Check Point SOS! A Case of Cemiplimab-Associated Sinusoidal Obstruction Syndrome

Introduction: Hepatic veno-occlusive disease (VOD) or sinusoidal obstruction syndrome (SOS), is a clinical syndrome characterized by hepatomegaly, right-upper quadrant pain, and ascites that occurs most commonly in the setting of high-dose chemotherapy or hematopoietic stem cell transplantation (HSCT). The diagnosis can be confirmed on biopsy. Cemiplimab is an immune checkpoint inhibitor recently approved for the treatment of cutaneous squamous cell carcinoma. There are currently no known reports of immune checkpoint inhibitor-related VOD/SOS. Case Description/Methods: A 58-year-old female with a history of locally advanced basal cell carcinoma of the left eye treated with six months of Cemipilimab presented with ascites. On admission, labs were notable for a total bilirubin of 1.2, mildly elevated liver function tests, alkaline phosphatase 884, and international normalized ratio 2.1. A diagnostic tap revealed a high SAAG ascites that was negative for infection. A comprehensive serological workup for viral, metabolic and autoimmune causes was unrevealing. A transjugular liver biopsy demonstrated a hepatic venous pressure gradient of 18mmHg, nodular regenerative hyperplasia (NRH), and portal venopathy. The patient was discharged on steroids but returned one month later for recurrent ascites and worsening bilirubin to 12.6 (direct 7.3);COVID PCR was negative. A full rheumatologic and vasculitis workup was unremarkable. Repeat biopsy (Figure 1) demonstrated moderate NRH changes, prominent central vein sclerosis with fibrous obliteration, signs of SOS/ VOD and central venulitis with fibrotic changes with sinusoidal portal hypertension. Discussion(s): VOD occurs most often with hematopoietic stem cell transplantation, and chemotherapeutic agents. Here we present the first case of checkpoint inhibitor-induced VOD/SOS. Despite discontinuation of the offending agent and a trial of steroids, the patient's clinical course continued to deteriorate. She eventually developed refractory ascites and portosystemic encephalopathy. She was deemed not a candidate for liver transplant given her underlying malignancy. She was transitioned to home hospice before further treatment, such as Defibrotide could have been pursued. VOD associated with immune checkpoint inhibition should be considered in the differential of patients who develop new onset liver dysfunction and ascites while receiving these medications (Figure Presented).

TCR Alpha Beta and CD19+ Depleted Haploidentical Peripheral Stem Cell Transplantation Using Reduced Toxicity Conditioning Regimen with Pharmacokinetics Guided Busulfan, Fludarabine, Thiotepa and Thymoglobulin Offers Durable Donor Engraftment in Children with Primary Immune Deficiency Disorders

