SPiReL is a phase II clinical trial evaluating combination immunotherapy, pembrolizumab and cyclophosphamide, with maveropepimut-S, in survivin-expressing relapsed/refractory (R/R) Diffuse Large B Cell Lymphoma (DLBCL). We describe baseline tumor survivin expression and associations with clinico-pathological variables in 25 participants. The median number of survivin-expressing cells was 99%, and the intensity of survivin expression within tumors was heterogeneous by semi-quantitative immunohistochemistry assessment. Tumors with higher numbers of cells expressing 2+/3+ survivin were associated with characteristics of poor outcome, (Lactate dehydrogenase and cell-of-origin). Greater total baseline tumor area was associated with lower proportions of 1+ cells and greater proportions of 2+/3+ cells. High intensity survivin expression is associated with aggressive clinical features supporting a pathobiological role in R/R DLBCL. Future prognostic models incorporating survivin as a clinical biomarker require assessment of intensity, overall expression and should include potential threshold effects of survivin in DLBCL pathobiology.

BACKGROUND:Previous studies showed HIV-negative immunocompromised patients are susceptible to Pneumocystis pneumonia (PCP). However, the PCP outcome has not been compared among HIV-negative immunocompromised patients. METHODS:In this retrospective cohort study at the University Health Network, we included all HIV-negative immunocompromised patients who fulfilled the European Organization for Research and Treatment of Cancer (EORTC) PCP diagnosis criteria from December 2018 to December 2019. We compared the demographics, comorbidities, course of illness, and PCP outcome (28-day mortality and composite outcome [i.e., death or intensive care unit (ICU) admission]) between solid organ transplant (SOT) and non-SOT patients. RESULTS:Of 160 non-HIV patients with PCP diagnoses, 118 patients fulfilled EORTC criteria (76 males [64.4%], median [range] age: 65.5 [21-87] years). PCP presentation in SOT recipients (n = 14) was more severe than non-SOT patients (n = 104): acute presentation (onset <7 days before admission: 11/14 [78.6%] vs. 51/104 [56%], p = .037), shortness of breath (100% vs. 75/104 [74.3%], p = .037), median [range] O2 saturation (88% [75%, 99%] vs. 92%[70%, 99%], p = .040), and supplemental O2 requirement (12/14 [85.7%] vs. 59/104 [56.7%], p = .044). The mortality [4/14, (28.6%) vs. 15/104 (14.4%), p = .176], ICU admission (10/14 [71.4%] vs. 18/104 [17.3%], p < .0001), and mechanical ventilation (8/14 [57.1%] vs. 18/104 [17.3%], p = .0007) in SOT patients was different from non-SOT patients. In multivariable analysis, SOT recipients were at greater risk of composite outcome than non-SOT patients (aOR [CI95%]: 12.25 [3.08-48.62], p < .001). CONCLUSION:PCP presentation and outcomes in SOT recipients are more severe than in non-SOT patients. Further studies are required to explore the biological reasons for this difference.

Background: Waldenström's macroglobulinaemia (WM) is an uncommon lymphoproliferative disorder. An optimal first-line therapy for WM has not been defined. We postulated that combining bendamustine and rituximab (BR) with the second generation covalent BTK inhibitor Acalabrutinib would result in deeper responses as measured by complete response (CR) and very good partial response (VGPR) rates, and provide a longer duration of response. Objectives: The primary objective of this trial is to document the CR and VGPR rates. Methods: The BRAWM clinical trial (NCT04624906) combines BR with acalabrutinib in a one-year, fixed duration treatment course of six 28-day cycles BR and 365 days of concurrent acalabrutinib. This ongoing trial is taking place at 9 clinical sites across Canada. The Intent to Treat (ITT) population includes all participants who have started treatment and were evaluable for safety. Participants who reached cycle 7 were evaluable for response. The sample size was calculated to be able to detect a CR + VGPR rate whose lower level of confidence is greater that the historically defined CR + VGPR rates of 23%. Clinical responses were defined using 6th IWWM. Minimal residual disease (MRD) negativity, assessed with clonoSEQ assay, was a secondary endpoint. Mutational analysis of screening biopsy samples from participants with adequate sample for assessment (n=56), showed 50 with MYD88 L265P mutation, 16 with a CXCR4 mutation of which 8 were S338fs, and 1 with a TP53 l195T mutation. Preliminary minimal residual disease (MRD) analysis of peripheral blood (PB) and bone marrow (BM), using next generation sequencing with a sensitivity of 10-6, shows that most evaluable participants (those with MRD samples at two or more time-points) have become MRD negative in PB, with increasing rates of BM MRD negativity over time. From baseline screening levels, there was a median log reduction in the PB of 4.42 (IQR 1.32) by cycle 7, 4.11 (IQR 1.25) by cycle 12, and 4.06 (IQR 0.81) by month 18. Uni- and multi-variate analyses of clinical variables that may be associated with clinical and MRD outcomes are underway. Conclusions: Bendamustine, rituximab and acalabrutinib front-line therapy for WM is safe and well tolerated in a relatively elderly population with a toxicity profile consistent with the utilized drugs and not greater than that seen with BR and Placebo in the randomized ECHO trial in untreated Mantle Cell Lymphoma. Initial clinical results show that this treatment is associated with a very high proportion of CR + VGPRs as well as MRD negativity.

