Structural Characterization of a Pathogenic Antibody Underlying Vaccine-Induced Immune Thrombotic Thrombocytopenia (VITT).

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but dangerous side effect of adenoviral-vectored COVID-19 vaccines. VITT had been linked to production of autoantibodies recognizing platelet factor 4 (PF4). Here, we characterize anti-PF4 antibodies obtained from a VITT patient's blood. Intact mass measurements indicate that a significant fraction of these antibodies represent a limited number of clones. MS analysis of large antibody fragments (the light chain and the Fc/2 and Fd fragments of the heavy chain) confirms the monoclonal nature of this component of the anti-PF4 antibodies repertoire and reveals the presence of a mature complex biantennary N-glycan within the Fd segment. Peptide mapping using two complementary proteases and LC-MS/MS was used to determine the amino acid sequence of the entire light chain and over 98% of the heavy chain (excluding a short N-terminal segment). The sequence analysis allows the monoclonal antibody to be assigned to the IgG2 subclass and verifies that the light chain belongs to the λ-type. Incorporation of enzymatic de-N-glycosylation into the peptide mapping routine allows the N-glycan in the Fab region of the antibody to be localized to the framework 3 region of the VH domain. This novel N-glycosylation site is the result of a single mutation within the germline sequence. Peptide mapping also provides information on lower-abundance (polyclonal) components of the anti-PF4 antibody ensemble, revealing the presence of all four subclasses (IgG1-IgG4) and both types of the light chain (λ and κ). This case study demonstrates the power of combining the intact, middle-down, and bottom-up MS approaches for meaningful characterization of ultralow quantities of pathogenic antibodies extracted directly from patients' blood.

[Acquired thrombotic thrombocytopenic purpura during durvalumab monotherapy for non-small cell lung cancer].

Immune checkpoint inhibitor (ICI)-induced thrombocytopenias are rare immune-related adverse events (irAE), but ICI-related thrombotic thrombocytopenic purpura (TTP) is extremely rare. A 79-year-old woman with non-small cell lung cancer received maintenance therapy with the anti-human PD-L1 monoclonal antibody durvalumab. Four weeks after the last infusion, she developed overt TTP. Remission was achieved by plasma exchange and prednisolone, and the patient has now been recurrence-free for over 12 months. To our knowledge, this is the first report of TTP occurring as an irAE of durvalumab.

Durable remission of thrombotic thrombocytopenic purpura in the setting of pembrolizumab therapy.

BACKGROUND: There is a small but growing number of thrombotic thrombocytopenic purpura (TTP) cases attributed to immune checkpoint inhibitor therapy, with nivolumab and ipilimumab therapy being the most frequently described in the literature. STUDY DESIGN AND METHODS: This report evaluates the course of a patient with a history of metastatic adenocarcinoma of the lung who developed TTP following treatment with the PD-1 inhibitor Pembrolizumab. The patient was treated with six sessions of therapeutic plasma exchange and appeared to be in remission. Exacerbation occurred 4 days later, and seven more sessions of plasma exchange were performed along with four total doses of Rituximab, and a steroid taper with monitoring of platelet counts and ADAMTS13 activity. RESULTS: His platelet count recovered to a peak of 318,000 UL with an ADAMTS13 activity of 77% at the time of discharge. The patient has been following up regularly for outpatient testing with no TTP relapse as of the completion of this report. DISCUSSION: This is one of a few cases of Pembrolizumab-associated TTP reported in the literature with successful complete remission following treatment. Plasma exchange in this setting may be an especially beneficial therapeutic intervention because of the removal of both the anti-ADAMTS13 antibody as well as the immune system upregulating anti-PDL1 monoclonal antibody with replacement of ADAMTS13 from donor plasma. Longer duration of plasma exchange and monitoring for normalization of ADAMTS13 levels in addition to platelet count before cessation of treatment may improve durable remission rates in this entity.

Mild forms of thrombotic microangiopathy in patients with advanced pancreatic cancer receiving gemcitabine and nab-paclitaxel.

