Class of 2012 Abstract / Specific Aims: To compare and evaluate the therapies prescribed, the incidence of adverse drug events, and the time to clinical cure in transplant patients with a cytomegalovirus (CMV) infection at an academic medical center before and during the foscarnet nationwide shortage. Methods: This study was a retrospective chart review to compare CMV treatment prescribed and clinical outcomes in pediatric and adult transplant patients at an academic medical center. Transplant patients were evaluated over a 16 month time period between December 2009 and March 2011. The average dose (mg/kg) and prevalence ganciclovir, foscarnet, and cidofovir prescribed in transplant patients with CMV infection were evaluated. Additionally, the incidence of adverse drug events including acute renal dysfunction and myelosuppression were characterized. Main Results: There were 30 subjects diagnosed with CMV disease during the evalutaion period. Of all of the patients treated for CMV before the shortage, 79% received ganciclovir, 43% received foscarnet, and 21% received cidofovir. Following the shortage in September 2010, the usage of the antiviral agents changed to 100%, 25%, and 13% respectively. Overall the usage of ganciclovir increased while the usage of foscarnet decreased when there was a shortage of medication. Conclusions: The antiviral prescribing patterns changed significantly during the foscarnet shortage. The average dose and incidence of ganciclovir increased which likely contributed to serious adverse events. Due to the limited amount of patients treated for CMV and the short time frame, clinical cure could not be determined at this time. Drug shortages are a serious problem and significantly influence patient outcomes.

Class of 2012 Abstract / Specific Aims: To compare and evaluate the therapies prescribed, the incidence of adverse drug events, and the time to clinical cure in transplant patients with a cytomegalovirus (CMV) infection at an academic medical center before and during the foscarnet nationwide shortage. Methods: This study was a retrospective chart review to compare CMV treatment prescribed and clinical outcomes in pediatric and adult transplant patients at an academic medical center. Transplant patients were evaluated over a 16 month time period between December 2009 and March 2011. The average dose (mg/kg) and prevalence ganciclovir, foscarnet, and cidofovir prescribed in transplant patients with CMV infection were evaluated. Additionally, the incidence of adverse drug events including acute renal dysfunction and myelosuppression were characterized. Main Results: There were 30 subjects diagnosed with CMV disease during the evalutaion period. Of all of the patients treated for CMV before the shortage, 79% received ganciclovir, 43% received foscarnet, and 21% received cidofovir. Following the shortage in September 2010, the usage of the antiviral agents changed to 100%, 25%, and 13% respectively. Overall the usage of ganciclovir increased while the usage of foscarnet decreased when there was a shortage of medication. Conclusions: The antiviral prescribing patterns changed significantly during the foscarnet shortage. The average dose and incidence of ganciclovir increased which likely contributed to serious adverse events. Due to the limited amount of patients treated for CMV and the short time frame, clinical cure could not be determined at this time. Drug shortages are a serious problem and significantly influence patient outcomes.

The quality of immune responses develops from birth into adulthood and in the context of the host microbial environment. The aim of this work was to study immune maturation during childhood, and how this process can be affected by the common herpesviruses; Epstein-Barr virus (EBV) and cytomegalovirus (CMV). In paper I we studied monocytes, an important cell type for immunity in the newborn. We showed that the neonatal monocyte subsets exist in similar frequencies as adult subsets, and have a potent capacity for pro-inflammatory cytokine production. In paper II, III and IV we studied the effects of EBV and CMV infections on immune cell function in children. In paper II we found that monocyte-induced NK-cell production of IFN-γ, and plasma IFN-γ levels, were decreased in 2-year old EBV- and/or CMV-seropositive children and mostly so in co-infected children. In paper III we found that in 5-year old children, EBV and CMV co-infection was associated with the highest levels of differentiated NKG2C+ NK cells. CMV+ children had higher plasma IFN-γ and IL-15 levels and higher NK-cell cytotoxic capacity. In vitro PBMC systems showed elevated frequencies of NKG2C+ NK cells in the presence of EBV-infected cells. In paper IV we showed that a child’s age and subsequent capacity for anti-viral cytokine production affects in vitro EBV infection in terms of B-cell proliferation and B-cell acquisition of memory phenotype. PBMC from CMV+ children had lower EBV-induced accumulation of switched memory B cells, which was connected to high prevalence of CD57+CD8+ T cells and IFN-γ production. Taken together, this thesis work shows that monocyte subsets at birth can give potent functional responses and that latency with EBV and CMV has a significant effect on the differentiation process and functional capacity of anti-viral effector cells during childhood. This in turn could affect responses to related or unrelated infections or even to non-invasive antigens such as allergens. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>

