Immune-mediated Drug Reactions Research Articles

Low Inter-Rater Reliability of Calculating the 4T's Score for Heparin Induced Thrombocytopenia

Introduction Heparin induced thrombocytopenia (HIT) is an immune-mediated drug reaction that can cause thromboembolism in the setting of thrombocytopenia following heparin exposure. The “4T's score” has been validated to determine the pre-test probability of HIT and to assist in decision making around ordering testing for HIT. The 4T's scoring system requires an individual clinician to determine each component of the score. The objective of our study is to investigate the inter-rater reliability of calculating the 4T's score among clinicians. Methods Through retrospective query of Northwestern Enterprise Data Warehouse, we identified patients who had a HIT antibody (Ab) test ordered between 10/2019 and 10/2022 after implementation of a clinical decision support (CDS) tool that asked clinicians to calculate a 4T's score as part of HIT PF-4 Ab orders. From this cohort, an independent clinician randomly selected 15 patients. Four raters, including an attending hematologist, a hospital medicine attending, a hematology/oncology fellow, and an internal medicine resident, performed manual chart review of the randomly selected subjects to calculate a 4T's score. Data collected for each case included individual components of the 4T's score and overall 4T's score from each rater. In addition, we compared raters' scores to the 4T's score entered by the ordering clinician for the patient. We then categorized the numerical scores into validated pre-test probability categories: 0-3 as low, 4-5 as intermediate, and ≥6 as high. Inter-rater reliability for the categories was calculated using the Fleiss kappa statistic. Our study was approved by the Northwestern University Institutional Review Board. Results Of 15 cases selected, 5 each were scored as low, intermediate, and high probability 4T's scores by the ordering clinician (associated with the HIT Ab order). The overall agreement between the score categories for the 5 clinicians (4 raters and the ordering clinician) was 50.7%, with a Fleiss Kappa statistic of 0.26 (95% CI [0.07-0.45]), indicating poor inter-rater reliability (Figure 1). Excluding the ordering clinician, the overall agreement in score category between the 4 raters was 58.9%, with a Fleiss Kappa statistic of 0.38 (95% CI [0.14-0.62]). The same 4T's score pre-test probability category was calculated by the 4 raters in 5 cases, with only one case in which all four raters calculated the same numerical 4T's score. There was one case in which all 5 clinicians calculated the same 4T's score probability category, but none with the same numerical 4T's score. The hematology/oncology fellow had highest inter-rater agreement with the original clinical (Kappa 0.30 [-0.09-0.69]), whereas the internal medicine attending and resident had the lowest (both with Kappa 0.00 [-0.37-0.37]). Of the 15 4T's scores, 12/15 ordered by the hematology attending, 5/15 by the internal medicine attending, 12/15 by the hematology/oncology fellow, and 11/15 by the internal medicine resident were lower than those calculated by the original ordering clinicians. Conclusion Our study demonstrates poor inter-rater reliability of HIT 4T's score calculation, across levels of training and specialty. Importantly, poor inter-rater reliability was seen across 4T's categories, which has implications for clinical management of patients undergoing evaluation for HIT. This suggests that different strategies are necessary to help clinicians better use the 4Ts score.

Improving Judicious Use of Heparin-Induced Thrombocytopenia Testing Through Electronic Health Record-Based Intervention.

Heparin-induced thrombocytopenia (HIT) is an immune-mediated drug reaction that can cause thromboembolism in the setting of thrombocytopenia. An enzyme-linked immunosorbent assay (ELISA)-based assay to screen for HIT antibodies (HAb) is available but has relatively low specificity and a correspondingly high false positive rate. The 4Ts score has been validated to determine the pretest probability of HIT. The authors hypothesized that an electronic health record (EHR)-based clinical decision support (CDS) tool incorporating the 4Ts score would reduce the volume of HAb orders. After implementing a CDS tool into the EHR, the researchers retrospectively evaluated the impact from November 2019 to October 2021, compared to a preintervention period (January to October 2019). The primary outcome was average tests per month. Secondary outcomes included rates of tests ordered per total inpatient encounters and proportion of HAb sent despite low 4Ts score in the postintervention study period. Of 1,833 HAb sent during the study period, 1,217 occurred in the postintervention period. In the postintervention period compared with the preintervention period, the average orders per month was 50.5 (standard deviation [SD] 9.7) vs. 61.6 (SD 7.2) (p = 0.003), and the order incidence rate was 8.0 per 1,000 patient encounters postintervention vs. 9.2 per 1,000 patient encounters preintervention (rate ratio [RR] 0.87, 95% confidence interval [CI] 0.79-0.96, p = 0.002). Postintervention, 252 (20.7%) had a 4Ts score calculated as low probability, 759 (62.4%) as intermediate probability, and 131 (10.8%) as high probability, and 75 had no associated 4Ts score. Implementation of a simple CDS tool reduced the rate of HAb orders, reducing unnecessary HAb testing.

Transgenic murine models for the study of drug hypersensitivity reactions linked to HLA-I molecules.