INTRODUCTION: Thrombotic microangiopathy (TMA) is an uncommon complication that may occur in cancer patients usually as an expression of cancer-associated coagulopathy or due to drug-related toxicity. The clinical spectrum of TMA may vary from an incidental laboratory finding in cancer outpatients to potentially severe life-threatening clinical forms with organ involvement requiring prompt recognition and multidisciplinary evaluation. CASE REPORTS: We present the clinical characteristics and outcomes of four patients with advanced pancreatic cancer with acute non-immune intravascular haemolysis compatible with microangiopathic acute haemolytic anaemia associated with mild thrombocytopenia during long-term gemcitabine and nab-paclitaxel treatment. MANAGEMENT AND OUTCOMES: Abnormal blood parameters (all four cases) and renal involvement (one case) were reversed with a conservative approach and chemotherapy discontinuation. One patient required a short hospitalization while the other three were managed as outpatients. The rapid reversibility of the blood abnormalities supported gemcitabine dose-related toxicity as the most likely aetiologic mechanism and demonstrates the current challenges in daily long-term cancer survivor care. DISCUSSION: Clinicians must take into account TMA in the differential diagnosis of acute anaemia with or without thrombocytopenia and organ damage, since adequate recognition and early treatment discontinuation allow effective outpatient management and favourable patient outcomes.

Thrombotic thrombocytopenic purpura developed after pegylated interferon treatment for hepatitis B infection.

BACKGROUND: Thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening thrombotic microangiopathy characterized by microangiopathic hemolytic anemia, severe thrombocytopenia, and organ ischemia. It is related to severe deficiency in ADAMTS13, which is usually acquired via ADAMTS13 autoantibodies or inherited via mutations of the ADAMTS13 gene. The etiology of acquired TTP including HIV infection, pregnancy, autoimmune disease, organ transplantation, drugs, malignancy and so on. Here, we firstly reported a patient diagnosed as acquired TTP after pegylated interferon therapy for hepatitis B and COVID-19 vaccination. CASE PRESENTATION: A 36-year-old male attended to our unit with a five-day history of intermittent hematuria and progressive fatigue on January 5th, 2022. He had a 13 years history of hepatitis B infection and undergone pegylated interferon treatment (which was paused for two months because of COVID-19 vaccination) for nearly 3 years. Laboratory evaluation revealed a haemoglobin level of 61 g/L, platelet count of 11 × 109/L, lactate dehydrogenase 2133 U/L. The direct and indirect Coombs test were both negative. On a peripheral blood smear, there were about 18.8% schistocytes. Meanwhile, the results of ADAMTS 13 activity and antibody were < 5% and 181.34 ng/ml (131.25-646.5), respectively CONCLUSION: This case firstly reported the rare complication of TTP after pegylated interferon treatment for hepatitis B and COVID-19 vaccine injection. This unique sign warrants more attention as an early cue of diagnosis of TTP and be aware of the rarity adverse effect of interferon therapy and COVID-19 vaccination.

Acquired thrombotic thrombocytopenic purpura associated with immune checkpoint inhibitors: A real-world study of the FDA adverse event reporting system.

INTRODUCTION: Immune checkpoint inhibitors (ICIs) are used for a variety of cancers and are associated with a risk of developing immune-related adverse events, most commonly colitis, dermatitis, hepatitis, and thyroiditis. Rare autoimmune hematologic toxicities have been reported but are less well-described in the literature. Acquired thrombotic thrombocytopenic purpura (TTP) is a life-threatening autoimmune condition that has been reported with ICIs but has been limited to case reports. METHODS: We performed a retrospective observational analysis of the United States Food and Drug Administration Adverse Event Reporting System (FAERS) data. We searched for cases of TTP reported with exposure to ICIs from initial FDA approval for each agent to December 31, 2021. Disproportionality signal analysis was done by calculating the reporting odds ratio (ROR). RESULTS: There were 35 reports of TTP with ICIs in the FAERS database, including atezolizumab (n = 7), durvalumab (n = 2), nivolumab (n = 18), and pembrolizumab (n = 8). The ROR was significant for atezolizumab (ROR 6.22, 95% CI 2.96-13.09), nivolumab (ROR 3.16, 95% CI 1.99-5.03), and pembrolizumab (ROR 2.56, 95% CI 1.28-5.12). CONCLUSIONS: There is a significant reporting signal of TTP with several ICI agents. Clinicians should be aware of and monitor for signs of this potentially serious adverse event.