OBJECTIVE:To identify which components of maternal vascular malperfusion (MVM) pathology are associated with adverse pregnancy outcomes and to investigate the morphological phenotypes of MVM placental pathology and their relationship with distinct clinical presentations of pre-eclampsia and/or fetal growth restriction (FGR). DESIGN:Retrospective cohort study. SETTING:Tertiary care hospital in Toronto, Canada. POPULATION:Pregnant individuals with low circulating maternal placental growth factor (PlGF) levels (<100 pg/mL) and placental pathology analysis between March 2017 and December 2019. METHODS:Association between each pathological finding and the outcomes of interest were calculated using the chi-square test. Cluster analysis and logistic regression was used to identify phenotypic clusters, and their association with adverse pregnancy outcomes. Cluster analysis was performed using the K-modes unsupervised clustering algorithm. MAIN OUTCOME MEASURES:Preterm delivery <34+0 weeks of gestation, early onset pre-eclampsia with delivery <34+0 weeks of gestation, birthweight <10th percentile (small for gestational age, SGA) and stillbirth. RESULTS:The diagnostic features of MVM most strongly associated with delivery <34+0 weeks of gestation were: infarction, accelerated villous maturation, distal villous hypoplasia and decidual vasculopathy. Two dominant phenotypic clusters of MVM pathology were identified. The largest cluster (n = 104) was characterised by both reduced placental mass and hypoxic ischaemic injury (infarction and accelerated villous maturation), and was associated with combined pre-eclampsia and SGA. The second dominant cluster (n = 59) was characterised by infarction and accelerated villous maturation alone, and was associated with pre-eclampsia and average birthweight for gestational age. CONCLUSIONS:Patients with placental MVM disease are at high risk of pre-eclampsia and FGR, and distinct pathological findings correlate with different clinical phenotypes, suggestive of distinct subtypes of MVM disease.

Introduction:Patients with relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL) have an unmet medical need. The objective of this trial was to assess the efficacy and toxicities of a novel triple immunotherapy regimen-pembrolizumab, low-dose cyclophosphamide, and maveropepimut-S (MVP-S). This regimen was designed to activate tumor-specific T cells by targeting the tumor-associated antigen survivin with MVP-S and reducing two important T cell inhibitory pathways: T cell exhaustion and regulatory T cells with pembrolizumab and metronomic cyclophosphamide, respectively. Methods:This was a single-arm Phase II clinical trial in 25 participants with R/R DLBCL-SPiReL trial (NCT03349450). Results:The median overall survival was 10.1 months and a third of participants survived over 2 years. Enhanced long-term survival was associated with favorable clinical characteristics and enhanced immune reactivity, as assessed by ELISpot and ISR-immune reactive responses. The regimen was well-tolerated with minimal Grade 3-4 toxicities. Conclusion:Combination immunotherapy regimens such as this could offer a promising alternative to other treatments with significant toxicities for select patients.

Background Metformin is increasingly being used during pregnancy, with potentially adverse long-term effects on children. We aimed to examine adiposity in children of women with type 2 diabetes from the Metformin in Women with Type 2 Diabetes in Pregnancy (MiTy) trial, with and without in-utero exposure to metformin, up to 24 months of age.Methods MiTy Kids is a follow-up study that included infants of women who participated in the MiTy randomised controlled trial, receiving either oral 1000 mg metformin twice daily or placebo. Caregivers and researchers remained masked to the type of medication (metformin or placebo) mothers received during their pregnancy. Anthropometric measurements, including weight, height, and skinfold thicknesses, were taken at 3, 6, 12, 18, and 24 months. At 24 months, linear regression was used to compare the BMI Z score and sum of skinfolds in the metformin versus placebo groups, adjusted for confounders. Fractional polynomials were used to assess growth trajectories. This study is registered with ClinicalTrials.gov, NCT01832181.Findings Of the 465 eligible children, 283 (61%) were included from 19 centres in Canada and Australia. At 24 months, there was no difference between groups in mean BMI Z score (0middot84 [SD 1middot52] with metformin vs 0middot91 [1middot38] with placebo; mean difference 0middot07 [95% CI -0middot31 to 0middot45], p=0middot72) or mean sum of skinfolds (23middot0 mm [5middot2] vs 23middot8 mm [5middot4]; mean difference 0middot8 mm [-0middot7 to 2middot3], p=0middot31). Metformin was not a predictor of BMI Z score at 24 months of age (mean difference -0middot01 [95% CI -0middot42 to 0middot37], p=0middot92). There was no overall difference in BMI trajectory but, in males, trajectories were significantly different by treatment (p=0middot048); BMI in the metformin group was higher between 6 and 24 months. Children of women with type 2 diabetes were approximately 1 SD heavier than the WHO reference population.Interpretation Anthropometrics were similar in children exposed and those not exposed to metformin in utero; hence, overall, data are reassuring with regard to the use of metformin during pregnancy in women with type 2 diabetes and the long-term health of their children.Funding Canadian Institute for Health Research.Copyright (c) 2023 Published by Elsevier Ltd. All rights reserved.