Natural Killer (NK) cells, members of the innate lymphoid cells (ILCs), are known to play an important role in the defense against foreign cells and abnormal host cells that have arisen due to viral infection or cancer inducing mutations. The typical immune response of NK cells involves the release of cytotoxic granules containing perforin and granzyme, and the secretion of immune-regulatory cytokines such as interferon gamma (IFN-γ). Unlike the adaptive lymphocytes such as T cells and B cells, NK cells do not require prior sensitization, enabling them to initiate an immune response much faster. This unique feature of NK cells is made possible by the utilization of an array of germline encoded receptors; but on the other hand, it limits NK cells ability to respond against rapidly evolving pathogens. NK cells overcome this shortcoming with an antibody-assisted process called antibody dependent cellular cytotoxicity (ADCC). A novel subset of human NK cells, which displays potent and broad antiviral responsiveness in concert with virus-specific antibodies, was recently discovered in cytomegalovirus positive (CMV+) individuals. This NK cell subset, called g-NK cell, was characterized by a deficiency in the expression of FcεRIγ, an adaptor protein that associates with CD16 which enables ADCC. Surprisingly, despite this deficiency, g-NK cells displayed an enhanced ADCC as compared to their conventional counterparts. Furthermore, having a long-lasting memory-like NK-cell phenotype suggests a role for g-NK cells in chronic infections. This study investigates the importance of g-NK-cells in clinical settings, first by investigating whether the presence of g-NK cells is associated with the magnitude of liver disease during chronic hepatitis C virus (HCV) infection. Analysis of g-NK cell proportions and function in the peripheral blood mononuclear cells (PBMCs) of healthy controls and chronic HCV subjects showed that chronic HCV subjects had slightly lower proportions of g-NK cells, while having similarly enhanced ADCC responses compared to conventional NK cells. Notably, among CMV+ chronic HCV patients, lower levels of liver enzymes and fibrosis were found in those possessing g-NK cells. g-NK cells were predominant among the CD56neg NK cell population often found in chronic HCV patients, suggesting their involvement in the immune response against HCV. Rituximab is a chimeric anti-CD20 antibody used to treat B cell lymphoma patients; and studies have suggested that its efficacy is associated with the ADCC potency and CD16 affinity. Since g-NK cells are characterized by their superior ADCC compared to their conventional counterpart, I decided to investigate whether the presence of g-NK cells can improve the effectiveness of rituximab against malignant B cells in the context of lymphoma and leukemia. The analysis of g-NK cells’ ADCC response against rituximab-coated lymphoma cell lines and B cells from a CLL patient indicated a superior ADCC by g-NK cells compared to their conventional NK cell counterparts. Taken together, for the first time, my findings indicate that the presence of g-NK cells in CMV+ individuals is associated with milder liver disease in chronic HCV infection. In addition, an enhanced ADCC response by g-NK cells upon encountering rituximab coated target cells suggests the beneficial roles of g-NK cells, and opens an avenue for novel therapeutic approaches where g-NK cells can be utilized to treat persistent diseases such as chronic viral infection and cancer.

Les infections virales en particulier celles dues aux virus de la famille des Herpesviridae pendant la période d’aplasie et de lymphopénie à la suite d’une greffe de cellules souches hématopoïétiques (GCSH) peuvent occasionner des complications très graves, souvent associées à une morbidité et mortalité élevées. Les recommandations cliniques actuelles préconisent l’utilisation des antiviraux pour la prévention de certaines de ces infections. L’efficacité du famciclovir et de l’acyclovir contre les virus de l’herpès simplex (HSV), le virus varicella-zoster (VZV) et l’herpésvirus humain de type 6 (HHV-6) est bien reconnue, cependant il nous manque des données quant à leur effet contre le virus Epstein-Barr (EBV) et le cytomégalovirus (CMV) dans la population pédiatrique. L’objectif principal de ce projet de maitrise a été de mesurer l’incidence de l’infection aux virus HSV, VZV, EBV, CMV et HHV-6 et de mesurer l’association entre l’utilisation de la prophylaxie antivirale (acyclovir et famciclovir) et l’infection (virémie asymptomatique et maladie) avec le CMV et l’EBV dans une cohorte pédiatrique de GCSH allogéniques. Les données d'une cohorte de sujets ayant subis pour la première fois une GCSH enrôlés dans quatre centres