Thrombotic thrombocytopenic purpura following administration of the Moderna booster vaccine.

Thrombotic thrombocytopenic purpura (TTP) is a type of thrombotic microangiopathy that is characterized by microangiopathic haemolytic anaemia, consumption thrombocytopenia and organ injury. It is caused by a severe deficiency of ADAMTS13, which can be either congenital or acquired. There is a plethora of things that can cause the acquired form, including medications and infections. Vaccines have also been shown to cause TTP. In the midst of the COVID-19 pandemic, with multiple new vaccines being developed and distributed to the masses, the medical community needs to be aware of adverse events associated with these new vaccines. We present a case of TTP following administration of the Moderna booster vaccine.

Thrombotic Thrombocytopenic Purpura associated with Pembrolizumab.

INTRODUCTION: Thrombotic thrombocytopenic purpura (TTP) is a life threatening type of thrombotic microangiopathy (TMA) caused by a deficiency in ADAMTS13. Here, we describe a case of TTP in association with pembrolizumab treatment for metastatic urothelial carcinoma. CASE REPORT: Our patient was a 68-year-old male who received three cycles of pembrolizumab. Shortly after he developed an acute onset of numbness of the right side of his arm and face, slurred speech, generalized weakness, loss of appetite and shortness of breath. Initial laboratory changes in emergency department revealed hyponatremia, elevation in blood urea nitrogen (BUN) and serum creatinine, decreased hemoglobin, significant thrombocytopenia and leukocytosis. His thrombocytopenia continued to worsen, reaching low levels of 19,000 × 10 9 /L. Given the presence of schistocytes, a PLASMIC score was calculated (5). ADAMTS13 activity and inhibitor returned 8% (ref. >80%) and 3% (ref. <0.4%), respectively. The patient passed away. MANAGEMENT & OUTCOME: He received two 500 mL normal saline boluses and 1 unit of packed red blood cells (pRBC) as well as an extensive imaging workup. On admission, his renal function and platelet counts continued to decline. Given multiple comorbitidies his family opted out of further treatment and the patient ultimately passed away. DISCUSSION: Pembrolizumab could possibly induce TMA. In this case the abnormal ADAMTS13 activity level makes TTP more likely, though through an unknown mechanism. Although immunotherapies play an important role in the field of oncology, the effects are not entirely cell specific and unwarranted treatment related complications should be considered.

[A Case of Effective Plasma Exchange for Thrombotic Microangiopathy during Chemotherapy for Pancreatic Cancer].

The patient was a 78-year-old man. After 4 courses of GEM plus nab-PTX therapy for multiple recurrent liver metastases after pancreatic body cancer surgery, the patient was aware of general malaise and edema of the extremities. Blood tests showed pancytopenia, and he was admitted to the hospital with a diagnosis of chemotherapy-induced pancytopenia. On the second day, hemolytic anemia with crushed red blood cells was observed, suggesting thrombotic microangiopathy (TMA). Considering the possibility of thrombotic thrombocytopenic purpura(TTP), the patient was started on plasma exchange with steroids. After 7 days of plasma exchange, his thrombocytopenia, hemolytic anemia, and renal dysfunction improved, and he was discharged from the hospital on the 28th day. Although GEM-induced TMA is a life-threatening complication, there is no established treatment for it. We report a case of GEM-induced TMA that was successfully treated with plasma exchange.

First diagnosis of thrombotic thrombocytopenic purpura after SARS-CoV-2 vaccine - case report.