Background: Allogeneic hematopoietic cell transplantation (HCT) with ex vivo T cell receptor (TCR) alphabeta+ T cell and CD19+ B cell depletion is an effective approach for children with primary immune deficiency disorders (PIDD) as it combines advantages of high CD34+ cell dose facilitating rapid engraftment with low risk of Graft Versus Host Disease (GVHD). The ideal pre-conditioning regimen that facilitates robust donor engraftment without increasing risk of transplant related mortality has not been well defined with this approach. Method(s): We report the outcomes of 4 pediatric subjects: Chronic Granulomatous Disease (CGD) (2), Wiskott Aldrich Syndrome (WAS) (1), and RAC2 deficient Severe Combined Immunodeficiency (1) who underwent haploidentical HCT with TCRalphabeta+ T cell/CD19+ depletion at Johns Hopkins All Children's Hospital/Moffitt Cancer Center from 2020-2022 (NCT04414046). Pre-conditioning regimen consisted of distal thymoglobulin (7.5 mg/kg), fludarabine (175 mg/m2), thiotepa (10 mg/kg) and pharmacokinetic guided busulfan targeting a cumulative area under curve (cAUC) (65-75 mgxhr/L). Rituximab (200 mg/m2) was administered on day +1. Result(s): The median age at HCT was 51 months (range 10-163 months). All patients received mobilized peripheral blood stem cells from HLA- haploidentical donors (paternal=1, maternal=1 sibling=2). Median busulfan cAUC for all patients was 69 mgxhr/L (range 65-76). Median CD34 and TCR alphabeta T cell dose was 9.13x106 cells/kg (range 7.0-18.9x106) and 0.7x105 cells/kg (range 0.09-1.0x105). Median times to neutrophil and platelet engraftment were 11 days (9-12) and 11 days (range 8-15), respectively. All 4 patients are alive with median follow-up of 19.5 months (range 7-24). One patient developed late VOD without organ dysfunction that resolved with defibrotide. At last follow up, peripheral T and myeloid chimerisms exceeded 90% in all 4 patients. Average time to CD4 recovery (> 200x106/L) was 142 days. Pre-existing inflammatory bowel disease in CGD (n=1) and WAS (n=1) patients resolved immediately following transplant. There was no graft failure, and none developed Grade III-IV acute or extensive chronic GVHD. Patient with WAS developed recurrent autoimmune cytopenias requiring corticosteroids, rituximab, sirolimus and daratumumab, and ultimately resolved. Viral reactivations included EBV (n= 1), adeno (n= 1), HHV6 (n= 2), BK (n=1), norovirus (n=1), and late HSV (n=1), all responded to antivirals without disease. All patients acquired SARS-Cov-2 after transplant and recovered without sequelae. Conclusion(s): TCR alphabeta+ and CD19+ depleted haploidentical transplantation using a reduced toxicity conditioning regimen with pharmacokinetic guided busulfan, fludarabine, thiotepa and thymoglobulin is well-tolerated in young children with PIDD that results in rapid, durable engraftment with low likelihood of GVHD and graft rejection.Copyright © 2023 American Society for Transplantation and Cellular Therapy

Defibrotide mitigates endothelial cell injury induced by plasmas from patients with COVID-19 and related vasculopathies.

BACKGROUND AND OBJECTIVES: COVID-19 progression is characterized by systemic small vessel arterial and venous thrombosis. Microvascular endothelial cell (MVEC) activation and injury, platelet activation, and histopathologic features characteristic of acute COVID-19 also describe certain thrombotic microangiopathies, including atypical hemolytic-uremic syndrome (aHUS), thrombotic thrombocytopenic purpura (TTP), and hematopoietic stem cell transplant (HSCT)-associated veno-occlusive disease (VOD). We explored the effect of clinically relevant doses of defibrotide, approved for HSCT-associated VOD, on MVEC activation/injury. METHODS: Human dermal MVEC were exposed to plasmas from patients with acute TMAs or acute COVID-19 in the presence and absence of defibrotide (5µg/ml) and caspase 8, a marker of EC activation and apoptosis, was assessed. RNAseq was used to explore potential mechanisms of defibrotide activity. RESULTS: Defibrotide suppressed TMA plasma-induced caspase 8 activation in MVEC (mean 60.2 % inhibition for COVID-19; p = 0.0008). RNAseq identified six major cellular pathways associated with defibrotide's alteration of COVID-19-associated MVEC changes: TNF-α signaling; IL-17 signaling; extracellular matrix (ECM)-EC receptor and platelet receptor interactions; ECM formation; endothelin activity; and fibrosis. Communications across these pathways were revealed by STRING analyses. Forty transcripts showing the greatest changes induced by defibrotide in COVID-19 plasma/MVEC cultures included: claudin 14 and F11R (JAM), important in maintaining EC tight junctions; SOCS3 and TNFRSF18, involved in suppression of inflammation; RAMP3 and transgelin, which promote angiogenesis; and RGS5, which regulates caspase activation and apoptosis. CONCLUSION: Our data, in the context of a recent clinical trial in severe COVID-19, suggest benefits to further exploration of defibrotide and these pathways in COVID-19 and related endotheliopathies.

Defibrotide Therapy for SARS-CoV-2 ARDS.