Immune-mediated drug hypersensitivity reactions (DHRs) can be life-threatening and an impediment to drug development. Mechanism of disease studies are difficult to perform in humans. Here we review human leukocyte antigens class I (HLA-I) transgenic murine models and highlight how these systems have helped to elucidate drug-specific and host immune factors that initiate, propagate and control severe drug toxicities to skin and liver. HLA transgenic mice have been developed and used to study immune-mediated drug reactions in vitro and in vivo. CD8+ T cells from HLA-B∗57:01-expressing mice respond strongly to abacavir (ABC) in vitro but have self-limited responses to drug exposure in vivo. Immune tolerance can be overcome by depleting regulatory T cells (Treg) allowing antigen-presenting dendritic cells to express CD80/86 costimulatory molecules and signal through CD28 on the CD8+ T cell. Depletion of Treg also removes competition for interleukin 2 (IL-2) to allow T cell expansion and differentiation. Fine tuning of responses depends on inhibitory checkpoint molecules such as PD-1. Improved mouse models express only HLA in the absence of PD-1. These models show enhanced liver injury to flucloxacillin (FLX) which depends on drug priming, CD4+ T cell depletion, and lack of PD-1 expression. Drug-specific HLA-restricted cytotoxic CD8+ T cells can infiltrate the liver but are suppressed by Kupffer and liver sinusoidal endothelial cells. HLA-I transgenic mouse models are now available to study ABC, FLX and carbamazepine-induced adverse reactions. In vivo studies range from characterizing drug-antigen presentation, T cell activation, immune-regulatory molecules and cell-cell interaction pathways that are specifically involved in causing or controlling unwanted DHRs.

Perindopril/amlodipine-induced thrombotic microangiopathy

This is the first report on a case of perindopril/amlodipine-induced thrombotic microangiopathy (TMA) syndrome. A 48-year-old female was admitted complaining of nettle rash all over the body, bloody urine, and weakness shortly after starting antihypertensive therapy with perindopril/amlodipine. Shortly thereafter, she developed pronounced hemiparesis, somnolence, and sensorimotor aphasia. Laboratory findings were compatible with microangiopathic hemolytic anemia and thrombocytopenia. She was diagnosed with TMA. Cessation of perindopril/amlodipine therapy and treatment with plasma exchange and systemic corticosteroids resulted in full recovery. Very seldom perindopril/amlodipine may cause hematologic abnormalities, probably through an immunological mechanism, but there were no reports of causing TMA so far. In our case, the symptoms began shortly after the start of perindopril/amlodipine use. The clinical course of TMA in the case was compatible with TMA related to an acute, immune-mediated drug reaction. The most important thing is to promptly recognize TMA and its induction by a drug because distinctive treatment and cessation of the suspected drug can prevent severe outcome, as it was avoided in our patient.

What’s Your Motivation?

What’s Your Motivation?

2411 Acute Liver Injury in a Patient Treated With Rosuvastatin: A Rare Adverse Effect

INTRODUCTION: As recently as 2014, Rosuvastatin was the most prescribed brand name drug in the US, with 22.3 million prescriptions filled and $5.8 billion in sales. Its use is associated with mild, asymptomatic, and usually transient, serum aminotransferase elevations, occurring in 1-3% of patients. However, levels above 3 times the ULN occur no more frequently among rosuvastatin-treated [0.2%] as placebo-treated [0.3%] recipients. Rarely, patients can present with clinically apparent acute liver injury, occurring in 1/10,000 patients. CASE DESCRIPTION/METHODS: A 47 y/o Peruvian man was told by his PCP that he had high cholesterol, and he was started on rosuvastatin 5 mg daily. At the time, his LFTs showed AST 17 and ALT 19. However, labs performed a month later showed AST 1282, ALT 2245, ALP 295, total bilirubin (TB) 7.1 (direct 5.5). He was advised to visit his local ER. He was admitted, the rosuvastatin was stopped, he received mainly supportive care, his LFTs continued to rise, and he underwent a liver biopsy. He was then transferred to a tertiary care hospital. His labs upon arrival showed AST 1400, ALT 2253, ALP 277, TB 9.9, and INR 1.1. He was admitted for acute liver failure due to drug-induced liver injury from rosuvastatin. Despite IV NAC therapy for five days and initiation of Ursodiol, his LFTs showed no recovery. His liver biopsy showed acute severe hepatitis with a mixed inflammatory infiltrate with many plasma cells. There was interface activity and bile duct damage. The histopathology was consistent with an immune-mediated drug reaction. He was approved to be listed for liver transplantation due to a high MELD score of 21. Before discharge, his labs improved to AST 942, ALT 1312, and ALP 167, but the TB rose to 17.2. He remained hemodynamically stable with no mental status changes during the hospital course. Afterward, repeated labs showed improvement in the LFTs, except for increasing hyperbilirubinemia. He was re-admitted and given a trial course of IV methylprednisolone after which the TB proceeded to decrease. Ultimately, his liver enzymes improved, he remained asymptomatic, and he was removed from the liver transplantation waitlist. DISCUSSION: The acute liver failure attributed to rosuvastatin is often accompanied by autoimmune features and may be caused by immune mechanisms. Corticosteroids have been used when recovery does not occur promptly. If used, the dose and duration of treatment should be kept to a minimum, and careful follow up after discontinuation is essential.