BACKGROUND: We report a case of a 25-year-old male patient, who developed acquired thrombotic thrombocytopenic purpura (aTTP) after receiving a first dose of mRNA-based SARS-CoV-2 vaccine Spikevax (mRNA-1273, Moderna Biotech, USA). While this is the first case in literature describing a case of aTTP after receiving the Spikevax vaccine, there are two other cases after mRNA-based Covid-19 vaccine and two after adenoviral SARS-CoV-2 vaccine. CASE PRESENTATION: The patient presented with persisting malaise, fever, headache, word-finding difficulties, nausea, vomiting, petechial bleeding, and hematuria 13 days after receiving a first dose of vaccination. Laboratory testing showed low platelet count, Coombs-negative hemolytic anemia, and mild acute kidney injury. We excluded vaccine induced immune thrombotic thrombocytopenia (VITT) as another important differential diagnosis and the final diagnosis was established after ADAMTS-13 (A Disintegrin And Metalloproteinase with a ThromboSpondin type 1 motif, member 13) activity was found to be < 1% (reference range > 40%) and ADAMTS-13 antibodies being 72.2 IU/L (reference range < 12 IU/L). We initiated empiric therapy of plasmapheresis and corticosteroids on admission and started caplacizumab the day after. The patient's thrombocyte count normalized 3 days after admission, hemolysis and acute kidney injury resolved after 2 weeks. The patient received 2 doses of rituximab (1 g each) after the diagnosis of immune TTP was established. One month after the initial presentation, the patient is in good overall condition, but still receives daily caplacizumab due to ADAMTS-13 activity of < 1%. CONCLUSIONS: Low platelet count after vaccination against SARS-CoV-2 has gained attraction after vaccine-induced immune thrombotic thrombocytopenia (VITT) has been described as a rare but severe complication of adenoviral-based vaccines. Thrombotic thrombocytopenic purpura (TTP) is an important differential diagnosis, but there are only few reports of TTP following SARS-CoV-2 vaccination. Despite pathophysiological and clinical differences of both entities, diagnostic uncertainty can result in the acute setting, since they share main symptoms such as headache and neurological alterations in addition to thrombocytopenia. In difference to other cases reported, this patient developed first symptoms of TTP as early as 4 days after vaccination, which suggests that vaccination merely acted as trigger for occult TTP, instead of truly inducing an autoimmunological process.

Refractory thrombotic thrombocytopenic purpura related to checkpoint inhibitor immunotherapy.

BACKGROUND: Checkpoint inhibitors enhance T-lymphocyte-mediated antitumor responses, resulting in increased survival for patients with neoplastic disease. However, a subset of patients receiving checkpoint inhibitor therapy may experience adverse complications that include the development of autoimmune conditions, such as thrombotic thrombocytopenic purpura (TTP). Given the potential etiologic differences of checkpoint inhibitor-related autoimmunity, TTP that develops in the presence of checkpoint inhibitors may be refractory to current treatment methods and therefore may require additional treatment and prognostic consideration. CASE REPORT: Herein, we describe the unique clinical course of a patient who was treated with the combined checkpoint inhibitors nivolumab and ipilimumab for Stage IV malignant melanoma, who subsequently developed TTP. Unlike many patients with TTP, this patient failed to develop a sustained response to therapeutic plasma exchange. Additional use of steroids, anti-CD20, and plasma cell-targeting therapy (bortezomib) also failed to substantially reverse thrombocytopenia in a sustainable fashion. During this time, her melanoma progressed, and she ultimately succumbed. CONCLUSION: This case illustrates not only that TTP may be a potential complication of checkpoint inhibitor therapy, but also that TTP developing in this setting may result in an unpredictable response to commonly employed TTP treatment modalities. Ultimately, checkpoint inhibitor-related TTP may require distinct management approaches and prognostic considerations.

Nivolumab-Induced Thrombotic Thrombocytopenic Purpura in a Patient with Anal Squamous Cell Carcinoma: A Lesson on Hematologic Toxicity from Immunotherapy.