BACKGROUND: SARS-CoV-2-related ARDS is associated with endothelial dysfunction and profound dysregulation of the thrombotic-fibrinolytic pathway. Defibrotide is a polyanionic compound with fibrinolytic, antithrombotic, and antiinflammatory properties. RESEARCH QUESTION: What is the safety and tolerability of defibrotide in patients with severe SARS-CoV-2 infections? STUDY DESIGN AND METHODS: We report a prospective, open-label, single-center safety trial of defibrotide for the management of SARS-CoV-2-related ARDS. Eligible participants were 18 years of age or older with clinical and radiographic signs of ARDS, no signs of active bleeding, a serum D-dimer of more than twice upper limit of normal, and positive polymerase chain reaction-based results for SARS-CoV-2. Defibrotide (6.25 mg/kg/dose IV q6h) was administered for a planned 7-day course, with serum D-dimer levels and respiratory function monitored daily during therapy. RESULTS: Twelve patients (median age, 63 years) were treated, with 10 patients receiving mechanical ventilation and 6 receiving vasopressor support at study entry. The median D-dimer was 3.25 µg/ml (range, 1.33-12.3) at study entry. The median duration of therapy was 7 days. No hemorrhagic or thrombotic complications occurred during therapy. No other adverse events attributable to defibrotide were noted. Four patients met the day 7 pulmonary response parameter, all four showing a decrease in serum D-dimer levels within the initial 72 h of defibrotide therapy. Three patients died of progressive pulmonary disease 11, 17, and 34 days after study entry. Nine patients (75%) remain alive 64 to 174 days after initiation of defibrotide. Day 30 all-cause mortality was 17% (95% CI, 0%-35%). All patients with a baseline Pao2 to Fio2 ratio of ≥ 125 mm Hg survived, whereas the three patients with a baseline Pao2 to Fio2 ratio of < 125 mm Hg died. INTERPRETATION: The use of defibrotide for management of SARS-CoV-2-related ARDS proved safe and tolerable. No hemorrhagic or thrombotic complications were reported during therapy, with promising outcomes in a patient population with a historically high mortality rate. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT04530604; URL: www. CLINICALTRIALS: gov.

Use of Defibrotide in Patients with COVID-19 Pneumonia;Results of the Defi-VID19 Phase 2 Trial