Potential Role of Direct Oral Anticoagulants in the Management of Heparin-induced Thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is a rare, potentially life-threatening condition secondary to unfractionated heparin or low molecular weight heparin exposure. This immune-mediated drug reaction manifests as thrombocytopenia with a paradoxical hypercoagulable state that can result in life-threatening thrombosis. It is imperative to ensure cessation of heparin-based products as soon as HIT is identified. Traditional treatment options include argatroban, bivalirudin, fondaparinux, and danaparoid with a transition to warfarin upon platelet recovery. These anticoagulants are notwithstanding limitations including parenteral administration and routine laboratory monitoring leading to prolonged hospitalizations, emphasizing the need for new therapies. Direct oral anticoagulants (DOACs) have been increasingly investigated for the management of HIT and may overcome the aforementioned challenges of current therapies. The objective of this narrative review is to summarize the current HIT guidelines, discuss limitations to contemporary treatment options, provide insight into the emerging evidence for the DOACs rivaroxaban, apixaban, and dabigatran, and conclude with a clinical summary for their use in this setting. The PubMed, Google Scholar, and MEDLINE databases were searched for peer-reviewed literature from January 1, 2012, to June 31, 2018. Twenty-seven articles met inclusion criteria for review: 1 prospective trial, 5 retrospective cohort studies, and 21 case reports totaling 104 patients treated with a DOAC for HIT. The DOACs prevented new and recurrent thrombosis in 98% (n=102) of cases, and bleeding complications occurred in 3% (n=3). While current literature remains limited, it is suggestive of a potential role of DOACs for HIT, which has led to their integration into the 2018 American Society Hematology Guidelines with a conditional recommendation.

Risk of Subsequent Thrombosis in Patients with Isolated Heparin-Induced Thrombocytopenia

Background: Heparin-Induced Thrombocytopenia (HIT) is one of the most important and commonly encountered immune-mediated drug reactions which can lead to significant morbidity and mortality. In up to 25% of patients, thrombosis can be the presenting finding of HIT. Isolated HIT occurs in patients without clinically evident thrombosis at the time of diagnosis. The management of HIT focuses on reducing the risk of thrombotic complications. In addition to prompt discontinuation of heparin products, anticoagulation is recommended. The risk of thrombosis is thought to remain high for up to 4 weeks due to persistent circulating PF4-heparin antibodies. Prior studies have shown that in patients with isolated HIT, the subsequent 30-day risk of thrombosis is up to 53%.Guidelines recommend 3 months of anticoagulation for patients with HIT-associated thrombosis. The optimal duration of anticoagulation in isolated HIT is unknown. Many experts recommend prophylactic anticoagulation for up to 4 weeks after diagnosis. However in the era of direct thrombin inhibitors, the need for prophylactic anticoagulation and risk of thrombosis beyond normalization of platelet count remains to be determined. The aim of this study was to determine the incidence of subsequent thrombosis in patients with isolated HIT.Methods: In this retrospective review, we identified patients with a documented positive HIT (heparin-PF4 antibody) enzyme immunoassay (ELISA) at our affiliated hospitals between January 2006 and December 2016. Laboratory data from these patients were reviewed. Patients who met criteria for HIT, defined as HIT ELISA optical density ≥ 2 or positive serotonin release assay were included in the analysis. From this cohort of patients with confirmed HIT, clinical data was extracted from the electronic medical record, including anticoagulation management and documented thrombotic events within 3 months of HIT diagnosis. Patients with evidence of thrombosis at the time of diagnosis were excluded in the final analysis as our focus was on patients with isolated HIT. The incidence of subsequent thrombosis was compared in patients who received anticoagulation versus those who did not receive anticoagulation.Results: A total of 403 charts were reviewed from patients with a documented positive HIT ELISA, defined as an optical density of > 0.4. Of the 403 patients, 49.5% (n = 107) met criteria for HIT, with an optical density > 2 or positive serotonin release assay. In patients with HIT, 48.6% (n = 52) did not have evidence of thrombosis at the time of diagnosis. Of these patients with isolated HIT, 14 patients (26.9%) received no prophylactic anticoagulation, 8 patients (15.4%) received prophylactic anticoagulation for at least 4 weeks but less than 3 months, and 30 patients (57.7%) were anticoagulated for 3 months or longer. The total incidence of subsequent thrombosis in isolated HIT was 7.7%. In the cohort of patients that did not receive prophylactic anticoagulation, two patients (14.3%) developed a thrombotic event in the 3 months following the HIT diagnosis. No documented thrombotic complications occurred in the eight patients that received prophylactic anticoagulation for at least 4 weeks but less than 3 months. Three patients (10%) who received long-term anticoagulation (≥3 months) developed a subsequent thrombotic event. There was no significant difference in the incidence of subsequent thrombosis in patients who did not receive prophylactic anticoagulation versus patients who received short-term prophylactic anticoagulation (p=0.141). In addition, there was no significant difference in the incidence of subsequent thrombosis in patients who did not receive prophylactic anticoagulation versus those who received long-term anticoagulation (p=0.701).Conclusions: The optimal duration of anticoagulation in patients with isolated HIT is unknown. Our incidence of thrombosis following the diagnosis of HIT was lower than previously described. Patients who did not receive prophylactic anticoagulation did not have a significantly higher incidence of thrombosis compared to patients who received short-term prophylactic or long-term anticoagulation. The study was limited by the retrospective nature and small sample size. Further studies are needed to better understand the ideal length of anticoagulation to prevent thrombotic complications without leading to unnecessary increased risk of bleeding. DisclosuresNo relevant conflicts of interest to declare.