OBJECTIVE:Animal literature has suggested that the impact of antenatal corticosteroids (ACS) may vary by infant sex. Our objective was to assess the impact of infant sex on the use of multiple courses versus a single course of ACS and perinatal outcomes. STUDY DESIGN:We conducted a secondary analysis of the Multiple Courses of Antenatal Corticosteroids for Preterm Birth trial, which randomly allocated pregnant people to multiple courses versus a single course of ACS. Our primary outcome was a composite of perinatal mortality or clinically significant neonatal morbidity (including neonatal death, stillbirth, severe respiratory distress syndrome, intraventricular hemorrhage [grade III or IV], cystic periventricular leukomalacia, and necrotizing enterocolitis [stage II or III]). Secondary outcomes included individual components of the primary outcome as well as anthropometric measures. Baseline characteristics were compared between participants who received multiple courses versus a single course of ACS. An interaction between exposure to ACS and infant sex was assessed for significance and multivariable regression analyses were conducted with adjustment for predefined covariates, when feasible. RESULTS:Data on 2,300 infants were analyzed. The interaction term between treatment status (multiple courses vs. a single course of ACS) and infant sex was not significant for the primary outcome (p = 0.86), nor for any of the secondary outcomes (p > 0.05). CONCLUSION:Infant sex did not modify the association between exposure to ACS and perinatal outcomes including perinatal mortality or neonatal morbidity or anthropometric outcomes. However, animal literature indicates that sex-specific differences after exposure to ACS may emerge over time and thus investigating long-term sex-specific outcomes warrants further attention. KEY POINTS:· We explored the impact of infant sex on perinatal outcomes after multiple versus a single course of ACS.. · Infant sex was not a significant effect modifier of ACS exposure and perinatal outcomes.. · Animal literature indicates that sex-specific differences after ACS exposure may emerge over time.. · Further investigation of long-term sex-specific outcomes is warranted..

Patients with relapsed/refractory diffuse large B‐cell lymphoma (R/R DLBCL) have limited treatment options.

Neutralization of Omicron subvariants by different bivalent vaccines has not been well evaluated. This study characterizes neutralization against Omicron subvariants in 98 individuals on dialysis or with a kidney transplant receiving the BNT162b2 (BA.4/BA.5) or mRNA-1273 (BA.1) bivalent COVID-19 vaccine. Neutralization against Omicron BA.1, BA.5, BQ.1.1, and XBB.1.5 increased by 8-fold one month following bivalent vaccination. In comparison to wild-type (D614G), neutralizing antibodies against Omicron-specific variants were 7.3-fold lower against BA.1, 8.3-fold lower against BA.5, 45.8-fold lower against BQ.1.1, and 48.2-fold lower against XBB.1.5. Viral neutralization was not significantly different by bivalent vaccine type for wild-type (D614G) (P = 0.48), BA.1 (P = 0.21), BA.5 (P = 0.07), BQ.1.1 (P = 0.10), nor XBB.1.5 (P = 0.10). Hybrid immunity conferred higher neutralizing antibodies against all Omicron subvariants. This study provides evidence that BNT162b2 (BA.4/BA.5) and mRNA-1273 (BA.1) induce similar neutralization against Omicron subvariants, even when antigenically divergent from the circulating variant.

To assess the role of infant sex as a potential effect modifier on the use of multiple courses versus a single course of antenatal corticosteroids (ACS) and perinatal outcomes through a secondary analysis of a randomized controlled trial.