Background: The clinical spectrum of COVID-19 ranges from pauci-symptomatic forms to severe disease characterized by respiratory failure requiring mechanical ventilation and intensive care unit (ICU) management, as well as multisystem involvement characterized by sepsis, organ dysfunction and death. Treatment of COVID-19 is not standardized, and respiratory failure from ARDS is the leading cause of mortality;in-hospital mortality at 28-days in our tertiary care center in Lombardia, northern Italy was 23% during the first wave in 2020(Ciceri et al. 2020). Endothelial damage and thrombo-inflammation have been identified as common to both COVID-19 pathophysiology and veno-occlusive disease (VOD/SOS). Defibrotide (DF) has endothelial-protective properties, with pro-fibrinolytic, anti-thrombotic, anti-ischemic, anti-inflammatory, and anti-adhesive activity, but no significant systemic anticoagulant effects and is approved for the treatment of severe VOD/SOS. Aim: A prospective, multicenter, phase II, single-arm, open label trial (DEFI-VID19, NCT04335201) was conducted in patients (pts) with COVID-19 ARDS to evaluate the efficacy of DF in addition to best available therapy per institutional guidelines. The primary endpoint was respiratory-failure rate (RFR) defined as progression of respiratory failure, i.e. severe gas transfer deficit (PaO2/FiO2<200 mmHg), need of ICU or death at day+14 from treatment start. Secondary endpoints included overall survival (OS) at 28 days, duration of hospitalization and safety. A sample size of 50 pts was calculated to detect an absolute reduction of 20% in RFR at day+14, assuming a failure rate in non-treated pts of 70% (alpha=5%, power=90%, two-sided test). Pts received DF intravenously at 6.25 mg/kg/dose by 2-hour infusion repeated every 6 hours. Expected treatment duration was 14 days, with earlier discontinuation if clinical improvement occurred. LMWH at prophylactic dose was allowed. Approval was provided by the National IRB for COVID-19 trials at Institute Spallanzani (Rome) and by the Italian Agency for Drug (AIFA). All patients provided written informed consent. Results: Overall, 52 pts were enrolled from September 2020 to April 2021;48 were evaluated for efficacy and safety;4 pts were excluded due to screen failure (n=2) or withdrawal of informed consent at day 2 after defibrotide was initiated (n=2). Median age was 60.5 years (range 53-71);35 pts (73%) were male and 65% had comorbidities, with high blood pressure, obesity and COPD most common. Two pts had pre-existing diagnoses of non-Hodgkin lymphoma. Median time from onset of COVID-19 symptoms and from Sars-COV2 PCR by nasal swab to enrollment were 8 (range 7-10) and 3 days (range 1-6), respectively. All pts were hospitalized and scale 5 of 8-category ordinal scale by WHO criteria, requiring noninvasive ventilation with CPAP or high-flow oxygen, with a median P/F ratio of 211 (range 134-275) mmHg. At treatment start, the median and (range) lymphocyte counts, LDH, CRP, ferritin, D-dimer and IL-6 were 0.7 (0.5-0.9) x 10e9/L;404 (291-491) U/L;49 (22-97) mg/L;823 (363-1088) ng/ml;0.44 (0.28-1.29) µg/mL and 20 (11-32), respectively. Median treatment duration was 8.5 days (range 6-11). Overall, 13/48 pts (27%) discontinued the treatment due to clinical worsening and/or need of further therapies: 9 pts experienced progressive respiratory failure and 6 of those were transferred to ICU for IOT (one pt required ECMO), and 4 required full anticoagulation due to pulmonary embolism (n=1), ischemic stroke (n=1), and femoral deep venous thrombosis (n=2). All pts who completed the treatment 35/48 (73%) were discharged with no need of oxygen support. Overall, 14 SAEs have been reported in a median time of 6 days (range 2-10): all unrelated to DF. No pts experienced hemorrhagic events. The incidence of RFR at day 14 was 25 (+/- 6)%, and at day 28, 27 (+/- 6) %. Probability of OS at day 28 was 89 (+/-4) %, at day 60 83 (+/- 5)%. Overall, 8 pts died from COVID-19 -related complications. No pts required re-admission after hospital discha ge (median 14 days) or died after discharge. Conclusion: Treatment with DF in pts with grade 5 WHO COVID 19 ARDS does not induce bleeding, and is associated with rapid restoration of respiratory function (73% of pts). Notably, no oxygen support was needed at discharge and a 1-month OS rate of 89% was observed, which is higher than historical controls (77%) treated in the same setting. Disclosures: Richardson: Takeda: Consultancy, Research Funding;AbbVie: Consultancy;Karyopharm: Consultancy, Research Funding;AstraZeneca: Consultancy;Oncopeptides: Consultancy, Research Funding;Jazz Pharmaceuticals: Consultancy, Research Funding;Protocol Intelligence: Consultancy;Secura Bio: Consultancy;Regeneron: Consultancy;Celgene/BMS: Consultancy, Research Funding;GlaxoSmithKline: Consultancy;Janssen: Consultancy;Sanofi: Consultancy. Ciceri: IRCCS Ospedale San Raffaele: Current Employment. Carlo-Stella: Incyte: Honoraria;Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding;Sanofi: Consultancy, Research Funding;AstraZeneca: Honoraria;Celgene: Membership on an entity's Board of Directors or advisory committees;ADC Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding;Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees;Janssen Oncology: Honoraria;Karyopharm Therapeutics: Membership on an entity's Board of Directors or advisory committees.