In vitro assays supporting the safety assessment of immunomodulatory monoclonal antibodies

Many monoclonal antibodies (mAbs) licensed for human use or in clinical development for cancer and autoimmune disease directly interact with the immune system. These immunomodulatory mAbs have an inherent risk of adverse immune-mediated drug reactions, including infusion reactions, cytokine storms, immunosuppression and autoimmunity. A thorough understanding of the potential for immunotoxicity of a mAb is required to support administration to humans. This review will highlight the key role of in vitro assays in defining the immunopharmacology, immunotoxicity and immunogenicity of mAbs. A wide range of in vitro tests with multiple formats of different complexity can be utilized to characterize i) the antibody-binding domains of the mAb, such as on-target binding and downstream pharmacological effects (e.g. immunosuppression, immune activation, cytokine release) in both humans and animal species used for toxicology studies and off-target binding; ii) Fc-dependent effects such as Fc-mediated cellular activation (e.g. of leukocytes, platelets) and cytokine release, complement activation; and iii) product-related factors (sequence, physical-chemical properties and impurities) that can impact both pharmacological activity and immunogenicity potential of a mAb. These assays can be crucial to the selection of mAbs with an optimum balance of safety and efficacy, in defining whether a mAb is a high risk molecule, and together with animal data, can inform human safe starting doses and escalation schemes.

Drug induced exfoliative dermatitis: state of the art.

Drug induced exfoliative dermatitis (ED) are a group of rare and severe drug hypersensitivity reactions (DHR) involving skin and usually occurring from days to several weeks after drug exposure. Erythema multiforme (EM), Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are the main clinical presentations of drug induced ED. Overall, T cells are the central player of these immune-mediated drug reactions. Here we provide a systematic review on frequency, risk factors, pathogenesis, clinical features and management of patients with drug induced ED.Electronic supplementary materialThe online version of this article (doi:10.1186/s12948-016-0045-0) contains supplementary material, which is available to authorized users.

Optimization of the THP-1 activation assay to detect pharmaceuticals with potential to cause immune mediated drug reactions

Despite important impacts of systemic hypersensitivity induced by pharmaceuticals, for such endpoint no reliable preclinical approaches are available.We previously established an in vitro test to identify contact and respiratory allergens based on interleukin-8 (IL-8) production in THP-1 cells. Here, we challenged it for identification of pharmaceuticals associated with systemic hypersensitivity reactions, with the idea that drug sensitizers share common mechanisms of cell activation. Cells were exposed to drugs associated with systemic hypersensitivity reactions (streptozotocin, sulfamethoxazole, neomycin, probenecid, clonidine, procainamide, ofloxacin, methyl salicylate), while metformin was used as negative drug. Differently to chemicals, drugs tested were well tolerated, except clonidine and probenecid, with no signs of cytotoxicity up to 1–2mg/ml. THP-1 activation assay was adjusted, and conditions, that allow identification of all sensitizing drugs tested, were established. Next, using streptozotocin and selective inhibitors of PKC-β and p38 MAPK, two pathways involved in chemical allergen-induced cell activation, we tested the hypothesis that similar pathways were also involved in drug-induced IL-8 production and CD86 upregulation. Results indicated that drugs and chemical allergens share similar activation pathways.Finally, we made a structure–activity hypothesis related to hypersensitivity reactions, trying to individuate structural requisite that can be involved in immune mediated adverse reactions.

Optimized nonclinical safety assessment strategies supporting clinical development of therapeutic monoclonal antibodies targeting inflammatory diseases.

An increasing number of immunomodulatory monoclonal antibodies (mAbs) and IgG Fc fusion proteins are either approved or in early-to-late stage clinical trials for the treatment of chronic inflammatory conditions, autoimmune diseases and organ transplant rejection. The exquisite specificity of mAbs, in combination with their multi-functional properties, high potency, long half-life (permitting intermittent dosing and prolonged pharamcological effects), and general lack of off-target toxicity makes them ideal therapeutics. Dosing with mAbs for these severe and debilitating but often non life-threatening diseases is usually prolonged, for several months or years, and not only affects adults, including sensitive populations such as woman of child-bearing potential (WoCBP) and the elderly, but also children. Immunosuppression is usually a therapeutic goal of these mAbs and when administered to patients whose treatment program often involves other immunosuppressive therapies, there is an inherent risk for frank immunosuppression and reduced host defence which when prolonged increases the risk of infection and cancer. In addition when mAbs interact with the immune system they can induce other adverse immune-mediated drug reactions such as infusion reactions, cytokine release syndrome, anaphylaxis, immune-complex-mediated pathology and autoimmunity. An overview of the nonclinical safety assessment and risk mitigation strategies utilized to characterize these immunomodulatory mAbs and Fc fusion proteins to support first-in human (FIH) studies and futher clinical development in inflammatory disease indications is provided. Specific emphasis is placed on the design of studies to qualify animal species for toxicology studies, early studies to investigate safety and define PK/PD relationships, FIH-enabling and chronic toxicology studies, immunotoxicity, developmental, reproductive and juvenile toxicity studies and studies to determine the potential for immunosuppression and reduced host defence against infection and cancer. Nonclinical strategies to facilitate clinical and market entry in the most efficient timeframe are presented.

