Cardiopulmonary Complications after Pulmonary Embolism in COVID-19.

Although pulmonary embolism (PE) is a frequent complication in COVID-19, its consequences remain unknown. We performed pulmonary function tests, echocardiography and computed tomography pulmonary angiography and identified blood biomarkers in a cohort of consecutive hospitalized COVID-19 patients with pneumonia to describe and compare medium-term outcomes according to the presence of PE, as well as to explore their potential predictors. A total of 141 patients (56 with PE) were followed up during a median of 6 months. Post-COVID-19 radiological lung abnormalities (PCRLA) and impaired diffusing capacity for carbon monoxide (DLCOc) were found in 55.2% and 67.6% cases, respectively. A total of 7.3% had PE, and 6.7% presented an intermediate-high probability of pulmonary hypertension. No significant difference was found between PE and non-PE patients. Univariate analysis showed that age > 65, some clinical severity factors, surfactant protein-D, baseline C-reactive protein, and both peak red cell distribution width and Interleukin (IL)-10 were associated with DLCOc < 80%. A score for PCRLA prediction including age > 65, minimum lymphocyte count, and IL-1ß concentration on admission was constructed with excellent overall performance. In conclusion, reduced DLCOc and PCRLA were common in COVID-19 patients after hospital discharge, but PE did not increase the risk. A PCRLA predictive score was developed, which needs further validation.

NOTCH1 Gene as a Novel Cause of Thoracic Aortic Aneurysm in Patients with Tricuspid Aortic Valve: Two Cases Reported.

Thoracic aortic aneurysms (TAA) consist of abnormal dilation or the widening of a portion of the ascending aorta, due to weakness or destructuring of the walls of the vessel and are potentially lethal. The congenital bicuspid aortic valve (BAV) is considered a risk factor for the development of TAA because asymmetric blood flow through the bicuspid aortic valve detrimentally influences the wall of the ascending aorta. NOTCH1 mutations have been associated with non-syndromic TAAs as a consequence of BAV, but little is known regarding its haploinsufficiency and its relationship with connective tissue abnormalities. We report two cases in which there is clear evidence that alterations in the NOTCH1 gene are the cause of TAA in the absence of BAV. On the one hand, we describe a 117 Kb deletion that includes a large part of the NOTCH1 gene and no other coding genes, suggesting that haploinsufficiency can be considered a pathogenic mechanism for this gene associated with TAA. In addition, we describe two brothers who carry two variants, one in the NOTCH1 gene and another in the MIB1 gene, corroborating the involvement of different genes of the Notch pathway in aortic pathology.

Anti-GD2 synergizes with CD47 blockade to mediate tumor eradication.

The disialoganglioside GD2 is overexpressed on several solid tumors, and monoclonal antibodies targeting GD2 have substantially improved outcomes for children with high-risk neuroblastoma. However, approximately 40% of patients with neuroblastoma still relapse, and anti-GD2 has not mediated significant clinical activity in any other GD2+ malignancy. Macrophages are important mediators of anti-tumor immunity, but tumors resist macrophage phagocytosis through expression of the checkpoint molecule CD47, a so-called 'Don't eat me' signal. In this study, we establish potent synergy for the combination of anti-GD2 and anti-CD47 in syngeneic and xenograft mouse models of neuroblastoma, where the combination eradicates tumors, as well as osteosarcoma and small-cell lung cancer, where the combination significantly reduces tumor burden and extends survival. This synergy is driven by two GD2-specific factors that reorient the balance of macrophage activity. Ligation of GD2 on tumor cells (a) causes upregulation of surface calreticulin, a pro-phagocytic 'Eat me' signal that primes cells for removal and (b) interrupts the interaction of GD2 with its newly identified ligand, the inhibitory immunoreceptor Siglec-7. This work credentials the combination of anti-GD2 and anti-CD47 for clinical translation and suggests that CD47 blockade will be most efficacious in combination with monoclonal antibodies that alter additional pro- and anti-phagocytic signals within the tumor microenvironment.

Familial Dilated Cardiomyopathy and Sudden Cardiac Arrest: New Association with a SCN5A Mutation.