Defibrotide Therapy for Sars CoV2 Acute Respiratory Distress Syndrome

Background: SARS-CoV-2 related acute respiratory distress syndrome (ARDS) is associated with endothelial dysfunction and profound dysregulation of the thrombotic/fibrinolytic pathway, with thrombotic complications common in affected patients (pts). Fibrin deposition may be a key feature of the pathobiology, with markedly elevated levels of PAI-1 reported. Defibrotide (DF), a polyanionic naturally-derived polydeoxyribonucelotide with endothelial stabilizing activity, has fibrinolytic, antithrombotic and anti-inflammatory properties, with known activity in reducing PAI-1 levels and inhibiting heparanase. We now report a prospective, open label, safety and tolerability trial of defibrotide for the management of patients with advanced SARS-CoV-2 related ARDS. Patients and Methods: Eligible patients (pts) were ≥18 years in age, with clinical and radiographic signs of ARDS, no signs of active bleeding, a serum D-Dimer > 2X ULN, and a positive PCR-based assay for SARS-CoV-2. Concomitant use of systemic anticoagulants or fibrinolytics was initially precluded, with the study amended to allow prophylactic doses of systemic heparin in its latter stages. Defibrotide (6.25 mg/kg/dose IV q. 6 hours) was administered for a planned 7-day course, with day 1 defined as the first day of study therapy. Therapy was able to be discontinued prior to day 7 in pts who met the pulmonary response parameter at that earlier timepoint. Patients with a partial response to therapy (> 20% reduction in FiO2) by day 7 were allowed to receive an additional 7 days of therapy (14 days total). Response was defined as complete cessation of supplemental O2 support, or ≥ 2 point reduction in WHO ordinal score for 48 consecutive hours by day 7. Patients were recruited from a single center between October 2020 and March 2021. Results: Twelve pts (median 63 years, range 35-73 years) were treated, with 10 of 12 pts on mechanical ventilation (median FiO2 55%, PEEP 18 mmHg), and six on vasopressor support at the time of study entry. Baseline PaO2/FiO2 ratios ranged from 82 - 200 mmHg. The median D-Dimer was 3.25 mcg/ml (range 1.33-12.3 mcg/ml), and fibrinogen 637 mg/dl (range 250-1208 mg/dl) at study entry. Dexamethasone and remdesivir had been administered prior to DF in all pts, with no other SARS-CoV-2 targeted treatment given during DF therapy. Eleven pts received ≤7 days of therapy, with one pt receiving 14 days. The first 9 pts received DF without other concomitant anticoagulants, with the last 3 pts concurrently receiving prophylactic heparin plus DF. No hemorrhagic or bleeding complications occurred during DF therapy, including the 3 pts receiving concurrent heparin prophylaxis. Likewise, no thrombotic complications developed during study therapy, including the 9 patients in which DF was their sole anti-coagulant. All 12 patients were evaluable for response. Four pts met the day 7 pulmonary response parameter, with 2 pts having a complete cessation of O2 support within this period. Three pts died from progressive pulmonary disease, at 11, 17 and 34 days from study entry. The 3 pts (who died) had the lowest baseline PaO2/FiO2 ratios (82-115 mmHg) of all study subjects. Nine pts (75%) remain alive, 64 to 174 days from study entry, all 9 discharged from their primary hospitalization. Day 30 all-cause mortality was 17% (95%CI: 0-35%). Serial coagulation and fibrinolytic assays were available in 7 patients. Total PAI-1 levels decreased from a median 167 ng/ml (range 105-264 ng/ml) to a median 104 ng/ml (range 55-166 ng/ml) by day 4 of therapy, with all 7 subjects showing a decline in PAI-1 levels at that time point. Total tPA levels increased from a median 3.02 ng/ml (range 0.72 - 36.1 ng/ml) at baseline to 4.5 ng/ml (range 1.1-8.2 ng/ml) by day 4 in study subjects. Allowing for the small sample size, baseline PAI-1, tPA or D-Dimer levels did not impact response. One of two patients with a baseline D-Dimer > 10 mcg/ml responded, while both patients with a baseline D-Dimer <2.0 mcg/ml failed to meet the response parameter. Conclusion: The use of DF for t e management of SARS-CoV-2-related ARDS proved safe and tolerable in a prospective, open label trial. No hemorrhagic or thrombotic complications were reported during therapy. Outcomes were promising, including an overall survival of 75% in a patient population with a historically high mortality rate. (The study was supported by a research grant from Jazz Pharmaceuticals) Disclosures: Yanik: Jazz Pharmaceutical: Research Funding. Pipe: Sangamo Therapeutics: Other: Scientific Advisory Board;ASC Therapeutics: Other: Scientific Advisory Board;Apcintex: Consultancy;Bayer: Consultancy;Biomarin: Consultancy;Catalyst Biosciences: Consultancy;CSL Behring: Consultancy;Freeline: Consultancy;Grifols: Consultancy;HEMA Biologics: Consultancy;Novo Nordisk: Consultancy;Octapharma: Consultancy;Pfizer: Consultancy;Roche: Consultancy;Sanofi: Consultancy;Takeda: Consultancy;Spark Therapeutics: Consultancy;uniQure: Consultancy. Sisson: Translatebio: Other: Data Safety Committee member. Richardson: Celgene/BMS: Consultancy, Research Funding;Karyopharm: Consultancy, Research Funding;Oncopeptides: Consultancy, Research Funding;Janssen: Consultancy;Secura Bio: Consultancy;AstraZeneca: Consultancy;Takeda: Consultancy, Research Funding;Regeneron: Consultancy;AbbVie: Consultancy;Protocol Intelligence: Consultancy;GlaxoSmithKline: Consultancy;Sanofi: Consultancy;Jazz Pharmaceuticals: Consultancy, Research Funding. Lawrence: MDI Therapeutics: Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: Defibrotide: Off label use for ARDS