Abstract 497: Clinical Significance of Heparin Induced Thrombocytopenic Thrombotic Syndrome with Initiation of Anti-heparin Antibodies Negative: A Case Report and Literature Review

Introduction Heparin induced thrombocytopenia thrombosis Syndrome has a high mortality and morbidity in cardiac surgical patients in spite of early diagnosis and management. We present a case with multiple acute deep venous thrombosis (DVT) after using unfractionated heparin (UFH) during coronary artery bypass graft (CABG) with initiation of HIT antibodies negative. Case presentation A 70-year-old male complained of left leg pain 2 days after CABG for an acute ST-elevation myocardial infarction. Patient was treated with UFH intravenous during CABG. Platelet count was 78 x 109/L that was 130 x 109/L before the procedure. Anti-heparin antibodies IgM/IgG were negative. Venous Doppler ultrasound showed an acute deep venous thrombosis (DVT) in the left peroneal vein. However, after the patient was treated with Coumadin anticoagulation for 7 days with INR in therapeutic range (2-3), the patient presented for right low extremity pain. Platelet count was 40 x 109/L. Anti-heparin antibodies IgM and IgG were repeatedly positive. Venous Doppler ultrasound showed multiple bilateral lower extremities acute DVTs. Patient had thrombectomy and continued with coumadin anticoagulation at INR in therapeutic range for 3 months. Discussion HITTS is an immune-mediated drug reaction that occurs more frequently in patients undergoing cardiovascular surgery. Thrombosis caused by the HIT/T syndrome is most commonly venous thromboembolism. Thrombosis is arterial in about 20% of cases, including acute limb ischemia, myocardial infarction, or stroke. Previous clinical data has shown that about 40% of high titer-negative HIT antibodies were associated with a positive result in repeated testing several days later, which is the same as our presentation. The mortality and morbidity rates of HITTS are approximately 30% and 60%, respectively, and an additional ~10% of patients require amputations or suffer other major morbidity. However, with early recognition and intervention, mortality can be reduced from >30 to <10%. Obviously, repeated testing to identify patients who have HIT despite a negative initial HIT test in several days is greatly recommended. Diagnosis is essentially clinical and negative results from laboratory assays do not exclude the diagnosis.

Heparin-Induced Thrombocytopenia in Liver Transplant Recepients

Abstract 4668 Background:Heparin-induced thrombocytopenia (HIT) is an adverse immune-mediated drug reaction, resulting in a platelet count decrease of 50% within 5 to 10 days after heparin administration. HIT is often associated with venous and/or arterial thrombosis (HITT). The clinical course of HIT developing after liver transplantation (LT) had not been reported. Direct thrombin inhibitors (DTI) were reported to be safe and efficacious in patients who developed HIT yet their safety and efficacy had not been determined in patients who had LT. Also, the optimal management of HIT developing after LT has not been defined. Objectives:To evaluate the incidence and the clinical course of patients who developed HIT after LT and the safety of use of DTI in this population. Methods:We performed a retrospective analysis of all patients who had a LT and had clinical HIT confirmed by the anti-PF4/heparin (HIT) antibody by ELISA at our institution between January 2006 and July 2011. A positive test is defined as optical density of > 0.4 with > 50% inhibition. Bleeding was defined per GUSTO (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Arteries) scale. Alternate causes of thrombocytopenia were excluded by relevant hematologic testing. Results:During the study period, 438 patients received LT and163 patients were diagnosed with clinical HIT in our 689 bed hospital. Clinical HIT was confirmed in 11 LT patients (2.5%) based on a positive HIT antibody. LT cases constitute 11/163 (6.75%) of all HIT diagnosed in our center. Clinical characteristics of these are described in attached table. Previous thrombosis was reported in 7/11 (63%) patients, of these 5/11 (46%) received prior therapeutic anticoagulation. Baseline thrombocytopenia below 150K was present in 10/11 (90%) cases and 7/11 (63%) had INR prolongation ≥ 1.5. HIT was documented in 2 patients before LT, in 3 patients within 14 days of surgery and in 6 patients more than 14 days post LT. Six (54%) developed HITT and 7/11 (63%) were treated with a DTI (bivalirudin in 6 cases and argatroban in 1 case). On discharge 2/11 (18%) received fondaparinux and 5/11 (45%) received warfarin. Median dose of IV bivalirudin was 0.3 (0.09-0.89) mg/kg/hr. Platelet recovery was noted in all patients at mean of 9.8 (3-30) days. Progressive thrombosis was noted in 2/11 (18%). Moderate bleeding events within 40 days of LT included 2 gastrointestinal bleeds and one episode of epistaxis. Two traumatic bleeds occurred with prolonged anticoagulation for HITT. No deaths or amputations were documented as a direct consequence of HIT. Only one patient with HIT and LT died as a complication of sepsis.Clinical characteristics of HIT in LT patients: n=11M:F8:3Median age48 (18–75)%Platelet decline57% (16–94)Days from heparin exposure8 (3–20)Nadir platelet count40 (4–94)*4T score calculation:≤354–536–83Bleeding GUSTO scale:mild1 (9%)moderate3 (27%)severe0Progressive thrombosis2 (18%)*-one patient with myeloproliferative disease excluded. Conclusion:HIT is common (2.5%) in LT recipients despite low rates of deep venous thromboprophylaxis with heparin due to underlying coagulopathy. Basal thrombocytopenia is frequent in these patients and widely accepted 4T probability score has low predictive value. The risk of HITT and progressive thrombosis is high. Despite baseline coagulopathy, in our experience the use of DTI, especially bivalirudin, seems to be well tolerated and efficacious in this population. Future studies are needed to optimize dosing to reduce bleeding risk. Disclosures:Off Label Use: Use of bivalirudin and fondaparinaux in the treatment of heparin-induced thrombocytopenia.