Dilated cardiomyopathy (DCM) has significant morbidity and mortality. Familial transmission is reported in 20-35% of cases, highlighting the role of genetics in this disorder. We present an interesting family in which the index case is a 64-year-old woman who survived a sudden cardiac arrest. She presented left ventricular dilatation and dysfunction, which indicated the presence of DCM, as well as a history of DCM and sudden arrest in her family (mother and sister). Genetic testing identified a heterozygous mutation c.74A > G missense change that causes an amino acid, p.Glu25Gly, change in the N-terminal domain of the SCN5A protein. After performing an exhaustive family medical history, we found that this previously not described mutation segregated within the family. All relatives with the DCM phenotype were carriers, whereas none of the noncarriers showed signs of heart disease, so this mutation is the most likely cause of the disease. This is the first time that a variant in the N-terminal domain of SCN5A has been associated with DCM.

Evorpacept alone and in combination with pembrolizumab or trastuzumab in patients with advanced solid tumours (ASPEN-01): a first-in-human, open-label, multicentre, phase 1 dose-escalation and dose-expansion study.

BACKGROUND: Both innate and adaptive immune responses are important components of anticancer immunity. The CD47-SIRPα interaction could represent an important pathway used by tumour cells to evade immune surveillance. We aimed to evaluate the safety, pharmacokinetics, pharmacodynamics, and anticancer activity of evorpacept (also known as ALX148), a high-affinity CD47-blocking protein with an inactive IgG Fc region in patients with solid tumours. METHODS: We did a first-in-human, open-label, multicentre, phase 1 dose-escalation and dose-expansion study at nine hospitals and one clinic in the USA and Korea. Eligible patients for the dose-escalation and safety lead-in phases were aged 18 years or older with histological or cytological diagnosis of advanced or metastatic solid tumours with no available standard therapy, measurable or unmeasurable disease according to the Response Evaluation Criteria in Solid Tumors version 1.1, and an Eastern Cooperative Oncology Group performance status score of 0 or 1. In the dose-escalation phase, which used a 3 + 3 design, patients received intravenous evorpacept at either 0·3, 1, 3, or 10 mg/kg once per week in 21-day cycles, or 30 mg/kg once every other week in 28-day cycles. In the safety lead-in phase, patients were given the maximum tolerable dose of evorpacept from the dose-escalation phase plus either intravenous pembrolizumab (200 mg administered once every 3 weeks) or intravenous trastuzumab (8 mg/kg loading dose followed by 6 mg/kg once every 3 weeks). In the dose-expansion phase, additional patients aged 18 years or older with second-line or later-line advanced malignancies were enrolled into three parallel cohorts: those with head and neck squamous cell carcinoma (HNSCC) and those with non-small-cell lung cancer (NSCLC) were given the maximum tolerated dose of evorpacept plus intravenous pembrolizumab (200 mg administered once every 3 weeks), and patients with HER2-positive gastric or gastroesophageal junction cancer were given the maximum tolerated dose of evorpacept plus intravenous trastuzumab (8 mg/kg loading dose followed by 6 mg/kg once every 3 weeks) until disease progression, voluntary withdrawal from the study, or unacceptable toxicity. The primary endpoint was the maximum tolerated dose of evorpacept administered as a single agent and in combination with pembrolizumab or trastuzumab, measured by the occurrence of dose-limiting toxicities during the first cycle, and was assessed in all patients who had received at least one dose of evorpacept. Secondary outcomes included the safety, tolerability, and antitumour activity of evorpacept, alone or in combination with pembrolizumab or trastuzumab. The primary outcome, safety, and tolerability were assessed in all patients who had received at least one dose of evorpacept, and antitumour activity was assessed in those who recieved at least one dose of study treatment and underwent at least one post-baseline tumor assessment. This trial is registered with ClinicalTrials.gov, NCT03013218. FINDINGS: Between March 6, 2017, and Feb 21, 2019, 110 patients received single-agent evorpacept (n=28), evorpacept plus pembrolizumab (n=52), or evorpacept plus trastuzumab (n=30), and were included in the safety analysis. Median follow-up was 29·1 months (95% CI not calculable [NC]-NC) in the single-agent cohort, 27·0 months (25·1-28·8) in the evorpacept plus pembrolizumab cohort, and 32·7 months (27·0-32·7) in the evorpacept plus trastuzumab cohort. Two (7%) dose-limiting toxicities in the first cycle were reported in patients who received single-agent evorpacept; neutropenia with an associated infection in one patient with gastroesophageal junction cancer who received 3 mg/kg once per week, and thrombocytopenia with associated bleeding in one patient with pancreatic cancer who received 30 mg/kg once every other week. No maximum tolerated dose was reached; the maximum administered doses were 10 mg/kg once per week or 30 mg/kg once every other week. The 10 mg/kg once per week dose was used in the expansion cohorts in combination with pembrolizumab or trastuzumab. The most common grade 3 or worse treatment-related adverse events were thrombocytopenia with single-agent evorpacept (two [7%] patients) and evorpacept plus pembrolizumab (two [4%]), and thrombocytopenia (two [7%]) and neutropenia (two [7%]) with evorpacept plus trastuzumab. In patients who received single-agent evorpacept, four treatment-related serious adverse events were reported. Five serious treatment-related adverse events related to evorpacept plus pembrolizumab were reported, and one serious adverse event related to evorpacept plus trastuzumab was reported. In response-evaluable patients in the dose-escalation phase (n=15) receiving single-agent evorpacept once per week, four (27%) had a best overall response of stable disease (two received 0·3 mg/kg, one received 3 mg/kg, and one received 10 mg/kg); in the 11 patients who received single-agent evorpacept at the highest dose of 30 mg/kg once every other week, two (18%) had stable disease. In the dose-expansion cohort, overall responses were recorded in four (20·0%; 95% CI 5·7-43·7) of 20 patients with HNSCC who received evorpacept plus pembrolizumab, in one (5·0%; 0·1-24·9) of 20 patients with NSCLC who received evorpacept plus pembrolizumab, and in four (21·1%; 6·1-45·6) of 19 patients with gastric or gastroesophageal junction cancer who received evorpacept plus trastuzumab. INTERPRETATION: The safety findings support the use of evorpacept in combination with pembrolizumab or trastuzumab for patients with advanced solid tumours. Preliminary antitumour activity results support future investigation of evorpacept combined with pembrolizumab or trastuzumab in patients with HNSCC, gastric or gastroesophageal junction cancer, and NSCLC. FUNDING: ALX Oncology.