Introduction: The SPiReL phase II clinical trial evaluated combination immunotherapy with an immunogenic vaccine formulation to the tumor antigen survivin comprised of maveropepimut-S (MVP-S), pembrolizumab and cyclophosphamide in survivin-expressing relapsed or refractory (R/R) diffuse large B cell lymphoma (DLBCL). The efficacy of this survivin-directed T cell educating therapy may be influenced by the survivin antigen burden in the DLBCL. To further explore this potential relationship, we evaluated the heterogeneity of tumor survivin expression in the SPiReL study cohort and its associations with established clinical-pathological DLBLC variables. Methods: Survivin immunohistochemistry (IHC) was performed at NeoGenomics Laboratories (Aliso Viejo, California, USA) on formalin fixed paraffin embedded (FFPE) tumor slides from diagnostic biopsies obtained at trial screening. Inclusion criteria stipulated >10% of tumor cells expressing survivin by IHC. Semi-quantitative survivin expression metrics, as determined by pathologist assessment, included: total percentage of survivin-positive cells; intensity of survivin staining scored as 0 = None, 1+ = Weak, 2+ = Moderate, 3+ = Strong; and H-score, a linear weighted average (% positive cells x staining intensity level). Radiologic tumor burden was measured at up to 4 time points during the trial by computed tomography (CT). Other pathology (e.g. cell of origin) and laboratory biomarkers (e.g. lactate dehydrogenase, LDH) were extracted from clinical results. Results: The mean and median percentage of survivin-positive tumor cells for all enrolled participants (n= 25) was 91% and 99%, respectively. At the per participant level, the range of survivin expression was 50-100% of the cellular content. The heterogeneity of survivin expression intensity among participants is shown in Figure 1. All participants had some proportion of biopsied cells expressing strong (3+) intensity survivin (range: 5-100% of cells, mean: 30% while only 52% of tumors contained non-survivin expressing (0) cells, ranging from 0% to 50% (mean: 9%) Greater proportions of cells that expressed moderate (2+) and/or strong (3+) survivin significantly correlated with clinical and biological markers of aggressive DLBCL. Non-GCB tumours (11/25) showed greater H-scores compared to GCB tumours (212 vs 167, p = 0.0287). Non-GCB tumours contained greater proportions of strong intensity (3+) survivin cells compared to GCB tumours (44% vs 25%, p= 0.045). In addition, participants with LDH above the upper limit of normal at screening (52%, 13/25) had a greater mean proportion of cells expressing moderate and strong intensity survivin (proportion of 2+ and 3+ combined) (72% vs 54%, p = 0.0447) and a lower mean proportion of weak survivin intensity (1+) cells (p = 0.0374) compared to those with normal LDH. A relationship between total tumor area at baseline and survivin intensity levels was explored. Higher proportions of cells expressing weak intensity (1+) survivin were associated with smaller total tumour area at baseline (p=0.0201). In contrast, higher combined proportions of moderate (2+) and high (3+) intensity survivin was associated with larger total tumour area at baseline (p=0.0285). The significant association with the 2+/3+ intensity of survivin with LDH, cell of origin and tumour burden may suggest a mechanistic threshold in DLBCL pathobiology that drives aggressive clinical behavior. Discussion: Here we demonstrate substantial heterogeneity of survivin protein expression in baseline tumour biopsies of R/R DLBCL patients. Given our findings, it may be of clinical and pathobiological significance to assess both the proportion of survivin-expressing cells as well as the intensity of survivin expression. As the known functions of survivin include protection from apoptosis and cell-cycle progression, the associations demonstrated here support the relevance of survivin and in particular high intensity (2+, 3+) survivin as a biomarker linked with aggressive R/R DLBCL features. These results further support the targeting of survivin pathways in interventional trials and development of validated clinical laboratory survivin assays. Further analysis by multiplex immunofluorescence is in progress to further explore how 2+/3+ vs. 0 host immune cells may also influence survivin immunogenicity and clinical response post-MVP-S immunotherapy.

Neutralization of Omicron subvariants by different bivalent vaccines have not been well evaluated. This study characterized neutralization against Omicron subvariants in 98 individuals receiving dialysis or with a kidney transplant receiving the BNT162b2 (BA.4/BA.5) or mRNA-1273 (BA.1) bivalent COVID-19 vaccine. Neutralization against Omicron BA.1, BA.5, BQ.1.1, and XBB.1.5 increased by 8-fold one month following bivalent vaccination. In comparison to wild-type (D614G), neutralizing antibodies against Omicron-specific variants were 7.3-fold lower against BA.1, 8.3-fold lower against BA.5, 45.8-fold lower against BQ.1.1, and 48.2-fold lower against XBB.1.5. Viral neutralization was not significantly different by bivalent vaccine type for wild-type (D614G) (P=0.48), BA.1 (P=0.21), BA.5 (P=0.07), BQ.1.1 (P=0.10), nor XBB.1.5 (P=0.10). Hybrid immunity conferred higher neutralizing antibodies against all Omicron subvariants. Given that both BNT162b2 (BA.4/BA.5) and mRNA-1273 (BA.1) induced similar neutralization against all Omicron subvariants, this suggests that bivalent vaccines confer protection even when they are antigenically divergent from the circulating variant.