Thrombotic thrombocytopenic purpura (TTP) is a rare but life-threatening microangiopathic hemolytic anemia characterized by thrombocytopenia, hemolytic anemia, and ischemic organ damage. It is mainly caused by an autoreactive antibody directed at ADAMTS13. Immunotherapy is frequently associated with autoimmune complications in patients with cancer, but only three cases of TTP have been reported, none implicating single treatment with the anti-programmed cell death receptor 1 ligand antibody nivolumab. We present the first identified and reported case of nivolumab-associated TTP in a 51-year-old woman with stage IIIc anal carcinoma who achieved complete response following chemoradiation and received adjuvant nivolumab as part of a randomized clinical trial. Twelve weeks into treatment, she presented with dark urine, progressive fatigue, and headache. TTP diagnosis was based on laboratory evidence of hemolytic anemia, thrombocytopenia, and ADAMTS13 activity of 9% associated with an inhibitor. She was treated with daily plasma exchange and oral prednisone and responded well to treatment, with platelet counts over 100 K/cmm within 4 days. We reviewed and summarized data from all reported cases of TTP associated with cancer immunotherapy. We provide guidance on identification and management of this devastating hematologic complication, focusing on the importance of early recognition, as most patients achieve complete recovery with appropriate treatment. KEY POINTS: Thrombotic thrombocytopenic purpura (TTP) was originally excluded from previous reviews of hematologic immune-related adverse events; however, several cases have been reported in the past 2 years in patients treated with either single agent or combination of cytotoxic T-lymphocyte-associated antigen 4 and the programmed cell death receptor 1 (PD-1) or the PD-1 ligand inhibitors. Although rare, TTP is a life-threatening condition that could be challenging to diagnose, and early recognition is key as delayed treatment is associated with significant increase in mortality. The pathophysiology of immunotherapy-induced TTP is likely related to autoimmune inhibition of ADAMTS13; the addition of prednisone and rituximab to urgent plasmapheresis appears to be effective and should be part of the up-front management for these patients.

Thrombotic thrombocytopenic purpura associated to dual checkpoint inhibitor therapy for metastatic melanoma.

Dual checkpoint inhibitor therapy has known immune-related adverse events. However, checkpoint inhibitor-associated thrombotic thrombocytopenic purpura is very rarely reported. We present a case of a 70-year old man with advanced melanoma, presenting with severe thrombocytopenia, hemolytic anemia with schistocytes and suppressed ADAMTS-13 activity by ADAMTS-13 inhibitors. We discuss differential diagnoses and speculated mechanisms of this obviously therapy-related adverse event, which should be considered by clinicians prescribing these drugs.

Pembrolizumab-induced thrombotic thrombocytopenic purpura.

INTRODUCTION: Pembrolizumab is a humanised monoclonal antibody targeting the receptor programmed cell death protein-1 (PD-1), with anti-tumour activity demonstrated for many malignancies. Such immune checkpoint inhibitors are associated with many immune-related adverse events including rash, colitis, hepatitis, pneumonitis, endocrinopathy and, rarely, haematological adverse events, including immune-related thrombocytopenia. CASE REPORT: We report a 60-year-old female with metastatic non-small cell lung cancer treated with pembrolizumab every three weeks. Following her fifth cycle, she presented to our hospital with community-acquired pneumonia. Thrombocytopenia developed the next day and, after detailed investigations, thrombotic thrombocytopenic purpura was diagnosed. MANAGEMENT AND OUTCOME: Pembrolizumab was immediately ceased and plasma exchange commenced along with IV methylprednisolone 250 mg daily for three days followed by oral prednisolone. After five days of plasma exchange, platelet counts normalised and haemolytic anaemia resolved. DISCUSSION: Acquired thrombotic thrombocytopenic purpura is an autoimmune disorder caused by an inhibitory autoantibody against ADAMTS-13. While most cases of acquired thrombotic thrombocytopenic purpura are idiopathic, certain conditions (e.g. bacterial infection, autoimmune disorders, malignancies) and medications are associated with thrombotic thrombocytopenic purpura. Other potential causes were eliminated in our patient. As acquired thrombotic thrombocytopenic purpura is an autoimmune disorder, pembrolizumab, given its unique mechanism of action and association with immune-related adverse events, is believed to be implicated in the development of thrombotic thrombocytopenic purpura. This case is one of only two linking anti-PD-1 therapy to thrombotic thrombocytopenic purpura development (the other occurring in a patient on nivolumab plus ipilimumab). Thrombotic thrombocytopenic purpura is life-threatening and clinicians are advised to be aware of its possible occurrence in immune checkpoint inhibitor-treated patients.