Predicting mortality for patients with heart failure beyond oxygen consumption: a prognostic risk score.

Cardiopulmonary exercise test (CPET) is a crucial tool for the functional evaluation of cardiac patients. We hypothesized that maximal oxygen consumption (V̇o2max) and ventilatory efficiency-minute ventilation to carbon dioxide production (V̇e/V̇co2) slope are not the only parameters of CPET able to predict major cardiac events (mortality or cardiac transplantation urgently or elective). We aimed to identify the best CPET predictors of major cardiac events in patients with severe chronic heart failure and to propose an integrated score that could be applied for their prognostic evaluation. We evaluated 140 patients with chronic heart failure who underwent CPET between 2011 and 2019. Major cardiac events were evaluated during follow-up. Univariate and multivariate logistic regression analyses were applied to study the predictive value of different clinical, echocardiographic, and CPET parameters in relation to the major cardiac events. A score was generated, and c-statistic was used for the comparisons. Thirty-nine patients (27.9%) died or underwent cardiac transplantation over a median follow-up of 48 mo. Five parameters (maximal workload, breathing reserve, left ventricular ejection fraction, diastolic dysfunction, and nonidiopathic cardiomyopathy) were used to generate a risk score that had better risk discrimination than the New York Heart Association dyspnea scale, V̇o2max, V̇e/V̇co2 slope > 35 alone, and combined V̇o2max and V̇e/V̇co2 slope (P = 0.009, 0.004, <0.001, and 0.005, respectively) in predicting major cardiac events. A composite score of CPET and clinical/echocardiographic data is more reliable than the single use of V̇o2max or combined with V̇e/V̇co2 slope to predict major cardiac events.NEW & NOTEWORTHY This is a cohort study with a follow-up of maximum of 8 years of patients with chronic heart failure that demonstrates a simple integrated score consisting of CPET (breathing reserve, workload at maximal exercise), echocardiographic (LVEF, diastolic dysfunction), and clinical (etiology of cardiac disease) data. The generated score was a better predictor of major cardiac events (mortality or cardiac transplantation) than Weber classification (V̇o2max classification) or NYHA functional class as single factors.

Assessment of the ESC quality indicators in patients with acute myocardial infarction: a systematic review.