Defibrotide: potential for treating endothelial dysfunction related to viral and post-infectious syndromes.

INTRODUCTION: Defibrotide (DF) is a polyribonucleotide with antithrombotic, pro-fibrinolytic, and anti-inflammatory effects on endothelium. These effects and the established safety of DF present DF as a strong candidate to treat viral and post-infectious syndromes involving endothelial dysfunction. AREAS COVERED: We discuss DF and other therapeutic agents that have the potential to target endothelial components of pathogenesis in viral and post-infectious syndromes. We introduce defibrotide (DF), describe its mechanisms of action, and explore its established pleiotropic effects on the endothelium. We describe the established pathophysiology of Coronavirus Disease 2019 (COVID-19) and highlight the processes specific to COVID-19 potentially modulated by DF. We also present influenza A and viral hemorrhagic fevers, especially those caused by hantavirus, Ebola virus, and dengue virus, as viral syndromes in which DF might serve therapeutic benefit. Finally, we offer our opinion on novel treatment strategies targeting endothelial dysfunction in viral infections and their severe manifestations. EXPERT OPINION: Given the critical role of endothelial dysfunction in numerous infectious syndromes, in particular COVID-19, therapeutic pharmacology for these conditions should increasingly prioritize endothelial stabilization. Several agents with endothelial protective properties should be further studied as treatments for severe viral infections and vasculitides, especially where other therapeutic modalities have failed.

Defibrotide for the Treatment of Pediatric Inflammatory Multisystem Syndrome Temporally Associated With Severe Acute Respiratory Syndrome Coronavirus 2 Infection in 2 Pediatric Patients.

The pediatric inflammatory multisystem syndrome temporally associated with severe acute respiratory syndrome coronavirus 2 infection is a severe complication of coronavirus disease 2019. Since impaired coagulation and thrombosis/endotheliitis are suspected pathomechanisms, we treated 2 patients with defibrotide, a profibrinolytic, antithrombotic, antiinflammatory oligonucleotide. Symptoms resolved during treatment. Moreover, coagulation parameters indicating hypofibrinolysis and complement activation normalized. The pediatric inflammatory multisystem syndrome temporally associated with severe acute respiratory syndrome coronavirus 2 infection is a severe complication of coronavirus disease 2019. Since impaired coagulation and thrombosis/endotheliitis are suspected pathomechanisms, 2 patients received defibrotide, a profibrinolytic, antithrombotic, antiinflammatory oligonucleotide. Symptoms resolved and hypofibrinolysis/complement activation normalized during treatment.