de greffes pédiatriques au Canada entre juillet 2013 et mars 2017 (Étude TREASuRE) ont été utilisées. Le recrutement a été effectué au : CHU Sainte-Justine (Montréal) (n=86), British Columbia Children’s Hospital (Vancouver) (n=31), Winnipeg Children's Hospital and CancerCare Manitoba (n=28) et Alberta Children’s Hospital (n=11). Le suivi des patients avait débuté 1 mois avant la greffe et avait duré 13 mois. L’âge médian des patients au recrutement était de 6,3 ans. Les courbes de Kaplan-Meier ont permis d’estimer l'incidence cumulée des infections CMV et EBV avec intervalle de confiance (IC) à 95% à 100 jours post-greffe en fonction de la prophylaxie antivirale (acyclovir ou famciclovir). Les modèles multivariés de régression de Cox à risques proportionnels ont permis de mesurer l'association entre la prise d’antiviraux (acyclovir ou famciclovir) et le développement de ces infections. L’étude a inclus 156 sujets âgés de 0 à 21 ans. Les incidences cumulées de la virémie des virus de HSV, VZV, EBV, CMV et HHV-6 à 100 jours de suivi ont été respectivement de 2.5% (IC 95% : 0.8–7.6), 0.8% (IC 95% : 0.1–6.1), 34.5% (IC 95% : 27.6–42.6), 19.9% (IC 95% : 14.5-27.1) et 3.4% (IC 95% : 1.2–9.1). Les incidences cumulées pour CMV et EBV n’ont pas montré de différence statistiquement significative entre les groupes ayant reçu la prophylaxie antivirale (acyclovir ou famciclovir) et ceux qui ne l’ont pas reçu. Les analyses de Cox n’ont montré aucun effet significatif des antiviraux sur le CMV avec un HR ajusté de 0.55 (IC 95% : 0.24–1.26) pour l’acyclovir et de 0.82 (IC 95% : 0.30–2.29) pour le famciclovir. Il en était de même pour l’EBV avec un HR ajusté de 1.41 (IC 95% : 0.63–3.14) pour l’acyclovir et de 0.79 (IC 95% : 0.36–1.72) pour le famciclovir. Notre étude n’a montré aucune preuve d’effet de la prophylaxie antivirale avec le famciclovir et l’acyclovir contre l’EBV et le CMV. Très peu de cas de HSV et de VZV ont été diagnostiqués dans cette cohorte ce qui est conforme avec l’idée selon laquelle l’acyclovir et le famciclovir sont efficaces pour ces virus. / Viral infections, especially those involving members of the Herpesviridae during the period of aplasia and lymphopenia following allogeneic hematopoietic stem cell transplantation (HSCT), cause very serious complications, often associated with high morbidity and mortality. Current clinical guidelines recommend prophylactic use of antivirals, which has proven to be effective against certain viruses. The efficacy of famciclovir and acyclovir against herpes simplex viruses (HSV), varicella zoster virus (VZV) and human herpesvirus type 6 (HHV-6) is well-recognized, however, we lack data on their effects against Epstein-Barr virus (EBV) and cytomegalovirus (CMV) in the pediatric population. The main objective of this master's project was to measure the incidence of herpes virus infection, specifically by HSV, VZV, EBV, CMV and HHV-6, and to measure the association between the use of antiviral prophylaxis (acyclovir and famciclovir) and infection (including both asymptomatic viremia and disease) by CMV and EBV in a pediatric cohort of allogeneic HSCT. We used data from the TREASuRE cohort, which includes patients enrolled for a first allogeneic HSCT in four pediatric centers in Canada between July 2013 and March 2017. Recruitment was carried out at: CHU Sainte-Justine (Montreal) (n = 86), British Columbia Children's Hospital (Vancouver) (n = 31), Winnipeg Children's Hospital and CancerCare Manitoba (n = 28) and Alberta Children's Hospital (n = 11). Patient follow-up began 1 month before transplant and lasted 13 months. Median patient age at recruitment was 6.3 years. Kaplan-Meier curves were used to estimate the cumulative incidence of CMV and EBV infections with 95% confidence interval (CI) at 100 days post-transplant according to antiviral prophylaxis (acyclovir or famciclovir). Multivariate proportional hazards Cox regression models were used to measure the association between antiviral use (acyclovir or famciclovir) and the detection of these infections. The study included 156 subjects aged 0 to 21 years. The cumulative incidences of viremia due to HSV, VZV, EBV, CMV and HHV-6 at day 100 of follow-up were respectively 2.5% (CI 95%: 0.8–7.6), 0.8% (CI 95%: 0.1-6.1), 34.5% (CI 95%: 27.6-42.6), 19.9% (CI 95%: 14.5-27.1) and 3.4% (95% CI: 1.2-9.1). The cumulative incidences for CMV and EBV did not show a statistically significant difference between the groups who received antiviral prophylaxis (acyclovir or famciclovir) and those who did not. Cox analyses showed no significant effect of antivirals on CMV with an adjusted HR of 0.55 (95% CI: 0.24–1.26) for acyclovir and 0.82 (95% CI: 0.30–2.29) for famciclovir. The same was true for EBV with an adjusted HR of 1.41 (95% CI: 0.63–3.14) for acyclovir and 0.79 (95% CI: 0.36–1.72) for famciclovir. Our study showed no evidence of an effect with use of famciclovir or acyclovir prophylaxis on EBV and CMV infections. Very few cases of HSV and VZV infections were diagnosed in this cohort, which is consistent with the idea that acyclovir and famciclovir are effective against the latter viruses.