AIMS: To help improving quality of care in patients with acute myocardial infarction (AMI), the European Society of Cardiology (ESC) set 20 quality indicators (QIs). There is a need to compile and summarize QI availability, feasibility, and global compliance in real-world registries. METHODS AND RESULTS: A systematic review of PubMed and Web of Science was conducted including all original articles reporting the use of the ESC QIs in AMI patients. Methods and reporting follow the guidelines of the PRISMA Statement and the protocol was registered in PROSPERO (CRD42020190541). Among the 220 screened citations, 9 studies met the inclusion criteria after full-text review. Among these 9 studies, there were 11 different cohorts. Patients were recruited from three different continents (31 countries). The number of QIs assessed ranged from 6 to 20, with 5 studies (56%) reporting data for at least 75% of the 20 QIs. There were room for improvement in terms of data availability (i.e. domain 6 measuring patient's satisfaction), feasibility (i.e. difficulties to find all data for composite QIs in domain 7), and attainment (i.e. high levels of compliance with the percentage of reperfused ST-segment elevation myocardial infarction patients, but low levels for a timely reperfusion). CONCLUSIONS: Our systematic review has shown that it is possible to measure most QIs in existing registries, and that there is room for improvement in terms of data availability, feasibility, and levels of attainment to QIs. Our findings may influence the design of future registries to capture this information and help in QIs definition updates.

Dexamethasone for the treatment of traumatic brain injured patients with brain contusions and pericontusional edema: Study protocol for a prospective, randomized and double blind trial.

BACKGROUND: Traumatic brain injury (TBI) constitutes a leading cause of death and disability. Patients with TBI and cerebral contusions developing pericontusional edema are occasionally given dexamethasone on the belief that this edema is similar to that of tumors, in which the beneficial effect of dexamethasone has been demonstrated. METHODS: The DEXCON TBI trial is a multicenter, pragmatic, randomized, triple-blind, placebo controlled trial to quantify the effects of dexamethasone on the prognosis of TBI patients with brain contusions and pericontusional edema. Adult patients who fulfill the elegibility criteria will be randomized to dexamethasone/placebo in a short and descending course: 4 mg/6 h (2 days); 4 mg/8 hours (2 days); 2 mg/6 hours (2 days); 2 mg/8 hours (2 days); 1 mg/8 hours (2 days); 1 mg/12 hours (2 days). The primary outcome is the Glasgow Scale Outcome Extended (GOSE) performed 1 month and 6 months after TBI. Secondary outcomes are: number of episodes of neurological deterioration; symptoms associated with TBI; adverse events; volume of pericontusional edema before and after 12 days of treatment; results of the neuropsychological tests one month and 6 months after TBI. The main analysis will be on an "intention-to-treat" basis. Logistic regression will estimate the effect of dexamethasone/placebo on GOSE at one month and at 6 months, dichotomized in unfavorable outcome (GOSE 1-6) and favorable outcome (GOSE 7-8). Efficacy will also be analyzed using the 'sliding dichotomy'. An interim and safety analysis will be performed including patients recruited during the first year to calculate the conditional power. A study with 600 patients would have 80% power (2 sided alpha = 5%) to detect a 12% absolute increase (from 50% to 62%) in good recovery. DISCUSSION: This is a confirmative trial to elucidate the therapeutic efficacy of dexamethasone in a very specific group of TBI patients: patients with brain contusions and pericontusional edema. This trial could become an important milestone for TBI patients as nowadays there is no effective treatment in this type of patients. TRIAL REGISTRATION: eudraCT: 2019-004038-41; Clinical Trials.gov: NCT04303065.

Direct control of CAR T cells through small molecule-regulated antibodies.

Antibody-based therapeutics have experienced a rapid growth in recent years and are now utilized in various modalities spanning from conventional antibodies, antibody-drug conjugates, bispecific antibodies to chimeric antigen receptor (CAR) T cells. Many next generation antibody therapeutics achieve enhanced potency but often increase the risk of adverse events. Antibody scaffolds capable of exhibiting inducible affinities could reduce the risk of adverse events by enabling a transient suspension of antibody activity. To demonstrate this, we develop conditionally activated, single-module CARs, in which tumor antigen recognition is directly modulated by an FDA-approved small molecule drug. The resulting CAR T cells demonstrate specific cytotoxicity of tumor cells comparable to that of traditional CARs, but the cytotoxicity is reversibly attenuated by the addition of the small molecule. The exogenous control of conditional CAR T cell activity allows continual modulation of therapeutic activity to improve the safety profile of CAR T cells across all disease indications.