Background: Waldenström's macroglobulinaemia (WM) is an uncommon lymphoproliferative disorder. Although many options are available, an optimal first-line therapy for WM has not been defined. We postulated that combining bendamustine and rituximab (BR) with a next generation BTK inhibitor would result in deeper responses as measured by complete response (CR) and very good partial response (VGPR) rates, and provide a longer duration of response. Objectives: The primary objective of this trial is to document the CR and VGPR rates Methods: The BRAWM clinical trial combines BR with acalabrutinib in a one-year, fixed duration treatment course including six cycles of BR and 12 months of acalabrutinib (6 months of monotherapy). This ongoing trial is taking place at 9 clinical sites across Canada and 44 patients have been enrolled as of July 1, 2023, with a recruitment goal of 59. Results: Median age of participants was 68; 34 were male; 3 participants were low risk, 21 intermediate and 20 high risk. 27 participants completed combination therapy, 17 completed monotherapy and 7 were followed-up at 18 months, and 3 at 24 months after first dose. Table 1 shows the observed Clinical Responses using 6 th IWWM; 2 participants improved from a VGPR to a CR between cycles 7 and 12, both of whom have not reached month 18 for assessment. The interim primary endpoint of combined CR and VGPR rate is 13/17 (77%), with no participants having progressed at this interim analysis. 3 participants discontinued treatment early: 1 at cycle 7 (with a VGPR) who experienced an adverse event requiring treatment; 1 at cycle 3 with inter-current illness, and 1 at cycle 2 for personal reasons not related to treatment. The total observed Treatment Related Adverse Events (TRAEs) in combination therapy was 188 amongst 35 participants, and n= 24 in 10 participants during monotherapy. There were 24 Grade 3/4 TRAEs (combination n= 20, monotherapy n= 4). Total observed Serious Adverse Events was 18, and 7 TRSAEs 7; 6 during combination therapy (3 febrile neutropenia and 1 for each fever, allergic reaction and bowel obstruction) and 1 pneumonia during monotherapy. Grade 3/4 TRAEs resulted in 29 dose interruptions in 13 participants, and 2 dose reductions. Mutational analysis of participants with adequate sample for assessment (n=35), showed 33 with MYD88 mutation, 10 with a CXCR4 mutation, and 1 with a TP53 mutation. Minimal residual disease (MRD) analysis of Peripheral Blood (PB) and Bone Marrow, using next generation sequencing, is underway. Initial review shows that most evaluable patients (those with samples at two or more time-points) have become MRD undetectable in PB. Uni- and multi-variate analyses of variables that may be associated with outcomes is underway. Conclusions: Bendamustine, rituximab and acalabrutinib front-line therapy for WM is safe and well tolerated and initial clinical results show that this treatment induces a high percentage of CR + VGPRs. Table 1: Clinical Responses using 6 th IWWM. *The 2 participants observed to have a CR at month 12 have not reached month 18 for progression or survival follow-up.

BACKGROUND:There is a lack of randomized controlled trial data regarding differences in immunogenicity of varying coronavirus disease 2019 (COVID-19) mRNA vaccine regimens in CKD populations. METHODS:We conducted a randomized controlled trial at three kidney centers in Toronto, Ontario, Canada, evaluating the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody response after third dose vaccination. Participants ( n =273) with CKD not on dialysis or receiving dialysis were randomized 1:1 to third dose 30- µ g BNT162b2 (Pfizer-BioNTech) or 100- µ g mRNA-1273 (Moderna). The primary outcome of this study was SARS-CoV-2 IgG-binding antibodies to the receptor-binding domain (anti-RBD). Spike protein (antispike), nucleocapsid protein, and vaccine reactogenicity were also evaluated. Serology was measured before third dose and 1, 3, and 6 months after third dose. A subset of participants ( n =100) were randomly selected to assess viral pseudovirus neutralization against wild-type D614G, B.1.617.2 (Delta), and B.1.1.529 (Omicron BA.1). RESULTS:Among 273 participants randomized, 94% were receiving maintenance dialysis and 59% received BNT162b2 for initial two dose COVID-19 vaccination. Third dose of mRNA-1273 was associated with higher mean anti-RBD levels (1871 binding antibody units [BAU]/ml; 95% confidence interval [CI], 829 to 2988) over a 6-month period in comparison with third dose BNT162b2 (1332 BAU/ml; 95% CI, 367 to 2402) with a difference of 539 BAU/ml (95% CI, 139 to 910; P = 0.009). Neither antispike levels nor neutralizing antibodies to wild-type, Delta, and Omicron BA.1 pseudoviruses were statistically different. COVID-19 infection occurred in 10% of participants: 15 (11%) receiving mRNA-1273 and 11 (8%) receiving BNT162b2. Third dose BNT162b2 was not associated with a significant different risk for COVID-19 in comparison with mRNA-1273 (hazard ratio, 0.78; 95% CI, 0.27 to 2.2; P = 0.63). CONCLUSIONS:In patients with CKD, third dose COVID-19 mRNA vaccination with mRNA-1273 elicited higher SARS-CoV-2 anti-RBD levels in comparison with BNT162b2 over a 6-month period. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER:COVID-19 Vaccine Boosters in Patients With CKD (BOOST KIDNEY), NCT05022329 .