Diclofenac-induced thrombotic thrombocytopenic purpura with concomitant complement dysregulation: a case report and review of the literature.

BACKGROUND: Thrombotic thrombocytopenic purpura and hemolytic uremic syndrome are two forms of thrombotic microangiopathies. They are characterized by severe thrombocytopenia, microangiopathic hemolysis, and thrombosis, leading to a systemic inflammatory response and organ failure. Plasmapheresis is used to treat thrombotic microangiopathies. A different entity known as atypical hemolytic uremic syndrome has garnered more clinical recognition because reported cases have described that it does not respond to standard plasmapheresis. Diclofenac potassium is a non-steroidal anti-inflammatory drug that is used to treat pain. CASE REPORT: A 35-year-old Hispanic man presented to our emergency department with complaints of generalized malaise, fever, and an evanescent skin rash. During admission, he reported the use of diclofenac potassium for back pain on a daily basis for 1 week. He was noted to have peripheral eosinophilia, so he was admitted for suspected drug reaction involving eosinophilia and systemic symptoms. His initial laboratory work-up showed microangiopathic hemolytic anemia and thrombocytopenia. He also experienced a seizure, encephalopathy, and had a PLASMIC score of 7, thus raising concerns for thrombotic thrombocytopenic purpura. He underwent emergent plasmapheresis, which improved his clinical condition. The diagnosis was confirmed by assessing the levels of disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13, which was less than 3%. In addition, his skin biopsy was positive for patchy complement deposition, demonstrating complement dysregulation. CONCLUSION: Thrombotic thrombocytopenic purpura is a rare condition that can be acquired. Our case is rare because it represents the first report of diclofenac potassium-induced thrombotic thrombocytopenic purpura with subjacent complement activation and dysregulation. Early recognition and aggressive management led to a favorable outcome.

Weekly carfilzomib and dexamethasone in Japanese patients with relapsed or refractory multiple myeloma: A phase 1 and PK/PD trial.

This open-label multicenter phase 1 study evaluated the safety, tolerability, efficacy, pharmacokinetics and pharmacodynamics of weekly carfilzomib and dexamethasone (Cd) in Japanese patients with relapsed or refractory multiple myeloma (RRMM). Carfilzomib was administered by 30-minute intravenous infusion on Days 1, 8 and 15 in a 28-day cycle starting at 20 mg/m2 on Day 1/Cycle 1 and 70 mg/m2 thereafter until progressive disease or unacceptable toxicity. Dexamethasone 40 mg was administered on Days 1, 8, 15 and 22 in Cycles 1-9 and on Days 1, 8 and 15 thereafter. Six patients were enrolled between March 2015 and June 2015. Patients had received a median of 4.5 (range, 4-8) prior regimens; all patients had previous therapies with bortezomib and immunomodulatory drugs. Of the 6 patients, 1 had a dose-limiting toxicity (DLT), and tolerability was confirmed. The DLT was grade 3 thrombotic microangiopathy, which was considered serious and occurred on Day 11/Cycle 1. All 6 patients (100%) experienced at least 1 grade ≥3 adverse event (AE). Two patients (33.3%) experienced AE (also considered adverse drug reactions) leading to study discontinuation: thrombotic microangiopathy (Day 11/Cycle 1) and thrombotic thrombocytopenic purpura (Day 6/Cycle 2). The overall response rate was 83.3% (95% confidence interval, 43.6-97.0). The weekly Cd regimen at a carfilzomib dose of 20/70 mg/m2 was well-tolerated among Japanese patients with RRMM. Our results could be the basis for the further development of carfilzomib treatment considering safety profiles including microangiopathy-related events and efficacy.