Targeting the myeloid checkpoint receptor SIRPα potentiates innate and adaptive immune responses to promote anti-tumor activity.

BACKGROUND: Signal regulatory protein α (SIRPα) is a myeloid-lineage inhibitory receptor that restricts innate immunity through engagement of its cell surface ligand CD47. Blockade of the CD47-SIRPα interaction synergizes with tumor-specific antibodies and T-cell checkpoint inhibitors by promoting myeloid-mediated antitumor functions leading to the induction of adaptive immunity. Inhibition of the CD47-SIRPα interaction has focused predominantly on targeting CD47, which is expressed ubiquitously and contributes to the accelerated blood clearance of anti-CD47 therapeutics. Targeting SIRPα, which is myeloid-restricted, may provide a differential pharmacokinetic, safety, and efficacy profile; however, SIRPα polymorphisms and lack of pan-allelic and species cross-reactive agents have limited the clinical translation of antibodies against SIRPα. Here, we report the development of humanized AB21 (hAB21), a pan-allelic anti-SIRPα antibody that binds human, cynomolgus monkey, and mouse SIRPα alleles with high affinity and blocks the interaction with CD47. METHODS: Human macrophages derived from donors with various SIRPα v1 and v2 allelic status were used to assess the ability of hAB21 to enhance phagocytosis. HAB21_IgG subclasses were evaluated for targeted depletion of peripheral blood mononuclear cells, phagocytosis and in vivo efficacy in xenograft models. Combination therapy with anti-PD1/anti-PD-L1 in several syngeneic models was performed. Immunophenotyping of tissues from MC38 tumor-bearing mice treated with AB21 and anti-PD-1 was evaluated. PK, PD and tolerability of hAB21 were evaluated in cynomolgus monkeys. RESULTS: SIRPα blockade with hAB21 promoted macrophage-mediated antibody-dependent phagocytosis of tumor cells in vitro and improved responses to rituximab in the Raji human tumor xenograft mouse model. Combined with PD-1/PD-L1 blockade, AB21 improved response rates by facilitating monocyte activation, dendritic cell activation, and T cell effector functions resulting in long term, durable antitumor immunity. In cynomolgus monkeys, hAB21 has a half-life of 5.3 days at 10 mg/kg and complete target occupancy with no hematological toxicity or adverse findings at doses up to 30 mg/kg. CONCLUSIONS: The in vitro and in vivo antitumor activity of hAB21 broadly recapitulates that of CD47 targeted therapies despite differences in ligand expression, binding partners, and function, validating the CD47-SIRPα axis as a fundamental myeloid checkpoint pathway and its blockade as promising therapeutic intervention for treatment of human malignancies.

Body Representations of Internal Pollution: The Risk Perception of the Circulation of Environmental Contaminants in Pregnant and Breastfeeding Women in Spain.

In this article, we analyze how pregnant and breastfeeding women perceive the inside of their bodies as well as their thoughts regarding the accumulation and elimination of chemical compounds present in food, and how these are then transmitted to the fetus. We explore different social perceptions of risk regarding the circulation of chemical compounds inside the body using qualitative research based on the technique of body mapping, comprised of women's drawings of their bodies in combination with comments on the drawings, food diaries and narratives from in-depth interviews. We examine how these 41 women (21 pregnant and 20 breastfeeding) perceive the body's internal mechanisms during the stages of pregnancy and breastfeeding, as well as the circulation of chemical contaminants within it. The body mapping technique allowed us to analyze participants' knowledge of internal pollution, a little-understood process in society. Thanks to these pregnant and breastfeeding women, who made an effort to represent and reflect on these new risks, this study shows that scientists and obstetricians need to collaborate with women in order to better understand and publicize the risks of internal pollution.