Background: In the MiTy trial [pregnant T2D randomized to metformin vs. placebo], infants exposed to metformin in-utero had a lower risk of large-for-gestational-age (LGA) but were at higher risk of small-for-gestational-age (SGA) . To date, there are limited data on the effect of in-utero exposure to metformin on infant/child growth in T2D, according to the intrauterine growth status. The MiTy Kids study followed the offspring of MiTy participants to 24 months of age to examine the effect of metformin exposure in-utero on child growth. Aim: Examine the weight and body mass index (BMI) trajectories of children of women with T2D, according to the intrauterine growth status [appropriate for gestational age (AGA) , LGA, and SGA] and metformin exposure. Methods: The study population included offspring of MiTy trial participants. Height and weight measurements were collected at 3, 6, 12, 18 and 24 months of age. Analysis of data was conducted using a fractional polynomial linear mixed effects approach to compare growth trajectories. Results: Of the 283 children who participated in MiTy Kids (46.3% female) , 194 children were AGA at birth (90 metformin and 1placebo) , 65 were LGA (29 metformin and 36 placebo) , and 24 were SGA (16 metformin and 8 placebo) . In children born AGA, both sexes in the metformin arm had a lower weight gain trajectory than those in the placebo group (p=0.008) . Treatment and sex did not have an effect on the growth trajectories of children born LGA. In SGA children, in both sexes, SGA children in the metformin group had a lower weight gain trajectory (p=<0.001) and BMI trajectory (p=0.042) than children in the placebo group, and achieved a lower weight than the WHO growth standard at 24 months. Conclusion: Metformin exposure in-utero was associated with lower weight gain trajectories and BMI trajectories in children of both sexes born SGA and lower weight gain trajectory in AGA children. Further follow-up will determine subsequent growth in these children. Disclosure J. Sanchez: None. J. Hamilton: Advisory Panel; Novo Nordisk Canada Inc. Research Support; Mead Johnson & Company, LLC. G. Tomlinson: None. E. Asztalos: None. K. Murphy: None. B. Zinman: Advisory Panel; Abbott Diabetes, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Merck & Co., Inc., Novo Nordisk Canada Inc., Sanofi K.K. D. Simmons: Research Support; Abbott, Hitachi, Ltd., Novo Nordisk. Speaker's Bureau; Sanofi. Other Relationship; Elsevier. A. Haqq: None. I.G. Fantus: None. A. Armson: None. J.F.R. Barrett: None. L.E. Donovan: Other Relationship; Dexcom, Inc., Inner Analytics, Medtronic, Tandem Diabetes Care, Inc. P. Karanicolas: Research Support; Baxter. Y. Jiang: None. S. Tobin: None. K. Mangoff: None. G. Klein: None. D. Feig: Advisory Panel; Novo Nordisk. Research Support; Apotex. Funding Canadian Institutes of Health Research