Safety Assessment and Dose Selection for First-in-Human Clinical Trials With Immunomodulatory Monoclonal Antibodies

Modulating immune responses with monoclonal antibodies (mAbs) that target immune molecules has become a promising therapeutic strategy and is under investigation for the treatment of cancer and (auto)-immune diseases. A major hurdle to the development and early clinical investigation of many immunomodulatory mAbs is the inherent risk of adverse immune-mediated drug reactions in humans, such as cytokine storms, autoimmunity, and immunosuppression. Dose selection for first-in-human (FIH) clinical trials involving immunomodulatory mAbs, and mAbs in general, is based on specifically designed preclinical safety studies, primarily in nonhuman primates (NHPs), and on mechanistic ex vivo investigations. Dose selection in such trials is challenging for a number of reasons related to safety. In this context, safety-relevant differences between NHP and human immune systems, species selection/qualification and preclinical study design considerations, the receptor occupancy model and its calculation, the minimal anticipated biological effect level (MABEL) and its use in the selection of a safe starting dose in humans, microdosing and the impact of immunogenicity on safety assessment of mAbs, and safety-relevant formulation properties of therapeutic mAbs are critically reviewed. In addition, the current regulatory requirements are presented and discussed to demonstrate how the TeGenero TGN1412 case is leading to increased regulatory scrutiny regarding dose selection for FIH clinical trials.

Hairdye-induced hepatitis: An unusal cause of acute hepatitis

Sir, We present an unusual case of acute hepatitis caused by hair dye. Hair dye contains various mutagenic and carcinogenic chemicals and is examined as a risk factor for various malignancies. Hair dye-induced hepatitis is a rare condition. There is only one case of hair dye-induced hepatitis reported in the literature.[1] A 33-year-old healthy young female presented with pruritus, skin lesions and jaundice 2 days after using a new hair dye rather than her usual one. Clinically, she was febrile, icteric, with hepatosplenomegaly but no ascites. Laboratory investigations showed hypereosinophilia of 20%, abnormal liver profile with total bilirubin of 13.5 mg/dL, conjugated 6.8 mg/dL, alanine transaminase 190 IU/L, aspartate transminase 152 IU/L, alkaline phosphatase of 227 IU/L and albumin being 3.7 g/dL. An ultrasound of the abdomen showed features of acute hepatitis and a normal biliary system. The prothrombin time was normal. Work-up for acute hepatitis indicated negative IgM antibody for hepatites A, E, and anti-HBc antibody. Additionally, hepatitis B virus DNA was undetectable. Serology for cytomegalovirus, Herpes simplex virus, Epstein barr virus, leptospira and malaria were negative. Wilson's and autoimmune markers were also negative. Drug-induced hepatitis was considered in view of chronology of events. Because the patient had an allergic reaction, lymphocyte activation test was performed to study if the hair dye in question induced immune-mediated drug reaction leading to acute hepatitis. Lymphocytes were isolated using Histopaque, 1077 (Sigma-Aldrich, St.louis, USA) by centrifugation.[2] Lymphocytes from a normal person and from a patient were subjected to hair dye exposure. Control was patient lymphocytes without hair dye. Suspension from the reaction mixture was taken out at different intervals and smears were examined for lymphocyte reactivity and adenosine deaminase (ADA) level represent lymphocyte activation. At the end of 60 min, 70% and at the second hour, 90% of the lymphocytes were activated as against the normal lymphocytes with no reactivity and only 3% of the controls. The ADA levels increased by 20% and 30% by the end of the first and second hour, respectively. Results obtained in this in vitro lymphocyte activity experiment strongly suggest that hair dye causes immune-mediated drug reaction in hypersensitive individuals [Figure 1]. Figure 1 All reactive lymphocytes after 20 hours of incubation (oil immersion pictures) Hair dye is a well-recognized cause of contact dermatitis. Routinely used hair dyes contain multiple components viz Toluene-2, 5-diamine, resorcin, cetearyl alcohol, polyethylene glycol, etc. Chemicals of the hair dye can be absorbed into the body through a wound, damaged skin or by aspiration of the spray during dyeing. The pathogenesis of drug-induced hepatotoxicity usually involves either the parent drug or its metabolite, which affects the hepatocytes directly or elicits an immune response.[3] The chronological course of the present patient, allergic skin manifestations and in vitro lymphocyte reactivity to hair dye supported hair dye-induced immune-mediated hepatitis.[4] Liver biopsy was not performed as investigations supported diagnosis and her liver functions improved after 2 weeks of cessation of hair dye. Thus, the present case suggests a possible role of hair dye in inducing an immune-mediated drug reaction in hypersensitive individuals and a lymphocyte activation test may be utilized to diagnose the immune-mediated drug-induced hepatotoxicity.