Prevalence of pulmonary embolism in patients with COVID-19 pneumonia and high D-dimer values: A prospective study.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) pneumonia is associated to systemic hyper-inflammation and abnormal coagulation profile. D-dimer elevation is particularly frequent, and values higher than 1µg/mL have been associated with disease severity and in-hospital mortality. Previous retrospective studies found a high pulmonary embolism (PE) prevalence, however, it should be highlighted that diagnoses were only completed when PE was clinically suspected. MATERIAL AND METHODS: Single-center prospective cohort study. Between April 6th and April 17th 2020, consecutive confirmed cases of COVID-19 pneumonia with D-dimer >1 µg/mL underwent computed tomography pulmonary angiography (CTPA) to investigate the presence and magnitude of PE. Demographic and laboratory data, comorbidities, CTPA scores, administered treatments, and, clinical outcomes were analysed and compared between patients with and without PE. RESULTS: Thirty consecutive patients (11 women) were included. PE was diagnosed in 15 patients (50%). In patients with PE, emboli were located mainly in segmental arteries (86%) and bilaterally (60%). Patients with PE were significantly older (median age 67.0 (IQR 63.0-73.0) vs. 57.0 (IQR 48.0-69.0) years, p = .048) and did not differ in sex or risk factors for thromboembolic disease from the non-PE group. D-dimer, platelet count, and, C reactive protein values were significantly higher among PE patients. D-dimer values correlated with the radiologic magnitude of PE (p<0.001). CONCLUSIONS: Patients with COVID-19 pneumonia and D-dimer values higher than 1 µg/mL presented a high prevalence of PE, regardless of clinical suspicion. We consider that these findings could contribute to improve the prognosis of patients with COVID-19 pneumonia, by initiating anticoagulant therapy when a PE is found.

Discovery of high affinity, pan-allelic, and pan-mammalian reactive antibodies against the myeloid checkpoint receptor SIRPα.

Targeting the CD47-signal-regulatory protein α (SIRPα) pathway represents a novel therapeutic approach to enhance anti-cancer immunity by promoting both innate and adaptive immune responses. Unlike CD47, which is expressed ubiquitously, SIRPα expression is mainly restricted to myeloid cells and neurons. Therefore, compared to CD47-targeted therapies, targeting SIRPα may result in differential safety and efficacy profiles, potentially enabling lower effective doses and improved pharmacokinetics and pharmacodynamics. The development of effective SIRPα antagonists is restricted by polymorphisms within the CD47-binding domain of SIRPα, necessitating pan-allele reactive anti-SIRPα antibodies for therapeutic intervention in diverse patient populations. We immunized wild-type and human antibody transgenic chickens with a multi-allele and multi-species SIRPα regimen in order to discover pan-allelic and pan-mammalian reactive anti-SIRPα antibodies suitable for clinical translation. A total of 200 antibodies were isolated and screened for SIRPα reactivity from which approximately 70 antibodies with diverse SIRPα binding profiles, sequence families, and epitopes were selected for further characterization. A subset of anti-SIRPα antibodies bound to both human SIRPα v1 and v2 alleles with high affinity ranging from low nanomolar to picomolar, potently antagonized the CD47/SIRPα interaction, and potentiated macrophage-mediated antibody-dependent cellular phagocytosis in vitro. X-ray crystal structures of five anti-SIRPα antigen-binding fragments, each with unique epitopes, in complex with SIRPα (PDB codes 6NMV, 6NMU, 6NMT, 6NMS, and 6NMR) are reported. Furthermore, some of the anti-SIRPα antibodies cross-react with cynomolgus SIRPα and various mouse SIRPα alleles (BALB/c, NOD, BL/6), which can facilitate preclinical to clinical development. These properties provide an attractive rationale to advance the development of these anti-SIRPα antibodies as a novel therapy for advanced malignancies. Abbreviations: ADCC: antibody-dependent cellular cytotoxicity; ADCP: antibody-dependent cellular phagocytosis; CFSE: carboxyfluorescein succinimidyl ester; Fab: fragment antigen binding; Fc: fragment crystallizable; FcγR: Fcγ receptor; Ig: immunoglobulin; IND: investigational new drug; MDM⊘: monocyte-derived macrophage; NOD: non-obese diabetic; scFv: single chain fragment variable; SCID: severe combined immunodeficiency; SIRP: signal-regulatory protein.

ALX148 blocks CD47 and enhances innate and adaptive antitumor immunity with a favorable safety profile.