Background: Differences in immunogenicity between mRNA SARS-CoV-2 vaccines have not been well characterized in patients undergoing dialysis. We compared the serologic response in patients undergoing maintenance hemodialysis after vaccination against SARS-CoV-2 with BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna). Methods: We conducted a prospective observational cohort study at 2 academic centres in Toronto, Canada, from Feb. 2, 2021, to July 20, 2021, which included 129 and 95 patients who received the BNT162b2 and mRNA-1273 SARS-CoV-2 vaccines, respectively. We measured SARS-CoV-2 immunoglobulin G antibodies to the spike protein (anti-spike), receptor binding domain (anti-RBD) and nucleocapsid protein (anti-NP) at 6-7 and 12 weeks after the second dose of vaccine and compared those levels with the median convalescent serum antibody levels from 211 controls who were previously infected with SARS-CoV-2. Results: At 6-7 weeks after 2-dose vaccination, we found that 51 of 70 patients (73%) who received BNT162b2 and 83 of 87 (95%) who received mRNA-1273 attained convalescent levels of anti-spike antibody (p < 0.001). In those who received BNT162b2, 35 of 70 (50%) reached the convalescent level for anti-RBD compared with 69 of 87 (79%) who received mRNA-1273 (p < 0.001). At 12 weeks after the second dose, anti-spike and anti-RBD levels were significantly lower in patients who received BNT162b2 than in those who received mRNA-1273. For anti-spike, 70 of 122 patients (57.4%) who received BNT162b2 maintained the convalescent level versus 68 of 71 (96%) of those who received mRNA-1273 (p < 0.001). For anti-RBD, 47 of 122 patients (38.5%) who received BNT162b2 maintained the anti-RBD convalescent level versus 45 of 71 (63%) of those who received mRNA-1273 (p = 0.002). Interpretation: In patients undergoing hemodialysis, mRNA-1273 elicited a stronger humoral response than BNT162b2. Given the rapid decline in immunogenicity at 12 weeks in patients who received BNT162b2, a third dose is recommended in patients undergoing dialysis as a primary series, similar to recommendations for other vulnerable populations.

Contexte: Les différences d’immunogénicité entre les vaccins anti-SRAS-CoV-2 à ARNm n’ont pas été bien caractérisées chez les patients hémodialysés. Nous avons comparé la réponse sérologique chez les patients sous hémodialyse après la vaccination contre le SRAS-CoV-2 au moyen des vaccins BNT162b2 (Pfizer-BioNTech) et mRNA-1273 (Moderna). Méthodes: Nous avons procédé à une étude de cohorte observationnelle et prospective dans 2 centres universitaires de Toronto, au Canada, du 2 février au 20 juillet 2021, et avons inclus 129 et 95 patients qui ont reçu respectivement les vaccins anti-SRAS-CoV-2 BNT162b2 et mRNA-1273. Nous avons mesuré les taux d’anticorps IgG dirigés contre la protéine S (anti-S), contre le domaine de liaison au récepteur (ou RBD, pour receptor-binding domain [anti-RBD]) et contre la protéine de la nucléocapside (anti-N) du SRAS-CoV-2 6–7) puis 12 semaines après la deuxième dose de vaccin et nous avons comparé ces taux aux taux médians d’anticorps présents dans le sérum de 211 témoins convalescents qui avaient déjà contracté le SRAS-CoV-2. Résultats: Six à 7 semaines après la deuxième dose de vaccin, nous avons constaté que 51 patients sur 70 (73 %) ayant reçu le BNT162b2 et 83 patients sur 87 (95 %) ayant reçu le mRNA-1273, ont obtenu des taux équivalents à ceux du sérum de convalescents pour ce qui est de l’anticorps anti-S (p < 0,001). Chez ceux qui ont reçu le BNT162b2, 35 sur 70 (50 %) ont atteint le taux du sérum de convalescents pour l’anti-RBD, contre 69 sur 87 (79 %) de ceux qui ont reçu le mRNA-1273 (p < 0,001). Douze semaines après la deuxième dose, les taux d’anti-S et d’anti-RBD étaient significativement moindres chez les patients ayant reçu le BNT162b2 que chez ceux qui avaient reçu le mRNA-1273. Pour l’anti-S, 70 patients sur 122 (57,4 %) ayant reçu le BNT162b2 ont maintenu un taux équivalent à celui du sérum de convalescents, contre 68 sur 71 (96 %) de ceux qui avaient reçu le mRNA-1273 (p < 0,001). Pour l’anti-RBD, 47 patients sur 122 (38,5 %) ayant reçu le BNT162b2 ont maintenu des taux anti-RBD équivalant à celui du sérum de convalescents, contre 45 sur 71 (63 %) de ceux qui avaient reçu le mRNA-1273 (p = 0,002). Interprétation: Chez les patients hémodialysés, le mRNA-1273 a généré une réponse humorale plus forte que le BNT162b2. Étant donné le déclin rapide de l’immunogénicité à 12 semaines chez les patients ayant reçu le BNT162b2, une troisième dose est recommandée chez les patients hémodialysés dans le cadre d’une première série, ce qui concorde avec les recommandations concernant d’autres populations vulnérables.

