGROUND: Hyperhemolysis syndrome (HHS) is a posttransfusion complication most frequently seen in sickle cell disease (SCD), characterized by rapid destruction of transfused and autologous red blood cells (RBCs), resulting in reticulocytopenia and a decrease in hemoglobin to below pretransfusion levels. Additional RBC transfusion can be life threatening. Most patients improve with intravenous immune globulin and steroids, but in refractory cases, hyperhemolysis may result in multiorgan failure and death in the absence of salvage therapy. The exact pathophysiology of HHS remains uncertain, yet new insights suggest that RBC destruction is driven by activated macrophages. Therefore, we propose that antimacrophage therapy may represent an effective treatment. CASE REPORT: A case of life-threatening HHS, refractory to intravenous immune globulin and steroids, in a patient with SCD is presented. Marked elevation in ferritin, an indirect marker of macrophage activation, a negative direct antiglobulin test, and the absence of RBC alloantibodies was noted. A hemoglobin nadir of 2.1 g/dL and resultant hypoxemia-induced organ failure prompted the use of tocilizumab, an interleukin-6 receptor monoclonal antibody. Hemoglobin-based oxygen carrier-201, a cell-free polymerized bovine hemoglobin, was used to support the patient during critical anemia. RESULTS: Hemolysis resolved and ferritin dramatically decreased after administration of tocilizumab, which was well tolerated. A full recovery was achieved. CONCLUSION: This case highlights both a novel and successful approach to managing refractory transfusion-induced hyperhemolysis with tocilizumab and provides further evidence supporting the role for macrophage activation in the destruction of RBCs in antibody-negative HHS. We propose that tocilizumab is an effective and rapid salvage therapy for refractory HHS.

Neuroendocrine Carcinoma as a Cause of Humoral Hypercalcemia of Malignancy: A Case of a Patient With Elevated Parathyroid Hormone-Related Protein.

Humoral hypercalcemia of malignancy (HHM) is a paraneoplastic syndrome caused by elevations in parathyroid hormone-related protein (PTH-rP). HHM often presents in patients with squamous cell carcinomas of the lung, head, and neck, as well as breast, ovarian, renal, and bladder carcinomas. HHM associated with neuroendocrine carcinoma (NEC) is rarely observed. Here, we report a case of NEC-associated HHM refractory to standard calcium-reducing therapies but improved with the off-label addition of cinacalcet. A 31-year-old male with metastatic NEC presented to the emergency department (ED) with symptoms of nausea, emesis, constipation, and progressive weakness. He was being treated via a clinical trial at a tertiary referral center after failing standard therapies. He had recently been admitted at an outside facility for hypercalcemia, which had been managed with denosumab (120 mg subcutaneously) over the previous four weeks. He was admitted from the ED with a serum calcium of 14.6 mg/dL, potassium of 2.9 mmol/L, and phosphate of 1.2 mg/dL; ionized calcium was elevated at 8.0 mg/dL. Despite hydration and aggressive electrolyte replacement, his calcium increased to 15.5 mg/dL. Further laboratory evaluation revealed parathyroid hormone (PTH) of 6 pg/mL (10-65 pg/mL), 25-hydroxyvitamin D of 25 ng/mL (25-80 ng/mL), 1,25-dihydroxyvitamin D of 513 pg/mL (18-64 pg/mL), and PTH-rP of 25 pmol/L (<2.5 pmol/L), consistent with HHM. Calcitonin was avoided due to a prior hypersensitivity reaction. He received prednisone 10 mg daily and pamidronate 90 mg IV, and his calcium improved to 11.5 mg/dL. He was discharged and investigational therapy was resumed. This therapy failed, and he did not qualify for additional cancer therapy due to refractory hypercalcemia. He was started on cinacalcet, and his calcium decreased enough to permit further cancer treatment. He had multiple hospitalizations with fluctuating calcium levels and ultimately died several months later after sustaining a subarachnoid hemorrhage from a fall. In conclusion, we report a rare case of HHM associated with NEC. While many cases of HHM are effectively managed with hydration, calcitonin, antiresorptive therapies, and glucocorticoids, some are refractory. Our patient was refractory and differed from most patients with HHM in at least two ways. As mentioned previously, NEC causing HHM is quite uncommon (~2% of cases); it is unclear, but this malignancy might predispose to refractory hypercalcemia. Our patient's elevated vitamin D may also have made his HHM more resistant to treatment. Ultimately, while not first line, cinacalcet was an effective treatment in our patient. This provides additional evidence that cinacalcet may be considered for refractory hypercalcemia secondary to malignancy.