CD47 is a widely expressed cell surface protein that functions as an immune checkpoint in cancer. When expressed by tumor cells, CD47 can bind SIRPα on myeloid cells, leading to suppression of tumor cell phagocytosis and other innate immune functions. CD47-SIRPα signaling has also been implicated in the suppression of adaptive antitumor responses, but the relevant cellular functions have yet to be elucidated. Therapeutic blockade of the CD47 pathway may stimulate antitumor immunity and improve cancer therapy. To this end, a novel CD47-blocking molecule, ALX148, was generated by fusing a modified SIRPα D1 domain to an inactive human IgG1 Fc. ALX148 binds CD47 from multiple species with high affinity, inhibits wild type SIRPα binding, and enhances phagocytosis of tumor cells by macrophages. ALX148 has no effect on normal human blood cells in vitro or on blood cell parameters in rodent and non-human primate studies. Across several murine tumor xenograft models, ALX148 enhanced the antitumor activity of different targeted antitumor antibodies. Additionally, ALX148 enhanced the antitumor activity of multiple immunotherapeutic antibodies in syngeneic tumor models. These studies revealed that CD47 blockade with ALX148 induces multiple responses that bridge innate and adaptive immunity. ALX148 stimulates antitumor properties of innate immune cells by promoting dendritic cell activation, macrophage phagocytosis, and a shift of tumor-associated macrophages toward an inflammatory phenotype. ALX148 also stimulated the antitumor properties of adaptive immune cells, causing increased T cell effector function, pro-inflammatory cytokine production, and a reduction in the number of suppressive cells within the tumor microenvironment. Taken together, these results show that ALX148 binds and blocks CD47 with high affinity, induces a broad antitumor immune response, and has a favorable safety profile.

Epitope Mapping Using Yeast Display and Next Generation Sequencing.

Monoclonal antibodies are the largest class of therapeutic proteins due in part to their ability to bind an antigen with a high degree of affinity and specificity. A precise determination of their epitope is important for gaining insights into their therapeutic mechanism of action and to help differentiate antibodies that bind the same antigen. Here, we describe a method to precisely and efficiently map the epitopes of multiple antibodies in parallel over the course of just several weeks. This approach is based on a combination of rational library design, yeast surface display, and next generation DNA sequencing and provides quantitative insights into the epitope residues most critical for the antibody-antigen interaction. As an example, we will use this method to map the epitopes of several antibodies that neutralize alpha toxin from Staphylococcus aureus.

The effects of single- and multiple-dose administration of bococizumab (RN316/PF-04950615), a humanized IgG2Δa monoclonal antibody binding proprotein convertase subtilisin/kexin type 9, in hypercholesterolemic subjects treated with and without atorvastatin: Results from four phase I studies.

AIMS: Three single-dose and one multiple-dose phase I studies were conducted in subjects with primary hypercholesterolemia to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of bococizumab, a proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor. METHODS: The dosing schedules for hypercholesterolemic subjects randomized in the four phase I studies were (1) ascending, single, intravenous (IV) bococizumab (0.3, 1, 3, 6, 12, or 18 mg/kg), or placebo (N = 48; baseline low-density lipoprotein cholesterol [LDL-C] ≥130 mg/dL); (2) single, IV bococizumab (0.5 or 4 mg/kg; no placebo) added to ongoing atorvastatin 40 mg/day (N = 24); (3) single, fixed, subcutaneous (SC) bococizumab (100 or 200 mg), or IV bococizumab (200 mg; no placebo; N = 49; baseline LDL-C ≥130 mg/dL); and (4) weekly IV bococizumab (0.25, 0.5, 1, or 1.5 mg/kg) or placebo for 4 weeks (N = 67; baseline LDL-C ≥130 mg/dL). RESULTS: Bococizumab pharmacokinetics were well characterized following single IV or SC doses and following multiple IV doses. Exposure to single-dose bococizumab increased slightly greater than dose-proportionally and clearance decreased with increasing dose. In the single-dose studies, maximal mean percent reductions from baseline in LDL-C ranged from 43% (0.3 mg/kg) to 84% (18 mg/kg) in bococizumab-treated subjects, compared with 2% for placebo. For the multiple-dose study, maximal reductions in LDL-C ranged from 55% (0.25 mg/kg) to 66% (1 mg/kg) in bococizumab-treated subjects, compared with 9% for placebo. In all studies, adverse events were infrequent, transient, and not dose-related. CONCLUSIONS: Bococizumab was generally safe and well tolerated. Bococizumab lowered LDL-C levels substantially in all four studies.