A simple measure to reduce the incidence of heparin induced thrombocytopenia (HIT) in cardiac intensive care patients – a retrospective observational analysis

Heparin induced thrombocytopenia (HIT) is an immune-mediated drug reaction associated with the administration of heparin that leads to a reduced platelet count. HIT has an incidence in the general population of around 3% and causes arterial and venous thromboses that are life threatening. The diagnosis of HIT should be considered if the platelet count falls by 50% or more or below the laboratory normal range [1]. The pathophysiology involves development of IgG antibodies that recognise and bind the platelet factor 4/heparin complex resulting in platelet aggregation and thrombus formation. Our unit stopped adding heparin to the pressure transducer flush systems in both theatres and cardiac intensive care unit (CICU) and the aim of this observational study was to audit the effect on the incidence of HIT. All patients with a diagnosis of HIT who tested antibody positive on an enzyme- linked immunosorbent assay (ELISA) for the HIT antibody between 30 January 2006 and 22 March 2007 were identified (Group 1). Following removal of heparin from pressure transducer flush, HIT positive patients were also identified between 23 March 2007 and 23 March 2008 (Group 2) The incidences of HIT were compared between the groups. Twenty-one of 884 patients identified in Group 1 were HIT antibody positive whilst eight of the 802 patients in Group 2 were HIT antibody positive (p < 0.03, Chi squared test). Eleven of the 29 patients from both groups who were HPIA positive died before leaving hospital. Before March 2007, the incidence of HIT on our cardiac unit was 2.6% which is in line with the national incidence. In the year following the removal of heparin from pressure transducer flush systems, our incidence of HIT fell to 1%. This action along with use of the British Society of Haematology 2006 guidelines for the estimation of pre-test probability (the 4 Ts) happened simultaneously and both may have contributed to the decreased incidence [1]. Removing heparin from the flush systems may not only have decreased the incidence of HIT and prevented life-threatening complications but it also less expensive (500 ml saline £0.40 versus 500 ml heparinised saline £3.88). Potentially, it also reduces the number of patients who have prolonged stays in the CICU which would have a less easily quantified cost saving [2]. We thank the Department of Haematology, University Hospital of Wales and Prof J. Hall, Head of Department of Anaesthesia, UHW.

Frequency of Heparin-Induced Thrombocytopenia and Heparin-Dependent IgG Antibodies in Hematopoietic Stem Cell Transplant Recipients.

BackgroundHeparin-induced thrombocytopenia (HIT) is an immune-mediated drug reaction in which heparin-dependant IgG antibodies (HIT-IgG) to heparin-platelet factor 4 complexes form with the potential for platelet activation with resultant thrombocytopenia (HIT) and thrombosis (HITT). The frequency of HIT-IgG formation and clinically apparent HIT or HITT varies considerably, according to the patient population (surgical versus medical) and type of heparin (unfractionated [UFH] vs low molecular weight [LMWH]). One large prospective study showed a frequency of HIT-IgG formation of 7.5% with clinical HITT in 34.5% of these orthopedic patients receiving prophylactic LMWH and corresponding figures in cardiac surgery patients receiving UFH were 50% and 2%, respectively [Warkentin et al. Blood 2000; 96: 1703]. Due to daily exposure to heparin flushes (UFH) and prophylactic LMWH (to prevent venoocclusive disease) hematopoietic stem cell transplant (HSCT) recipients may be at risk for HIT/HITT. However, due to anticipated post-transplant thrombocytopenia, clinical cases of HIT/HITT may be overlooked. We retrospectively determined the incidence of HIT-IgG formation and its clinical significance in this population.Methods: HIT-IgG was measured retrospectively using a commercially available ELISA kit in samples collected from patients prior to conditioning therapy and on day 14 post-HSCT. Medical records were reviewed to in order to determine the clinical significance (development of clinical HIT/HITT) in those with detectable HIT-IgG.PatientsSamples from a total of 103 HSCT recipients with hematologic malignancy (including 25 myeloma, 17 lymphoma, 16 AML, 14 amyloid, 10 MDS, 10 ALL, 8 CML and 3 CLL) were tested, of which 52 and 49 underwent allogeneic and autologous HSCT, respectively. All patients were exposed to UFH flushes during line care. In addition, all allogeneic recipients received prophylactic subcutaneous dalteparin 5000U daily beginning with conditioning until engraftment. Conditioning regimens included high dose melphalan (n=34), cyclophosphamide/TBI (n=30), carmustine, etoposide, cytarabine, melphalan (n=15), busulfan/cyclophosphamide (n=9), fludarabine/melphalan (n=10) and fludarabine/TBI (n=4). The median age was 51.5 years (20–72) and 68 were male.Results:The median platelet count prior to initiation of conditioning therapy and at day 14 was 157 × 109/L (range: 10–672) and 40 × 109/L (range: 9–289), respectively. Prior to conditioning, two of 103 (1.9%) patients had a positive HIT-IgG assay, that became negative in one and equivocal in the other by day 14 post-HSCT, and one patient had an equivocal HIT assay that became negative by day 14. All 3 were autologous recipients. None of the previously negative patients had a positive HIT-IgG assay at day 14, although 3 patients (2 autologous and one allogeneic) had an equivocal result of uncertain significance. No patients developed clinical or symptomatic thrombosis (HITT).Conclusion:In spite of frequent exposure to heparin, the frequency of seroconversion is low, and in those patients with preexisting HIT-IgG, no patient developed symptomatic thrombosis, including the 2 patients with positive HIT IgG assays prior to conditioning. The low frequency of HIT-IgG formation may reflect the profound immunosuppression of the conditioning regimens employed. Nevertheless, in this population, a high index of clinical suspicion must be maintained.