Background: Human pluripotent stem cell (hPSC)–derived cardiomyocytes (hPSC-CMs) have tremendous promise for application in cardiac regeneration, but their translational potential is limited by an immature phenotype. We hypothesized that large-scale manufacturing of mature hPSC-CMs could be achieved through culture on polydimethylsiloxane (PDMS)-lined roller bottles and that the transplantation of these cells would mediate better structural and functional outcomes than with conventional immature hPSC-CM populations. Methods: We comprehensively phenotyped hPSC-CMs after in vitro maturation for 20 and 40 days on either PDMS or standard tissue culture plastic substrates. All hPSC-CMs were generated from a transgenic hPSC line that stably expressed a voltage-sensitive fluorescent reporter to facilitate in vitro and in vivo electrophysiological studies, and cardiomyocyte populations were also analyzed in vitro by immunocytochemistry, ultrastructure and fluorescent calcium imaging, and bulk and single-cell transcriptomics. We next compared outcomes after the transplantation of these populations into a guinea pig model of myocardial infarction using end points including histology, optical mapping of graft- and host-derived action potentials, echocardiography, and telemetric electrocardiographic monitoring. Results: We demonstrated the economic generation of >1×10 8 mature hPSC-CMs per PDMS-lined roller bottle. Compared with their counterparts generated on tissue culture plastic substrates, PDMS-matured hPSC-CMs exhibited increased cardiac gene expression and more mature structural and functional properties in vitro. More important, intracardiac grafts formed with PDMS-matured myocytes showed greatly enhanced structure and alignment, better host-graft electromechanical integration, less proarrhythmic behavior, and greater beneficial effects on contractile function. Conclusions: We describe practical methods for the scaled generation of mature hPSC-CMs and provide the first evidence that the transplantation of more mature cardiomyocytes yields better outcomes in vivo.

BackgroundAtrioventricular nodal re-entrant tachycardia is the most common type of paroxysmal supraventricular tachycardia. We sought to assess whether important anatomic factors, such as the location of the slow pathway, proximity to the bundle of His, and coronary sinus ostium dimensions, varied with patient age, and whether these factors had an impact on procedural duration, acute success, and complications.MethodsBaseline demographic and procedural data were collected, and the maps were analyzed. Linear regression models were performed to evaluate the associations between age and these anatomic variations. Associations were also assessed, with age categorized as being ≥ 60 years or < 60 years.ResultsThe slow pathway was more commonly located in a superior location relative to the coronary sinus ostium in older patients. The location of the slow pathway moved in a superior direction by 1 mm for every increase in 2 years from the mean estimate of age. Additionally the slow pathway tended to be closer to the coronary sinus ostium in older patients, and the diameter of the ostium was larger in older patients. This resulted in longer procedure time, longer ablation times, and a greater need for long sheaths for stability.ConclusionsThe location of the slow pathway becomes more superior and closer to the coronary sinus ostium with increasing age. Additionally, the coronary sinus diameter increases with age. These factors result in longer ablation and procedural times in older patients.

Introduction: Current strategies for mapping the atrial substrate in patients with a history of atrial fibrillation rely on bipolar peak-to-peak voltage mapping of the atria. This is limited by its reliance on the direction of conduction at the time of recording which may lead to inaccuracies in demarcating low voltage areas and produce false-positive results when assessing for PV isolation at the end of a procedure. We have developed a novel approach, termed omnipolar (OTmax) mapping which provides signals devoid of catheter-orientation dependence but generates the greatest possible voltage. Our hypothesis is that OT mapping may result in a more accurate visualization of the atrial substrate and that this may also help to accurately assess for possible regions of intact conduction across ablation lesions delivered around pulmonary vein antra.Methods: Electroanatomical maps created using the EnSite PrecisionTM cardiac mapping system from data acquired using the AdvisorTM HD Grid Sensor EnabledTM Mapping Catheter were extracted from the system and processed using the Matlab programming environment (R2020b, The MathWorks, Inc) using custom written Matlab functions. OT Vmax, bipolar along ,across, and the maximum peak voltages and surface locations for each mapping point were exported from Velocity and imported into Matlab for analysis and a comparison was made between all of these parameters. Results: OTmax was superior to bipolar mapping in all configurations in the quantification of the mean voltage recorded. OTmax was also found to result in the quantification of signals which would otherwise have been classified as regions of fibrosis. OTmax resulted in higher density physiologically relevant voltage map when compared with all bipolar modalities. OT mapping was superior to bipolar along, across and all bipoles in the detection of electrical points within the ablation zone which revealed regions of conduction not evident on bipolar mapping.Conclusion: OT mapping was superior to bipolar mapping modalities in the visualization of atrial substrate amongst patients undergoing catheter for atrial fibrillation. OT mapping was also shown to be superior to bipolar mapping for the identification of regions of conduction across ablation lesions, which may in part explain recurrences of atrial tachyarrhythmias.