Productive common light chain libraries yield diverse panels of high affinity bispecific antibodies.

The commercial success of bispecific antibodies generally has been hindered by the complexities associated with generating appropriate molecules for both research scale and large scale manufacturing purposes. Bispecific IgG (BsIgG) based on two antibodies that use an identical common light chain can be combined with a minimal set of Fc mutations to drive heavy chain heterodimerization in order to address these challenges. However, the facile generation of common light chain antibodies with properties similar to traditional monoclonal antibodies has not been demonstrated and they have only been used sparingly. Here, we describe the design of a synthetic human antibody library based on common light chains to generate antibodies with biochemical and biophysical properties that are indistinguishable to traditional therapeutic monoclonal antibodies. We used this library to generate diverse panels of well-behaved, high affinity antibodies toward a variety of epitopes across multiple antigens, including mouse 4-1BB, a therapeutically important T cell costimulatory receptor. Over 200 BsIgG toward 4-1BB were generated using an automated purification method we developed that enables milligram-scale production of BsIgG. This approach allowed us to identify antibodies with a wide range of agonistic activity that are being used to further investigate the therapeutic potential of antibodies targeting one or more epitopes of 4-1BB.

Follicular T Cells from smB- Common Variable Immunodeficiency Patients Are Skewed Toward a Th1 Phenotype.

Germinal center follicular T helper (GCTfh) cells are essential players in the differentiation of B cells. Circulating follicular T helper (cTfh) cells share phenotypic and functional properties with GCTfh cells. Distinct subpopulations of cTfh with different helper capabilities toward B cells can be identified: cTfh1 (CXCR3+CCR6-), cTfh2 (CXCR3-CCR6-), and cTfh17 (CXCR3-CCR6+). Alterations in cTfh function and/or distribution have been associated with autoimmunity, infectious diseases, and more recently, with several monogenic immunodeficiencies. Common variable immunodeficiency (CVID) disease is the commonest symptomatic primary immunodeficiency with a genetic cause identified in only 2-10% of patients. Although a heterogeneous disease, most patients show a characteristic defective B cell differentiation into memory B cells or antibody-secreting cells. We investigated if alterations in CVID cTfh cells frequency or distribution into cTfh1, cTfh2, and cTfh17 subpopulations and regulatory follicular T (Tfr) cells could be related to defects in CVID B cells. We found increased percentages of cTfh exhibiting higher programmed death-1 expression and altered subpopulations distribution in smB- CVID patients. In contrast to smB+ patients and controls, cTfh from smB- CVID patients show increased cTfh1 and decreased cTfh17 subpopulation percentages and increased CXCR3+CCR6+ cTfh, a population analogous to the recently described pathogenic Th17.1. Moreover, Tfr cells are remarkably decreased only in smB- CVID patients. In conclusion, increased cTfh17.1 and cTfh1/cTfh17 ratio in CVID patients could influence B cell fate in smB- CVID patients, with a more compromised B cell compartment, and the decrease in Tfr cells may lead to high risk of autoimmune conditions in CVID patients.

Improved Lysosomal Trafficking Can Modulate the Potency of Antibody Drug Conjugates.

Antibody drug conjugates (ADCs) provide an efficacious and relatively safe means by which chemotherapeutic agents can be specifically targeted to cancer cells. In addition to the selection of antibody targets, ADCs offer a modular design that allows selection of ADC characteristics through the choice of linker chemistries, toxins, and conjugation sites. Many studies have indicated that release of toxins bound to antibodies via noncleavable linker chemistries relies on the internalization and intracellular trafficking of the ADC. While this can make noncleavable ADCs more stable in the serum, it can also result in lower efficacy when their respective targets are not internalized efficiently or are recycled back to the cell surface following internalization. Here, we show that a lysosomally targeted ADC against the protein APLP2 mediates cell killing, both in vitro and in vivo, more effectively than an ADC against Trop2, a protein with less efficient lysosomal targeting. We also engineered a bispecific ADC with one arm targeting HER2 for the purpose of directing the ADC to tumors, and the other arm targeting APLP2, whose purpose is to direct the ADC to lysosomes for toxin release. This proof-of-concept bispecific ADC demonstrates that this technology can be used to shift the intracellular trafficking of a constitutively recycled target by directing one arm of the antibody against a lysosomally delivered protein. Our data also show limitations of this approach and potential future directions for development.