Pattern of Platelet Recovery in Predicting Outcome in Heparin-Induced Thrombocytopenia and Thrombosis.

Heparin-induced thrombocytopenia and thrombosis (HITT), a severe immune-mediated drug reaction, is often underdiagnosed. Early management of HITT with alternative anticoagulants can result in a favorable outcome. However, the morbidity and mortality associated with HITT remain high, posing challenges for patient management. We describe the clinical profile and pattern of platelet count recovery in a cohort of 34 patients diagnosed with HITT. This retrospective study consists of 164 patients screened for HITT over 18 months at our institution based on positive platelet factor 4 (PF4) IgG antibodies in the proper clinical setting. Patients who tested positive were divided on the basis of recovery of platelet count (increase to >100 × 109/L or by 1.5-fold by day 5 of diagnosis) into two groups: delayed and normal recovery. Of the 164 patients screened, 107 were admitted with cardiac diseases while 57 non-cardiac conditions. A total of 34 patients (21%) were tested positive for PF4 antibodies. Patients with underlying cardiac conditions were more likely to be diagnosed with HITT than non-cardiac patients (28% versus 7%, p=0.0012). The male to female ratio was 1:1.1, and the median age was 65 years. Nineteen of 34 patients (56%) had delayed platelet recovery, while the remaining 15 patients (44%) had normal platelet recovery by day 5. The mortality rate was 68% (13 of 19) in the delayed recovery group, compared to only 7% (1 of 15) in the normal recovery group (p=0.0004). Twelve of the 34 patients with liver dysfunction had delayed platelet recovery and died (figure 1). There were 6 venous and 5 arterial thrombotic episodes. A total of 13 patients (38%) were treated with Argatroban, a direct thrombin inhibitor (DTI) indicated for the treatment of HITT, but it did not seem to improve platelet recovery (Table 1). Eight of the 13 treated patients (62%) and 11 of the 21 untreated patients (52%) showed no platelet recovery by day 5. In conclusion, early diagnosis of HITT is critically important for patient management, and yet, diagnosis is often elusive due to a general lack of awareness of this condition. Underlying cardiac diseases appear to predispose patients to HITT, probably due to previous exposure and sensitization to heparin. Despite the availability of new anticoagulants, HITT remains an undertreated and highly fatal condition with overall mortality of 38% in our series. Underlying liver dysfunction appears to be associated with delayed platelet recovery and poor survival. Affect of DTI on platelet recovery needs to be further investigated. Optimal response to therapy requires early diagnosis and intervention. Further studies are necessary to enhance our understanding of this devastating condition to facilitate early diagnosis and proper treatment.Treatment and Survival of HITT PatientsOutcomeTreated with DTINot treatedTotalDead6713Alive71421Total132134 [Display omitted] [Display omitted]

Management of liver transplantation in a patient with a history of heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is an adverse immune-mediated drug reaction in which antibodies are generated usually towards complexes of the soluble platelet protein platelet-factor-4 (PF4) and heparin. The resulting immune complexes activate platelets intravascularly, which increases the generation of thrombin. Therefore, HIT is strongly associated with thrombosis and heparin is thought to be contraindicated. As HIT antibodies decline rapidly in titre, short-term re-exposure to heparin is feasible in special situations. We report an uneventful liver transplantation of a heparinized donor in a patient with a 20-month history of HIT. Before, 2, 5, 12 and 25 days after transplantation, the patient's blood was drawn for analysis of heparin-induced antibodies by a functional assay (HIPA) and by an antigen assay (PF4-heparin/ELISA). Lepirudin was used for postoperative anticoagulation. Apart from hepatic artery bleeding, the clinical course was uncomplicated, neither thrombocytopenia nor thromboembolic complications occurred. Weak heparin-induced platelet activation, caused by pre-existing HIT antibodies was detected before and 12 days after transplantation by the HIPA test; moreover borderline amounts of anti-PF4-heparin antibodies were found. Twenty months after an episode of HIT, a patient may receive an organ from a heparin-treated donor without risk of thrombocytopenia or thromboembolic complications. Avoidance of heparin for postoperative anticoagulation is recommended.