Familial Essential Thrombocythemia With Novel MPL L502G and G208K Mutations.

Familial essential thrombocythemia is characterized by the inheritance of germline mutations to progeny, thereby increasing the risk for the development of essential thrombocythemia. Here, we present two cases of young women who developed thromboembolic phenomena, one of whom with an ischemic event despite adequate anticoagulation. Through extended mutational testing, both were characterized as having novel mutations in the myeloproliferative leukemia virus (MPL) gene, and both individuals have fathers being treated for essential thrombocythemia. This case provides insight that in familial essential thrombocythemia, there remain uncharacterized mutations in this inherited conditional landscape.

Identification of acidic pH-dependent ligands of pentameric C-reactive protein.

C-reactive protein (CRP) is a phylogenetically conserved protein; in humans, it is present in the plasma and at sites of inflammation. At physiological pH, native pentameric CRP exhibits calcium-dependent binding specificity for phosphocholine. In this study, we determined the binding specificities of CRP at acidic pH, a characteristic of inflammatory sites. We investigated the binding of fluid-phase CRP to six immobilized proteins: complement factor H, oxidized low-density lipoprotein, complement C3b, IgG, amyloid ß, and BSA immobilized on microtiter plates. At pH 7.0, CRP did not bind to any of these proteins, but, at pH ranging from 5.2 to 4.6, CRP bound to all six proteins. Acidic pH did not monomerize CRP but modified the pentameric structure, as determined by gel filtration, 1-anilinonaphthalene-8-sulfonic acid-binding fluorescence, and phosphocholine-binding assays. Some modifications in CRP were reversible at pH 7.0, for example, the phosphocholine-binding activity of CRP, which was reduced at acidic pH, was restored after pH neutralization. For efficient binding of acidic pH-treated CRP to immobilized proteins, it was necessary that the immobilized proteins, except factor H, were also exposed to acidic pH. Because immobilization of proteins on microtiter plates and exposure of immobilized proteins to acidic pH alter the conformation of immobilized proteins, our findings suggest that conformationally altered proteins form a CRP-ligand in acidic environment, regardless of the identity of the protein. This ligand binding specificity of CRP in its acidic pH-induced pentameric state has implications for toxic conditions involving protein misfolding in acidic environments and favors the conservation of CRP throughout evolution.

Neutropenic Fever in a Patient With SARS-CoV-2-Induced Hemophagocytic Lymphohistiocytosis (HLH).

Hemophagocytic lymphohistiocytosis (HLH) is a severe systemic inflammatory syndrome that is often fatal. In the adult population, it is believed to develop secondary to immune dysregulation due to rheumatologic, infectious, malignant, and recently, immunomodulatory drugs. It has been well documented that infectious etiologies can lead to HLH however to date there is a paucity of case reports of HLH stemming from the 2019 novel coronavirus (SARS-CoV-2). Furthermore, it is well established that overlap exists between the extensive hyper-inflammatory syndromes produced from both HLH and severe COVID-19 infection. Here, we present a case of COVID-19-associated HLH with recurrent neutropenic fever in a patient with controlled follicular non-Hodgkin lymphoma who received treatment with etoposide after continued hospital admissions with refractory medical treatment.